| The soil-structure dynamic interaction(SSI)is objectively present when the earthquake occurs,and the seismic load the structure is subjected to is transmitted by the contact between the soil and the structure.Soil and structure contact surface may appear discontinuous deformation such as slip and crack under the action of earthquake,so the special mechanical behavior of contact surface has important influence on the deformation of soil and structure.In the past,when a large number of researchers considered the SSI problem,either simplification into two-dimensional models or irrespective of contact effects,especially in the three-dimensional state,most of the simulations considering the effect of the pile-soil-structure dynamic interaction were on the contact part.Corresponding simplifications have been made,which will inevitably have a certain influence on the dynamic response of the pile and the superstructure.In this paper,based on the study of the SSI problem and the constitutive model of the soil-structure interface,the dynamic interaction between the pile-soil-upper structure coupled system is considered comprehensively.According to the different contact conditions,the 3D seismic response analysis under horizontal earthquake is performed.Get some regular understanding,to provide a reference for a more accurate response of the pile foundation and the upper structure of the three-dimensional seismic response law under the action of horizontal earthquakes.The specific content is as follows:(1)Based on the Perzyna's viscoplastic theory and the Clough-Duncan hyperbolic relational soil-structure interface elastoplastic constitutive model,through the secondary development in the ABAQUS subroutine FRIC,a viscoplastic constitutive model of the contact surface elastohydrodynamics is realized.Application in software.In addition,it can be verified through an example that the subroutine can better simulate the mechanical properties of the contact surface.(2)Establish three-dimensional finite element numerical analysis model of pile-soil-superstructure and perform modal analysis of the structure under three differentworking conditions.They are respectively do not consider soil-structure interaction(Bounding constraints)and consider soil-structure interaction(coulomb friction between the pile and soil interface)and considering soil-structure interactions(using the elasto-viscoplastic constitutive model at the pile-soil interface),the conclusion is reached:considering the soil-structure interaction,the basic frequency of the structure is reduced,the period of natural vibration is prolonged,and the structure is softened.Considering the interaction and not considering the interaction,as well as the contact part of the simulation method,the influence of the low-order vibration mode characteristics is not obvious,but it will affect the high-order vibration mode characteristics.(3)According to the different types of processing during the simulation,the three types of conditions are divided.The seismic responses of the structural system under the binding constraints,hard contact Coulomb friction,and elastic-viscoplastic interface calculation conditions are simulated respectively.Under the operating conditions,the displacement response of the soil and the peak displacement,shear force,bending moment of the pile along the depth of the pile,and the displacement angle of the superstructure,the peak bending moment of the frame column of each layer,the shear force and other results,reached the conclusion: Under the action of small earthquakes,the choice of the contact surface model has little influence on the dynamic response of the structure,and the impact under large earthquakes is relatively large.The displacement,bending moment and shear response of the structure obtained by the simulation of the elastic viscous-plastic contact has different degrees of increase,and the response to the upper structure is more obvious.In the upper part of the structure,the contact effect is more pronounced,and the acceleration and displacement time history curves of the HEP are better than those of the HC and Tie constraints.The fluctuation of the time curve is more abundant and closer to the actual seismic response,and the simulation results are better. |
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