| The frame-corewall structure is the most commonly used structural system in(super)highrise buildings.Presently,the characteristic value of structural stiffness ? is mostly used as a parameter to study the seismic performance of reinforced concrete frame-corewall in academic and engineering community.The elastic shear distribution ratio of the frame is taken as the main basis for evaluating the second fortification line of frame-corewall.However,the shear distribution ratio of frame and corewall is closely related to their stiffness.The characteristic value ? of structural stiffness only reflects the stiffness ratio between frame and corewall in the elastic stage,while the rule of shear distribution and the availability of the frame as the second fortification line are ambiguous in the elastic-plastic stage.Therefore,it is necessary to study the mechanical behavior of frame-corewall structure on the elastic-plastic level.In this dissertation,the elastic-plastic analysis method is adopted to systematically study the variation rule of the frame shear force in the frame-corewall structure under the influence of different component cross-sections,corewall plane layout and frame overturning moments.Furthermore,combined with experimental test and theoretical analysis,the force mechanism is further investigated.Based on this,the conception of constructing a multiple fortification lines for frame-corewall structure is proposed and preliminary verified.The main research contents and conclusions are as follows:(1)The improvement of the whole process analysis method of frame-corewall structure.Based on ABAQUS general finite element analysis platform,the secondary development of material constitutive model of frames and two-dimensional reinforced concrete shearwall is completed.An explicit analysis method for construction simulation is proposed,and a structural analysis method based on explicit algorithm is establelished.According to the simulation results of frame structure and frame-corewall structure,this proposed method has strong convergence and can completely simulate the whole process nonlinear mechanical behavior of a structure.The failure modes and mechanical characteristics obtained from the analyses are reasonable and reliable,which can be an effective analysis method in subsequent research.(2)Research on the variation rule of story shear force distributed to the frame.The frame shear force adjustment approach in the existing standard has slight effect on improving the structural strength and deformation capacity of the frame-corewall structure.Thus,through the simulation analysis of the frame-corewall structure,the variation rule of the horizontal shear force distributed to the frame in the whole process is obtained: in the elastic stage,as the frame shear increases,the shear force follows the elastic stiffness distribution principle between the frame and the corewall;when the frame beam has yielded,the shear force of the frame basically remains unchanged,and the shear distribution principle on the basis of elastic stiffness is no longer applicable.Parametric analysis results in terms of the cross-sectional dimension of wall,column and beam,the frame overturning moment and the corewall plane layout,and the results show that the variation rule of frame shear force mentioned above is universal,and the yield moment at the end of frame beam is the only factor affecting the shear force.(3)Research on force mechanism of frame shear force variation.The influence of different cross-sections of components,corewall plane layout and wall openings on the shear distribution characteristics of the typical strory-frame and corewall is systematically analyzed,and bending moment variation law and force mechanism of frame beam and column are further investigated correspondingly.The results show that the frame can only play the role of the second fortification line in the elastic stage,but not play the role when the frame beam has yielded.Based on the internal force balance condition of frame joints,the force mechanism that frame shear force depending on the yield moment of frame beam ends is clarified,and the calculation formula of shear adjustment coefficient of frame column is proposed.This proposed formula improves the calculation method of inter-storey shear capacity ratio of frame-corewall structure in existing standard.Furthermore,an 1:2 scaled equivalent frame joint test is carried out to verify the variation rule of story shear force distributed to the frame and the rationality of the mechanism.(4)Effects of corewall offset on mechanical properties of frame-corewall structure.The influence of corewall offset on the displacement of frame-corewall structure is studied.The relationship between the horizontal seismic influence coefficient in the offset direction and the height-width ratio of corewall is deduced,and a simplified formula for discriminating the eccentric tension of the shear wall is provided.The shear force distribution feature of vertical components under the seismic event which is perpendicular to the offset direction is also analyzed.Based on the influence of corewall offset on the displacement and internal force distribution of frame-corewall structure,the design requirements are proposed,which can be used as a reference for similar engineering projects.(5)The proposal and verification of the second fortification line in corewall.Considering the limitation of the frame as the second fortification line in frame-corewall structure,the conception of constructing the second fortification line in corewall is proposed.The seismic performance is systematically studied on the case-study frame-multi-corewall structure with common coupling beams and with energy dissipating coulping beams.The results reveal that the seismic and collapse performance of the structure can be effectively improved by constructing the second fortification line in corewall,while the relevant structural design and optimization methods need to be further studied. |
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