Seismic Design of Non-Conventional Bridges (2019)

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31 This appendix contains design criteria documents for the following bridge projects described in this report: Sixth Street Bridge Replacement Project (California) New Benicia Martinez Bridge (California) Tacoma Narrows Parallel Suspension Bridge (Washington) Gerald Desmond Bridge Replacement Project (California) Hoover Dam Bypass Colorado River Bridge (Nevada/Arizona) I-74 Bridge (Iowa) Port Mann Bridge Highway 1 Project (Vancouver, BC) San Francisco-Oakland Bay Bridge Self-Anchored Suspension Bridge (California) San Francisco-Oakland Bay Bridge Skyway Structures (California) Tappan Zee Hudson River Crossing Project (New York) Willamette River Transit Bridge (Tilikum Crossing Bridge) (Oregon) A P P E N D I X A Design Criteria Documents

32 Seismic Design of Non-Conventional Bridges Design Criteria Reference for Sixth Street Bridge Replacement Project, California Photo credit: HNTB

Design Criteria Documents 33 Sixth Street Viaduct Replacement May 14, 2016 Design Criteria Draft 6 Page i SIXTH STREET BRIDGE REPLACEMENT PROJECT STRUCTURAL DESIGN CRITERIA DRAFT 6 May 14, 2016 Prepared by HNTB Corp

34 Seismic Design of Non-Conventional Bridges Commentary Sixth Street Viaduct Replacement May 14, 2016 Design Criteria Draft 6 Page 14 5. SEISMIC DESIGN Seismic design of the Project shall be performed in accordance with Caltrans Draft Memo to Designers 20-22 - Seismic Design of Bridges with Isolation Bearing and Caltrans Seismic Design Criteria, augmented with pertinent provi- sions of ATC-32, NCHRP 472, AASHTO LRFD Bridge Design Specifications, AASHTO Guide Specifications for Seismic Isolation Design and project spe- cific criteria as detailed in this document. 5.1 General Performance Requirements Seismic design of the Project shall consider both the Safety Evaluation Earth- quake (SEE) and the lower level Functional Evaluation Earthquake (FEE). Seismic performance levels, expressed in terms of damage levels, are defined as follows: “No Damage”: Defined for structural members as the nominal capacity as described in AASHTO LRFD Bridge Design Specifications. Nominal, not expected material properties shall be used and increased member strength due to the effects of confinement steel shall be ignored. “No damage” is defined as full serviceability without repair or replacement. “Minimal damage”: Although minor inelastic response may occur, post- earthquake damage is limited to narrow cracking in concrete, and inconse- quential yielding of secondary steel members. Damage to non-structural components of the cable system would be allowed. “Moderate damage”: Inelastic response may occur, resulting in concrete cracking, reinforcement yield, minor spalling of cover concrete and minor yielding of structural steel. The extent of damage shall be sufficiently lim- ited such that the structure can be restored essentially to its pre-earthquake condition without replacement of reinforcement or replacement of struc- tural members. “Significant damage”: Damage consisting of concrete cracking, rein- forcement yielding, major spalling of concrete and deformations in minor bridge components which may require closure of the bridge to repair. Par- tial or complete replacement of secondary elements may be required in some cases. Secondary elements are those that are not a part of the gravity load resisting system. As a fully isolated structure, the primary seismic design criteria are specified by Caltrans Draft Memo to Designers 20-22 - Seismic Design of Bridges with Isolation Bearing. With the exception of expansion joints that act as an inter- face of the isolated structure and the approach roadway, the performance goal of seismic isolation is to provide a structure that remains elastic during the de- sign earthquake. Therefore, except for abutment expansion joints, the No Damage criteria will be achieved for both the SEE and FEE. RFP page 6 and NCHRP 472 Table 3.10.1-1 RFP page 7 5.1.1 Safety Evaluation – Structural Components The SEE for structural evaluation corresponds to a mean return period of 1,000 years, representing approximately a 10% probability of occurrence in 100 years. Bridge components shall be designed to the following behavior levels under the SEE: RFP page 7 All Bridge Component except Expansion Joints: No damage. Expansion Joints: Significant damage. Expansion joints shall not become unseated from supports and shall continue to support vehicular traffic. 5.1.2 Safety Evaluation – Geotechnical Considerations

Design Criteria Documents 35 Commentary Sixth Street Viaduct Replacement May 14, 2016 Design Criteria Draft 6 Page 15 Soil Liquefaction: The SEE event will be used to assess liquefaction potential and corresponding downdrag forces, if applicable. If liquefiable soils are de- termined to be present under the design earthquake for the site, the structure shall be designed to withstand the forces and moments resulting from the lat- eral and vertical movements caused by the liquefaction. Soil stabilization may be used to mitigate liquefaction conditions. Additionally, the design of the foundations shall be evaluated with the soil in a liquefied state. Slope Stability: For the SEE event, deformations of the supporting ground mass and displacements of the slopes shall be considered in the design of the bridge components. If necessary, the soil shall be stabilized to protect the bridge from damage due to lateral spreading, soil deformation and associated applied forces. 5.1.3 Functional Evaluation The FEE is defined as an earthquake that has a return period of 100 years, rep- resenting approximately a 60% probability of occurrence in 100 years. In this earthquake, the all components of the Viaduct shall meet the requirements of the “No Damage” performance level unless noted otherwise. Expansion joints shall meet the requirements of the “Minimal Damage” performance level. 5.1.4 Performance Assessment The seismic performance of all structures shall be assessed by verifying esti- mated structural demands on components are less than or equal to estimated structural capacities of those components. Methods for determining demands and capacities are defined in following sections. When significant yielding of components is allowed, demand and capacity are defined by strain, rotational or ductility limits. When components are required to remain elastic or experience minor yielding, demand and capacity are de- fined by force Demand/Capacity (D/C) ratios. All capacity-protected components, as defined by Caltrans Seismic Design Cri- teria or these criteria, shall have a force D/C ratio of 1.0 or less when subjected to over-strength forces. When checking seismic conditions, use the corrosion allowance for pile cas- ings at 50 percent of the 100-year design life. 5.1.5 Seismic Loading during Construction For all bridges, the seismic loading during all phases of construction shall be designed to resist forces as described in Caltrans Bridge Memo to Designers 20-2. 5.2 Definition of Ground Motions Ground motions for use in dynamic seismic analysis of the bridge structures shall be taken from the Project Geotechnical Report(s). The ground motions shall consist of seven, 3-component time histories consistent with the SEE and one, 3-component time history consistent with the FEE. Each time history shall consist of 2-horizontal orthogonal components and one vertical compo- nent. For the SEE, the average of the seven time-history ground motion anal- yses results shall be used to design the bridge. The Project Site is located in the seismically active southern California area. The principal faults affecting the seismic hazard of the bridge are the Elysian Park Fault north of the bridge and the Puente Hills Fault southwest of the bridge. Since the location of the bridge places it in close proximity to the two active faults, near-fault directivity effects shall be included in the design. Non-linear time-history analyses shall be used in the evaluation of the bridges, as described in Section 5.3.2. The SEE and FEE acceleration response spectra

36 Seismic Design of Non-Conventional Bridges Commentary Sixth Street Viaduct Replacement May 14, 2016 Design Criteria Draft 6 Page 16 shall be based on the outcrop of the firm ground. Seven sets of reference mo- tion time histories shall be used for the safety evaluation; one set of reference motion time history shall be used for the functional evaluation. These time histories shall be spectrum compatible for their respective firm ground acceler- ation spectra. Due to close proximity to the active faults, the startup motions for generating the reference time histories shall contain velocity flings associ- ated with the near-fault directivity effects. Development of the Acceleration Response Spectrum (ARS) curves shall con- sider wave propagation in local soil conditions and a soil-structure interaction (SSI) mechanism. The equivalent linear one-dimensional site response analysis using site-specific soil properties is conducted to evaluate the free-field mo- tions. Either acceleration or displacement based input ground motions may be used. The effects of spatial variation of ground motions shall be considered when using displacement-based multiple support time histories analysis. The spatial- ly varying motions shall consider as a minimum the following factors: Local site response effect Soil pile interaction effect 5.3 Analyses for Determination of Demands Demands on structural components of a bridge shall be determined by analysis of global three dimensional computer models of the bridge that represent its dominant linear and nonlinear behavior and the effects of soil-foundation- structure interaction. Grillage models may be used at the Viaduct without ex- plicit modeling of the deck diaphragm to reduce the size of models. The trans- verse stiffness of floor beams and edge girders shall be increased sufficiently so that the eigenvalues and corresponding participation mass ratios are stabi- lized and therefore comparable to models with the deck explicitly modeled. It shall be acceptable to use the seismic model for all other strength and services analyses, with appropriate adjustments to member stiffness. Demands shall be evaluated as load-type quantities (forces and moments) or as displacement-type quantities (displacements, relative displacements, and rotations) as required by the evaluation rules for various components. 5.3.1 Service Load Demands and Combination with Seismic Demands For combination with seismic demands, component demands due to dead load, traffic load, temperature changes, and wind shall be determined by static anal- yses of global models. 5.3.2 Seismic Demands Seismic demands shall be determined by nonlinear multi-support dynamic time-history analysis for the Viaduct. The analysis will be for multiple-support excitations developed considering the vertical propagation of the seismic waves in soils and soil pile interaction at the bridge support locations. Con- stant acceleration and displacement may be used along the length of individual piles. Non-linear dynamic time-history analysis shall incorporate the following: • Both dead load and seismic load analyses will be geometrically non-linear to account for the geometric stiffness of the arch hanger elements. • Boundary condition non-linearities will be accounted for in the form of gap elements at expansion joints and foundation impedances. • The structural model shall explicitly consider the geometric nonlinearity, inelastic structural components and other inelastic elements (e.g. dampers).

Design Criteria Documents 37 Commentary Sixth Street Viaduct Replacement May 14, 2016 Design Criteria Draft 6 Page 17 Criteria specified damping is applicable to seismically isolated structures with the following damping provisions applicable to modal time history analysis. Rayleigh damping is to be used for the dynamic time-history analysis. Ray- leigh damping shall be set to zero for all isolation modes. For other modes, the range of dominant periods for the various bridge components used to select Rayleigh damping shall capture at least 90% of the mass of the bridge compo- nents under consideration in two orthogonal horizontal directions with a max- imum Rayleigh damping of 2% selected for the captured mass. The Rayleigh mass proportional coefficient shall be selected for the highest non-isolated mode and the stiffness proportional damping coefficient selected for the lowest mode that captures at least 90% of the mass in the two orthogonal horizontal directions. If direct integration nonlinear time-history analysis is used, Rayleigh damping as specified for modal time-history analysis shall also be used with the follow- ing modifications. The mass proportional coefficient shall be selected for the characteristic period of the primary isolation bearings at a displacement equal to the Total Design Displacement (TDD) as defined by the Isolation Guide Specifications and a maximum Rayleigh damping of 1% shall be selected for the captured mass. Modeling Triple Friction Pendulum Isolators in Pro- gram SAP2000. A.A.S. Sarlis and M.C. Constantinou The global seismic analysis model for the Viaduct shall use explicit foundation modeling. The explicit foundation modeling shall include a representation of each individual pile, with distributed soil supports over the entire length of the pile. Pile mass may be ignored in models for those portions of piles founded below grade and in competent soil. When checking AASHTO LRFD Bridge Design Specifications Extreme Event I, a permanent load factor, p, of 1.0 shall be used for Load Type DC. AASHTO LRFD Bridge De- sign Specifications Table 3.4.1-2 5.3.3 Nonlinear Local Analysis for Evaluating Seismic De- mands Nonlinear local analyses may be performed on selected bridge elements to supplement the global three dimensional nonlinear multi-support dynamic time- history analysis. These analyses shall provide independent assessment of controlling seismic demands based on the assumption of maximum plastic moments and forces developed by potential plastic hinges or other inelastic behavior. These analyses may be used to confirm adequate structural perfor- mance in the event that the SEE demands obtained from the global time-history analysis are exceeded. 5.4 Determination of Capacities and Bridge Element Re- quirements Capacities of structural components of a bridge shall be determined by analysis of local elastic and inelastic computer models of the components. Capacities shall be evaluated as load-type quantities (forces and moments) or as displace- ment-type quantities (displacements, relative displacements, rotations, and cur- vatures) as required by the evaluation rules for various components. 5.4.1 Structural Steel Component Capacities Arch Hangers: Resistance factor for Extreme Events shall be as specified in PTI Recommendations for Stay Cable Design, Testing and Installation, Section 5.3.3. 5.4.2 Reinforced Concrete Component Capacities The expected nominal moment capacity Mne of ductile reinforced concrete members and capacity protected members shall be based on expected material Caltrans Seismic Design Cri- teria Section 3.4

38 Seismic Design of Non-Conventional Bridges Design Criteria Reference for New Benicia Martinez Bridge, California Photo credit: Vince Streano

Design Criteria Documents 39 NEW BENICIA MARTINEZ BRIDGE Contract 59S742 DESIGN CRITERIA ( May 17, 2000) Revision 3 Prepared by T.Y.Lin International/CH2M Hill, A Joint Venture USED WITH PERMISSION OF CALIFORNIA DEPARTMENT OF TRANSPORTATION

