Study On The Effect Of Story Height Variations To The Seismic Performanceof Super High-rise Frame-core Wall Structures Based On OpenSEES

With the development of globalization and economic integration,the economic strength of all countries has been rapidly improved.Under such economic background,it can not only make the population concentrated and improve work efficiency,but also reduce the land area of high-rise buildings and super-high-rise buildings in various countries,Frame-core tube structure has become a common structural form of such buildings because of its good mechanical performance.With the increase of building height and the diversification of use functions,the non-uniform design of floor height becomes inevitable.Based on an engineering example,this paper explores the influence of story height change on the structure of super high-rise frame-core tube.The main research work and achievements are as follows:(1)Summarizing the research results of the theory of seismic design analysis of structures so far,introducing the basic principles and implementation methods of static method,bottom shear method,mode decomposition response spectrum method,static elastic-plastic analysis method and dynamic time-history analysis method,and defining the applicable scope of five different calculation methods.(2)In order to investigate the influence of the change of floor height at different locations and amplitudes on the mechanical properties of the structure,some models with different change ranges at the bottom,middle and upper parts is designed.The response spectrum analysis of mode decomposition under frequent earthquakes is carried out.It is found that the increase of floor height will lead to sudden changes in the stress and deformation of the corresponding floor structure,in which the continuity of stress on the upper floor is more destroyed,and the continuity of deformation on the bottom floor is more destroyed.The stiffness of the frame part decreases faster than that of the shear wall tube part due to the increase of story height,the percentage of floor shear and overturning moment taken by the frame part decreases correspondingly.(3)Based on the four lateral stiffness calculation methods given in the code,the lateral stiffness ratio of the model is calculated by using the results of response spectrum method,The characteristics and differences of the four lateral stiffness calculation methods are analyzed.Suggestions are given for the applicability of the four lateral stiffness calculation methods.As far as frame-core tube structure is concerned,Considering the standard calculation method of layer height correction,it may lead to the wrong judgment of the upper weak layer in the structure.the stiffness ratio can be calculated by the ratio of Interlayer displacement angle to reflect the change of stiffness after the change of story height.(4)Reinforcement design of example models based on the calculation results of response spectrum method.The finite element model of shear wall is established by using THUShell and compared with the low-cycle reciprocating test data of Dr.Zhang Hongmei's shear wall components to verify the feasibility of OpenSEES simulation of shear wall.Based on OpenSEES,refined structural models of super high-rise building are established by using fiber beam-column element and shear wall element of THUShell,and the correctness of the model is verified by comparing with Etabs' model.(5)Static elastic-plastic analysis is carried out for reinforcement cases under inverted triangular load mode to investigate the structural performance points of the cases under frequent,fortified and rare earthquakes,and to analyze the influence of story height change on the overall bearing capacity and energy consumption.With the increase of storey height,the curvature change of the shear-vertex displacement curve of the structure base accelerates,the plastic development accelerates,and the overall bearing capacity decreases.Those examples are equivalent to single degree of freedom systems.It is found that the increase of story height will reduce the overall energy consumption of the structure.It is suggested that energy dissipation braces should be set up in the storeys with different storey heights to enhance the lateral stiffness of the storey,reduce the inter-storey displacement and improve the energy dissipation capacity of the structure.(6)The dynamic time history analysis of EI wave,Taft wave and artificial wave after amplitude modulation is carried out to investigate the deformation of the structure under frequent and rare earthquakes,and the response of different seismic wave input to the structure is slightly different.Under the action of frequent earthquakes,the continuity of displacement is more destroyed when the floor height changes at the bottom,and its reflection law is also consistent with the results of response spectrum analysis.The results of artificial wave calculation are the closest to those of response spectrum calculation.Under rare earthquakes,the maximum inter-story displacement angle of the structure under frequent earthquakes will be magnified.(7)Comparing the position of maximum interlayer displacement angle calculated by modal decomposition response spectrum method and dynamic time history analysis method,it is found that the position of maximum interlayer displacement angle calculated by dynamic time history method is higher than that calculated by modal decomposition response spectrum method.In view of the strong discreteness of the actual ground motion,it is suggested that the seismic wave with good spectral characteristics and site conformity should be selected as far as possible in dynamic time history analysis.The maximum interlayer displacement angle position should be determined by the results of dynamic time history analysis and mode decomposition response spectrum method,so as to ensure the safety of the structure.