Seismic Analysis and Design of Minpu Double-Deck Cable-Stayed Bridge

The Minpu Bridge for the Pudong Airport Expressway is a large double-deck cable-stayed bridge over the Huangpu River, Shanghai. It is also an important structure to link the local road system. The bridge has two towers, double cable planes and composite truss stiffening girder. Its substructure includes piers on drilled piles. Its spans are arranged as: 4 × 63 + 708 + 4 × 63m,with a total length of 1212m. It becomes the longest double-deck highway cablestayed bridge in the world on its completion. The basic seismic fortification intensity at bridge site is 7 degrees, and there are no specific seismic design codes for such special bridge in China. Therefore, it is very important to carry out the seismic performance study of the Minpu Bridge to ensure the seismic safety. In this paper, the dynamic response simulations of the entire bridge are undertaken on the procedure as following: The first stage is to establish a threedimensional dynamic finite element analytical model to analyze the dynamic characters and seismic response of structure by the methods of response spectrum and nonlinear time-history analysis, then to identify the vulnerable parts of the bridge and to check its seismic capacity according to the seismic performance requirements assigned by owner. Next, to propose the design revision or to develop seismic damping and isolation measures such as viscous dampers parameters and girder-pier lateral restraints to improve the structural seismic performance. At last, according to the results of the dynamic analysis, the suggestions of the bridge design and the seismic safety evaluation of the structure are presented. Application of research results shows that seismic damping and isolation measures described in the paper is feasible, effective and applicable.