40 Seismic Design of Non-Conventional Bridges Caltrans/Division of Structures New Benicia Martinez Bridge- Design Criteria May 17, 2000 Contract 59S742 Prepared by T.Y. Lin International/CH2MHill, A Joint Venture Page 9 6. SEISMIC DESIGN Seismic design will be performed in accordance with BDS, augmented with pertinent provisions of ATC-32 and project specific criteria as detailed in this document. 6.1 Performance Criteria The Benicia-Martinez Bridge is classified in the important bridge category. ATC-32 3.21.2 Functional Evaluation: Service Level Immediate, Minimal Damage Safety Evaluation: Service Level Immediate, Repairable Damage The intended structural action under seismic loading is that of a Limited- Ductility Structure with potential plastic mechanisms in pier shafts (Criteria for piles shall be developed later). ATC-32 3.21.3 6.2 Seismic Loading Five-percent-damped site-specific elastic response spectra will be provided by Caltrans for both the safety evaluation and functional evaluation earthquakes. The depth and characteristics of the soil deposits surrounding the piles shall be taken into consideration. Three sets of time histories will also be provided by Caltrans for the inelastic dynamic analysis. 6.2.1 Seismic Loading During Construction During normally scheduled construction, the sections of the bridge under construction at that time, shall be designed to withstand a lateral seismic force of 0.1g. If the construction schedule is interrupted, the structure shall be stabilized against seismic loads. 6.3 Seismic Analysis 6.3.1 Elastic dynamic analysis ATC-32 3.21.6 6.3.2 Inelastic static analysis ATC-32 3.21.7 6.3.3 Inelastic dynamic analysis ATC-32 3.21.8 6.4 Combination of Effects Seismic effects from elastic dynamic analysis shall be combined in accordance with the BDS 3.21.1.1. No highway live load shall be considered on the bridge during the seismic event. The effect of vertical ground accelerations shall be considered on the superstructure only. These effects shall be based on the site specific vertical response spectrum and shall not exceed 0.5g. 6.5 Design Displacements ATC-32 3.21.10.3 6.6 Design Forces ATC-32 3.21.11.1 The force reduction coefficient Z shall be taken as 3 for well confined concrete pier shafts when the structural period is greater than the predominant ground ATC-32 Fig. R3-13

Design Criteria Documents 41 Caltrans/Division of Structures New Benicia Martinez Bridge- Design Criteria May 17, 2000 Contract 59S742 Prepared by T.Y. Lin International/CH2MHill, A Joint Venture Page 10 motion period. The force reduction factor for piles would be as follows: Steel encased portion: 1.5 Rock Socket: 1.0 The method utilizing the Z factor will be used for preliminary design only. Final reinforcement will be designed such that strain demands from elastic or inelastic time history analyses do not exceed the allowable values of section 6.13. 6.7 Capacity Design ATC-32 3.21.14 6.8 Restraining Features ATC-32 3.21.12 6.9 P- Effects P-delta moments may be ignored where the following relation is satisfied: W Mu p0 25. where: W = Weight of the frame u = maximum displacement of the top of the frame Mp = plastic capacity of the pier 6.10 Strength Reduction Factors for Columns ATC-32 8.16.1.2.2 6.11 Material Properties for Ductile Columns 6.11.1 Design flexural strength ATC-32 8.16.2.4 6.11.2 Maximum plastic moment ATC-32 8.16.4.4 6.11.3 Steel strain hardening strains For A706 steel: sh = .0150 #8 and smaller (25M and smaller) sh = .0100 #10 and #11 (30M and 35M) sh = .0075 #14 (45M) sh = .0050 #18 (55M) Assumed upper bound steel strength, considering the effects of strain hardening: fuo = 1.4 fyo 6.12 Displacement Capacity The displacement capacity shall be assessed from the plastic hinge length calculated according to ATC-32 8.18.2.4.2 and the plastic rotations corresponding to the allowable material strains 6.13 Allowable Strains 6.13.1 Normal Weight Concrete Functional evaluation cFunc 0.004

42 Seismic Design of Non-Conventional Bridges Caltrans/Division of Structures New Benicia Martinez Bridge- Design Criteria May 17, 2000 Contract 59S742 Prepared by T.Y. Lin International/CH2MHill, A Joint Venture Page 11 Safety evaluation cSafety 2/3 cu Where cu is the ultimate concrete strain according to the Mander model (Mander et. al. J. Struct. Engineering, ASCE, 1988 114(8), p 1804-1849) 6.13.2 Sand Light Weight Concrete Functional evaluation cFunc 0.003 Safety evaluation cSafety 2/3 cu Where cu is the ultimate concrete strain according to the Mander model 6.13.3 Reinforcing steel Functional evaluation sFunc = 0.015 Safety evaluation sSafety = 2/3 su Where su is the ultimate steel strain. For Grade 60 (A706) reinforcement su maybe taken as: Main reinforcing steel Bar No. 9 - 18 (30M - 55M) su = 0.09 Confinement reinforcing steel Bar No. 3 - 8 (10M -25M) su = 0.12 ATC-32 C3.21.11.1 7. GEOTECHNICAL AND FOUNDATION DESIGN 7.1 Pile Capacity The bearing and uplift capacity of the piles shall be determined by the geotechnical engineer. A preliminary estimate of the ultimate shear strength of the pile-rock interface is: Compression 0.48 MPa Tension 0.34 MPa 7.2 Scour The scour potential will be evaluated by Caltrans. 8. EXPANSION JOINTS The expansion joint assembly will be selected based on the hinge movement rating, MR. MR is defined as follows: MR=1.5x C + 1.5x S + FEE Where, C= expected creep movement from the time of installation of expansion joint. S = expected shrinkage movement from the time of installation of expansion joint. FEE = sum of opening and closing movement due to a functional level earthquake.

Design Criteria Documents 43 Design Criteria Reference for Tacoma Narrows Parallel Suspension Bridge, Washington Photo credit: Washington State DOT

44 Seismic Design of Non-Conventional Bridges Tacoma Narrows Bridge – Parallel Crossing Design Criteria August 31, 2000 STRUCTURAL DESIGN CRITERIA For TACOMA NARROWS PARALLEL SUSPENSION BRIDGE August 31, 2000 Revision 4 Washington State Department of Transportation United Infrastructure Washington Tacoma Narrows Constructors PTG / HNTB Tacoma Narrows Joint Venture USED WITH PERMISSION OF WASHINGTON STATE DEPARTMENT OF TRANSPORTATION

Design Criteria Documents 45 Tacoma Narrows Bridge – Parallel Crossing Design Criteria August 31, 2000 Page 22 References 5. SEISMIC DESIGN Seismic design of the bridge will be performed in accordance with the WSDOT BDM, augmented with pertinent provisions of project specific criteria as detailed in this document. 5.1 General Performance Requirements Seismic design of the Tacoma Narrows Bridge – Parallel Crossing shall consider both the Safety Evaluation Earthquake (SEE) and the lower level Functional Evaluation Earthquake (FEE). The performance levels expressed in terms of damage levels are de- fined as follows: “No Damage”: Defined for structural members as the nominal capacity as described in AASHTO for LFD or as defined in Section 5.1.3. For components such as bearings, expansion joints, railings, rocker links, “no damage” is defined as full serviceability without repair or replace- ment. “Minimal damage”: Although minor inelastic response may occur, post- earthquake damage is limited to narrow cracking in concrete and incon- sequential yielding of secondary steel members. Permanent offsets should be avoided, except that permanent offsets of the foundations are permissible if the strain limits specified in Section 5.4 of this docu- ment are not exceeded. Permanent offsets of the foundations will be permitted only if they do not prevent immediate use of the bridge sub- sequent to the SEE event. Damage to non-structural components of the cable system would be allowed. “Repairable damage”: Inelastic response may occur, resulting in con- crete cracking, reinforcement yield, minor spalling of cover concrete, and minor yielding of structural steel. The extent of damage should be sufficiently limited that the structure can be restored essentially to its pre-earthquake condition without replacement of reinforcement or re- placement of structural members. Repair should not require closure. Replacement of secondary stiffening truss elements will be allowed if it can be done under traffic. “Significant damage”: Although there is minimum risk of collapse, per- manent offsets may occur in elements other than the foundations. Damage consisting of concrete cracking, reinforcement yielding, major spalling of concrete, and deformations in minor bridge components may require closure to repair. Partial or complete replacement of secondary elements may be required in some cases. Secondary elements are those which are not a part of the gravity load resisting system. ATC-32 C3.21.2.3 5.1.1 Safety Evaluation – Structural Components The Safety Evaluation Earthquake (SEE) for structural evaluation cor- responds to a mean return period of 2,500 years. In this earthquake, the bridge can be subject to primarily “minimal damage” with some “re- pairable damage” and some “significant damage” in secondary compo- nents as described in this section. The basic approach is to design the bridge components to the following behavior levels under the safety evaluation earthquake:

46 Seismic Design of Non-Conventional Bridges Tacoma Narrows Bridge – Parallel Crossing Design Criteria August 31, 2000 Page 23 References Piles/Drilled Shafts: Minimal damage. Pile Caps: Minimal damage Tower Caissons: Minimal damage Anchorage Blocks: No damage. Anchorage Deck & Girders over “Exclusion Zone”: Minimal Dam- age. Towers (above pile caps or caissons): Repairable damage. Stiffening Truss (except Secondary Elements): No damage. Secondary Stiffening Truss Elements: Repairable damage Bearings and Shear Keys: Repairable damage. Expansion Joints: Significant damage. Cable System – Structural Elements: No damage. Cable System – Non Structural Elements: Minimal Damage. Additional limitations for the SEE event expressed in terms of perma- nent lateral displacement or drift resulting from inelastic deformation of structural components or soil deformations at the anchorages are as follows: Longit. Direction Transv. Direction Tower Foundation Drift between mudline elevation and Pile Cap Tower Leg Drift between Founda- tion and top of Tower 12” 12” 24” 24” Tower Displacement at Top 12” 36” Anchorage Displacement 12” 6” 5.1.2 Safety Evaluation – Geotechnical Considerations Commentary C5.1.2 The Safety Evaluation Earthquake (SEE) for evaluation of the following geotechnical issues corresponds to a mean return period of 2,500 years: Slope Stability: For this earthquake, stability of the bridge anchorages shall be assessed using psuedo-static analysis methods. Deformations of the supporting ground mass and displacements of the anchorages shall be considered in the design of the bridge components. If neces- sary, the soil shall be stabilized to protect the bridge from damage due to lateral deformation and applied forces. Soil Liquefaction: This earthquake will be used to assess liquefaction potential and corresponding downdrag forces, if applicable. If liquefiable soils are determined to be present, and it has been determined that they will in fact liquefy under the design earthquake for the site, the soil shall be stabilized to protect the bridge from damage due to lateral de-

Design Criteria Documents 47 Tacoma Narrows Bridge – Parallel Crossing Design Criteria August 31, 2000 Page 24 References formation and downdrag caused by the liquefaction, or the structure shall be designed to withstand the forces and moments resulting from the lateral and vertical movements caused by the liquefaction. Addition- ally, the design of the foundations shall be evaluated with the soil in a liquefied state. 5.1.3 Functional Evaluation The Functional Evaluation Earthquake (FEE) will correspond to an event with a mean return period of 100 years. For this event, the per- formance level will be “No Damage”, with no permanent offsets for all structural elements. For reinforced concrete elements, “No Damage” for the FEE event shall be based on the member strengths determined using the strain limitations given in Sections 5.4.2 and 5.4.3. 5.1.4 Performance Assessment The seismic performance of the bridge shall be assessed by comparing estimated structural demands on components with estimated structural capacities of those components. Demands and capacities are defined in following sections. When checking seismic conditions, use the corrosion allowance for pile casings at 50 percent of the design service life (75 years). 5.2 Definition of Ground Motions Ground motions for use in dynamic seismic analysis of the bridge struc- ture shall be taken from the project Geotechnical Report. The ground motions shall consist of three, 3-component time histories consistent with the Safety Evaluation Earthquake (SEE) and one, 3-component time history consistent with the Functional Evaluation Earthquake (FEE). Each time history shall consist of 2-horizontal orthogonal com- ponents and one vertical component. The ground motions will be based on a Probabilistic Seismic Hazard Analysis (PSHA). Seismogenic sources to be considered in the PSHA will include but are not limited to the Cascadia Subduction Zone (CSZ), shallow crustal sources (including the Seattle Fault), and the subcrustal intraplate zone within the subducted Juan de Fuca plate beneath the region. Uniform hazard spectra shall be developed for the SEE and FEE risk levels based on the results of the PSHA. Deaggregation of the hazard identified in the PSHA at both the SEE and FEE levels will be conducted to evaluate predominant earthquake sources, magni- tudes, and distances at the SEE and FEE levels. The ground motion time histories for the SEE and FEE will be selected based on their re- spective uniform hazard spectra developed from the PSHA such that the average spectral intensity of the horizontal ground motion compo- nents are at least equal to the spectral intensity of the uniform hazard spectra over a period range of engineering significance for the bridge. The ground motion time histories for the SEE and FEE will also be se- lected consistent with the predominant earthquake sources, magni- tudes, and distances identified in the deaggregation. The ground mo- tions shall also consider the site response characteristics at each foun- dation location and spatial incoherency between foundations. 5.3 Analyses for determination of demands Demands on structural components of the bridge shall be determined by analysis of global three dimensional computer models of the bridge

