| The step-terrace structure is a typical form of mountain structure buildings,and is widely used in mountain city and town buildings.The unequal grounding characteristic of the step-terrace structure will cause uneven distribution of the lateral stiffness of the up and down grounding parts.Among this characteristic that how the arrangement of shear-walls affects the seismic performance of the step-terrace frame shear-wall structure is a difficult problem.Therefore,this paper takes the arrangement of shear walls of up and down grounding parts as the research focus,and explores the influence of shear wall layout scheme on the mechanical behavior and seismic performance of the step-terrace frame shear-wall structure.Based on single span and single layer unequal height rigid / bent frame hybrid simplified model,lateral stiffness calculation method and mechanical characteristics of step-terrace frame shear-wall structures are derived;at the same time lateral stiffness calculation method of step-terrace frame shear wall structures with multi span and multi layer are studied;by designing 5 kinds of step-terrace shear wall structures examples with different shear-wall arrangement,elastic analysis under frequently earthquakes and elastic and plastic analysis under rare earthquakes are carried out;then according to the uniform stiffness criterion,2 stiffness uniform examples are set up,elastic analysis under frequently earthquakes and elastic and plastic analysis under rare earthquakes are carried out too;finally combining the above calculation results,an optimal shear wall arrangement is proposed by comparing the mechanical and deformation properties of the structures.The main work and conclusions are as follows:(1)By studying the continuity assumption,the conclusion that the assumption of continuity is not applicable to the step-terrace frame and shear-wall structure concluded。(2)According to the basic geometric characteristics of the step-terrace structure,based on single span and single layer model,stiffness and stress characteristics of 3 kinds shear-wall arrangement structures are studied,the single hinge model(left single hinge model and right single hinge model)and double hinge model and bottom stiffness calculation formula of different structure are proposed.(3)Based on stiffness distribution and mechanical behavior of multi storey and multi span step-terrace structures,the structure is divided into the up ground and down ground half structure simplified model;at same time according to the strength characteristics of the up and down part relative stiffness,the influence of multilayer and multi span structures on bottom stiffness and its correction calculation method are proposed through simplified calculation model of single layer and single span.(4)When the shear-wall is arranged in the down grounding half structure,the deformation demand of up grounding member will be larger;when the shear-wall is arranged in the up half structure,the displacement of step-terrace part will be too large and the local vibration will be formed;if the number of structural layers is large,the distribution of the up and down ground shear walls can not achieve the uniform distribution of the bottom stiffness of the structure.(5)Under large earthquake,the structural shear will be transferred downward down half structure as the up grounding member enters the plastic state.When the shear-walls are arranged on the up ground half structure,the up shear-wall has higher plasticity and serious damage;when the bottom stiffness is uniform,the plastic deformation of the shear-wall is more uniform and lower;the shear-wall is strengthened at step-terrace part with up layer designed as frame,the overall deformation and energy dissipation capacity are better,and overall seismic performance of the structure is improved;the feasibility of Stiffness matching with structure design is verified. |
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