LATERAL IMPACT OF RAILROAD BRIDGES WITH HYBRID COMPOSITE BEAMS: FINITE ELEMENT MODELING AND PRELIMINARY DYNAMIC BEHAVIOR STUDY OF HCB

摘要

Grade separations have been used along High-Speed Rail (HSR) to decrease traffic congestion and the danger that occurs at grade crossings. However, the concern with grade separations is the potential damage due to lateral impact of bridge superstructures by over-height vehicles. This is a concern with existing bridges, and lateral impact is not included in standard bridge code provisions. A new bridge technology, Hybrid Composite Beam (HCB), was proposed to meet the requirements of another HSR objective, that of a sustainable solution for the construction of new and replacement bridges in rail infrastructure. The hybrid composite beam combines advanced composite materials with conventional concrete and steel to create a bridge that is stronger and more resistance to corrosion than conventional materials. The HCB is composed of three main parts; the first is a FRP (fiber reinforced polymer) shell, which encapsulates the other two parts. The second part is the compression reinforcement which consists of concrete or cement grout that is pumped into a continuous conduit fabricated into the FRP shell. The third part of the HCB is the tension reinforcement that could consist of carbon or glass fibers, prestressed strands, or other materials that are strong in tension, which is used to equilibrate the internal forces in the compression reinforcement. The combination of conventional materials with FRP exploits the inherent benefits of each material and optimizes the overall performance of the structure. The behavior of this novel system has been studied during the last few years and some vertical static tests have been performed, but no dynamic or lateral impact tests have been conducted yet. Therefore, the main objective of this study is to evaluate the performance of HCB when subjected to lateral impact loading caused by over-height vehicles. This paper explains the advantages of HCB when used in bridge infrastructures. The commercial software ABAQUS was used to perform the finite element (FE) modeling of a 30ft long HCB. Test data was used to validate the results generated by FE analysis. A constant impact loading with a time duration of 0.1 second was applied to an area at the mid-span of the HCB. Lateral deflection and stress distribution were obtained from FE analysis, and local stress concentration can be observed from the stress contour. Full-scale beam dynamic testing will be conducted in the future research to better study the behavior of HCB when subjected to over-height vehicles.