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From page 113... ... B-1 A P P E N D I X B Design Examples B1 DESIGN EXAMPLE 1 Application This design example addresses estimating normal wind loads for strength design and fatigue design for an overhead bridge-type monotube structure supporting two traffic signs. Information • Length of monotube: Lt = 80 ft • Diameter of monotube: dtube = 3.5 ft (circular cross-section) Read the entire page →
From page 114... ... B-2 Wind Drag Coefficients for Highway Signs and Support Structures • Signs: Kds = 0.85 • Monotube: Kdm = 0.85 Loads on the signs Using the proposed methodology Sign 1: b1/h1 = 3.75, h1/(h1 + hg1) = 0.29, As1 = b1h1 = 240 ft2 Use Figure 3.1 to get Cd0s1 = 1.22 Sign 2: b2/h2 = 2, h2/(h2 + hg2) Read the entire page →
From page 115... ... Design Examples B-3 Drag coefficient for the isolated monotube: Re = 9200Vdtube = 3.7 × 106 (using units of mph for V) AR = Lt/dtube = 22.9 Use Figure 3.7 to get Cd0t = 0.37 Lengths and drag coefficients for Zones 1 to 8 (Figure B1) Read the entire page →
From page 116... ... B-4 Wind Drag Coefficients for Highway Signs and Support Structures B1.2 Estimation of Wind Loads for Fatigue Design B1.2.1 Natural wind gust The equivalent static natural wind gust pressure is calculated by assuming IF = 1 (Importance Category I, overhead non-cantilevered sign support) Read the entire page →
From page 117... ... Design Examples B-5 • Zone 7: Flow-acceleration region L7 = 6.8 ft, Km,7 = 2, CdNWt,7 = Km,7Cd0NWt = 1.0, PNWt,7 = 5.2CdNWt,7IF = 5.2 psf • Zone 8: Uniform-flow region L8 = 11.15 ft, Km,8 = 1, CdNWt,8 = Km,8Cd0NWt = 0.50, PNWt,8 = 5.2CdNWt,8IF = 2.6 psf Using the current AASHTO specifications Estimation of static natural wind gust pressure acting on monotube, based on current AASHTO specifications (Table 3.8.7-1 in LRFDLTS-1) : Cv = 0.8 for the extreme limit state (load combination that includes wind) Read the entire page →
From page 118... ... B-6 Wind Drag Coefficients for Highway Signs and Support Structures Using the proposed methodology ReTG = 9200VTGdtube = 2.1 × 106 AR = Lt/dtube = 22.9 Use Figure 3.7 to get Cd0TGt = 0.37 Using the same analysis as the one performed in Section B1.1, determine the length of each zone and the drag coefficients for Zones 1 to 8, CdTGt (Figure B1) Read the entire page →
From page 119... ... Design Examples B-7 B2 DESIGN EXAMPLE 2 Application This design example addresses estimating normal and transverse wind loads for an overhead bridge-type 3-chord truss structure supporting one dynamic message sign. The vertical columns (posts) Read the entire page →
From page 120... ... B-8 Wind Drag Coefficients for Highway Signs and Support Structures Note: The sketches show elevation views looking toward the front of the truss. The back chord of the truss is not shown. Read the entire page →
From page 121... ... Design Examples B-9 Height and exposure factor: Kz = 1 Wind directionality factor (Table 3.8.5-1 in LRFDLTS-1) : • Sign: Kds = 0.85 • Chord members: Kdc = 0.85 • Secondary truss members: Kdt = 0.85 • Column (post) Read the entire page →
From page 122... ... B-10 Wind Drag Coefficients for Highway Signs and Support Structures L3 = b = 36 ft Km3H1 = 0, Cd3H1 = 0 Km3H2 = 0, Cd3H2 = 0 Calculate: L1-2 = L4-5 = (Lc − b) /2 = 32 ft (Figure B4) Read the entire page →
