SEISMIC EVALUATION OF PADMA MULTIPURPOSE BRIDGE PIER USING RESPONSE SPECTRUM ANALYSIS
The Padma Multipurpose Bridge (PMB) is a dream infrastructure to connect the southwest to northern and eastern regions of Bangladesh. It is considered one of the most challenging engineering projects in the world in terms of concept, design, management, and construction. In this study, a 3D Finite Element (FE) model of the actual PMB has been developed using a commercial computer package. Since the bridge is composed of seven repetitive (6x150m) 900mm modules made of composite steel warren truss, the FE model is idealized for a single module six-span continuous straight module. The superstructure of the bridge is separated from the substructure by the Friction Pendulum Bearing (FPB). Accounting loads from all possible sources, HL-93 vehicular live load is considered for the upper deck and Dedicated Freight Corridor (DFC) loadings are assumed for the railway where wagon loads are combined from different locomotives. To achieve accurate soil-structure interaction, p-y soil spring following API guideline was adopted to conform flexible support system. The bridge's displacement responses have been evaluated for the 475, 975, and 2475-year return periods for Service Level, Design Basis, and the Maximum Credible Earthquake (MCE), respectively.