48 Seismic Design of Non-Conventional Bridges Tacoma Narrows Bridge – Parallel Crossing Design Criteria August 31, 2000 Page 25 References that represent its dominant linear and nonlinear behavior and the ef- fects of soil-structure interaction. Demands will be evaluated as load- type quantities (forces and moments) or as displacement-type quanti- ties (displacements, relative displacements, and rotations) as required by the evaluation rules for various components. 5.3.1 Demands For combination with seismic demands, component demands due to dead load, live load, temperature changes, and wind shall be deter- mined by static analyses of global models. 5.3.2 Seismic Demands For final design, seismic demands shall be determined by nonlinear multi-support dynamic time history analysis. The analysis will be for multiple-support excitations developed considering the propogation of the seismic waves from the fault to the bridge site and the passage of seismic waves through the site to account for incoherence of the seis- mic motions. Three sets of ground motions shall be used for the safety evaluation (SEE); one set of ground motions shall be used for the func- tional evaluation (FEE). The design shall be based on the maximum response obtained from these analyses in conjunction with the perfor- mance goals for the SEE and FEE events. Seismic analysis will be performed using ADINA general-purpose finite element software. Both dead load and seismic load analyses will be geometrically non-linear to account for the geometric stiffness of the cable elements. Boundary condition non-linearities will be accounted for in the form of gap elements at expansion joints and foundation im- pedances. The nonlinear structural model will explicitly consider the geometric nonlinearity, inelastic structural components and other inelas- tic elements (e.g. dampers). Any reinforced concrete members with a force Demand/Capacity (D/C) ratio larger than 0.5 will be modeled with adjusted material and section properties to represent the cracked sec- tion. Structural steel members with a force D/C ratio less than 1.5 will be modeled with elastic elements. Any members with a force D/C ratio larger than 1.5 will be modeled with nonlinear elements. Rayleigh damping will be incorporated into the model with values for each element group representing the expected extent of inelastic ener- gy dissipation in that group. Groups of members represented with non- linear properties will exclude Rayleigh damping if energy dissipation characteristics are modeled. Service Load Demands and Combination with Seismic

Design Criteria Documents 49 Tacoma Narrows Bridge – Parallel Crossing Design Criteria August 31, 2000 Page 26 References Soil- Structure Interaction shall be considered using nonlinear springs in the global model. The properties of the springs will be determined from local models, and shall include group effects. See Section 6.3 for fur- ther discussion. For seismic evaluation, reinforced concrete strength shall be calculated as 30% higher than the 56-day concrete strength. 5.3.3 Seismic Demands for Initial Design Nonlinear stand-alone analyses shall be performed on the bridge tower- foundation system to supplement the elastic global three-dimensional multi-support dynamic time history analyses during the Initial Design Phase. These analyses will provide an acceptable assessment of con- trolling seismic demands for tower components for the SEE or FEE events in support of the Initial Design deliverables. Final design of the tower-foundation system will be based on results of global three- dimensional nonlinear multi-support dynamic time history analyses. 5.4 Analyses for determination of capacities Capacities of structural components of the bridge shall be determined by analysis of local elastic and inelastic computer models of the com- ponents. Capacities will be evaluated as load-type quantities (forces and moments) or as displacement-type quantities (displacements, rela- tive displacements, rotations, and curvatures) as required for various components. 5.4.1 Structural Steel Component Capacities Cable System: The load capacity of cables shall be taken as the net cable area, which is based on the gross wire area, times the propor- tional limit stress of the wire. The load capacity of the suspenders shall be taken as half the ultimate strength of the wire rope. For Group VII and VIIA Load Cases, the stiffening truss, deck plate, ribs and floor beams will be designed for a demand to capacity (D/C) ratio of no greater than 1.0. The D/C ratio for the floor truss bracing members and bottom laterals should not exceed 1.5. 5.4.2 Allowable Concrete Strain Values SEE event: The stress-strain relationships developed by Mander for confined concrete will be used. For all reinforced and prestressed con- crete elements, including steel cased piles and drilled shafts, the maxi- mum allowable concrete strains shall be taken as 75 percent of the ul- timate strains determined by Mander’s equations. FEE event: A maximum concrete strain of 0.004 shall be used for all reinforced concrete elements. 5.4.3 Allowable Reinforcement Strain Values Commentary C5.4.2 SEE event: To achieve the performance goals for the SEE event, the strains in tower leg reinforcement shall be limited to pg, and strains in Nonlinear Stand-Alone Analysis for Evaluating Tower

50 Seismic Design of Non-Conventional Bridges Tacoma Narrows Bridge – Parallel Crossing Design Criteria August 31, 2000 Page 27 References REINFORCEMENT u pg pp Main Column Bars #11, #14 & #18 0.08 0.05 0.02 Main Column Bars #10 and Smaller 0.12 0.06 0.02 Spirals & Hoops #8 and Smaller 0.12 0.08 0.06 Tower Leg Spirals & Ties #8 and Smaller 0.12 0.05 NA pile and drilled shaft reinforcement limited to pp as follows: Commentary C5.4.3 Where: u = ultimate steel strain pg = design level of peak cyclical steel strain for tower "per- formance goals" pp = design level of peak steel strain for pile and drilled shaft "per- formance goals" The values of pg and pp given in this table are to be used for evaluat- ing the moment-curvature relationship for all column and pile plastic hinges. FEE event: To achieve the performance goals for the FEE event, the strains in tower leg and pile reinforcement shall be limited to s = 0.015. 5.4.4 Steel Pile Casings and Permanent Steel Shells Steel pile casings and permanent steel shells for drilled shafts (herein- after called “casings”) will supplement the pile strength and ductility provided that the effective casing thickness after full allowance for cor- rosion is at least 1/16 inch. For all BDM Load Groups except Groups VII, VIIA, XIA and XIB, the effective casing shall consider full allowance for corrosion as defined in Section 3.2.2. For Load Groups VII, VIIA, XIA and XIB, the effective casing shall consider one-half the allowance for corrosion as defined in Section 3.2.2. Steel pile casings may be assumed to act compositely with the interior reinforced concrete section provided that an adequate shear transfer mechanism is included at the casing/concrete interface. Shear transfer may be augmented by the addition of welded shear rings or other me- chanical devices at the casing/concrete interface. Shear transfer will be assessed as described in American Petroleum Institute (API) RP- 2A/LRFD, 1st edition, July 1993 and February 1997 supplement - Sec- tion H.4, Grouted Pile to Structure Connection.

Design Criteria Documents 51 Tacoma Narrows Bridge – Parallel Crossing Design Criteria August 31, 2000 Page 28 References At the pile casing tip and casing cut-off elevations, the casing will be assumed to contribute only lateral confinement for a distance of 2 times the pile diameter. With the allowance for corrosion considered, the cas- ing in these regions may be assumed to contribute 100 percent of its net area for confinement. In any case, piles shall have minimum spiral or hoop confinement reinforcing equal to #5 @ 6” spacing. With the allowance for corrosion considered, the casing may be as- sumed to contribute up to 80 percent of its net area to flexural capacity of a section and up to 20 percent of its net area to confinement of the pile interior. In any case, piles shall have minimum spiral or hoop con- finement reinforcing equal to #5 @ 6” spacing. Also, the pile longitudinal reinforcing bars within the casing should contribute to at least 50 per- cent of the pile flexural capacity. Excess pile flexural capacity provided by the steel casing will be ignored. The casing contribution to foundation stiffness will be based on the net casing thickness after allowance for corrosion . A sensitivity study will be performed to assess the structural seismic response with no allow- ance for corrosion in pile casings. The maximum allowable casing strains are as follows: Longitudinal Tension (along pile axis) 0.02 Longitudinal Compression (along pile axis) 0.01 Where steel casing acts compositely with the concrete pile interior: Hoop Tension (on net casing with 0.040 corrosion allowance) Where details are provided such that the steel casing does not act compositely with the concrete pile interior and longitudinal compression strains in the casing are negligible: Hoop Tension (on net casing with 0.060 corrosion allowance)

52 Seismic Design of Non-Conventional Bridges References 5.4.5 Plastic Hinge Length The maximum length of plastic hinges (Lp) in a solid section may be taken as Lp = 0.08*Lc + 9*db ATC-32 Lc = Distance from point of maximum moment to point of con- tra-flexure in a column. db = diameter of reinforcement For initial design, the maximum length of column plastic hinges in a hol- low section may be taken as: Lp = 1.0 * H where H = Section dimension in the direction of seismic loading. For final design, the length of column plastic hinges in a hollow section shall be determined by detailed component modeling of the section, considering the section geometry, aspect ratio, working stresses under dead load and reinforcing ratio. Commentary C5.4.5 5.4.6 Curvature Ductility Check Commentary C5.4.6 For reinforced concrete sections which are anticipated to experience inelastic behavior in a SEE event, the minimum section curvature ductil- ity capacity shall be : c u y 4.0 Where : u section ultimate curvature defined by using u given in Section 5.4.3. y section yield curvature defined by using y Tacoma Narrows Bridge – Parallel Crossing Design Criteria August 31, 2000 Page 29

Design Criteria Documents 53 Design Criteria Reference for Gerald Desmond Bridge Replacement Project, California Photo credit: Port of Long Beach

54 Seismic Design of Non-Conventional Bridges Gerald Desmond Bridge Replacement Exhibit 2-13-A - Design Criteria Page i Exhibit 2-13-A GERALD DESMOND BRIDGE REPLACEMENT PROJECT STRUCTURAL DESIGN CRITERIA USED WITH PERMISSION OF CALTRANS AND PORT OF LONG BEACH, CA

Design Criteria Documents 55 Gerald Desmond Bridge Replacement Exhibit 2-13-A - Design Criteria Page 11 5. SEISMIC DESIGN Seismic design of the Project shall be performed in accordance with Caltrans Seismic Design Criteria and Cal- trans Guide Specifications for Seismic Design of Steel Bridges, augmented with pertinent provisions of ATC- 32, NCHRP 12-49, AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments, AASHTO Guide Specifications for Seismic Isolation Design, PTI Recommendations for Cable Stay Design, Testing, and Installation, and Project specific criteria as detailed in this document. 5.1 General Performance Requirements Seismic design of the Project shall consider both the Safety Evaluation Earthquake (SEE) and the lower level Functional Evaluation Earthquake (FEE). Seismic performance levels, expressed in terms of damage levels, are defined as follows: “No Damage”: Defined for structural members as the nominal capacity as described in AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments. Nominal, not expected material properties shall be used and increased member strength due to the effects of confinement steel shall be ig- nored. “No damage” is defined as full serviceability without repair or replacement. “Minimal damage”: Although minor inelastic response may occur, post-earthquake damage is limited to narrow cracking in concrete, and inconsequential yielding of secondary steel members. Damage to non- structural components of the cable system would be allowed. “Moderate damage”: Inelastic response may occur, resulting in concrete cracking, reinforcement yield, minor spalling of cover concrete and minor yielding of structural steel. The extent of damage shall be suf- ficiently limited such that the structure can be restored essentially to its pre-earthquake condition without replacement of reinforcement or replacement of structural members. “Significant damage”: Damage consisting of concrete cracking, reinforcement yielding, major spalling of concrete and deformations in minor bridge components which may require closure of the bridge to repair. Partial or complete replacement of secondary elements may be required in some cases. Secondary ele- ments are those that are not a part of the gravity load resisting system. Meeting the stress and strain limits specified in these criteria form the basis for satisfying the seismic perfor- mance level goals of the Project. 5.1.1 Safety Evaluation – Structural Components The SEE for structural evaluation corresponds to a mean return period of 1,000 years, representing approx- imately a 10% probability of occurrence in 100 years. In this earthquake, the bridge can be subject to primarily “minimal damage” with some “moderate damage” and some “significant damage” in secondary components as described in this section. The Design-Builder shall design the bridge components to the following behavior levels under the SEE: Piles/Drilled Shafts: Minimal damage. Pile Caps: Minimal damage Approach Bridge columns and abutments (above pile caps): Moderate damage. Main Span Bridge Towers and End Bents (above pile caps): Minimal damage. Energy Dissipating Shear Links, if used (at Main Span Bridge Towers and End Bents): Significant dam- age. Approach Bridge abutment backwalls: Significant damage. Superstructure: Minimal damage.

56 Seismic Design of Non-Conventional Bridges Gerald Desmond Bridge Replacement Exhibit 2-13-A - Design Criteria Page 12 Bearings, Hinge Beams and Shear Keys: Moderate damage. Expansion Joints: Significant damage, without collapse of the joint Cable Systems (structural elements): No damage. Cable Systems (non-structural elements): Minimal damage. Permanent offsets at Main Span Bridge towers and end bents at the deck level relative to pile caps must be avoided, except at the SEE level permanent offsets not exceeding 6” in any direction are permitted. Such offsets are exclusive of affects from adjoining Approach Bridges. Seismic affects from supported Approach Bridge spans shall be considered and shall not contribute to the end bents exceeding the 6" re- sidual displacement. Approach Bridge span residual displacements at the end bents need not comply with the 6" residual displacement limit. Permanent offsets of the foundations are also permissible if the strain limits specified in Section 5.4 of this document are not exceeded and the permanent offsets do not prevent use of the bridge subsequent to the SEE event after repairs are completed. 5.1.2 Safety Evaluation – Geotechnical Considerations Soil Liquefaction: The SEE event shall be used to assess liquefaction potential and corresponding downdrag forces, if applicable. If liquefiable soils are determined to be present, and it has been determined that they may in fact liquefy under the design earthquake for the site, the structure shall be designed to withstand the forces and moments resulting from the lateral and vertical movements caused by the liquefaction. Soil stabilization may be used to mitigate liquefaction conditions. Additionally, the design of the foundations shall be evaluated with the soil in a liquefied state. Slope Stability: For the SEE event, deformations of the supporting ground mass and displacements of the slopes shall be considered in the design of the bridge components. If necessary, the soil shall be stabilized to protect the bridge from damage due to lateral spreading, soil deformation and associated applied forces. 5.1.3 Functional Evaluation The FEE is defined as an earthquake that has a return period of 100 years, representing approximately a 60% probability of occurrence in 100 years. In this earthquake, Approach Bridges can be subject to damage only if it can be classified as “minimal”. The Main Span Bridge, including Main Span Bridge tower, end bents, sup- porting piles, superstructure, and stay cable system shall meet the requirements of the “No Damage” perfor- mance level. Main Span Bridge and Approach Bridge bearings shall meet the requirements of the “No Dam- age” performance level. The expansion joint between the Main Span Bridge and Approaches Bridges shall meet the requirements of the “Minimal Damage” performance level. For reinforced concrete elements, “mi- nimal damage” for the FEE event shall be based on the member strengths determined using the strain limita- tions given in Section 5.4. 5.1.4 Performance Assessment The seismic performance of all structures shall be assessed by verifying estimated structural demands on com- ponents are less than or equal to estimated structural capacities of those components. Methods for determining demands and capacities are defined in the following sections. When significant yielding of components is allowed, demand and capacity are defined by strain or rotational limits. When components are required to remain elastic or experience minor yielding, demand and capacity are defined by force Demand/Capacity (D/C) ratios. All capacity-protected components, as defined by Caltrans Seismic Design Criteria or these criteria, shall have a force D/C ratio of 1.0 or less when subjected to over-strength forces. When checking seismic conditions, use the corrosion allowance for pile casings at 50 percent of the 100-year design life. The horizontal diaphragms and tension elements that transfer for from one stay to the next between shafts or elements that make up a tower or end bent column, if used, shall be capacity protected.

