Study On Seismic Performance Of Double Deck Viaduct With Integrated Public Rail System

With the implementation of the fifth generation of China's seismic parameter zoning map(gb18306-2015)on June 1,2016,the seismic fortification requirements of various regions in China have been properly improved.In some regions,the basic seismic peak acceleration in degree 6 region has changed from 0.05 g to 0.10 g in degree 7 region.In addition,the concept of "extremely rare ground motion" has been put forward.In this paper,based on the actual engineering of an integrated double deck viaduct,at the beginning of the design,the seismic fortification intensity of the bridge site is 6 degrees,and the design basic seismic peak acceleration is 0.05 g.After the design,the bridge site is increased from 6 degrees(0.05g)to 7 degrees(0.10g).In this paper,the seismic performance of the double deck viaduct is studied based on the actual project,taking the near field vibration,far field vibration and the adjustment of the seismic parameter zoning map of China as the starting point.The integrated double-layer viaduct is the viaduct on the upper layer and the rail transit on the lower layer.Because of its higher utilization efficiency in the construction and use space,it is especially suitable for municipal engineering projects such as vehicle traffic and rail transit.The main research contents of this paper are as follows:(1)In this paper,MIDAS / civil is used for the finite element modeling of the double-layer viaduct.Considering the pile-soil interaction,Kent park model is used for the concrete,and menegotto Pinto model is used for the reinforcement.A four span double-layer viaduct model is established.The modal analysis of the bridge is carried out and the dynamic characteristics of the double-layer viaduct are studied.(2)Seven groups of general site vibration are selected to analyze the seismic response of the double deck Viaduct under 6 degree rare,7 degree rare and 7 degree rare earthquake.The internal force and displacement response of the lower column,upper column and main beam of the pier are studied,the elastic-plastic state of the pier is analyzed,and the seismic performance of the bridge under 6 degree rare and 7degree rare earthquake is evaluated.It is found that the development of the internal force and displacement of the control section is greatly influenced by the ground motion under different intensity.(3)The near-field pulse ground motion and the far-field harmonic groundmotion are selected to analyze the seismic response of the double-layer Viaduct under the action of 6-degree rare,7-degree rare and 7-degree rare earthquake,and the influence of the near-field pulse ground motion and the far-field harmonic ground motion on the seismic response of the structure is analyzed combined with the comparison of the general site vibration.It is found that the near-field impulse ground motion has the greatest damage to the structure,and the far-field harmonic like component has a significant amplification effect on the structure.