From page 123... ... Design Examples B-11 Km2H3 = 1.4, Cd2H3 = Km2H3CduH3 = 0.756 • Zone 1': Uniform-flow region L1' = L1-2 − L2' = 32 − 11 = 21 ft Km1H3 = 1, Cd1H3 = Km1H3CduH3 = 0.54 • Zone 4': Flow-acceleration region L4' = 0.75(bh) 0.5, so L4' = 11 ft Km4H3 = 1.4, Cd4H3 = Km4H3CduH3 = 0.756 • Zone 5': Uniform-flow region L5' = L4-5 − L4' = 32 − 11 = 21 ft Km5H3 = 1, Cd5H3 = Km5H3CduH3 = 0.54 Wind load acting on chord H3: FH3 = 0.00256V2KzKdcG = 0.00256V2KzKdcG = 645 lbf Using the current AASHTO specifications (Table 3.8.7-1 in LRFDLTS-1) Read the entire page →
From page 124... ... B-12 Wind Drag Coefficients for Highway Signs and Support Structures Note: The figure also displays the approximate position of the five zones (Zone m1 to Zone m5) to which secondary members are assigned. Read the entire page →
From page 125... ... Design Examples B-13 • Zone m2: Flow-acceleration region Lm2 = 0.65(bh) Read the entire page →
From page 126... ... B-14 Wind Drag Coefficients for Highway Signs and Support Structures 14 A13 Flow-acceleration region 0.65 5.5 2.31 49.2 15 A14 11 4.62 98.5 16 A15 5.5 2.31 39.4 17 A16 Uniform-flow region 0.52 11 4.62 78.8 18 A17 5.5 2.31 39.4 19 A18 11 4.62 78.8 Index i Member Region Cdm,Bi Lmt,Bi (ft) Read the entire page →
From page 127... ... Design Examples B-15 16 C15 27.6 17 C16 23.6 18 C17 Uniform-flow region 0.312 5.5 2.31 23.6 19 C18 23.6 20 C19 23.6 Wind loads acting on the secondary members of Groups A to C (Table B1) : Fm = = 0.00256V2KzKdtG + 0.00256V2KzKdtG + + 0.00256V2KzKdtG = 0.00256V2KzKdtG +0.00256V2KzKdtG = 1,370 lbf Table B2: Drag coefficients, projected length of secondary members, projected area of secondary members, and wind loads acting on secondary members along wind direction (estimated based on AASHTO specifications) Read the entire page →
From page 128... ... B-16 Wind Drag Coefficients for Highway Signs and Support Structures 3 B2 Unshielded region 1.10 5.5 2.31 83.4 4 B3 83.4 5 B4 83.4 6 B5 83.4 7 B6 0 8 B7 0 9 B8 0 10 B9 Shielded region 0 5.5 2.31 0 11 B10 0 12 B11 0 13 B12 0 14 B13 0 15 B14 83.4 16 B15 83.4 17 B16 Unshielded region 1.10 5.5 2.31 83.4 18 B17 83.4 19 B18 83.4 20 B19 83.4 Index i Member Region Cdm,CiAASHTO Lmt,Ci (ft) Read the entire page →
From page 129... ... Design Examples B-17 Wind loads acting on the secondary members of Groups A to C (Table B2) : FmAASHTO = = 0.00256V2KzKdtG + 0.00256V2KzKdtG + 0.00256V2KzKdtG = 0.00256V2KzKdtG + 0.00256V2KzKdtG + 0.00256V2KzKdtG = 3,501 lbf Difference between the proposed and the current specifications (Fm − FmAASHTO) Read the entire page →
From page 130... ... B-18 Wind Drag Coefficients for Highway Signs and Support Structures B2.2 Estimation of Wind Loads if Wind Is Parallel to the Sign and the Plane of the Support Structure (Transverse Wind Loads) The incoming wind is assumed to be oriented from left to right in Figures B2, B5, and B6. Read the entire page →
From page 131... ... Design Examples B-19 Lengths and drag coefficients for all secondary members (Figure B5) : Assign the secondary members exposed to the wind (A0, B0, C0) Read the entire page →
From page 132... ... B-20 Wind Drag Coefficients for Highway Signs and Support Structures 4 B3 23.5 5 B4 23.5 6 B5 23.5 7 B6 23.5 8 B7 23.5 9 B8 Shielded region 0.31 5.5 2.31 23.5 10 B9 23.5 11 B10 23.5 12 B11 23.5 13 B12 23.5 14 B13 23.5 15 B14 23.5 16 B15 23.5 17 B16 23.5 18 B17 23.5 19 B18 23.5 20 B19 23.5 Index i Member Region Cdm,Ci Lmt,Ci (ft) Read the entire page →