Design Criteria Documents 57 Gerald Desmond Bridge Replacement Exhibit 2-13-A - Design Criteria Page 13 5.1.5 Seismic Loading during Construction For all bridges, the seismic loading during all phases of construction shall be designed to resist forces as de- scribed in Caltrans Bridge Memo to Designers 20-2. 5.2 Definition of Ground Motions Ground motions for use in dynamic seismic analysis of the bridge structures shall be taken from the Project Seismic Ground Motion Report information provided in Book 2, Section 8, Exhibit 2-8-F which documents the project-specific ARS design curves and spectrum-compatible ground motion time histories for the SEE and FEE. The Project consists of three soil zones: West Approach, Main Span, and East Approach. For each soil zone, ARS design curves and earthquake time histories that were spectrally matched to the ARS design curves were developed using the Probabilistic Seismic Hazard Analyses (PSHA) and considering the site response characteristics of the subsoils. Revision to the project-specific ARS design curves and earthquake time histo- ries provided in in Book 2, Section 8, Exhibit 2-8-F will not be allowed. Non-linear time history and response spectrum analyses shall be used in the evaluation of the bridges, as de- scribed in Section 5.3.2. For the purpose of non-linear time history analyses, the ground motions shall consist of three, 3-component time histories consistent with the SEE and one, 3-component time history consistent with the FEE. Each time history shall consist of 2-horizontal orthogonal components and one vertical compo- nent. For the SEE, the envelope of the three time-history ground motion analyses results shall be used to de- sign the bridge. The Project Site is located in the seismically active southern California area. The principal faults affecting the seismic hazard of the bridge are the Newport-Inglewood (Cherry Hill Segment) Fault northeast of the bridge and the Palos Verdes Fault southwest of the bridge. Since the location of the bridge places it in close proximity to the two active faults, near-fault directivity effects, including velocity pulses, shall be included in the time history analyses. 5.3 Analyses for Determination of Demands Demands on structural components of a bridge shall be determined by analysis of global three dimensional computer models of the bridge that represent its dominant linear and nonlinear behavior and the effects of soil- foundation-structure interaction. Demands shall be evaluated as load-type quantities (forces and moments) or as displacement-type quantities (displacements, relative displacements, and rotations) as required by the eval- uation rules for various components. 5.3.1 Service Load Demands and Combination with Seismic Demands For combination with seismic demands, component demands due to dead load, traffic load, temperature changes, and wind shall be determined by static analyses of global models. 5.3.2 Seismic Demands Seismic demands shall be determined by nonlinear dynamic time history analysis for the Main Span Bridge and at least one Approach Bridge frame, but not less than 700 feet of Approach Bridge, adjacent to each end of the Main Span Bridge. The analysis shall be completed for uniform support excitations for all pier locations within the same soil zone developed for the project. Appropriate analysis methods as specified in Caltrans Seismic Design Criteria shall be used for all other Ap- proach Bridge structures. Non-linear dynamic time-history analysis shall incorporate the following: Both dead load and seismic load analyses shall be geometrically non-linear to account for the geometric stiffness of the cable elements. Boundary condition non-linearities shall be accounted for in the form of gap elements at expansion joints and foundation impedances. The structural model shall explicitly consider the geometric nonlinearity, inelastic structural components • • •

58 Seismic Design of Non-Conventional Bridges Gerald Desmond Bridge Replacement Exhibit 2-13-A - Design Criteria Page 14 and other inelastic elements (e.g. dampers). Any reinforced concrete members with a force De- mand/Capacity (D/C) ratio larger than 0.5 shall be modeled with adjusted material and section properties to represent the cracked section. Structural steel members with a force D/C ratio less than 1.5 shall be mod- eled with elastic elements. Any members with a force D/C ratio larger than 1.5 shall be modeled with non- linear elements. Rayleigh damping is to be used for non-linear dynamic time-history analysis. Modal damping may be used for other analytical tools. The range of Rayleigh damping values represents the target maximum and minimum damping values that apply over the dominant periods of the various element groups. The maximum upper range of Rayleigh damping for non-linear dynamic time-history analysis shall not ex- ceed the following: Reinforced Concrete Columns: 4% - 6% Reinforced Concrete Towers: 4% - 6% Steel Towers: 2% - 5% Steel Superstructure: 2% - 5% Concrete Superstructure: 3% - 5% Foundations: 8% Rayleigh damping shall be incorporated into the model with values for each element group representing the expected extent of inelastic energy dissipation in that group. The range of dominant periods for the various bridge components used to select Rayleigh damping shall capture at least 90% of the mass of the bridge com- ponents under consideration. If higher Rayleigh damping is used at a foundation, the higher damping shall be limited to piling and pile caps that are entirely below grade and shall be established from bridge foundation only component models. Anchor points used for establishing Rayleigh damping at foundations shall be se- lected for the range of dominate periods of the foundation elements that capture at a minimum 90% of the mass of the foundation elements. When the pile cap dominates the foundations response, it is acceptable to exclude the mass of piles from the bridge foundation only component model. When soil springs or other foundation elements are represented by hysteretic elements in global models, total foundation damping shall not exceed an equivalent viscous damping of 8% with respect to the foundation stiffness and mass in defining the Rayleigh damping parameters. Modal Damping for Other Analytical Tools: Reinforced Concrete Columns: 5% Reinforced Concrete Towers: 5% Steel Towers: 3% Steel Superstructure: 3% Concrete Superstructure: 5% Main Span Bridge tower shafts and end bent column shaft seismic energy dissipation elements, if used, shall be explicitly modeled to represent the energy dissipation characteristics of each seismic energy dissipation element. The global seismic analysis model for the Main Span Bridge shall use explicit foundation modeling for the Main Span Bridge and at least one Approach Bridge frame, but not less than 700 feet of Approach Bridge, adjacent to each end of the Main Span Bridge. Explicit foundation modeling in the global model shall use the same spectrum-compatible motions applied uniformly at all depth at the ground nodes along the full length of the pile. The explicit foundation modeling shall include a representation of each individual pile, with distri- buted soil supports over the entire length of the pile. The uniform ground motions documented in Book 2, Sec- tion 8, Exhibit 2-8-F shall be used to excite the soil-pile structure system. For all other structures, foundation substructure models may be used to capture significant soil-pile interaction effects. The foundation substructure should consist of a linear stiffness and mass matrices representing the entire soil-pile system. The linearized foundation stiffness and mass matrices must be approximated with the anticipated strain levels during the design earthquake. The project ground motions developed in each soil zone shall be used to excite the foundation substructure. The same input earthquake ground motions shall be used for all supports within the same soil zone.

Design Criteria Documents 59 Gerald Desmond Bridge Replacement Exhibit 2-13-A - Design Criteria Page 15 When modeling of foundations for seismic demand evaluations, softening effects of local soils shall be consi- dered including seismic induced large deformations and liquefaction. The ground motions documented in Book 2, Section 8, Exhibit 2-8-F shall be used for all cases of foundation modeling, with and without soften- ing effects. When checking AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments, Extreme Event I, a permanent load factor , p, of 1.0 shall be used for Load Type DC. Damping curves shall be submitted with the seismic analysis and design. 5.3.3 Nonlinear Local Analysis for Evaluating Seismic Demands At a minimum, nonlinear local analyses shall be performed on the following bridge elements or conditions to supplement the global three dimensional nonlinear multi-support dynamic time- history analysis: Regions of significant Stress Concentrations (such as seismic energy dissipation elements, tower diaph- ragms, tower tension ties, mid-span pipe hinges, etc) Locations of discontinuous load path Fracture critical elements Energy dissipating regions and devices These analyses shall provide independent assessment of controlling seismic demands based on the assumption of maximum plastic moments and forces developed by potential plastic hinges or other inelastic behavior. These analyses shall be used to confirm adequate structural performance in the event that the SEE demands obtained from the global time-history analysis are exceeded. 5.4 Analyses for Determination of Capacities Capacities of structural components of a bridge shall be determined by analysis of local elastic and inelastic computer models of the components. Capacities shall be evaluated as load-type quantities (forces and mo- ments) or as displacement-type quantities (displacements, relative displacements, rotations, and curvatures) as required by the evaluation rules for various components. 5.4.1 Structural Steel Component Capacities Cable Stays: The load capacity of cable stays shall in accordance with PTI Recommendations for Cable Stay Design, Testing, and Installation. 5.4.2 Tower Shafts and Strain Limits The towers shall be designed in accordance with ATC-32 Improved Seismic Design Criteria for California Bridges: Provisional Recommendations augmented by the following requirements: req > 2.0 b/t 2l Pmax /Area 0.6Fy Where: the relative stiffness of the longitudinal stiffener to the tower skin wall b/t = the width to thickness ratio of the skin wall Pmax /Area = the maximum axial stress ll/ = l

60 Seismic Design of Non-Conventional Bridges Gerald Desmond Bridge Replacement Exhibit 2-13-A - Design Criteria Page 16 Main Span Bridge steel tower allowable strain limit value at the SEE Event shall meet the following require- ments: Tower without seismic energy dissipation elements: 4* y where y is the yield strain of the steel Tower with seismic energy dissipation elements: The tower shall be designed to remain essentially elastic. Main Span Bridge steel tower allowable strain limit value at the FEE Event shall not exceed y. 5.4.3 Tower Connections Tower splices shall be designed for the expected yield strength capacity of the component in accordance with AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments. Tower anchorage to the foundation shall be designed based on global push-over of the tower. The capacity of the tower anchorage shall be larger than the over strength demands associated with plastic hinging of the tower shaft. The capacity shall be evaluated in accordance with AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments. 5.4.4 Reinforced Concrete Component Capacities The expected nominal moment capacity Mne of ductile reinforced concrete members and capacity protected members as defined in Caltrans Seismic Design Criteria Section 3.4 shall be based on expected material strengths: f’ce = 1.3 * f'c (expected concrete compressive strength) fye =68 ksi (ASTM A706, Grade 60) (expected reinforcement yield) Maximum concrete strains at the nominal moment capacity Mne shall not exceed 0.003, and the reinforcing steel strains shall be limited to the allowable reinforcement strain values defined in Section 5.4.6 of this docu- ment. Capacity protected members shall be designed for forces derived from design overstrength moments (Mo) of the members framing into the capacity protected member. The design overstrength moment Mo shall be based on expected material strengths. Plastic moments shall be determined from moment-curvature analysis that considers the effects of concrete confinement and strain hardening of the reinforcement. The overstrength moment shall be taken as 1.20 times the calculated plastic moment at the design deformation of the element. The horizontal diaphragms between shafts or elements that make up a tower or end bent column, if used, shall be capacity protected.

