Seismic Behavior And Application Of Double-tube Type All-steel Buckling-restrained Brace

Under the action of fortification intensity earthquake and rare earthquake,the ordinary support frame structure system is very easy to undergo buckling and instability damage under seismic load.In order to solve the problem of buckling instability failure in the structure of common supporting frame structure,this paper proposes a double-tube type all-steel buckling brace,which is supported by an external buckling restraint mechanism(constrained outer tube).Energy-consuming support that inhibits plastic deformation of the core load-bearing member(core tube).The buckling-restrained brace not only has good bearing capacity and hysteretic performance,but also has the advantages of simple manufacturing process,convenient assembly and light weight.When the double-tube type buckling-restrained brace is set in the frame structure,the buckling-restrained brace is the first line of defense for building structures.The shear wall,beam and column structural members are used as the second and third anti-seismic lines of the building structure,and the plastic hinges are used to generate energy after the double-tube type buckling-restrained brace yield failure.Therefore,it is of great significance to study the double-tube type buckling-restrained brace for the application of building structures.In this paper,the ABAQUS finite element software is used to analyze the compressive bearing capacity,hysteresis curve,skeleton curve and stiffness degradation curve of double-tube buckling-restrained brace with different clearance,core tube diameter-thickness ratio and stiffness ratio,and comparative analysis of mechanical properties of double-tube buckling-restrained brace and ordinary support.In order to further deepen the research,SAP2000 was used to analyze the seismic performance of frame structure,hinged and rigid joint buckling support frame structures.The response spectrum analysis and nonlinear time history analysis method were used to carry out the interlayer displacement ratio,inter-layer shear force,time-history displacement and time-course acceleration of three different support frame structures are studied.The results of finite element simulation show that the double-tube buckling-restrained brace designed in this paper does not produce buckling instability before the core tube reaches yield.The double-tube buckling-restrained brace is more effective than the ordinary support to improve the material of the bearing member.Utilization,while preventing buckling instability damage of the core tube.As the gap of the double-tube buckling-restrained brace decreases,the bearing capacity of the support member increases,and the maximumcompressive bearing capacity exceeds 55.4% of the ordinary support,and the maximum hysteretic energy exceeds 80.2% of the ordinary support.As the diameter-thickness ratio of the double-tube buckling-restrained brace core tube decreases,the bearing capacity of the support member increases,and the bearing capacity of the TinT-D22.5 specimen is increased as compared with the TinT-D25.7 specimen 30.0%,and the total hysteresis energy of TinT-D22.5 specimens increased by 13.7% compared with TinT-D25.7 specimens.Similarly,with the increase of the stiffness ratio,the bearing capacity of the double-tube buckling-restrained brace also increases.The TinT-R7.24 specimen has a maximum increase by 7.1% compared with the TinT-R6.04 specimen,and the total hysteresis energy of TinT-R7.24 increased by 5.5% compared with TinT-R6.04.In addition,the analysis of five different structures by SAP2000 shows that the buckling-restrained bracet of X form is arranged in the side span of the frame structure,and the double-tube buckling-restrained brace can effectively restrain the interlayer displacement,and time history acceleration.Under the 8 degree seismic load,the hinged and rigid joint buckling-restrained brace reduces the interlaminar displacement ratio of the frame structure by 37.5% and 44.44% in the X direction,respectively.The interlaminar displacement ratio of the hinged and rigidly connected buckling-restrained brace in the Y direction is a maximum reduction of 64.7%.The interlaminar shear force of the hinged and rigidly connected buckling-restrained brace frame structure is reduced by 39.6% and44.62%,respectively.In the Y direction,the interlaminar shear force of the hinged and rigidly connected buckling-restrained brace is reduced by 23.04% and 23.57%,respectively.It can be seen that the rigid joint connection method suppresses the seismic response of the frame structure better than the hinged connection method.When the displacement reaches the limit,the frame structure has developed 238 LS-CP stage plastic hinges,42 C-D stage plastic hinges,and the hinged buckling support frame has developed 136 LS-CP stage plastic hinges,2 The plastic hinge of the CD stage,just connected to the buckling support frame,developed 140 plastic hinges of the LS-CP stage.The buckling-resistant support is a frame structure that significantly slows down the development of plastic hinges.