Investigation On The Seismic Energy Response And Structure Damage Of High-rise Buildings With A Frame-core Tube Structure Considering Soil-structure Interactions

Soil-structure interactions(SSIs)are currently a hot research topic in the field of civil engineering.To investigate the dynamic characteristics,energy responses,and structure damage of high-rise buildings with a frame-core tube structure considering the SSI effect under the excitation of seismic activity,a shaking table test model of high-rise buildings with a frame-tube structure at a 1/50 scale that considers the SSI effect was established.The vibration phenomena for high-rise buildings with a frame-core tube structure that is designed with two foundation types(fixed-base[FB]and SSI)under excitations with different seismic magnitudes were reproduced via shaking table tests,numerical simulations,and theoretical research.In this paper,the law of the dynamic characteristics,transmission,dissipation,and distribution of energy responses,and structure damage of the SSI system under different earthquake magnitudes were highlighted from the perspective of energy considerations by comparing the results of the dynamic characteristics,energy responses,and structure damage of the FB and SSI test model.The finite element software ANSYS was used to perform parametric modeling.Moreover,the influence mechanism of the "soil box effect" and soil material characteristics on the dynamic characteristics,energy response,and structure damage of the SSI system were further investigated by changing the thickness,diameter,and compression modulus of the SSI numerical model.The main contents of this paper are as follows:(1)The dynamic characteristics,dynamic response,and design method of the shaking table test model of the FB and SSI systems of high-rise buildings with a frame-core tube structure were investigated.The fabrication method and design experience of the shaking table test model of high-rise buildings were introduced and concluded.The determination method of the 3D inherent modal of the shaking table test model was explored.The dynamic characteristic and dynamic response differences of the two system test models,such as the inherent frequency,mode shape,damping ratio,peak acceleration,maximum displacement,maximum story shears,and maximum dynamic strain,were compared and analyzed under simulated earthquakes with different intensities.Results showed evident differences in the dynamic characteristics and dynamic response of the FB and SSI system high-rise buildings with a frame-core tube structure.(2)Numerical models for the prototype structure,FB test model and SSI test model were established using the finite element software ANSYS.A methodology was developed to address the difficulties of refining the numerical modeling of the SSI system.The difficulties of numerical modeling,solution method,and modeling steps for the SSI system were investigated and summarized.For example,a node for the pile-soil interface and a definition for the contact element were discussed in detail.The rationality of simplifications to the experimental model was verified by comparing of the dynamic characteristics and responses of the prototype and the FB numerical model under different conditions.The reliability of the original test data and established numerical models were verified by comparing the dynamic characteristics and responses of each system of numerical models under different excitations.Results showed that the design and fabrication methods of the shaking table test models for the two systems are reliable.The research results can provide a scientific theoretical basis for the energy response and structural damage analysis of the test and numerical models.(3)The pretreatment approach for the original shaking table data was investigated and developed.The pretreatment requirement of the original shaking table test data was analyzed,and the methodology and procedure of discriminate and filtering high-frequency noise and random interference waves were explored.Moreover,the rationality for pretreating the original test data was verified.The research results can provide a scientific and technical support for data analysis of the shaking table test model with various structures.(4)The variation law for the seismic energy response of high-rise buildings with a frame-tube structure considering the SSI effect under excitations at different seismic intensities was revealed.The energy equation of the MDOF system was derived.A simplified calculation model for the test apparatus,the selection of the seismic duration index before the energy calculation,and approaches to calculate the mass,stiffness,and damping matrices of the test model were investigated.Variation law differences of the energy response between the FB and SSI test models with excitations at different seismic intensities were calculated and analyzed.The analysis included the time history of the total energy input,the kinetic energy,elastic strain energy,damping and hysteretic dissipation energy of the measured points,the distribution laws of the maximum kinetic energy,maximum elastic strain energy,maximum damping and hysteretic dissipation energy along the height of the two test models,the variation law of soil energy dissipation,and the influence of soil energy dissipation on the total input energy of the superstructure.The research results can provide a reliable reference for the investigation of the seismic response of high-rise buildings with a frame-core tube structure.(5)The variation law for the global damage of the FB and SSI high-rise buildings with a frame-core tube structure under excitations from seismic activity was analyzed.The wavelet packet energy theorem was explored in MATLAB to calculate the wavelet packet energy and the maximum energy variation index for each measurement point of the superstructure for the FB and SSI test models based on the pretreatment test data.The differences in vibration intensity and global structure damage of the two test models were quantitatively analyzed by comparing the wavelet packet energy and the maximum energy variation index of the two test models under excitations from simulated earthquakes at different intensities.A new seismic design of high-rise buildings with a frame-core tube structure considering the SSI effect was proposed.The research results can provide an effective reference for the seismic design of high-rise buildings with a frame-tube structure.(6)The finite element software ANSYS was used to perform parametric modeling.Moreover,the influence mechanism of the "soil box effect" and soil material characteristics on the dynamic characteristics,energy response,and structure damage of the SSI system were further investigated by changing the thickness,diameter,and compression modulus of the established SSI numerical model with certain parameters.The results can further justify the soil box design and provide a scientific theoretical basis for the design and investigation of the SSI shaking table test model.