From page 133... ... Design Examples B-21 Wind loads acting on secondary members of Groups A to C (Table B3) : Fm = = 0.00256V2KzKdtG + 0.00256V2KzKdtG + 0.00256V2KzKdtG = 0.00256V2KzKdtG + 0.00256V2KzKdtG + 0.00256V2KzKdtG = 1,434 lbf Loads on the column-to-truss connections Drag coefficient for the column-to-truss connection: Cdctc = 1.7 (for flat members, use Table 3.8.7-1 in LRFDLTS-1) Read the entire page →
From page 134... ... B-22 Wind Drag Coefficients for Highway Signs and Support Structures B3 DESIGN EXAMPLE 3 Application This design example shows how to estimate normal wind loads for a cantilever-type 4-chord truss structure supporting two traffic signs. The example considers the wind loads on the gusset plates. Read the entire page →
From page 135... ... Design Examples B-23 Note: Some of the main geometrical variables are indicated in the figure. Figure B8: Design plans for the cantilever-type 4-chord truss Read the entire page →
From page 136... ... B-24 Wind Drag Coefficients for Highway Signs and Support Structures Notes: The members are distributed in five groups (A to E) Read the entire page →
From page 137... ... Design Examples B-25 Note: The figure also shows the lengths of the different zones defined for the front-face chords (Zone 1 to Zone 7) and for the back-face chords (Zone 1' to Zone 7') Read the entire page →
From page 138... ... B-26 Wind Drag Coefficients for Highway Signs and Support Structures Effect of sign support structure: 2dc/h1 = 0.112 > 0.1, Ks1 = 1.04 2dc/h2 = 0.112 > 0.1, Ks2 = 1.04 Drag coefficients for the signs: Cds1 = Kt1Ka1Kp1Ks1Cd0s1 = 1.33 Cds2 = Kt2Ka2Kp2Ks2Cd0s2 = 1.33 Estimation of wind loads acting on the two signs (using units of mph for V) : Fs1 = 0.00256V2KzKdsGCds1As1 = 4,363 lbf Fs2 = 0.00256V2KzKdsGCds2As2 = 4,363 lbf Using the current AASHTO specifications (Table 3.8.7-1 in LRFDLTS-1) Read the entire page →
From page 139... ... Design Examples B-27 • Zone 4: Gap region associated with Sign 2 L4 = s/2 = 4 ft, L4/(b2h2) Read the entire page →
From page 140... ... B-28 Wind Drag Coefficients for Highway Signs and Support Structures • Zone 1': Flow-acceleration region L1' = 0.5 ft and L1'/(b1h1) 0.5 = 0.05 < 0.75 so there is no uniform-flow region near the left free end Km1H3 = 1.6, Cd1H3 = Km1H3CduH3 = 0.53 Km1H4 = 1.6, Cd1H4 = Km1H4CduH4 = 0.48 • Zone 3': Gap region associated with Sign 1 L3' = s/2 = 4 ft, L3'/(b1h1) Read the entire page →
From page 141... ... Design Examples B-29 Note: The figure shows the approximate positions of the six zones (Zone m1 to Zone m6) to which secondary members are assigned. Read the entire page →
From page 142... ... B-30 Wind Drag Coefficients for Highway Signs and Support Structures Use Figure 3.7 to get Cd0t = Cd0t1 = Cd0t2 = Cd0t3 ≈ 0.55 Lengths and drag coefficients for Zone m1 to Zone m6 for all secondary members (Figure B12) : Each secondary member is assigned to a zone (Zone m1 to Zone m6 in Figure B12) Read the entire page →
From page 143... ... Design Examples B-31 Km5b = 1.2, Cd5b = Km5bCd0t = 0.66 (B14, B16) More than 35% of B14 is in the flow-acceleration region Km5c = 0.3, Cd5c = Km5cCd0t = 0.17 (C15, C17) Read the entire page →
