Retrofit Bridge Rail Design and Testing for a Historic Texas Steel Truss Bridge

Author(s):  
William Williams

The State Loop 481 steel truss bridge over the Llano River in Junction, Texas, is classified as a historic structure. The bridge is approximately 1,423 ft long and has a railing that attaches directly to the steel truss members and does not meet the current AASHTO Test Level 2 (TL-2) strength requirements. Many supporting truss members were not adequate to resist TL-2 crash force. The purpose of this research was to design a crashworthy retrofit bridge rail that met the current AASHTO TL-2 strength requirements without overstressing the supporting truss members. The new design maintains the historic appearance of the structure. This paper presents details of the new bridge rail design and an analytical procedure for determining the magnitude of force transmitted to the supporting truss members. Crushable-pipe blockouts located between the new retrofit rail design and the truss members were developed as part of this research and were used to minimize the crash force transmitted to the steel truss members. The new bridge rail design was successfully crash tested in accordance with the TL-2 requirements of NCHRP Report 350. A bridge rail expansion splice was developed for the new bridge rail design and was successfully crash tested in accordance with the Test Level 3 requirements of NCHRP Report 350. This paper presents the results of this research, details of the expansion splice, the new bridge rail design, the design procedure, and the results of the crash testing.

2017 ◽  
Vol 2642 (1) ◽  
pp. 139-146
Author(s):  
Matthew Yarnold ◽  
Stephen Salaman ◽  
Eric James

Author(s):  
Matteo Vagnoli ◽  
Rasa Remenyte-Prescott ◽  
John Andrews

Bridges are one of the most important assets of transportation networks. A closure of a bridge can increase the vulnerability of the geographic area served by such networks, as it reduces the number of available routes. Condition monitoring and deterioration detection methods can be used to monitor the health state of a bridge and enable detection of early signs of deterioration. In this paper, a novel Bayesian Belief Network (BBN) methodology for bridge deterioration detection is proposed. A method to build a BBN structure and to define the Conditional Probability Tables (CPTs) is presented first. Then evidence of the bridge behaviour (such as bridge displacement or acceleration due to traffic) is used as an input to the BBN model, the probability of the health state of whole bridge and its elements is updated and the levels of deterioration are detected. The methodology is illustrated using a Finite Element Model (FEM) of a steel truss bridge, and for an in-field post-tensioned concrete bridge.


Author(s):  
Mojdeh Asadollahi Pajouh ◽  
Robert W. Bielenberg ◽  
Jennifer D. Schmidt-Rasmussen ◽  
Ronald K. Faller

Concrete box culverts are usually installed under roadways to allow water drainage without affecting the motoring public. Culvert openings can represent a hazard on the roadside when they do not extend outside of the clear zone, and often require safety treatments in the form of roadside barriers. In this study, a modified design of Midwest Guardrail System (MGS) was evaluated for installation on a low-fill culvert with the strong-post attachment using through-bolts and epoxy anchorage through full-scale crash testing. The test installation consisted of MGS with a 31 in. top rail height, supported by W6 × 9 posts, spaced at 37½ in., attached to a low-fill culvert’s top slab with a 12 in. offset from the back of the post to the culvert headwall. Two crash tests were conducted according to the American Association of State Highway and Transportation Officials’ (AASHTO) Manual for Assessing Safety Hardware (MASH) 2016 Test Level 3 impact safety criteria. In test number CMGS-1, a 2,428-lb car impacted the MGS attached to the culvert at a speed of 61.3 mph and at an angle of 25.1°. In test number CMGS-2, a 5,013-lb pickup truck impacted the MGS attached to the culvert at a speed of 62.8 mph and an angle of 25.7°. In both tests, the vehicle was safely redirected and captured. Both tests were deemed acceptable according to TL-3 safety criteria in MASH. Recommendations were made for the safe installation of MGS atop low-fill culverts as well as transitions from the standard MGS to the culvert-mounted MGS.


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