Effect of seat-type abutment load path and failure mode on seismic response of straight ordinary bridges

摘要

The simplified modeling and analysis procedures commonly used in the design and assessment of bridges utilize one-dimensional (1D) spine elements and springs. These procedures have been well vetted for columns and some capacity-protected members, such as the girders. However, the abutment also contributes to the lateral load resisting system, and the simplified models may not capture the actual load path, failure modes, or dynamic response of either the bridge system or the abutment itself. This paper identifies through static three-dimensional continuum modeling the load path, component contributions to subsystem resistance, and failure modes that should be used in simplified modeling approaches of seat-type abutments. The consequences of common modeling assumptions and simplifications on bridge design and assessment were determined by comparison with 1D simplified models. It was found that the use of modeling simplification substantially underestimates the subsystem resistance. The effect of abutment characteristics, including stiffness and strength in the longitudinal and transverse directions, on nonlinear dynamic bridge seismic demand prediction were investigated with reduced order dynamic models. The increase in abutment stiffness and strength reduces the bridge system's displacements and increase forces significantly.