Numerical investigation of seismic performance of bridge piers with spread footings considering pier plastic hinging and footing rocking, sliding, and settlement

In this study, we conducted numerical parametric analyses to investigate the seismic performance of a bridge pier with a spread footing on dense sandy ground. For the numerical model, we considered plastic hinging in the pier and foundation rocking, sliding, settlement, and embedment. The investigated parameters included pier height, footing width, excitation intensity and type, and footing embedment. With an increase in the pier height-tofoundation width ratio, the rocking response became more pronounced. The direction of the foundation's permanent tilt was highly dependent on that of the maximum foundation rotation. Near-fault pulse-like ground motions destabilized a system easily. In addition, the maximum drift ratio of the pier and the maximum rotation and settlement of the footing were highly dependent on the minimum contact area. Thus, the ratio of minimum contact area to footing base area (minimum contact area ratio) is an important index for evaluating the performance and stability of the model. When the minimum contact area ratio exceeded 30%, the overall performance of the pier-footing system was suitable; by contrast, when it was below 30%, the drift ratio of the pier and rotation of footing dramatically increased, influencing the system stability.