From page 144... ... B-32 Wind Drag Coefficients for Highway Signs and Support Structures 2 B2 Behind-the-sign region 0 8.7 2.08 0 3 B4 5.4 1.30 0 4 B6 Gap region 0.72 8.7 2.08 49.3 5 B8 5.4 1.30 30.6 6 B10 Behind-the-sign region 0 8.7 2.08 0 7 B12 5.4 1.30 0 8 B14 Flow-acceleration region 0.66 8.7 2.08 45.2 9 B16 5.4 1.30 28.0 10 B18 Uniform-flow region 0.39 8.7 2.08 26.7 11 B20 5.4 1.30 16.6 Index i Member Region Cdm,Ci Lmt,Ci (ft) Read the entire page →
From page 145... ... Design Examples B-33 11 D10 -- -- 0 12 D11 Behind-the-sign region 0 2.5 0.60 0 13 D12 -- -- 0 14 D13 2.5 0.60 0 15 D14 0 -- -- 0 16 D15 Flow-acceleration region 0.17 2.5 0.60 3.3 17 D16 0 -- -- 0 18 D17 0.17 2.5 0.60 3.3 19 D18 0 -- -- 0 20 D19 Uniform-flow region 0.17 2.5 0.60 3.3 21 D20 0 -- -- 0 Index i Member Region Cdm,Ei Lmt,Ei (ft) Read the entire page →
From page 146... ... B-34 Wind Drag Coefficients for Highway Signs and Support Structures 5 A8 5.4 1.30 46.9 6 A10 Shielded region 0 8.7 2.08 0 7 A12 5.4 1.30 0 8 A14 8.7 2.08 75.1 9 A16 Unshielded region 1.10 5.4 1.30 46.9 10 A18 8.7 2.08 75.1 11 A20 5.4 1.30 46.9 Index i Member Region Cdm,Bi AASHTO Lmt,Bi (ft) Read the entire page →
From page 147... ... Design Examples B-35 Index I Member Region Cdm,Di AASHTO Lmt,Di (ft) Read the entire page →
From page 148... ... B-36 Wind Drag Coefficients for Highway Signs and Support Structures Note: The figure also shows the approximate positions of the five zones (Zone g1 to Zone g5) to which gusset plates are assigned. Read the entire page →
From page 149... ... Design Examples B-37 ∑6i=1 C A dgp,Pi gp,Pi Table B6: Drag coefficients, projected area of gusset plates, and wind loads acting on gusset plates (estimated using the proposed methodology) Note: Results are given for gusset plates that are part of each of the four groups (P to S) Read the entire page →
From page 150... ... B-38 Wind Drag Coefficients for Highway Signs and Support Structures Using the current AASHTO specifications (Table 3.8.7-1 in LRFDLTS-1) Assume a zero wind load for the shielded plates bgp1/hgp = 2.2 Cdgp1AASHTO = 1.20 (unshielded region) Read the entire page →
From page 151... ... Design Examples B-39 4 S12 Shielded region 0 0.55 0 5 S16 Unshielded region 1.20 0.55 21.6 6 S20 1.19 0.35 13.7 Wind loads acting on the gusset plates of Groups P, Q, R, and S (Table B7) : FgpAASHTO = = 0.00256V2KzKdgG +0.00256V2KzKdgG +0.00256V2KzKdgG +0.00256V2KzKdgG = 243 lbf Difference between the proposed and the current specifications (Fgp − FgpAASHTO) Read the entire page →
From page 152... ... B-40 Wind Drag Coefficients for Highway Signs and Support Structures B4 DESIGN EXAMPLE 4 Application This design example shows how to estimate normal wind loads for an overhead bridge-type monotube structure supporting two traffic signs. Information • Length of monotube: Lt = 90 ft • Diameter of monotube: dtube = 4.0 ft (circular cross-section) Read the entire page →
From page 153... ... Design Examples B-41 Loads on the Signs Using the proposed methodology Sign 1: Sign 1 is equivalent to a rectangular sign with b1 = bm1 and h1 = (bm1hm1 + ba1ha1) Read the entire page →
From page 154... ... B-42 Wind Drag Coefficients for Highway Signs and Support Structures Difference between the proposed and the current specifications (Fs1 − Fs1AASHTO) Read the entire page →
