Seismic Performance Research Of "Integral Station-Bridge" Frame Structure Based On IDA And MPA Methods

At present, with the large-scale development of high-speed railway and urban railway transit in our nation, the "Integral Station-Bridge" structure has been widely applied into station structural systems in this new era. But the complicated force transmission path, the misfit with the capacity-based seismic design concept, the lack of the related seismic design codes and the need of further research in yield mechanism and failure mode of this type of structure, it is very necessary to conduct studies on the seismic behaviors of Integral Station-Bridge type of structure. This paper deals with the following aspects:1. The description of incremental dynamic analysis and modal pushover analysis methods fit for seismic behavior analysis for complex structures have been presented in which the theoretical basis were explained,at the same time advantages and disadvantages of these two theories were pointed out.2. Set Beijing South Railway Station featured with Integral Station-Bridge type of structure as an example, with the incremental dynamic analysis method, its seismic performance was analyzed in depth. The research shows, by and large, this station structure's seismic performance is good and under large magnitude earthquakes it meets the function requirements. With the increase in PGA, firstly the nodes of longitudinal girder and secondary beam get into plastic phase, secondly the reinforced concrete column and circular concrete-filled steel tube experience plastic phase in turn. When the PGA is 1.4g, few of square concrete-filled steel box columns fall into nonlinear state. In conclusion, nodes of this kind of structure are weak points in structural seismic design.3. With modal pushover analysis method, the effects of roof mass on a complex roof space truss structure were studied. It shows that the roof mass has certain effects on the seismic performance of station structure which in details says that while the mass of roof is 4% of the whole structure, its significant interactions towards the plastic development of track beam were found and under other circumstances its interactions fall down along parabola. Besides, in the seismic fortification of 7 and 8 degrees, the displacement of the top roof decreases monotonously whiles the roof mass increases. Meanwhile in 9 degrees, the displacement of the top were found to be in non-uniform increase with the gain of roof mass which shows that the inelastic phase of top maximizes the deformation of structure under high intensity earthquakes.4. With modal pushover analysis method, the effects of roof stiffness on structural performance were studied. It shows that the stiffness of top roof has slight influences on the seismic behavior of station structure that while the stiffness of roof is 4% of the whole structure, its negative interactions to inelastic phase development of track beam were found, namely it advances the development of track beam's inelastic phase, so the stiffness ratio of various roofs in structure need to be optimized.