Design Criteria Documents 61 Gerald Desmond Bridge Replacement Exhibit 2-13-A - Design Criteria Page 17 5.4.5 Allowable Concrete Strain Values The allowable concrete strain values for each earthquake level and components shall be according to the table below. The stress-strain relationships developed by Mander for confined concrete shall be used to calculate the values as a percentage of cu. When the “no damage” performance level is required, concrete strain limit of 0.003 pursuant to AASHTO LRFD Bridge Design Specifications, 4th Edition, with California Amendments, Section 5.7.2.1 shall be taken at the extreme face of the concrete component and not the confined core. ALLOWABLE CONCRETE STRAIN VALUES Location SEE FEE Dam- age Strain Dam- age Strain Main Span Bridge Towers Minimal cu No Main Span Bridge End Bents Minimal cu No Main Span Bridge CISS/CIDH Piles Minimal cu No Approach Bridge Columns Mod- erate cu Minimal Approach Bridge CISS/CIDH Piles Minimal cu Minimal All other Elements Mod- erate cu Minimal 0.003 0.003 0.003 0.004 0.004 0.004 cu definition shall be per Caltrans Seismic Design Criteria. 5.4.6 Allowable Reinforcement Strain Values To achieve the performance goals for the SEE and FEE event, the strains in reinforced concrete members, shall be limited to the values in the table below. The design level of peak steel strain values given in this table are to be used for evaluating the moment-curvature relationship for all potential plastic hinge areas. ALLOWABLE REINFORCEMENT STRAIN VALUES Location SEE FEE Damage Strain Dam- age Strain Main Span Bridge Towers Minimal No - Main Span Bridge End Bents Minimal No - Main Span Bridge Tower + End Bents Lateral Rein- forcement (Bars #8 and Smaller) Minimal No - Main Span Bridge CISS/CIDH Piles Minimal No - Approach Bridge Columns (Bars #11, #14 & #18) Moderate Minimal Approach Bridge Columns (Bars #10 and Smaller) Moderate Minimal Approach Bridge CISS/CIDH Piles Minimal Minimal All other Elements Moderate Minimal u, R su, sh fu, fue, y, ye, definitions shall be per Caltrans Seismic Design Criteria. 0.004 0.4 0.004 0.4 0.004 0.4 0.015 0.75 0.01 0.5 0.015 0.75 0.015 0.015 0.015 0.015 0.015 0.015 0.05 0.015 0.05 0.06 0.02 0.06

62 Seismic Design of Non-Conventional Bridges Gerald Desmond Bridge Replacement Exhibit 2-13-A - Design Criteria Page 18 5.4.7 Main Span Bridge Tower and End Bent Shaft Energy Dissipating Shear Link (If Energy Dissipating Shear Link Are Used) Except for base fixity resistance from the dual columns, frame lateral resistance shall only be from the interac- tion of the twin columns and Energy Dissipating Shear Links or Seismic Energy Fuses. All loading combina- tions not including seismic loads shall not exceed the nominal yield strength of the Energy Dissipating Shear Links or Seismic Energy Fuses. All components of Energy Dissipating Shear Link or Seismic Energy Fuse connections to Main Span Bridge tower shafts and end bent column shafts shall be designed as capacity-protected elements and shall be detailed to permit their removal and replacement after a seismic event. The rotation demand on Energy Dissipating Shear Links or Seismic Energy Fuses shall be limited to a maxi- mum value of 0.01 radians at the SEE level and 0.003 radians at the FEE level. 5.4.8 Energy Dissipating Shear Link Testing (If Energy Dissipating Shear Links Are Used) Full scale proto-type laboratory cyclic load testing of the Energy Dissipating Shear Links shall be performed to verify the required ductility and strength of the link is achieved; to confirm the adequacy of the connection to towers; and to demonstrate that the Energy Dissipating Shear Links can be readily removed and replaced after it has reached the required maximum ductility demand as shown by analysis. The over-strength factor to be used when designing Energy Dissipating Shear Link capacity protected components shall be established by the full-scale testing. The quasi-static loading protocol for testing the Energy Dissipating Shear Links shall consist of three distinc- tive phases as summarized in Tables 1 to 3 and illustrated in Figure 1. The first and the second phase of the loading history reflect the actual cumulative link rotation demands under design earthquake loadings. Each of them representing a complete deformation history resulted from design SEE event in terms of the maximum link rotation and the total number of inelastic cycles. In Phase I the de- formation sequence closely follows the response time history which contains large velocity pulses; whereas in Phase II the deformation sequence is arranged in the order of increasing rotation amplitude. Table 1: Energy Dissipating Shear Link Test Loading Sequence Phase I Load Step Link Rotation Amplitude (Radians) Number of Cycles 1 0.00375 1 2 0.03000 1 3 0.01000 1 4 0.00750 1 5 0.00500 2 6 0.00375 1 7 0.01500 1 8 0.01000 1 9 0.00500 1 10 0.00375 2 Table 2: Energy Dissipating Shear Link Test Loading Sequence Phase II Load Step Link Rotation Amplitude (Radians) Number of Cycles 11 0.00375 4 12 0.00500 3 13 0.00750 3 14 0.01000 4 15 0.01500 3 16 0.02000 1 17 0.03000 1

Design Criteria Documents 63 Gerald Desmond Bridge Replacement Exhibit 2-13-A - Design Criteria Page 19 Table 3: Energy Dissipating Shear Link Test Loading Sequence Phase III Load Step Link Rotation Amplitude (Radians) Number of Cycles 18 0.04000 1 19 0.06000 1 20 0.08000 1 21 0.10000 1 22 0.12000 1 FIGURE 1 – Loading History for Energy Dissipating Shear Link Test In Phase III the loading cycle continues at increments of 0.02 radians, with one cycle at each increment until link failure occurs. The link is considered as failed when significant loss of strength occurs. If in case the link failure does not occur when the actuator has reached its maximum capacity (of either force or stroke), the load- ing cycle shall be kept at the constant rotation amplitude that corresponding to the maximum capacity of the actuator and repeated until link failure occurs. The acceptance criterion is set forth as follows: For the given loading protocol, the test specimen must sustain the required shear link rotation angle for at least one full cycle prior to the link shear strength dropping below the nominal link shear strength. The Design-Builder shall provide a Energy Dissipating Shear Link Testing Protocol to the Port that includes the following: - Structural laboratory location and name of facility to test the specimen. - Step by step process for how testing is to be completed - Test goals and requirements - Evaluation of test acceptance criteria provided in the Contract Documents as well as additional test- ing requirements the Design tance criteria. -Builder may want to add - Explanation of design method with expected theoretical testing results - Roles and responsibilities of testing laboratory and the Design-Builder - Schedule - Test report table of contents - Post testing evaluation procedures - Mitigation procedures and strategies to limit impact to the Project if a test were to not meet accep-

64 Seismic Design of Non-Conventional Bridges Gerald Desmond Bridge Replacement Exhibit 2-13-A - Design Criteria Page 20 The minimum requirements for structural laboratory are, at a minimum: - The structural laboratory shall be capable of conducting the required full scale Energy Dissipating Shear Link test including: provision of loading mechanism, specimen setup, instrumentation installa- tion, testing of the instrumentation, acquisition and interpretation of the data; - Principal-in-charge and staff members shall have applicable experiences on similar tests; - The structural laboratory shall be able to finish the test within the time frame required. The Design-Builder shall submit a Energy Dissipating Shear Link Test Report showing the specimen(s) have met the test acceptance criterion provided in the Approved Energy Dissipating Shear Link Testing Protocol. Data shall be provided and certified by the testers and testing agency. 5.4.9 Concrete Pile Caps All concrete pile caps shall be designed as capacity protected members for over-strength forces generated from bent columns, towers, and piles. 5.4.10 Allowable CISS Pile Shell Strain Values Permanent steel shells for CISS concrete piles (hereinafter called “casings”) shall supplement the pile strength and ductility provided that the effective casing thickness after full allowance for corrosion is at least 1/16 inch. For all non-seismic loading conditions, the effective casing shall consider full allowance for corrosion as de- fined in Section 3.2.3. For all seismic evaluations, the effective casing shall consider one-half the allowance for corrosion as defined in Section 3.2.3. Steel pile casings may be assumed to act compositely with the interior reinforced concrete section provided that an adequate shear transfer mechanism is included at the casing/concrete interface. Shear transfer may be augmented by the addition of welded shear rings or other mechanical devices at the casing/concrete interface. Shear transfer shall be assessed as described in American Petroleum Institute (API) RP-2A/LRFD - Section H.4, Grouted Pile to Structure Connection. At the pile casing tip and casing cut-off elevations, the casing shall be assumed to contribute only lateral con- finement for a distance of 2 times the pile diameter. With the allowance for corrosion considered, the casing in these regions may be assumed to contribute 100 percent of its net area for confinement. In any case, piles shall have minimum spiral or hoop confinement reinforcing equal to #6 @ 6 inch spacing. With the allowance for corrosion considered, the casing may be assumed to contribute up to 80 percent of its net area to flexural capacity of a section and up to 20 percent of its net area to confinement of the pile interior. In any case, piles shall have minimum spiral or hoop confinement reinforcing equal to #6 @ 6 inch spacing. Also, the pile longitudinal reinforcing bars within the casing should contribute to at least 50 percent of the pile flexural capacity. The casing contribution to foundation stiffness shall be based on the net casing thickness after allowance for corrosion. A sensitivity study shall be performed to assess the structural seismic response with no allowance for corrosion in pile casings. The maximum allowable casing strains are as follows: Longitudinal Tension (along pile axis) 0.02 Longitudinal Compression (along pile axis) 0.01 Where steel casing acts compositely with the concrete pile interior: Hoop Tension (on net casing with 0.040 corrosion allowance) Where details are provided such that the steel casing does not act compositely with the concrete pile interior and longitudinal compression strains in the casing are negligible:

Design Criteria Documents 65 Gerald Desmond Bridge Replacement Exhibit 2-13-A - Design Criteria Page 21 Hoop Tension (on net casing with 0.060 corrosion allowance) 5.4.11 Shear Design of Ductile Concrete Members The shear design of reinforced concrete members that are detailed as ductile members that may experience yielding shall conform to Caltrans Seismic Design Criteria, Section 3.6. In addition, for any hollow sections as described in Section 5.4.12 and shown in Figure 2, the concrete shear capacity component, Vc, shall be based on the web sections only, where the web section is defined as the longer slender section parallel to the direction of the demand shear force. Similarly, the reinforcement shear capacity component, Vs, shall be based on the rebar in and extending along the full length of the web section, and parallel to the direction of the demand shear force only. No other rein- forcements (long bars, cross ties, rebars in flange sections) shall be allowed to contribute to the shear capacity, Vs. The web shear reinforcement shall be fully developed into the web/flange joints. For cross ties, lap splices shall be the full length of the bars, if lap splices are used. 5.4.12 Plastic Hinge Length The maximum length of plastic hinges (Lp) in a solid section shall be as specified by Seismic Design Criteria Equation 7.25 The length of plastic hinges at CISS pile connection to pile cap shall be as follows: Lp = G + 0.3fyedbl fyedbl Where fye, dbl, and L are defined by Seismic Design Criteria Equations 7.25 and 7.26 G = The gap, if any, between the top of the CISS pile steel shell and the bottom of the pile cap. The required shape of hollow Approach Bridge bent columns is shown in Figure 2, have been reviewed by the Department, and have been determined to provide acceptable seismic performance characteristics up to a duc- tility demand of 3, if the following criteria are met: • Section Geometry: The hollow section walls with curved faces shall be configured with a flat inside face as shown in Figure 2. • Cross Ties in curved walls: 180 degree hooks shall be used for all cross ties in curved walls. • Cross Ties in flat walls: Cross ties shall have alternating 180 degree and 90 degree hooks. In lieu of 90 degree hooks, T-head bar ends may be used. The Design-Builder shall evaluate the performance of hollow Approach Bridge bent columns using the plastic hinge length (Lp) given in the Caltrans Seismic Design Criteria. The shear capacity of hollow Approach Bridge bent column sections shall not rely on lap spliced lateral ties. If the Design-Builder changes the hollow shape from that shown in Figure 2, full scale testing shall be pro- vided and the Design-Builder shall submit a testing protocol for Approval. 0.08L + 0.15

66 Seismic Design of Non-Conventional Bridges Design Criteria Reference for Hoover Dam Bypass Colorado River Bridge, Nevada/Arizona Photo credit: T.Y. Lin International

Design Criteria Documents 67 Colorado River Bridge Design Criteria October 30, 2003 page 1 STRUCTURAL DESIGN CRITERIA For Hoover Dam Bypass Colorado River Bridge October 30, 2003 Central Federal Lands Highway Division Hoover Dam Bypass Project HDR/Sverdrup/TYLinInternational

68 Seismic Design of Non-Conventional Bridges Colorado River Bridge Design Criteria October 30, 2003 page 2 6. SEISMIC DESIGN Seismic design of the bridge will be performed based on limit state design as an extreme limit state for the final configuration of the structure. 6.1 General Performance Requirements Seismic design shall be based on a 10% probability of exceedance in 100 years for the design seismic event for the permanent structure. The PGA for the site has been established as .2g. Construction stage tem- porary works design will be based on a 10% probability of exceedance in 2 years. The performance levels expressed in terms of damage levels are defined as follows: “No Damage”: Defined for structural members as the nominal capacity as described in LRFD. “No damage” is defined as full serviceability with- out repair or replacement. “Minimal damage”: Although minor inelastic response may occur, post- earthquake damage is limited to narrow cracking in concrete and incon- sequential yielding of secondary steel members. Permanent offsets should be avoided. “Repairable damage”: Inelastic response may occur, resulting in concrete cracking, reinforcement yield, minor spalling of cover concrete, and minor yielding of structural steel. The extent of damage should be sufficiently limited that the structure can be restored essentially to its pre-earthquake condition without replacement of reinforcement or replacement of struc- tural members. Repair should not require closure. “Significant damage”: Although there is minimum risk of collapse, perma- nent offsets may occur. Damage consisting of concrete cracking, rein- forcement yielding, major spalling of concrete, and deformations in sec- ondary bridge components may require closure to repair. Partial or com- plete replacement of secondary elements may be required in some cases. Secondary elements are those that are not a part of the gravity load resisting system. AMEC, “Seismic Exposure Evaluation,” May, 2002 ATC-32 C3.21.2.3 6.1.1 Evaluation of Structural Components The Design Earthquake for structural evaluation corresponds to a mean return period of 950 years. In this earthquake, the bridge can be subject to primarily “minimal damage” with some “repairable damage” and some “significant damage” in secondary components as described in this sec- tion. The basic approach is to design the bridge components to the following behavior levels under the design earthquake: Arch Ribs: Minimal damage.

