Seismic Behavior Of Semi-rigid Frame With Buckling-restrained Multi-stiffened Steel Plate Shear Walls

The semi-rigid steel frame with buckling-restrained multi-stiffened steel plate shear wall structures are excellent seismic structural systems with dual seismic fortification mechanism.It combines the advantage of the semi-rigid frame and the steel plate shear walls,and adapts to the requirements of prefabricated structures for convenient construction.The stiffener setting is an important method to reduce the buckling noise and improve the hysteresis energy performance of thin steel plate shear wall.However,the welding causes the steel sheet and the stiffener to produce significant defects,and the excellent plastic dissipation energy capacity of the thin steel shear wall cannot be fully utilized.Meanwhile,the same defects exist in the traditional bolt-welded steel frame structure joint,and hard to meet the requirements of prefabricated steel structure construction.Therefore,the buckling-restrained structural systems consisted of orthogonal interacted steel strip,the through-cored bolt and circular steel tube were adopted in the paper to replace the welding stiffeners,which not only avoids the influence of welding on steel wall and stiffeners,but also facilitates the filed installation of shear walls;same advantages are possessed by semi-rigid joints.Buckling-restrained multi-stiffened steel plate shear wall obtain the best way to coordinate the energy dissipation and ductility,and shows a good application prospect in high-intensity seismic regions.In this dissertation,the seismic table test was performed to investigate the failure modes,energy dissipation mechanism,ductility,buckling-restrained multi-stiffened structure,displacement response and acceleration response of semi-rigid steel frame with buckling-restrained multi-stiffened steel plate shear wall structure systematically;The parametric analysis of the structural system was carried out by numerical analysis.The influence of parameters of the multi-stiffened structure and the thin steel plate shear wall and rotational stiffness of the joint the on the ductility and displacement response of the structure were discussed;Through the verification and comparison of the simplified analysis model,the requirements of the calculation accuracy and calculationefficiency of the system in meeting the engineering design are discussed.The main contents of this dissertation are described as followings:(1)Firstly,a 1:3 scaled four-story structure was tested on the shaking table.The El-Centro wave,the Taft wave and an artificial wave are select as the simulated earthquake input and 33 operations are performed,and the peak ground acceleration(PGA)is controlled until it reaches 992 gal(rare earthquake level of nine-degree fortification intensity).It is observed that there is no out of plane instability of the structure and the semi-rigid frame and the connecting joint remain intact.The failure location of the wallboards is mainly occurring in the first and second stories,and the damage is extended from the grid at the junction of the edge components and the shear wall to the whole wallboards.The failure mode of the shear wall is repeated out of plane deformation in each wallboards grid and finally forms a regulated“X”shaped residual deformation.The shear walls of the third and fourth stories also show the slight plastic deformation.The buckling-restrained structural systems consisted of orthogonal interacted steel strip,the through-cored bolt and circular steel tube has enough rigidity to constrain the out of plane deformation of the inner steel plate and prevent the out-of-panel deformation of steel panels.(2)The tested structure possesses the excellent lateral stiffness.The maximum inter-story drift ratio of the structure is only 1/507,1/116 and 1/91 under frequent earthquake level of eight-degree fortification intensity,rare earthquake level of eight-degree fortification intensity and rare earthquake level of nine-degree fortification intensity respectively,which indicates that the tested structure and edge members have the satisfied lateral stiffness.(3)The tested structure has an excellent energy dissipation capacity.The energy dissipation mechanism of the walls is transformed into the tension belt mechanism from the shearing mechanism under earthquake excitation with eight-degree of seismic fortification level,and stable plastic energy dissipation is formed.Obvious plastic damage is observed in wallboards,but it not exists in the edge frame and the rest of the frame.It indicates that the tested structure fully exerts the function of "initial seismic fortification line".(4)A refined numerical analysis model is created to simulate shear walls,buckling-restrained steel strips,edge components and frame beams,columns with S4 shell elements.The relative rotation between the beams and columns is simulated with‘Hinge'.The accuracy of this refined model is proved by comparing the finite element results with the test.Through the research of the numerical analysis model,the failure history,stress state,deformation characteristics of the edge members and thedeformation and stress state of the buckling-restrained device are revealed.By comparing and analyzing the shear forces of the shear wall and other components,the contribution of shear walls and edge members to the seismic performance of the structure is verified.(5)Base on the simplified analysis model of tested structure,the SM model(Equivalent Strip Model),TSM model(Three Strip Model)and CSM model(Combined Strip Model)are used to simulate the effect of the tested structure on the accuracy of analysis.By comparing with the experimental results,it is proposed that the SM model,TSM model TSM have significant errors in engineering application,and provided that the SM model can obtain relatively reasonable calculation results.(6)A design method of semi-rigid steel frame with buckling-restrained multi-stiffened steel plate shear wall is proposed.The No.6 building of assembled steel structures affordable housing in Lanzhou new area is taken as an engineering case.Then,the design methods applied in engineering are discussed,the seismic performance of the structure and the technical problems in the construction are analyzed,which provides a reference basis and good suggestions for the application of the semi-rigid steel frame with buckling-restrained multi-stiffened steel plate shear wall structure in practical engineering.The IDA analysis method is used to analyze the tested structure,and the relationship curve between the PGA and the maximum inter-story drift ratio ? of the structure is established.It is verified that the structure has good seismic performance.According to the structural fragility curves,the damage probability of structural under different levels of earthquakes is studied.The results show that the tested structure has an excellent seismic performance and a low collapses probability.