Seismic Performance of the Wall Pier of Covered Bridge in the Weak Direction

This study aims to establish finite element models to investigate the seismic performance of typical wall piers used in beam-type covered bridges. The impacts of the mesh sensitivity and load pattern of the selected multi-layer shell element model on the out-of-plane seismic performance are evaluated, and comparisons with the seismic behaviors captured by a force-based beam–column element model are conducted. An analysis is carried out to determine the displacement ductility ratios in each damage state. The applicability of the limit values of the out-of-plane damage states reported in previous studies is assessed and validated. The results showed that in practice, no great improvement can be achieved through the addition of additional elements, from the comprehensive perspective of the global force‒displacement curves. Nevertheless, the pattern of loading is vital to the seismic performance of a wall pier, and a wall pier installed with three bearings is assumed to be more favorable for a covered bridge subjected to earthquake forces. The multi-layer shell element model is more applicable than the force-based beam–column element model for characterizing the seismic performance at the local positions of the wall piers under different lateral loading patterns. There is a limited divergence in the displacement ductility ratios of at the local position of a wall pier under the application of two different lateral loads in the same damage state. This finding verifies the feasibility of using the limit values of conventional column piers for out-of-plane wall piers in various damage states. The critical values for damage state division for the wall pier of interest can be taken to be 0.27, 1.00, 2.33 and 5.33.