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From page 33... ... 33 During the survey process, agencies were asked to provide load rating examples for bridges that are missing as-built information. In response, 13 agencies described a total of 24 examples of various bridge types with a wide range of ages, condition states, and load rating methodologies. Read the entire page →
From page 34... ... 34 Load Rating of Bridges and Culverts with Missing or Incomplete As-Built Information Load Rating Methodology and Summary The Colorado Department of Transportation publishes its own CDOT Bridge Rating Manual [61] , and the agency provided a copy of its April 2011 publication, in effect when this example of load rating was performed in September 2011. Read the entire page →
From page 35... ... Case Examples 35 Bridge Description is prestressed concrete slab bridge is located on the east side of San Francisco, CA, and carries Mariposa Street over two lines of railroad tracks, with I-280 crossing overhead. Built in 1968, this bridge is 106 feet long, with two simple rated spans, each 48 feet long. Read the entire page →
From page 36... ... 36 Load Rating of Bridges and Culverts with Missing or Incomplete As-Built Information Figure 11. Design load per year of design in California. Read the entire page →
From page 37... ... Case Examples 37 The NBI superstructure condition rating was set at 6. At the time of the provided load rating example, no essential repairs were necessary, and no damage signicant enough to aect the load rating was noted. Read the entire page →
From page 38... ... 38 Load Rating of Bridges and Culverts with Missing or Incomplete As-Built Information ODOT is more descriptive when considering the long service history of a bridge carrying legal loads without distress, dening a long history of service as 20 years or more. If a bridge satises this criterion, the assumption is that the safe capacity equals the worst load eect of the legal loads (up to the SU4 vehicle) Read the entire page →
From page 39... ... Case Examples 39 Case Example #4 Bridge Type: Reclaimed Concrete T-Beam Year Built: 1960 Controlling Span Length: 34 feet 6 inches Number of Spans: 1 Location: Idaho Bridge No./Name: X996260 100.30 Rating Procedure: RE Posted Bridge: Yes NBI Code, Item 63: Field Eval/Eng Judge (0) NBI Code, Item 65: Field Eval/Eng Judge (0) Read the entire page →
From page 40... ... 40 Load Rating of Bridges and Culverts with Missing or Incomplete As-Built Information and documented. If the required details to perform a load rating cannot be acquired, a load rating by engineering judgment is performed for an HS truck, with particular focus on the NBI condition ratings issued during inspection reports. Read the entire page →
From page 41... ... Case Examples 41 Figure 20. Recommended load posting in Idaho case example. Read the entire page →
From page 42... ... 42 Load Rating of Bridges and Culverts with Missing or Incomplete As-Built Information Case Example #5 Bridge Type: Masonry Arch Year Built: 1901 Controlling Span Length: 20 feet Number of Spans: 3 Location: Rhode Island Bridge No./Name: 38801 Rating Procedure: FH Posted Bridge: No NBI Code, Item 63: Allowable Stress (2) NBI Code, Item 65: Allowable Stress (2) Read the entire page →
From page 43... ... Case Examples 43 is set on top of an arch structure. is arch structure appears to be the east barrel (#3) Read the entire page →
From page 44... ... 44 Load Rating of Bridges and Culverts with Missing or Incomplete As-Built Information Load Rating Methodology and Summary e Rhode Island Department of Transportation (RIDOT) publishes its Bridge Load Rating Guidelines for load rating bridges in the state [70] Read the entire page →
From page 45... ... Case Examples 45 Because of the age, construction method, and materials associated with this bridge, several reference documents were consulted during the development of a load rating method, including the following critical references: • AASHTO MBE, 2nd Edition, 2010 (with 2011 interim revisions and revisions to Article 6A.4 per the 2012 AASHTO Bridge Committee Agenda Item 1) • AASHTO Manual for Condition Evaluation of Bridges (MCEB) Read the entire page →
From page 46... ... 46 Load Rating of Bridges and Culverts with Missing or Incomplete As-Built Information Figure 25. Earth pressures on culvert in Rhode Island case example. Read the entire page →
From page 47... ... Case Examples 47 by each truck. Once the live load and dead load eects were both quantied for a given truck, these values were compared to the capacity of the arch segments by using a simple stress block analysis, nding that no posting was needed. Read the entire page →
