Analytical Simulation of Vehicular Impact on Retrofit Bridge Barriers

This is one of two theses addressing the first phase of TxDOT Study 4823, whose goal is to develop a retrofit design for existing cast-in-place vehicular impact barriers. To ensure structural integrity and acceptability, such barriers must be subjected to both static and dynamic testing, as specified by the Federal Highway Administration (FHWA) requirements, which require that bridge rails conform to the testing standards and performance requirements outlined in the National Highway Cooperative Research Program (NCHRP) Report 350. In this project, finite element analyses and pendulum tests are used to evaluate the behavior of the cast-in-place T203 deformable barrier and the retrofit design for that same barrier. Working in conjunction with the experimental tests and NCHRP guidelines, good finite element models have been developed for studying vehicular impact and designing retrofit barriers. These models include the castin- place and retrofit barriers, the laboratory pendulum and associated crush package, and the use of pre-existing vehicle models. Experimental tests using a real laboratory pendulum impacting a rigid barrier, and analytical verifications of those pendulum tests, also show that the laboratory pendulum satisfies NCHRP standards based upon impact energy and the area under the force-time histories for the impact tests. The proposed testing procedure, including a refined crush package, should be implemented for crash tests. The response of the cast-in-place and the retrofit barriers to pendulum impact should be tested experimentally and simulated analytically. The retrofit design should be modified appropriately based on those test results. Finally, more advanced crash simulations can be created for the selected retrofit design to explore various initial impact conditions and vehicle responses such as snagging and rollover. After suitable retrofit bridge rail designs are developed as recommended above, they should be presented to TxDOT for implementation.