Design Criteria Documents 69 Colorado River Bridge Design Criteria October 30, 2003 page 3 Skewback Anchor Blocks: Minimal damage. Arch bracing and cross frames: Repairable damage. Spandrel Columns: Minimal damage. Roadway girders: Minimal damage. Secondary elements, joints and bearings: Repairable damage. 6.2 Definition of Ground Motions Site specific ground motions for use in dynamic seismic analysis of the bridge structure shall be taken from the project Geotechnical Report. The ground motions shall consist of three, 3-component time histories. Each time history shall consist of 2-horizontal orthogonal components and one vertical component. The ground motions will be based on a Probabilistic Seismic Hazard Analysis (PSHA) and be compatible with a defined target response spec- trum. The ground motions shall also consider the site response charac- teristics of the canyon and each individual foundation location and spatial incoherency between foundations. The following is the governing spectrum for final design: 6.3 Analyses for determination of demands Demands on structural components of the bridge shall be determined by analysis of global three dimensional computer models of the bridge that represent its dominant linear and nonlinear behavior and the effects of foundation response along the station of the structure, and foundation- structure interaction. Demands will be evaluated as load-type quantities (forces and moments) or as displacement-type quantities

70 Seismic Design of Non-Conventional Bridges Colorado River Bridge Design Criteria October 30, 2003 page 4 (displacements, relative displacements, and rotations) as required by the evaluation rules for various components. 6.3.1 Load Demands and Combination with Seismic Demands For combination with seismic demands, component demands due to dead load and live load may be determined by static analyses of elastic global models. The load factor for Extreme Event I ( EQ) shall be 0.25 for LL only, otherwise 0.0. The load factor for Extreme Event ( p) permanent loads shall be 1.0. The value of .25 is based on probable traffic loads for heavy truck traffic dur- ing an earthquake. 6.3.2 Seismic Demands Seismic analysis will be performed using LARSA or ADINA general-pur- pose finite element software. Both dead load and seismic load time his- tory analyses will be geometrically non-linear to account for the geometric stiffness of the arch. Any reinforced concrete members with a force De- mand/Capacity (D/C) ratio larger than 0.75 will be modeled with adjusted material and section properties to represent the cracked section. Capac- ities will be based on code strengths with = 1. Structural steel members with a force D/C ratio less than 1.5 will be modeled with elastic elements. Any members with a force D/C ratio larger than 1.5 will be modeled with nonlinear elements. 6.3.3 Seismic Detailing Where dynamic analysis indicates inelastic demand, detailing will con- form to the requirements for Zone 3. Where dynamic analysis shows essentially elastic response (D/C <=1.0 by conventional design rules), detailing will conform to the requirements of Zone 2, without special plas- tic hinge zone confinement steel. In areas with Zone 3 detailing, the following modifications to AASHTO LRFD will apply (ref ATC 32, Section 8.18): -The requirements of AASHTO 5.7.4.2 for precast, post-tensioned col- umns will be satisfied with MN>1.2 Mcr - The requirements of AASHTO 5.10.11.4.1d columns shall be modified by the factor (0.5 + 1.25P/FcAg). - Box column walls will be designed as a solid column for each unit width of wall in accordance with ATC 32, 8.18.2.3.2. Due to the foundation con- ditions and column flexibil- ity, it is not physically pos- sible for most columns to displace sufficiently far in order to develop ductility demand (rock abutments will restrain movement). Therefore, there is no pos- sibility of developing plas- tic hinges. Priestly, Seible, Calvi; Seismic Design and Retro- fit of Bridges, pg 313 6.4 Analyses for determination of capacities for Zone 3 Details Capacities of structural components of the bridge shall be determined by analysis of local elastic and inelastic models of displacements in the var- ious components. Initial analysis will be based on linear material proper- ties, with adjustments for nonlinear material behavior as noted in 6.3.2. Capacities will be evaluated as load-type quantities (forces and mo- ments) or as displacement-type quantities (displacements, relative dis- placements, rotations, and curvatures) as required for various compo- nents. Capacities will be verified by pushover analysis to the level of displacement demand determined by dynamic analyses.

Design Criteria Documents 71 Colorado River Bridge Design Criteria October 30, 2003 page 5 6.4.1 Structural Steel Component Capacities Primary steel arch rib, deck and spandrels will be designed for a force demand to capacity (D/C) ratio of no greater than 1.0. The displacement D/C ratio for transverse strut and bracing members and other secondary members shall not exceed 2.0. ATC 32-1 6.4.2 Allowable Concrete Strain Values The stress-strain relationships developed by Mander for confined con- crete in plastic hinge zones will be used. For all reinforced and pre- stressed concrete elements, the maximum allowable concrete strains shall be taken as 67 percent of the ultimate strains determined by Man- der’s equations for repairable damage; and 0.004, for minimal damage.. ATC 32-1 6.4.3 Ultimate Reinforcement Strain Values for Design REINFORCEMENT u pg pp Main Column Bars #11, #14 & #18 0.08 0.03 0.015 Main Column Bars #10 and Smaller 0.12 0.03 0.015 Spirals & Ties #8 and Smaller 0.12 0.05 NA Where: u = ultimate steel strain pg = design level of peak cyclical steel strain for struts and duc- tile member "performance goals" i.e., repairable damage pp = design level of peak steel strain for arch and spandrel "perfor- mance goals" i.e., minimal damage 6.4.5 Plastic Hinge Length The maximum length of plastic hinges (Lp) in a solid section may be taken as Lp = 0.08*Lc + 9*db ATC-32 Lc = Distance from point of maximum moment to point of con- tra-flexure in a column.

72 Seismic Design of Non-Conventional Bridges Colorado River Bridge Design Criteria October 30, 2003 page 6 db = diameter of reinforcement For initial design, the maximum length of column plastic hinges in a hol- low section may be taken as: Lp = 1.0 * H where H = Section dimension in the direction of seismic loading. For final design, the length of column plastic hinges in a hollow section shall be determined by detailed component modeling of the section, con- sidering the section geometry, aspect ratio, working stresses under dead load and reinforcing ratio. 6.4.6 Curvature Ductility Check For reinforced concrete sections which are anticipated to experience in- elastic behavior, the minimum section curvature ductility capacity shall be : c u y 4.0 Where : u section ultimate curvature defined by using u given in Section 6.4.3. y section yield curvature defined by using y

Design Criteria Documents 73 Design Criteria Reference for I-74 Bridge, Iowa Photo credit: Modjeski and Masters, Inc.

74 Seismic Design of Non-Conventional Bridges Due to the importance of the I-74 crossing, MM’s scope included an investigation of the effects of designing to a higher seismic standard than required by the AASHTO LRFD Specifications (AASHTO, 2007). Although bridges are designed for earthquake motions with a return period (Tr) of 1000 years, the Specifications recommend higher levels of performance for bridges classified as critical. For that reason, a return period of 2500 years will also be considered in this study, and the effects compared to a design for 1000 years. In addition, the effects of increasing the detailing requirements by moving to a higher seismic performance zone will also be evaluated. The seismic hazard in this study is defined in terms of acceleration response spectra and site coefficients determined in accordance with the General Procedure recommended in Section 3.10.2.1 of AASHTO Specifications (AASTHO 3.10.2.1). The Site Specific Procedure was not required due to the low level of seismic activity in the region and the fact that the foundations will be on rock, which we’ve taken as site class B (AASHTO 3.10.3.1). The spectral response parameters for the 1000 year Tr design spectrum were determined based on the 2007 AASHTO Seismic Hazard Maps that represent a spectral response for 7% of exceedance in 75 years, i.e. Tr = 1000 years. On the other hand, the 2500-year return period spectrum was determined using the 2008 USGS National Seismic Hazard Maps for a probability of exceedance of 2% in 50 years (USGS, 2008), even though AASHTO and USGS 2008 seismic hazard maps are not totally consistent, as shown in Figure 1. The two different maps were required since AASHTO does not provide spectra for return periods other than 1000 years, and therefore information from the USGS must be used. MEMORANDUM DATE: March 15, 2010 TO: TPM FROM: NYG RE: Seismic Study – I74 Bridge 1 Introduction 2 Seismic Ground Shaking Hazard

Design Criteria Documents 75 Figure 1. Seismic Response Spectra for 1000-year and 2500-year period return events. 3 Performance Criteria The operational classification of the bridge established by the owners determines the performance objectives to be considered in design and the corresponding seismic hazard levels. The I-74 Bridge is classified as “critical” implying higher levels of performance for the operational objective in accordance with the Specifications: “…Bridges must remain open to all traffic after the design earthquake and be usable by emergency vehicles and for security/defense purposes immediately after a large earthquake, e.g., a 2500-year return period event…” (AASHTO C3.10.5) On the other hand, the seismic requirements for design and detailing are defined based on the seismic performance zone (SZ) of the bridge which depends on the one second period spectral acceleration for the design earthquake (AASHTO 3.10.6). Due to the low seismicity in the region, the bridge is classified in the lowest design category (SZ=1) where only minimum requirements are required. Consequently, the benefits of increasing the detailing requirements from SZ1 to SZ3 are evaluated throughout this document. SZ2 was not included in the evaluation since for most of the details the corresponding requirements default to SZ3. The low seismic demand permits the definition of a global seismic design strategy consisting of an elastic substructure and an elastic superstructure. Structural elements designed elastically are permissible if no inelastic deformation is anticipated even under a large earthquake. However, minimum detailing is required according to the bridge SZ. 4 Model and Analysis The seismic demands in the structural components of the bridge were determined using a 3D finite element Lusas model of the East Bound Bridge (E.B.) (see Figure 2). A 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.0 0.5 1.0 1.5 2.0 2.5 3.0 Tm (s) C sm ( g ) Tr=1000yr - AASHTO 2007 Tr=1000yr - USGS 2008 Tr=2500yr - USGS 2008

76 Seismic Design of Non-Conventional Bridges multimode elastic method was selected for analysis in accordance with the Specifications for the corresponding operational classification and SZ (AASHTO 4.7.4.3). The seismic member forces and displacements were estimated using the Complete Quadratic Combination (CQC) of the individual mode responses. Directional load combinations that consider orthogonal effects were defined according to the Specifications to obtain the critical elastic forces and displacements due to earthquake loads (AASHTO 3.10.8). Figure 2. Finite element model of the East Bound Bridge The distributions of mass and stiffness throughout the model are consistent with the permanent loads and the expected behavior of the bridge under a seismic event in that region. Due to the detailed discretization of the model, a lump mass formulation was selected to avoid local modes of vibration that do not contribute significantly to the response. The number of modes and frequency ranges considered in the analyses were chosen such that the associated cumulative mass participation in the dynamic response was greater than 90% of the permanent mass in each of the principal horizontal directions. As a result, a total of 620 modes were required for the spectral analyses since the fundamental frequencies in each direction only obtain a mass participation of about 35% of the total mass, as shown in Figure 3. Reinforced concrete elements were analyzed using full section properties in complying with the recommendations for bridges located in SZ1 (AASHTO C4.7.1.3).

Design Criteria Documents 77 Figure 3. Modal periods and mass participation with relation to the considered spectra 5 Response Modification Factors Although the response modification factor (R) for substructure components of Critical bridges is 1.5 (AASHTO T3.10.7.1-1), a value of 1.0 was defined expecting that the bridge will behave elastically even under a large earthquake. However, the concrete 0.00 0.02 0.04 0.06 0.08 0.10 0.12 C sm ( g ) Tr=1000yr Tr=2500yr X Y Z X Y Z 0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 0.0 0.5 1.0 1.5 2.0 2.5 3.0 Tm (s) M as s (% ) X Y Z

78 Seismic Design of Non-Conventional Bridges members shall satisfy the detailing provisions for the corresponding SZ in accordance with the Specifications (AASHTO 5.10.2.2, 5.10.11 and 5.13.4.6). The R-factors recommended for connections are independent of the operational category of the bridge (AASHTO T3.10.7.1-1), as follows: Table 1. Response modification factors for connection design Connection Type R Superstructure to abutment (Steel rib - concrete rib) 0.8 Pile bents to superstructure (Concrete cross beam - stiffening girder) 1.0 Columns to foundations (Concrete ribs - foundation) 1.0 6 Design Forces 6.1 Superstructure Comparisons of the maximum elastic seismic effects with those produced by wind in the stiffening girder rib and the critical arch are shown in Figure 4 and Figure 5, respectively. The absolute values of the wind demands were used to compare with the results from the dynamic spectral analyses shown as positive because they are reversible. It is observed that the design in both cases will be controlled by load combinations different from the Extreme Load Event I (AASHTO 3.4.1), i.e. seismic does not control. Therefore, the assumption of an elastic behavior of the bridge under seismic loads due to a large earthquake (Tr = 2500yr) is valid. Figure 4. Magnitude of the seismic and wind axial forces in the stiffening girders 0 50 100 150 200 250 300 350 400 450 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Normalized length A xi al lo ad ( K ) P - EQ (1000yr) P - EQ (2500yr) P - WS (80mph)

Design Criteria Documents 79 Figure 5. Magnitude of the seismic and wind moments in the steel ribs 0 2000 4000 6000 8000 10000 12000 14000 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 Normalized distance from steel-concrete connection M o m en t (K -f t) EQ (1000yr) - Mz EQ (1000yr) - My WS (80mph) - Mz WS (80mph) - My 0 2000 4000 6000 8000 10000 12000 14000 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 Normalized distance from steel-concrete connection M o m en t (K -f t) EQ (2500yr) - Mz EQ (2500yr) - My WS (80mph) - Mz WS (80mph) - My Symm. Symm. Brace C.L. Brace C.L.

