Study On Classifications Of Seismic Design For Piers Of Railway Simple Supported Girder Bridges

The code for seismic design of railway engineering in China has been reformed and two-stage seismic design is realized primarily in recent years. However, many problems need to be solved in specific applications. For example, concrete bridge piers with small amount of steel bars can pass the checking as gravity type, but the displacement ductility requirement can be satisfied to the code only with a great deal of reinforcements added. Thus, in this paper, considering different site conditions and seismic fortification intensities, classification research of elastic seismic design method and ductility seismic design method for railway simple supported girder bridge pier was carried out based on the reinforcement ratio being index, Some useful conclusions for bridge seismic design were obtained:(1) The minimum reinforcement ratios acquired according to elastic seismic design method increase with the seismic fortification intensities rising, and first increase then decrease with the frequencies rising. Also, the minimum reinforcement ratios acquired according to ductility seismic design method increase with the seismic fortification intensities rising, and first increase then decrease with the frequencies rising.;(2) The classification ratios of reinforcements of elastic seismic design method and ductility design method increase with the increase of seismic fortification intensities, the sequence of seismic fortification intensities is site 7,8 and 9 in turn. The classification ratios of reinforcements of elastic seismic design method and ductility design method vary with the changes of site conditions. According to the ascending sort of the classification ratios, the sequence of site conditions is siteâ… ,â…¡andâ…£.(3) In this paper, when the shear span ratio is smaller than 2.1, the piers can be designed according to the elastic seismic theory, otherwise, turn to the ductility seismic theory;(4) Subjected to earthquakes with level 8 seismic intensity at siteâ…¡, when the spans are 16m,24m and 32m, the classification ratios of longitudinal reinforcements of elastic seismic design method and ductility design method increase with the increase of bridge spans and the ratios of longitudinal reinforcements are 0.9%,1.1%& 1.6% in turn.