From page 155... ... Design Examples B-43 (Fm − FmAASHTO) /FmAASHTO = 18% Total wind load acting on the monotube and the two signs Using the proposed methodology Total wind load acting on the monotube and the two signs: F = Fs1 + Fs2 + Fm = 13,039 + 1,653 + 3,621 = 18,313 lbf Using the current AASHTO specifications FAASHTO = Fs1AASHTO + Fs2AASHTO + FmAASHTO = 10,865 + 1,323 + 3,070 = 15,258 lbf Difference between the proposed and current specifications (F − FAASHTO) Read the entire page →
From page 156... ... B-44 Wind Drag Coefficients for Highway Signs and Support Structures Figure B15: Sketch of the monotube supporting the three highway signs, showing the nine zones for which drag coefficients need to be determined B5 DESIGN EXAMPLE 5 Application This design example shows how to estimate normal wind loads for strength design and for fatigue design for an overhead bridge-type monotube structure supporting three traffic signs. Information • Length of monotube: Lt = 90 ft • Diameter of monotube: dtube = 3.0 ft (circular cross-section) Read the entire page →
From page 157... ... Design Examples B-45 Loads on the signs Using the proposed methodology Sign 1: b1/h1 = 1, h1/(h1 + hg1) = 0.49, As1 = b1h1 = 400 ft2 Use Figure 3.1 to get Cd0s1 = 1.22 Static Sign 2: b2/h2 = 3, h2/(h2 + hg2) Read the entire page →
From page 158... ... B-46 Wind Drag Coefficients for Highway Signs and Support Structures Using the current AASHTO specifications (Table 3.8.7-1 in LRFDLTS-1) Sign 1: b1/h1 = 1 Cds1AASHTO = 1.12 Fs1AASHTO = 0.00256V2KzKdsGCds1AASHTOAs1 = 14,697 lbf Static sign 2: b2/h2 = 3 Cds2AASHTO = 1.20 Fs2AASHTO = 0.00256V2KzKdsGCds2AASHTOAs2 = 4,251 lbf Dynamic Message Sign 3: Cds3AASHTO = 1.70 Fs3AASHTO = 0.00256V2KzKdsGCds3AASHTOAs3 = 15,614 lbf Difference between the proposed and the current specifications (Fs1 − Fs1AASHTO) Read the entire page →
From page 159... ... Design Examples B-47 L7 = (s2-m + sm-3) /2= 3.75 ft, h3/dtube = 2.6 < 15, L7/(b3h3) Read the entire page →
From page 160... ... B-48 Wind Drag Coefficients for Highway Signs and Support Structures PNWs2 = 5.2CdNWs2IF = 8.32 psf PNWs3 = 5.2CdNWs3IF = 8.48 psf Using the current AASHTO specifications Estimation of drag coefficients for each sign based on current AASHTO specifications (Table 3.8.7-1 in LRFDLTS-1) : CdNWs1AASHTO = Cds1AASHTO = 1.12 CdNWs2AASHTO = Cds2AASHTO = 1.20 CdNWs3AASHTO = Cds3AASHTO = 1.70 PNWs1AASHTO = 5.2CdNWs1AASHTOIF = 5.82 psf PNWs2AASHTO = 5.2CdNWs2AASHTOIF = 6.24 psf PNWs3AASHTO = 5.2CdNWs3AASHTOIF = 8.84 psf Loads on the sign support structure Using the proposed methodology ReNW = 9200VNWdtube = 3.1 × 105 AR = Lt/dtube = 30 Use Figure 3.7 to get Cd0NWt = 0.51 Using the same analysis as that in Section B5.1, the length of each zone and drag coefficients for Zones 1 to 9, CdNWt (Figure B15) Read the entire page →
From page 161... ... Design Examples B-49 Static natural wind gust pressures acting on Zones 1 to 9 of the monotube: PNWt,1AASHTO = 5.72 psf PNWt,2AASHTO = 0 PNWt,3AASHTO = 5.72 psf PNWt,4AASHTO = 5.72 psf PNWt,5AASHTO =0 PNWt,6AASHTO = 5.72 psf PNWt,7AASHTO = 5.72 psf PNWt,8AASHTO =0 PNWt,9AASHTO = 5.72 psf B5.2.2 Truck-induced gust The equivalent static truck gust pressure is calculated by assuming IF = 1 (Importance Category I, overhead non-cantilevered sign support) Read the entire page →
