Analysis Of Seismic Response And Comparative Study On Seismic Design Methods Of High Speed Railway Bridge

Abstract:Rich experience has been accumulated about the design of inter-city railway bridge in China, and there is a good many research on numerical simulation about the seismic response analysis of the bridge. However, technical difficulties still exist in guiding the practical engineering production. In this paper, investigation on the key technology of seismic elastoplastic analysis method is developed based on the general graph design of a (25+30+25)m pre-stressed concrete continuous beams and piles in the program of Dalian Jinzhou-Puwan new district intercity railway engineering. The three following key technical problems are mainly solved.(1) Study of seismic analysis method. By summarizing the calculation principles of simplified algorithm of railway standards, mode response spectrum method and elastic-plastic time history analysis method based on fiber simulation, and the section of the pier is discretized and fiber meshed. Modified Kent-Park constitutive model was chosen for calculating input parameters such as the compressive strength of concrete, coefficient of strength magnification, the peak compressive strain, ultimate compressive strain, strain softening slope; the Menegotto-Pinto constitutive model was chosen for reinforcement bars.(2) Research and design response of continuous girder railway under the action of earthquake frequently occurring. From the comparative analysis on the results of simplified calculation method, response spectrum method and time history method elastically under earthquake frequently occurring horizontally and longitudinally, we may draw the conclusion. The scores of the three methods are more or less the same under earthquake frequently occurring longitudinally. Difference in time history analysis and response spectrum method is within2.6%, compared with simplified calculation method, the result of the response spectrum method is11%～19%smaller under earthquake frequently occurring horizontally. Thus response spectrum method and time history method are safer and more reasonable than Simplified calculation method.Research on Seismic response and check method of railway continuous girder under earthquake rarely occurring. From the comparative analysis on the results of response spectrum method, elastical time history method and elastoplastic fiber time history method under earthquake occurring horizontally and longitudinally, we may draw the conclusion. Compared to the results of elastical time history method and response spectrum method, under the condition of longitudinal earthquake, the inner force of pier bottom is only1/3of elastic results and the replacement of pier top is about1.9times of elastic results. Under the condition of vertical earthquake, the inner force of pier bottom is around43%of elastic results and the replacement of pier top is1.3times of that, which indicates a severe enlarge of the moment of pier bottom using elastic model, leading to an increase of the pier cross-sectional area and the amount of reinforcement in designing. The conclusion is as follows:Under rare earthquake, a comparatively more reasonable result can be obtained using elastoplastic fiber time history method, and thus elastoplastic models are preferred in designing.