Performance Test Of Mild Steel Damper And Its Application In Prefabricated Shear Wall

As a kind of steel with good plasticity,good hysteretic performance,and little influence of the external environment,mild steel can be used to make excellent structural energy dissipation damper.Because of the large self-weight and lateral stiffness of the structure,the ordinary shear wall has a large earthquake action,especially the brittle shear failure with poor ductility is easy to occur under the earthquake action.By setting up a vertical joint in the shear wall and a soft steel damper at the vertical joint,the failure characteristics of the wall can be transformed into a bending failure mode with good ductility.The soft steel damper and the shear wall can jointly bear the seismic action,store and dissipate the seismic energy,to reduce the damage of the main structure and improve the seismic performance of the shear wall structure.In view of this,the author studies the mechanical hysteretic performance,energy dissipation capacity,and application of the soft steel damper in the assembly shear wall with vertical joints by means of experimental research and numerical simulation.The main research contents and achievements are as follows:(1)Eight groups of soft steel dampers are designed and tested under low cycle repeated loading.The failure mode,hysteretic characteristics,ductility,stiffness degradation,and energy dissipation capacity of the dampers are studied.The results show that the setting of stiffeners can not only delay the buckling of the specimens but also improve the specimens The bearing capacity of.The increase of the middle width and the inclined angle of the soft steel can improve the bearing capacity of the specimen,but the ductility is reduced.Compared with the stiffener,the load-bearing capacity of the specimen is reduced but the ductility is improved,and the specimen buckling can also be delayed.(2)The finite element software ABAQUS is used to establish the numerical analysis model of the soft steel damper,and the results are in good agreement with the test results.Based on the finite element model,the finite element numerical simulation analysis and theoretical analysis of the soft steel damper with different design parameters are carried out.The results show that the increase of the width of the soft steel can improve the bearing capacity of the test piece,but the stress distribution of the section is not Uniform,based on the weakening degree of the section,the section weakening rate λ is proposed,and its reasonable value range is given.Under the same loading displacement,when the horizontal length of the soft steel is the same,with the increase of the inclination angle,the maximum bearing capacity of the test piece increases first and then decreases,and the ductility of the test piece decreases.To ensure that the test piece has a certain bearing capacity and good ductility,the recommended value of the inclination angle of the soft steel is 30 °.The arrangement of stiffeners has a certain influence on the effect of buckling prevention: when the mild steel is placed horizontally,the effect of the I-shape arrangement of stiffeners is the best;when the mild steel is arranged obliquely,the effect of increasing the thickness of stiffeners is the best.Through theoretical analysis,the yield load calculation formula of the full-length arrangement of stiffeners is obtained.The thickness of soft steel is a function of the initial elastic stiffness of the test piece.The increase of the thickness can not only improve the maximum bearing capacity of the test piece,but also delay the buckling of the test piece,but is not conducive to the damper as the first seismic line of defense.(3)Based on the experimental results,the ABAQUS numerical analysis model of the assembled shear wall with open vertical joints is established.The simulation results are in good agreement with the experimental results.On this basis,the different factors of the energy dissipation joint assembly shear wall are compared and analyzed.The results show that the setting of the vertical joint reduces the bearing capacity of the shear wall,but the ductility is improved.The setting of soft steel damper at the vertical joint of the shear wall not only makes the shear wall have certain bearing capacity and ductility but also has better energy dissipation capacity.The load-bearing capacity and ductility of partial shear wall with mild steel damper are higher than that of uniform arrangement and partial arrangement.With the increase in the number of dampers,the bearing capacity of the shear wall will be improved,but the ductility will be reduced.When the number of dampers is too large,the plastic damage of the concrete of the shear wall will be aggravated,and the energy consumption capacity will be reduced.With the increase of the width of the vertical joint of the shear wall,the restraint effect of the shear wall on the damper decreases,the bearing capacity of the specimen decreases,and the cumulative energy consumption decreases.Based on numerical simulation,the reasonable design suggestions of each influencing factor are given.The research results can provide a reference for engineering applications.