From page 162... ... B-50 Wind Drag Coefficients for Highway Signs and Support Structures • Zone 1: Flow-acceleration region L1 = 2.5 ft, Km,1 = 2, CdTGt,1 = Km,1Cd0TGt = 0.74, PTGt,1 = 18.8CdTGt,1IF = 13.91 psf • Zone 2: Behind-the-sign region L2 = 20 ft, Km,2 = 0, CdTGt,2 = Km,2Cd0TGt = 0, PTGt,2 = 18.8CdTGt,2IF = 0 • Zone 3: Gap region associated with Sign 1 L3 = 1 ft, Km,3 = 1, CdTGt,3 = Km,3Cd0TGt = 0.37, PTGt,3 = 18.8CdTGt,3IF = 6.96 psf • Zone 4: Gap region associated with Sign 2 L4 = 1 ft, Km,4 = 1, CdTGt,4 = Km,4Cd0TGt = 0.37, PTGt,4 = 18.8CdTGt,4IF = 6.96 psf • Zone 5: Behind-the-sign region L5 = 18 ft, Km,5 = 0, CdTGt,5 = Km,5Cd0TGt = 0, PTGt,5 = 18.8CdTGt,5IF = 0 • Zone 6: Gap region associated with Sign 2 L6 = 3.75 ft, Km,6 = 2, CdTGt,6 = Km,6Cd0TGt = 0.74, PTGt,6 = 18.8CdTGt,6IF = 13.91 psf • Zone 7: Gap region associated with Sign 3 L7 = 3.75 ft, Km,7 = 1.6, CdTGt,7 = Km,7Cd0TGt = 0.59, PTGt,7 = 18.8CdTGt,7IF = 11.13 psf • Zone 8: Behind-the-sign region L8 = 35 ft, Km,8 = 0, CdTGt,8 = Km,8Cd0TGt = 0, PTGt,8 = 18.8CdTGt,8IF = 0 • Zone 9: Flow-acceleration region L9 = 5 ft, Km,9 = 2, CdTGt,9 = Km,9Cd0TGt = 0.74, PTGt,9 = 5.2CdTGt,9IF = 13.91 psf Using the current AASHTO specifications Estimation of truck-induced gust pressure acting on the monotube based on current AASHTO specifications (Table 3.8.7-1 in LRFDLTS-1) : Cv = 0.8 for the extreme limit state (load combination that includes wind) Read the entire page →
From page 163... ... Design Examples B-51 B6 DESIGN EXAMPLE 6 Application This design example shows how to estimate normal wind loads for a traffic sign attached to a grade separation structure that includes a barrier rail (Configuration 1, as shown in Figure B16) or a separation rail (Configuration 2, as shown in Figure B17) Read the entire page →
From page 164... ... B-52 Wind Drag Coefficients for Highway Signs and Support Structures B16b: Side view showing wind loads for case when wind is directed toward the front face of the sign B16c: Side view showing wind loads for case when wind is directed toward the back face of the sign Figure B16: Sketch of the traffic sign placed on a grade separation structure with a barrier rail (Configuration 1) , showing the three subzones for which drag coefficients need to be determined Case 1: Wind is directed toward the front face of the sign Using the proposed methodology b/h = 2, h/(h + h0 + hg) Read the entire page →
From page 165... ... Design Examples B-53 Fmz = 0.00256V2KzKdsGCdmzAm = 7,441 lbf Fuz = 0.00256V2KzKdsGCduzAu = 10,039 lbf Total wind load acting on the sign: Fs = Flz + Fmz + Fuz = 24,517 lbf Using the current AASHTO specifications (Table 3.8.7-1 in LRFDLTS-1) Static sign: b/h = 2 CdsAASHTO = 1.19 FsAASHTO = 0.00256V2KzKdsGCdsAASHTOAs = 17,567 lbf Difference between the proposed and the current specifications (Fs − FsAASHTO) Read the entire page →
From page 166... ... B-54 Wind Drag Coefficients for Highway Signs and Support Structures B17a: Front view B17b: Side view showing wind loads for case when wind is directed toward the front face of the sign B17c: Side view showing wind loads for case when wind is directed toward the back face of the sign Figure B17: Sketch showing the traffic sign placed on a grade separation structure with a separation rail (Configuration 2) , showing the three subzones for which drag coefficients need to be determined Case 1: Wind is directed toward the front face of the sign Using the proposed methodology b/h = 2, h/(h + h0+hg) Read the entire page →
