Study On Seismic Damage Mechanism And Seismic Upgrading Of Steel Plate Shear Wall

In view of the frequent and violent earthquake activity in China,and also the accompanied many aftershocks,it is not only necessary to adopt a more elaborate performance-based design method in seismic design to make the seismic damage predictable and controllable,but also essential to study the method of seismic upgrading to ensure a efficient reinforcement.The goal of seismic reinforcement is to prevent secondary disasters caused by aftershocks and to further meet the higher requirements for normal use function throughout the service period.However,the research on seismic damage of building structures is relatively weak.The research on performance degradation of different structural systems under earthquake is relatively rare,which is difficult to meet the requirements of performance-based design and engineering reinforcement.As a kind of high-efficiency anti-side force component,the steel plate shear wall is widely used worldwide.The anti-side force system consisting of the shear wall and the surrounding frame will be destructed step by step under the action of earthquake,and has the advantages of good seismic performance,main structure safety and concentration of damaged sites.These properties have been confirmed by the seismic experience of building structures such as the Oliver View hospital building in California and the Kobe City Hall building.These characteristics of the steel plate shear wall allows us to concentrate the seismic damage on the embedded steel plate shear walls by reasonable design method to ensure the safety on the frame.After the earthquake,it is only necessary to reinforce the embedded steel plate to effectively restore the seismic performance of the overall structure.Therefore,it is of great significance for the damage mechanism and seismic strengthening research of steel plate shear wall.In order to study the earthquake catastrophe mechanism of steel plate shear wall and explore the performance-based design method that is more in line with its failure mode,this paper has carried out research combining experimental analysis,numerical simulation and theoretical derivation.Firstly,a two-stage pseudo-static loading was carried out on 3 single-span double-layer steel frame-steel plate shear wall specimens.The plastic development and failure mode of the steel plate shear wall under specific performance level were studied.In the second stage of the test,the mechanical properties of the damaged steel plate shear wall,multi-ribs reinforced steel plate shear wall and diagonal ribs reinforced steel plate shear wall were compared.The seismic damage mechanism of the steel plate shear wall was explored,and it is proved that a proper design of the steel plate shear wall can concentrate the damage to the embedded steel plates,thus protecting the main vertical force members such as the frame column and forming a disaster-disrupting structural system.After that,the performance of the damaged steel plate shear wall reinforced by additional ribs were studied.The result shows that the strengthened steel plate shear wall has a good seismic performance and can achieve the performance goal of the original structure,which provides a reference for practical engineering reinforcement.On this basis,the plastic cumulative damage based on stress triaxiality was introduced into the FE model,and the numerical model of damaged steel plate shear wall was established.The damage research of the steel plate shear wall with different high-thickness ratio and different damage conditions was carried out.The residual deformation and the degradation of bearing capacity,stiffness and energy dissipation capacity were given quantitatively.And the plastic development process and failure mode of the steel plate shear wall at various stages were further verified.The seismic damage quantification system of steel plate shear wall was established,which provided a basis for post-disaster damage assessment in actual disasters.In order to meet the increasingly detailed performance-based design requirements,the design method of disaster prevention and mitigation of steel plate shear shear was studied based on its reasonable failure mode.The axial force,shear force and bending moment of the vertical boundary elements under the ideal failure mode were derived,and the strength calibration formula of the frame column base under its limit state was given.The formula was verified by numerical simulation and experimental methods.The results show that the algorithm can reflect the real force of the frame column well,and the calibration method is safe and reasonable.On this basis,the influence of frame column strength on the stress mode of steel plate shear wall was explored.The influence of column strength on structural shear force distribution was analyzed and compared,which provided a basis for better understanding the working mechanism of steel plate shear wall.Lastly,on the basis of experimental research,the steel plate shear wall repair and reinforcement models were established.The numerical simulation of the "additional component" reinforcement method was realized by the function of model change.The design method of additional ribs was studied.The limit of rib spacing was calculated by theoretical derivation method.The FE analysis of the reinforcement effect of ribs with different spacing was carried out,and the bearing capacity,stiffness,energy consumption capacity,ductility of the reinforced structure were studied.The rationality of the design method was verified,which provides data support and theoretical basis for practical application and promotion of engineering.