Near-fault ground motion effects on reinforced concrete bridge columns

Characteristics of near-fault ground motions warrant special consideration due to their severe and impulsive effects on structures. These characteristics are unique compared to far-field ground motions, upon which nearly all seismic design criteria are based. The objectives of this study were to explore the shake table response of reinforced concrete, to investigate near-fault ground motion effects on reinforced concrete bridge columns subjected to near-fault ground motions, and to provide a framework for the evaluation of bridge columns near active faults. Two large-scale columns were designed and tested under a near-fault ground motion on a shake table at the University of Nevada, Reno. One column represented the current California Department of Transportation far-field design, and the other was based on the American Association of Highway and Transportation Officials provisions. The most unique measured response characteristic in both columns was the large residual displacements even under moderate motions. A new hysteresis model was developed to capture this effect and was incorporated in an analytical model. Based on this finding, a framework for the evaluation of reinforced concrete bridge columns with respect to the control of residual displacement was proposed.