From page 167... ... Design Examples B-55 subzones: • Lower subzone hlz = hb − h0 = 5 ft Cdlz = 1.0Cd0s = 1.3 • Middle subzone hmz = hd + hbr = 4 ft Cdmz = 1.2Cd0s = 1.56 • Upper subzone huz = h − hlz − hmz = 6 ft Cduz = 1.2Cd0s = 1.56 Drag coefficient for the sign: Cds = (AlCdlz + AmCdmz + AuCduz) /As = (bhlzCdlz + bhmzCdmz + bhuzCduz) Read the entire page →
From page 168... ... B-56 Wind Drag Coefficients for Highway Signs and Support Structures Cds = (AlCdlz + AmCdmz + AuCduz) /As = (bhlzCdlz + bhmzCdmz + bhuzCduz) Read the entire page →
From page 169... ... Design Examples B-57 B7 COMPARISON BETWEEN WIND LOADS CALCULATED WITH PROPOSED METHODOLOGY AND THOSE BASED ON AASHTO LRFDLTS-1 SPECIFICATIONS Table B8 summarizes the wind loads acting on the static and dynamic message signs in the six design examples. The table contains the values calculated using the proposed methodology, Fs; the values based on the current AASHTO specifications, FsAASHTO; and the relative difference between these two predictions. Read the entire page →
From page 170... ... B-58 Wind Drag Coefficients for Highway Signs and Support Structures The values in Table B9 do not include those for wind load acting on the signs supported by the structure, which are given in Table B8. Relative differences of between −20% and −50% are observed between predictions of the total wind load acting on the whole support structure based on the proposed methodology and those based on the AASHTO specifications. Read the entire page →
From page 171... ... Abbreviations and acronyms used without denitions in TRB publications: A4A Airlines for America AAAE American Association of Airport Executives AASHO American Association of State Highway Officials AASHTO American Association of State Highway and Transportation Officials ACI–NA Airports Council International–North America ACRP Airport Cooperative Research Program ADA Americans with Disabilities Act APTA American Public Transportation Association ASCE American Society of Civil Engineers ASME American Society of Mechanical Engineers ASTM American Society for Testing and Materials ATA American Trucking Associations CTAA Community Transportation Association of America CTBSSP Commercial Truck and Bus Safety Synthesis Program DHS Department of Homeland Security DOE Department of Energy EPA Environmental Protection Agency FAA Federal Aviation Administration FAST Fixing America's Surface Transportation Act (2015) FHWA Federal Highway Administration FMCSA Federal Motor Carrier Safety Administration FRA Federal Railroad Administration FTA Federal Transit Administration GHSA Governors Highway Safety Association HMCRP Hazardous Materials Cooperative Research Program IEEE Institute of Electrical and Electronics Engineers ISTEA Intermodal Surface Transportation Efficiency Act of 1991 ITE Institute of Transportation Engineers MAP-21 Moving Ahead for Progress in the 21st Century Act (2012) Read the entire page →
From page 172... ... Transportation Research Board 500 Fifth Street, NW Washington, DC 20001 ADDRESS SERVICE REQUESTED ISBN 978-0-309-69825-2 9 7 8 0 3 0 9 6 9 8 2 5 2 9 0 0 0 0 Read the entire page →

From page 113...

... B-1 A P P E N D I X B Design Examples B1 DESIGN EXAMPLE 1 Application This design example addresses estimating normal wind loads for strength design and fatigue design for an overhead bridge-type monotube structure supporting two traffic signs. Information • Length of monotube: Lt = 80 ft • Diameter of monotube: dtube = 3.5 ft (circular cross-section)