From page 48... ... 48 Load Rating of Bridges and Culverts with Missing or Incomplete As-Built Information Chapter 7 of its 2019 publication. Section 7.2.5.5 addresses bridges with missing information, stating that engineering judgment alone is not acceptable for rating superstructure elements. Read the entire page →
From page 49... ... Case Examples 49 uniform throughout the walls and slab. e GPR testing was useful on several fronts. Read the entire page →
From page 50... ... 50 Load Rating of Bridges and Culverts with Missing or Incomplete As-Built Information CME Associates performed an initial load rating, using AASHTOWare Bridge Rating Version 6.8 and considering the bridge as a rigid frame structure. Under this assumption, the walls of the structure fared poorly, with a rating factor of 0.37, while the top slab rating factor was 3.44 when considering an HS-20 loading. Read the entire page →
From page 51... ... Case Examples 51 Figure 34. Exposed reinforcement measured for diameter in Massachusetts case example. Read the entire page →
From page 52... ... 52 Load Rating of Bridges and Culverts with Missing or Incomplete As-Built Information Figure 36. Typical open joint between frames in Massachusetts case example. Read the entire page →
From page 53... ... Case Examples 53 All of these assumptions, plus the dimensions of the bridge, were entered into AASHTO Culvert LFR Engine Version 6.8.2, which analyzed the bridge for carrying all legal loads, the design load, and the EV and SHV loads, producing the satisfactory load ratings for vehicles listed in Figure 37. Case Example #7 Bridge Type: Prestressed Concrete Slab Units Year Built: Mid-1960s Span Length: 25 feet Number of Spans: 3 Location: Florida Bridge No./Name: Hillsboro Canal Bridge Rating Procedure: FT Posted Bridge: No NBI Code, Item 63: Field Testing (4) Read the entire page →
From page 54... ... 54 Load Rating of Bridges and Culverts with Missing or Incomplete As-Built Information length of the bridge was 78 feet 6 inches, and it carried a private access road over the Hillsboro Canal. e slab units were almost identical in length from one span to the next, measuring (from south to north) Read the entire page →
From page 55... ... Case Examples 55 goal of the test was verifying that the bridge could safely carry all Florida legal loads and the specied crane load shown in Figure 40. Because no plans existed for the bridge, the state required an initial eld visit to measure the dimensions of the bridge to develop a test setup, with the intent of proof testing the bridge. Read the entire page →
From page 56... ... 56 Load Rating of Bridges and Culverts with Missing or Incomplete As-Built Information Vehicle Type Maximum Moment (kip-feet) Span 1 Span 2 Span 3 HS-20 271.2 271.7 274.3 Tandem 348.0 348.3 350.5 FL SU2* Read the entire page →
From page 57... ... Case Examples 57 The test truck with 42 load blocks produced a moment of 499.7 kip-feet, which is 98.8% of the required moment. This test load was sufficient because the live load factor (Xp = 1.4) Read the entire page →
From page 58... ... 58 Load Rating of Bridges and Culverts with Missing or Incomplete As-Built Information 5. Place east truck adjacent to west truck in Position 2, and record gauge readings. Read the entire page →
From page 59... ... Case Examples 59 Figure 46. Longitudinal test truck positioning in Florida case example. Read the entire page →
From page 60... ... 60 Load Rating of Bridges and Culverts with Missing or Incomplete As-Built Information Figure 47. Transverse test truck positioning in Florida case example. Read the entire page →
From page 61... ... Case Examples 61 Truck Type Rating Factor Rating (tons) HS-20 1.30 46.8 Tandem 1.02 25.5 SU2 1.90 32.3 SU3 1.08 35.7 SU4 1.00 35.0 C3 1.72 48.1 C4 1.17 42.7 C5 1.22 48.8 ST5 1.37 54.7 Crane 1.08 47.5 Figure 50. Read the entire page →
From page 62... ... 62 Load Rating of Bridges and Culverts with Missing or Incomplete As-Built Information Summary The survey asked DOTs whether they could provide examples of load rating BCMI, and 13 agencies described a total of 24 case examples. The survey team selected seven case examples, presented here to illustrate the varying methods for load rating these structures, from a simple experience-based rating to the more complex field testing approach. Read the entire page →

From page 33...

... 33 During the survey process, agencies were asked to provide load rating examples for bridges that are missing as-built information. In response, 13 agencies described a total of 24 examples of various bridge types with a wide range of ages, condition states, and load rating methodologies.