Seismic Damage Analysis Of Steel Reinforced Concrete Column-Steel Beam Frame Structures With Asymmetrical Steel Allocation

The collapse of buildings is the main cause of a large number of casualties in earthquake disasters,Damage occurrence and evolution of building structures under earthquake will lead to elastoplasticity of structural components,failure-fracture of components,local collapse or overall collapse of structures.Asymmetric steel reinforced concrete frame structure has superior bearing capacity,good seismic performance,and can meet the requirements of building plane and uneven stress state.It has been widely used in engineering practice.Establishing a damage model that can truly reflect the degradation of strength and stiffness of structures under cyclic loads is the basis for evaluating the seismic collapse resistance of such structures.In this paper,the asymmetric steel reinforced concrete column-steel beam frame structure is taken as the research object,and the experimental research and numerical analysis method are adopted.The damage evolution law,failure mechanism and design preventive measures of this kind of structure under low cyclic repeated loading are taken as the main research lines.The seismic damage model of this kind of structure is established according to the level of component damage-structural layer damage-structural overall damage.In order to improve the ability of earthquake prevention and disaster reduction of asymmetric steel reinforced concrete frame structures,the main research contents and achievements are summarized as follows:(1)In this paper,two asymmetrical steel reinforced concrete column-steel beam frame structures with three stories,two spans and a scale of 1:3 are designed and manufactured based on the 8 degree seismic fortification and the second type site soil conditions.The hysteretic behavior,interstory displacement,ductility and energy dissipation of the structural model under constant axial force and low cyclic horizontal load are studied through quasi-static test.The mechanical characteristics and failure process of this kind of structure under earthquake are analyzed.The failure mode of the specimens belongs to the "beam hinge failure mechanism".The hysteretic behavior of the specimens is good.The skeleton curve is parabolic,and has obvious rising,level and descending stages.The specimens have good ductility and energy dissipation capacity.It meets the seismic design requirements of "strong column and weak beam,strong shear and weak bending,strong joint and weak member".The results show that the asymmetric steel reinforced concrete column-steel beam frame structure has good seismic performance.(2)The experimental model is numerically analyzed by using the non-linear finite element analysis software OpenSEES.The beam-column components are composed of macro-elements based on fiber section.The hysteresis curves and skeleton curves obtained by numerical simulation are in good agreement with the experimental results.The seismic performance indexes such as bearing capacity,stiffness,ductility and stress-strain distribution are also in good agreement with the test results.(3)Based on Park model,the non-linear combination of structural deformation and cumulative energy dissipation is considered.The weight coefficient method is used to calculate the damage-layer damage-overall damage level of components.According to the deformation and hysteretic energy dissipation under different load levels,the seismic damage analysis of asymmetric steel reinforced concrete frame structures is carried out.Based on the test results and numerical analysis,the damage evolution process of frame beams,columns,storeys and whole structures under low cyclic repeated loading is quantitatively calculated and polynomial fitting is carried out.The research results can better reflect the seismic damage evolution law of asymmetric steel reinforced concrete frame structures.