On energy-based seismic analysis and design of highway bridges.

摘要

Current seismic design of bridge piers relies on empirical code-based formulations to ensure ductile behavior. These formulations give no indication as to failure modes or how seismic performance may be improved by better design. Therefore, a systematic investigation traces all potential failure modes of columns (confinement, buckling and shear) using a fatigue based approach. Design recommendations are given for new bridge structures that should lead to improved performance. These recommendations are also compared with existing ones and critiqued.; Although the recommendations are mainly directed towards new construction, a potential application of them could be in retrofit design as well. As part of the current research a novel retrofit methodology is proposed that not only ensures superior performance but also easy repairability following an earthquake. This technique is verified against near full scale experimentation on circular bridge columns.; Most existing bridges in the United States, however, were built without due regard to their potential seismic risk. In order to assess the severity of that risk it is also necessary to have theoretical models that accurately predict failure modes and functional limit states. Hence a 3D elasto-plastic analysis is advanced for the purpose of rapidly assessing the seismic vulnerability of large number of bridges with limited data, such as that given by an owner's bridge management system. When coupled with a capacity-spectrum analysis and Monte Carlo simulations, fragility curves for various possible damage states are established. The analysis methodology is verified with limited data obtained from recent Californian earthquakes.