Seismic Response Analysis Of Multi-span Continuous Rigid Frame Bridge

With the rapid development of the highway transportation industry in the western region of China,a large number of bridges as control projects have been built on high-grade highways in the mountains.Curved bridges can overcome the restrictions of mountain terrain effectively which comply with the overall design requirements of the route,thus promoting the rapid development of curved rigid frame bridges.The seismic response of the curved girder bridges after the San Fernando earthquake in 1971 starts to the Wenchuan earthquake in 2008,and the curved bridge is still damaged to varying degrees.It shows that the earthquake response analysis and seismic performance of the curved bridge Of the study difficult,lack of understanding of the law,in urgent need of further study.In this paper,a multi-span prestressed concrete continuous rigid frame bridge was used as the engineering background.The structural model with consideration for pile-soil interaction was established utilize Midas Civil software.The analysis of dynamic characteristics,response spectrum and dynamic time history were carried out in this model.The specific research contents and conclusions are as follows:(1)The two models of the continuous rigid frame bridge-the bottom consolidation model and the model with consideration for the pile-soil interaction were established by Midas Civil finite element software.The modal analysis and comparison of the natural frequencies between the two models were carried out.The results showed that the periodicity of the first-order mode increases by 69.03% after considering the pile-soil interaction.However,with increased vibration modes,the period of the high-order mode changes to be close to the one in consolidation model gradually and the tenth-order vibration cycle only increased by 6.43%.It is shown that in the soft soil foundation,the pile foundation increases the self-vibration period of the structure,but it has little effect on the high-order mode cycle.(2)The seismic response of the curved rigid frame bridge under the E1 earthquake was used to obtain the seismic response to determine the most unfavorable level of vibration input.Then,analyzed the response spectrum and dynamic time history of the bottom consolidation model and the model considering pile-soil effect,it is concluded that the seismic response of the bridge structure is larger than that of the bridge bridge considering the pile-soil interaction.When the seismic performance of the continuous rigid frame bridge is analyzed,the effect of vertical ground motion can be ignored;under the earthquake,the dynamic time course calculation results are not less than 80% of the results of the response spectrum method,in line with the latest promulgated "highway bridge seismic design rules" requirements.(3)The results showed that the two-axis thin-walled hollow pier and the bridge can increase the internal force of the # 1 pier,and the three-piers,The internal bending of the bridge and the shear force are smaller than the rectangular solid pier,but the top of the pier is slightly increased,and the displacement of the pier is obviously increased.The maximum stress of the pier,the pier at the end of the pier is the largest,the rectangular solid pier is the largest,the inner octagonal hollow pier is the smallest.It is proposed to change the original rectangular solid pier into the octagonal hollow pier of which the seismic performance is better.