NONLINEAR ASEISMIC PERFORMANCE OF LIGHTWEIGHT BRIDGE WITH CFST COMPOSITE TRUSS GIRDER AND LATTICE PIER

Based on a simplified fiber finite element model (FEM) of the second unit of Ganhaizi Bridge, this paper presents the study on the aseismic performance, piers yield order and internal force redistribution effect in plastic scope. Compared with detailed FEM, real bridge test and shaking table test, the accuracy of simplified FEM is verified. Take the extreme edge strain of concrete-filled steel tubular (CFST) columns as a criteria, the most unfavorable horizontal seismic input direction is perpendicular to the bearing connection on both ends, and the influence of vertical action should be simultaneously considered. Results indicate that the bridge is within elastic scope under design seismic ground motion. When turn into plastic stage, the main stress direction of lattice piers and composite piers are both in plane, and the axial forces increase less than the seismic intensity, while the displacements increase larger than the seismic intensity. Bending moments of composite high piers increase greater than those of short piers, which facilitate the aseismic performance of the bridge.