The Study Of Seismic Response For Long-span Rigid Frame Bridges With High And Low Piers

With the rapid development of transport in China, more and more Long-span rigidframe bridges have been widely applied to the practical engineering. Especially in theSouthwest, where the terrain is very tuff, the Long-span rigid frame bridges with highpiers have many advantages, such as safety, serviceability, economy and beauty, atpresent, lots of this bridges were built and building in our country.Moreover, as Chinais an earthquake-prone country, therefore, it is very important to study the seismicresponse of Long-span rigid frame bridges.Because of the limitations of terrain, navigation requirements and especial designdemands, etc, asymmetric structure is usually applied to Long-span rigid frame bridgeswith high piers. There are lots of asymmetry side bridge instances, while correlativeLiteratures are lacked.This paper, setting the Niujiaoping Bridge in the second line of XiangfanChongqing Railway as a case, takes the stiffness changes of low pier as the main line tostudy the seismic response for Long-span rigid frame bridges with asymmetric piers,based on a large amount of numerical analysis, some valuable conclusions wereobtained about Long-span Rigid Frame Bridges with High and Low Piers under seismicaction, which are referable for the conceptual design of the same type bridges.The main contents and conclusions are following:1、 The structure mechanics analyses models of the bridges were established by thefinite element software ANSYS and researched the modal analysis and seismic response.The effect of pile-soil interaction was considered.2、 According to the site condition and the natural period of structure to chooseappropriate seismic wave and correct its intensity. The software-SeismoSignal was usedto adjust the baseline after choosing the appropriate seismic wave3、 The seismic response was studied for Long-span Rigid Frame Bridges withHigh and Low Piers in the change of the low pier’s height. Response spectrum and timehistory analysis method were used to research the seismic response for different modelsin transverse and longitudinal direction in order to find the principles about the seismicresponse peak for the main reference sections with the changes of the stiffness of lowpier.4、 The seismic response was studied for Long-span Rigid Frame Bridges with High and Low Piers in the change of the low pier’s section size and the constraint of thetop of low pier. Time history analysis method were used to research the seismicresponse for different models in transverse and longitudinal direction in order to find theprinciples about the seismic response peak for the main reference sections with thechanges of the stiffness of low pier.5、 During the seismic design of Long-span Rigid Frame Bridges with High andLow Piers, reducing the short pier’s stiffness or adjusting the constraint of short pier top,will help to reduce the seismic response of the bridge system.