80 Seismic Design of Non-Conventional Bridges 6.2 Connections According to the Specifications (AASHTO 3.10.9.2), the design connection forces for bridges in SZ1 with an acceleration coefficient, As, less than 0.05 (As = 0.035g, see Appendix A1) shall not be less than 0.15 times the vertical reaction due to permanent loads. The appropriate R factor is applied to each connection type. On the other hand, for bridges in SZ3 (AASHTO 3.10.9.4), the design forces shall be taken as the lesser of the elastic forces reduced by the appropriate R factor or the forces resulting from plastic hinging of the concrete support elements. In this case, the modified forces are much lower than the inelastic forces presented in Section 6.3. Regardless of the SZ, the connection design forces in the restrained directions shall be greater than the tributary load multiplied by As. The reaction forces due to the 1000-year and 2500-year return period events and the permanent loads are given in Table 2, and the corresponding connection design forces (based on the maximum earthquake) for each SZ considered in this study are presented in Table 3. It is observed that the restrictions imposed over SZ1 exceed those corresponding to SZ3 due to the low magnitude of As. Table 2. Seismic forces in the members at the connection points Member Axial Major axis Minor axis P (K) M (K-ft) V (K) M (K-ft) V (K) Tr = 1000yr Steel rib 85 1310 22 637 10 Deck system: Stiffening girder (SG) 149 0 23 0 1 Stringer (Str) 12 0 19 0 0.02 Total = 2 SG + 7 Str 382 0 179 0 2 Concrete rib 258 21500 332 3720 102 Tr = 2500yr Steel rib 129 2040 34 970 14 Deck system: Stiffening girder (SG) 231 0 36 0 1 Stringer (Str) 18 0 29 0 0.03 Total = 2 SG + 7 Str 588 0 275 0 2 Concrete rib 400 33400 515 5340 147 DL Steel rib 6240 5490 65 5360 81 Deck system: Stiffening girder (SG) 121 0 136 0 4 Stringer (Str) 19 0 85 0 0.08 Total = 2 SG + 7 Str 375 0 867 0 9 Concrete rib 8860 28900 657 4790 345

Design Criteria Documents 81 Table 3. Seismic forces for connection design Connection Axial Major axis Minor axis P (K) M (K-ft) V (K) M (K-ft) V (K) SZ1 (based on Tr=2500yr) Steel rib at concrete rib 161 2550 6240*0.15 =936 1213 6240*0.15 =936 Deck system at End floor beam 588 0 275 0 867*0.15 =130 Concrete rib at foundation 400 33400 8860*0.15 =1329 5340 8860*0.15 =1329 SZ3 (Tr=2500/R) Steel rib at concrete rib 161 2550 6240*As= 218 1213 6240*As= 218 Deck system at End floor beam 588 0 275 0 867*As= 30 Concrete rib at foundation 400 33400 515 5340 8860*As= 310 6.3 Substructure The inelastic forces of the concrete ribs presented in Table 4 (AASHTO 3.10.9.4) permit to compare with the modified forces of Section 6.2. The calculations are conservatively based on the cross section properties of the concrete ribs at the connection with the steel ribs. It is observed that the plastic hinging demands are much greater than the modified design forces because of the considerable size of the concrete ribs and the low seismic excitation. Table 4. Inelastic forces in the concrete ribs Connection Axial Major axis Minor axis P (K) M (K-ft) V (K) M (K-ft) V (K) Steel - concrete rib connection and Concrete rib at foundation 11475 202171 9403 104232 4848 For structures located in SZ1 where the acceleration coefficient, SD1, is less than 0.10 (SD1 = 0.036), seismic forces are not required for the design of the concrete structural elements (AASHTO 5.10.11.2). For SZ3, the modified forces presented in Table 3 for the concrete ribs at the foundation level are employed and no hinging effects need to be considered (AASHTO 3.10.9.4.3d). 7 Minimum requirements 7.1 Support length The minimum support length at expansion bearings without restrainers shall be the greater between the maximum calculated displacement and a percentage of the minimum support length, N (AASHTO 4.7.4.4). However, due to the longitudinal

82 Seismic Design of Non-Conventional Bridges restriction offered by the hangers, only the maximum calculated displacements shown in Table 5 are considered. Table 5. Maximum longitudinal seismic displacement of the deck Tr = 1000yr Tr = 2500yr Displacement (ft) 0.020 0.032 7.2 P- requirements Due to the low seismicity in the region and the large size of the concrete support members, the bridge is not susceptible to instabilities or amplification effects produced by lateral seismic displacements. 7.3 Concrete detailing requirements for concrete columns in SZ3 According to the Specifications, vertical supports or columns (e.g, concrete ribs) in SZ3 shall meet additional seismic requirements (AASHTO 5.10.11.4). Comparisons of reinforcement requirements between SZ1 and SZ3 are presented in Table 6. The calculations are based on a concrete prismatic member with the cross sectional properties taken from the steel-concrete rib connection design. It is assumed that the longitudinal reinforcement will be controlled by load cases different from the Extreme Event Load Combination I (AASHTO 3.4.1). As a result, the corresponding requirements specified for SZ3 were defined in SZ1 for comparison purposes. The total change in reinforcement steel quantity is 11,000 pounds per concrete rib. With an assumed price per pound of $1.10, this results in a cost increase of approximately $12,100 per concrete rib. Table 6. Reinforcement requirements in concrete ribs for Extreme Event Load Combination I SZ1 SZ3 • Longitudinal reinforcement: Maximum Area 0.04 Ag* (AASHTO 5.10.11.4.1a) 0.04 Ag (AASHTO 5.10.11.4.1a) Minimum Area 0.01 Ag (AASHTO 5.10.11.4.1a) 0.01 Ag (AASHTO 5.10.11.4.1a) • Transverse reinforcement (ties): Area and spacing Standard hooks (AASHTO 5.10.2.1) 6 & 9 # 4 @ 7in (AASHTO 5.8.2.5) Standard hooks (AASHTO 5.10.2.1) 6 & 9 # 4 bars @ 7in (AASHTO 5.8.2.5) Plastic hinge regions - Seismic hooks (AASHTO 5.10.2.2) 14 & 8 # 4 bars @ 4in At the top and bottom of the concrete rib over a length of 15ft (AASHTO 5.10.11.4.1d, -e) • Reinforcement weight: 0.97 K/ft 41.7 K 1.23 K/ft 52.7 K (Increase of 11.0 K 26 %) *Ag = Gross area of section

Design Criteria Documents 83 8 Hinging mechanism The assumption that the collapse mechanism begins in the concrete ribs without participation of the steel ribs is verified by using a push-over analysis (POA). The POA consists of a series of linear analyses where the bending rotation at the end nodes of the rib elements is released once the corresponding maximum bending capacity is reached. The moment resistances were determined using the axial load from the Extreme Event Load Combination I. The lateral load is proportional to the permanent loads and accounts for the critical orthogonal effects (i.e., 30% Longitudinal + 100% Transverse). Figure 6 and Figure 7 show the resultant hinging mechanism in the bridge and the corresponding capacity curve in the transverse direction, respectively. It is observed in effect that a moment mechanism in the concrete ribs precedes the initial hinging effects in the steel portion of the ribs. However, significant lateral accelerations, greater than approximately 1g, would be required to activate this mechanism. Step 1 Step 2 Step 3 Step 4 Figure 6. Sequential hinging mechanism 9 Conclusions and recommendations This study shows that even for a 2,500 year design event, seismic loads do not control the design. Thus, there is no cost penalty for moving from 1,000 year to 2,500 year design event. Requiring detailing associated with Seismic Zone 3, as opposed to Seismic Zone 1, will result in approximately 88,000 pounds of additional reinforcing steel for both bridges, mostly for confinement, with an estimated additional cost of $96,800 dollars. Consequently, it is recommended to design for the higher event, even if it has no practical effect on the design. The detailing requirements for the higher seismic zone are Minor-axis moment Major-axis moment Both moments

84 Seismic Design of Non-Conventional Bridges Figure 7. Capacity curve in the transverse direction also recommended, considering the fact that the difference is only caused by the transverse reinforcement steel for confinement. The detailing for the plastic zones significantly improves the ductile behavior of the structure, required in case of an extreme loading event not considered in the initial design (e.g. blast loads). No special detailing requirements are specified for the steel ribs as they remain elastic, since the failure mechanism under a large seismic event would be basically located in the concrete members only. 10 References AASHTO. (2007). LRFD Bridge Design Specifications, Customary U.S. units (4th ed.) – 2008 Interim Revisions. Washington, DC: Author. Imbsen, R. (2007). AASHTO Guide Specifications for LRFD Seismic Bridge Design. Washington, DC: AASHTO. USGS. (2008). 2008 United States National Seismic Hazard Maps. Reston, VA: Author. http://earthquake.usgs.gov/hazards/products/conterminous/2008/ 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 0 5 10 15 20 25 30 35 40 45 Transverse midspan displacement (ft) T ra n sv er se a cc el er at io n ( g ) USED WITH PERMISSION OF IOWA DEPARTMENT OF TRANSPORATION

Design Criteria Documents 85 Design Criteria Reference for Port Mann Bridge Highway 1 Project, Vancouver, BC Photo credit: Thomas Heinser

86 Seismic Design of Non-Conventional Bridges Project: Gateway Project - Port Mann Bridge Design Document: Port Mann Bridge No. 1614 – Design Criteria Doc No.:ZB-230-FR-1614-001 Revision: 2 Date: June 12, 2009 PORT MANN BRIDGE HIGHWAY 1 PROJECT PORT MANN BRIDGE #1614 DESIGN CRITERIA 1.0 INTRODUCTION The Design Criteria is based on Schedule 4 of the Concession Agreement, and by reference to the CAN/CSA-S6-06 “Canadian Highway Bridge Design Code” (CAN/CSA-S6-06) except as appended by the BC Ministry of Transportation “Supplement to CAN/CSA-S6-06” (2007) (MoT). This Criteria Document is presented as the proper interpretation and application of the DB requirements in Schedule 4, Part 2 of the Agreement, and presents specific criteria used to implement the performance standards of Schedule 4. 7.0 SEISMIC 7.1 General For cases where vertical component of ground motion is considered in seismic analysis, ULS 5 and 5A shall be based on a dead load factor = 1.0. (MoT 3.5.1). For strength load case 5A, a live load factor of 0.5 shall be included for live loads combined with seismic loads. The inertia affect of live load shall not be included in the dynamic analysis. Seismic demands will envelope foundation conditions with no scour and with 50% of the Q200 scour depth based on final design conditions. Seismic design shall meet the criteria in Schedule 4, with details of application as summarized in Table 1 that follows. Table 1 Schedule 4 Seismic Design Clauses Structure Requirement Sched. 4 Part 2 Main crossing and approaches Lifeline structure: Minimal; Repairable; Significant damage, No collapse criteria 4.2(a) App. D All other new structures (incl. retaining walls) Economic Sustainability Route Bridges: Repairable; Significant damage, no collapse; No loss-of-span damage criteria 4.2(b) App. D Seismic inputs Component level design criteria Foundations Retaining walls Liquefaction Slopes and embankments Base isolation 4.3 4.4 4.4.1 4.4.2 4.4.3 4.4.4 4.4.5 2 of 7 USED WITH PERMISSION OF TRANSPORTATION INVESTMENT CORPORATION

Design Criteria Documents 87 3 of 7 Project: Gateway Project - Port Mann Bridge Design Document: Port Mann Bridge No. 1614 – Design Criteria Doc No.:ZB-230-FR-1614-001 Revision: 2 Date: June 12, 2009 Structure Requirement Sched. 4 Part 2 Required analysis 4.5 Seismic Instrumentation 4.6 7.2 Analysis Requirements Minimum analysis requirements specified in Schedule 4 Part 2 Table 4.5 are associated with specific ground motions. Our application of these requirements is summarized in Table 2, associated with the performance objectives. In each case, the (more rigorous) analysis requirements for longer return period events may be used in lieu of those shown, at the discretion of the designer. Table 2 Analysis Requirements Category Minimum Analysis Requirement Event Structure Performance Objective Analysis 10% in 50 Lifeline Minimal damage Ground movement Damage assessment 5% in 50 Lifeline Repairable damage Pushover Ground movement Damage assessment 2% in 50 Lifeline Significant damage RSA (displacement limit) Pushover Time-history Damage assessment Subduction All Foundations to resist ground movement Ground movement (nonlinear) 7.3 Performance Requirements The required performance of structures is summarized in Table 3. The Port Mann Bridge is designated as a lifeline structure. Table 3 Performance Requirements Event Category Lifeline Structures 10% in 50 & subduction event Service: Damage: Evaluation: Immediate use Minimal damage Essentially elastic (see table 4) 5% in 50 Service: Damage: Evaluation: Limited access Repairable damage • Residual displacement 0.5% • Strain limits per table 4

88 Seismic Design of Non-Conventional Bridges 4 of 7 Project: Gateway Project - Port Mann Bridge Design Document: Port Mann Bridge No. 1614 – Design Criteria Doc No.:ZB-230-FR-1614-001 Revision: 2 Date: June 12, 2009 Service: Damage: Possible Loss of Service Significant damage / No collapse 2% in 50 Evaluation: • Displacements 80% displacement at peak resistance • Displacements 80% of elastic displacements • Strain limits per table 4 7.4 Analysis and Design Parameters Parameters for seismic analysis and design are given in Table 4. Table 4 Analysis and Design Parameters Item Parameters Reference Sched. 4, Part 2 Art 4, u.n.o.) GROUND MOTIONS Design level events Three level design: o 10% in 50 yr (1/475) o 5% in 50 yr (1/975) o 2% in 50 yr (1/2475) • Subduction earthquake (deterministic) Appendix D Seismic inputs • Firm-ground spectra for all three levels and subduction earthquake are provided • Spectra-matched firm-ground time history records are provided. Baseline correction shall be performed as required. • Use site-specific spectra and records (to be developed) 4.3 Golder Report ANALYSIS Inelastic dynamic analysis • Include P- effects • See ATC-32 3.21.8 for general guidelines • Design demands are the mean response from analysis for 3 time history records • Ground displacement, ground motions and soil undrained residual strength shall be considered for liquefied soils based on nonlinear effective stress soil column analysis for the three design earthquakes and the subduction zone event. 4.5(e, f) ATC-32 3.21.8 4.3 4.4.3.b

