Dynamic Response Analysis Of Structure On The Ground Caused By Near-fault Earthquake

There were dynamic characteristics including vertical effect,upper plate effect and directional effect on the near-fault ground motion causing destruction of buildings.In this paper,the investigated lump method was used to establish an integrated numerical model of finite fault source,earth medium and structures on the ground.The structure of the rupture forward and the epicenter area were studied respectively.According to the numerical simulation results,the dynamic response of the structures on the ground caused by near-fault ground motion can be obtained.Therefore,the advice of designing for practical projects was provided.In this paper,the near-fault ground motion can be simulated by constructing finite-fault source model.The multiple sub-faults was used to discrete the earthquake fault,and each multiple sub-fault was represented by a double-couple moment tensor source.Then each sub-fault was started in the direction of the seismic fault according to the fault rupture delay time.The P and SV waves generated by the rupture of each sub-fault propagate through the earth medium to the surface and structures on the ground.The earthquake dynamic response of the surface and structures on the ground was generated.Finally the numerical simulation of structural dynamic response caused by near-fault ground motion was realized.The numerical simulation method and specific steps of structural dynamic response caused by near-fault ground motion are introduced.First of all,the grid discretization can be realized by using the ANSYS software.The data of the unit node coordinates,the source parameters,the structural parameters,the load data,the calculation time step and the duration were provided to the main program in the form of documents.The numerical calculation process realized by using FORTRAN programming software.Finally,the earthquake dynamic response chart data of the surface and structure can be obtained by using ORIGIN software to processed the result data.The influence of two factors on the earthquake response of the structure was analyzed for different fault dip angles(20°,40°,60°,80°and 90°)and different structural heights(5,10,15,20,25 and 30 layers).The numerical simulation results show that the horizontal peak acceleration and the vertical peak acceleration of the roof in the ruptured front area were thelargest when the fault dip angle was 60°.The vertical peak acceleration of the structural roof varies with the structural height when the fault dip angle remains unchanged,and the structural height was changed.The influence of changing the dip angle on the earthquake response of the structure was analyzed according to the different dip angles(10°,20°,40°,60°,80°and 90°).The numerical simulation results showed that the peak acceleration of the structural roof increases rapidly when the fault angle was greater than 60°.The horizontal peak acceleration reaches the maximum when the fault angle reaches 90°.The fault dip and structural height were important factors affecting the peak acceleration of the structural roof seeing from the seismic response law of the fault front and the epicenter structure.The peak acceleration of the structural roof in the area was greatly affected when the dip angle of the fault was greater than 60°,and such conditions should be avoided as much as possible during design.The design should consider the multi-layer structure as much as possible when the structures located in the area before the fault rupture.