Design Criteria Documents 89 5 of 7 Project: Gateway Project - Port Mann Bridge Design Document: Port Mann Bridge No. 1614 – Design Criteria Doc No.:ZB-230-FR-1614-001 Revision: 2 Date: June 12, 2009 Item Parameters Reference Sched. 4, Part 2 Art 4, u.n.o.) Soil modeling for subsequent global analysis shall be based on mean response from analysis of 3 time history sets, for each design level. Material properties • Use expected properties for analysis and for evaluation of ductile elements: 1.1fy and 1.3f’c • Use overstrength properties for capacity design of adjacent elements: 1.25fy and 1.7f’c ATC-32 8.16.2.4.1 ATC-32 8.16.4.4 Strain limits (damage states refer to the condition of the bridge as a unit in accordance with Table 3) • For reinforced concrete: o Minimal Damage: c = 0.004, ps = 0.008 and s = 0.01 o Repairable Damage: c = 0.007, ps = 0.015 and s = 0.025 o Significant Damage: c = 0.75 cu, ps = 0.045 and s = 0.75 su • For main span (single) pylons: o All damage stages: c=.0041 and s=.01 • For steel piles: o Minimal Damage: s = 0.002 and p = 0.002 o Repairable Damage: s = 0.01 and p = 0.01 o Significant Damage: s = 0.025 and p = 0.025 1 Concrete strain based on material curve. Concrete strain for Whitney stress block shall be .003. ATC-32-1, 2.1 ATC-32-1, 2.1 4.4(a) Foundations; Foundation displacements • Liquefaction assessment per ATC-49 Section 7.6 and Appendix D. In accordance with 7.6.3, lateral spreading forces on foundations shall be analyzed separately from the time history demands based on liquefied conditions for the time history analysis. • Permanent foundation displacements are to be considered in satisfying damage criteria. • Design forces shall be determined from the time history analysis. Forces shall be verified by pushover analysis to the level of demand displacement derived from the time history analysis. • Allowable strain for concrete confined within pipe pile shells shall not exceed c = 0.75 cu. 4.4.3(a) ATC-49 4.4.3(b), 4.4.1

90 Seismic Design of Non-Conventional Bridges 6 of 7 Project: Gateway Project - Port Mann Bridge Design Document: Port Mann Bridge No. 1614 – Design Criteria Doc No.:ZB-230-FR-1614-001 Revision: 2 Date: June 12, 2009 Item Parameters Reference Sched. 4, Part 2 Art 4, u.n.o.) Slopes and embankments • Liquefaction assessment per ATC-49 Section 7.6 and Appendix D • Allowable foundation displacements: by analysis • Permanent foundation displacements to be considered in satisfying damage criteria 4.4.4 Base isolation • Use non-linear dynamic analysis for all return periods 4.4.5 DESIGN Geotechnical Properties and Design Pile and shaft foundations • Axial capacities based on lesser of geotechnical strength and limit of steel strain • Response spectrum analysis, lesser of: o elastic design forces (R=1) o column plastic overstrength forces • Time history analysis: design forces shall be derived from modeling columns and pylons with inelastic elements utilizing overstrength material properties. • Pile and shaft foundations shall be designed to satisfy strain limits for applicable damage states 4.4.1(a); S6-06 4.4.10.4; ATC- 32 4.5.1, 4.5.5 ATC-49 6.3 Spread footings • Ultimate bearing capacity, = 1.0 • Single-column footing: area of uplift 0.25 of width • Multi-column bent: eccentricity 0.33 of width 4.4.1(c); ATC-32 4.5.6 Structural Properties and Design Nominal material properties • Material weights: S6-06, Table 3.6 • Nominal strengths: see project structural design criteria S6-06 Section 3 Design material properties and section design (non-ductile elements) • Use nominal material properties, 1.0fy and 1.0f’c, for design. • Resistance factors per S6-06, Sections 8 and 10 • Use reinforcement limits from 0.8% to 4% in columns • Importance factor (in S6-06) = 1.0 4.4(g) BCMoT 4.7.4.1.1 4.5(h) Main span (single) pylons** • Main span (single) pylons shall remain essentially elastic for all three design level events. • Foundations shall satisfy strain limits of minimal damage for the 10% in 50 year event.

Design Criteria Documents 91 7 of 7 Project: Gateway Project - Port Mann Bridge Design Document: Port Mann Bridge No. 1614 – Design Criteria Doc No.:ZB-230-FR-1614-001 Revision: 2 Date: June 12, 2009 Item Parameters Reference Sched. 4,Part 2 Art 4, u.n.o.) • Foundations shall satisfy strain limits of repairable damage for the 5% in 50 year event and significant damage for the 2% in 50 year event. Capacity design • Use an overstrength factor of 1.4 for plastic moments, or moment-curvature analysis with 1.25fy and 1.7f’c ATC-32 8.16.4.4 Load combinations • Orthogonal EQ forces: 100%-30%-30%, to be applied to all possible combinations in 3 perpendicular directions (L,T,V) for RSA. • Ductile Substructure Load Combination (ULS 5): 1.0D+ EE+ PP+(EQ/R)* * Reduced EQ for flexure only, use R=1.0 from elastic or push-over results for axial component CAN SCA S6-06 4.4.9.2 S6-06 Table 3.1 modified Base isolation • Comparable ductility to “normal” structures • Displacement capacity = 1.25 times calculated 4.4.5 ** The main pylons are designed as essentially elastic members, without implementing the reduced inelastic demand levels allowed by the S6-06 Code. Demands are based on non-linear time history analysis for stiffness corresponding to over-strength properties of the pylons. Foundation capacity is provided corresponding to the essentially elastic seismic demands for all events as measured by the strain limited resistances noted in this Section.

92 Seismic Design of Non-Conventional Bridges Design Criteria Reference for San Francisco-Oakland Bay Bridge Self-Anchored Suspension Bridge, California Photo credit: Caltrans

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104 Seismic Design of Non-Conventional Bridges Design Criteria Reference for San Francisco-Oakland Bay Bridge Skyway Structures, California Photo credit: Caltrans

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Design Criteria Documents 113 Design Criteria Reference for Tappan Zee Hudson River Crossing Project, New York Photo credit: HDR, Inc.; New York State Thruway Authority

114 Seismic Design of Non-Conventional Bridges TAPPAN ZEE HUDSON RIVER CROSSING PROJECT PROJECT DESIGN CRITERIA Volume 6: Structural (Bridges) Contract D214134 PIN 8TZ1.00 Project TA# TANY 12-18B Revision 3 5/22/2015 Prepared by Tappan Zee Constructors 555 White Plains Rd., 4th Floor Tarrytown, NY 10591 Revision No. Design Package No. or Description Date 4 weiveR ngiseD evitinifeD rof dettimbuS :10-D21H A /19/13 31/81/9 )noissimbuseR( ngiseD evitinifeD :10-D21H 1 2 H12D-01: Definitive Design (Resubmission 2) 01/03/13 3 H12D-01: Definitive Design (Resubmission 3) 5/22/15 USED WITH PERMISSION OF NEW YORK THRUWAY AUTHORITY

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116 Seismic Design of Non-Conventional Bridges Tappan Zee Hudson River Crossing Project Project Design Criteria Volume 6: Structural (Bridges) Page 6-39 Reference Rev Date • Upper level event – 2500 year return period Safety Evaluation Earthquake (SEE). Approximately 4% probability of exceedance in 100 years.

Design Criteria Documents 117 Tappan Zee Hudson River Crossing Project Project Design Criteria Page 6-40 Volume 6: Structural (Bridges) Reference Rev Date 4.19.4 Seismic performance levels expressed in terms of damage levels are defined in the NYSDOT LRFD Blue Pages, which are as follows: • Minimal Damage: The Bridge should essentially behave elastically during the earthquake, although minor inelastic response could take place. Post-earthquake damage should be limited to narrow flexural cracking in concrete and masonry elements. There should be no permanent deformations to structural members. Only minor damage or permanent deformations to non- structural members should take place. • Repairable Damage: The extent of damage should be limited so that the structure can be restored to its pre- earthquake condition without replacement of structural members. Inelastic response may occur resulting in: concrete cracking, minor cover spalling and reinforcement yielding; minor yielding of structural steel members; some damage to secondary members and nonstructural components; some damage to masonry. Repair should not require complete closure of the bridge. Permanent offsets should be small and there should be no collapse. • Significant Damage: There is no collapse, but permanent offsets may occur. Extensive cracking, major spalling of concrete and reinforcement yielding may force closure for repair. Similar consequences could result from yielding or local buckling of steel members. There could be yielding of member connections, fracture of limited number of bolts/rivets, serious damage to secondary structural members and non-structural components, as well as to masonry. Partial or complete replacement may be required in some cases. NYSDOT Blue Pages 3.10.5 4.19.5 Safety Evaluation: The Crossing shall survive the Upper level event (SEE) with Minimal and Repairable Damage. Traffic access following this event may be limited: as a minimum, access shall be available within 48 hours for emergency/defense vehicles and within 2 months for general public traffic. The Bridge components will be designed for the following levels: • Piles: Minimal Damage • Pile Caps: Minimal Damage Part 3 Project Req. 11.3.1.9.5

118 Seismic Design of Non-Conventional Bridges Tappan Zee Hudson River Crossing Project Project Design Criteria Volume 6: Structural (Bridges) Page 6-41 Reference Rev Date • Towers and Anchors Piers: Repairable Damage • Approach Span Piers: Repairable Damage • Superstructure: Minimal Damage • Bearings: Repairable Damage • Expansion Joints: Repairable Damage • Cable Systems: Minimal Damage 4.19.6 Functional Evaluation: The Crossing shall survive the Lower level event (FEE) with only Minimal Damage. Access after this event shall be immediate for all traffic, with an allowance of a few hours for inspection. Part 3 Project Req. 11.3.1.9.5 4.19.7 The seismic analysis of the Crossing shall take into account the effects of Potential Future Loading and incorporate both dead loads and live loads in the seismic design. Part 3 Project Req. 11.3.1.9.5 4.19.8 The load factor of EQ shall be 0.50 for the Extreme Event I Load combination. Inertial effects (mass) due to live load shall not be included in the structural analysis models. NYSDOT Blue Pages 3.4.1 & AASHTO Guide Specifications for LRFD Seismic Bridge Design C3.7 4.19.9 Consideration of seismic loads during construction of the bridge is not required. 4.19.10 For elements protected by seismic isolation, the Response Modification factor shall be taken as 1.0. 4.19.11 Further discussion on seismic methodology is discussed in section 7.0. 4.20 Construction Loading 4.20.1 Approach Units 4.20.1.1 Load combinations and load factors for construction loading shall be in accordance with AASHTO LRFD Section 3.4.2.

Design Criteria Documents 119 Design Criteria Reference for Willamette River Transit Bridge (Tilikum Crossing Bridge), Oregon Photo credit: T.Y. Lin International

120 Seismic Design of Non-Conventional Bridges Project: Willamette River Transit Bridge Document: Supplemental Project Design Criteria Doc No.: ST-230-0001 Revision: 2 Date: September 30, 2011 WILLAMETTE RIVER TRANSIT BRIDGE Supplemental Project Design Criteria 1.0 INTRODUCTION The supplemental Project Design Criteria for the Willamette River Transit Bridge (WRTB) is based on the Conformed Project Specific Design Criteria – V10, October, 2010 (Criteria), and by reference, the AASHTO LRFD Bridge Design Specifications, 4th Edition, 2007 with 2008 and 2009 Interim Revisions (AASHTO LRFD). This Criteria Document supplements the Project Specific Design Criteria and presents specific supplemental design criteria used to satisfy the performance standards of the project. 1.1 Performance Requirements Concrete and steel reinforcement strain limits for the 475-year return period earthquake “Serviceable Earthquake Evaluation” (SEE) and the 975-year return period earthquake “No Collapse Earthquake” (NCE) are specified in Criteria Section 3.D.7.c and 3.D.7.d and are reproduced in Table 2. The ultimate concrete strain, e cu, shall be based on Mander’s Model for confined concrete (“Theoretical Stress-Strain Model for Confined Concrete”, Journal of Structural Engineering, 1988). The “No Collapse” strain limits shall apply to the structural performance evaluation from a vessel collision event. Reinforced concrete component capacities for ductile elements shall be based on expected material properties as defined in Criteria Section 3.D.7.b. Table 2: WRTB Performance limits for Seismic and Ship Impact Performance Evaluation Structural Element Material Component SEE Event Strain Limit NCE Event Strain Limit Minimal Damage Performance Strain Limit Cable Loss Strain Limit Drilled Shafts Concrete .005 0.5 cu 0.01 Longitudinal Mild Steel Reinforcement #18 0.01 #11, #14 & #18 0.02 #14 & smaller 0.015 #10 & smaller 0.02 Transverse Mild Reinforcement #8 & smaller 0.015 #8 & smaller 0.06 Main Tower and Columns Concrete .005 0.75 cu Longitudinal Mild Steel Reinforcement #18 0.01 #11, #14 & #18 0.05 #14 & smaller 0.015 #10 & smaller 0.06 Transverse Mild Reinforcement - Towers #8 & smaller 0.015 #8 & smaller 0.08

Design Criteria Documents 121 Project: Willamette River Transit Bridge Document: Supplemental Project Design Criteria Doc No.: ST-230-0001 Revision: 0 Date: January 26, 2011 Transverse Mild Reinforcement - Columns #8 & smaller 0.015 #8 & smaller 0.05 Non-Ductile Components Concrete 0.004 0.004 Post-Tensioning Reinforcement 0.008 0.008 Mild Reinforcement #18 0.005 .015#14 0.0075#11 & smaller 0.01 1.2 Prestressing Limits • Concrete compressive stress of 0.45 f`c for permanent loads and effective prestress • Concrete compressive stress of 0.6 f`c for SERVICE I limit state • Crack width of 0.012 in. for tension for the SERVICE limit states • Crack width of 0.016 in. for tension during construction, with crack closing to 0.012 in. at end of construction. USED WITH PERMISSION OF TRI-MET