| Shear panel dampers(SPDs)have attracted widely attention as a kind of energy dissipation device with good seismic performance.Their performance under shear unidirectional forcing has been widely studied.However,in practical applications,the damper is not only subjected to horizontal shear but also to in other directions,which is in a multi—directional state.According to some earthquake damages and researches,excessive axial force will cause outof-plane buckling before the target displacement is reached,which leads to the collapse of the structure.In addition,if the damper is applied to the energy dissipation bearing,it will be in a multi-directional force state at this time,and the energy dissipation performance of the damper needs to be studied at this time.Therefore,buckling restrained shear panel dampers(BRSPD)were developed,in order to explore the seismic performance of BRSPD under multi-directional force state,the following aspects are mainly explored in this paper:(1)The design method for BRSPDThe mechanical parameters of BRSPD are the basis for the design of the damper.For the convenience of engineering applications,the restoring force model of BRSPD under monotonic loading is given.The flange is an important part of the energy dissipation unit.Its size determines the stress distribution of the energy dissipation web and affects the fatigue performance of the damper.A design method for flange is proposed through theoretical and finite element analysis.In addition,in order to ensure that the restraining element can effectively restrain the out-of-plane deformation of the web,the design formulas of the restraining member size are given.At last,the formula for the limit value of the axial force of the damper is also obtained.(2)The effect of the axial force under the bidirectional forceIn this paper,four BRSPDs were set up under different axial forces.The results show that at lower axial force,BRSPD can effectively reduce the out-of-plane buckling of the web,and has good energy dissipation performance,similar to the case without axial force.However,when the axial force is too large,it will cause premature failure of the damper,which seriously affect the energy dissipation capacity.While the stiffness of the damper has almost no changes.Finally,the finite element model of BRSPD is built by ABAQUS.Then the parameter analysis of damper is carried out by using it.The design method of this kind of damper axial force is obtained.(3)The effect of the cross-section parameters under the bidirectional forceQuasi-static tests including three groups of specimens are set up to verify the correctness of the design method.Their parameters includ the gap between the web and the restraining plate,the thickness of the web and the thickness of the flange.The test results show that there is connection force between the web and the flange.They need to cooperate with each other to jointly consume energy.Only increasing the thickness of the web or flange can not improve the performance of the damper.So the design of their dimensions affects each other and needs to be considered at the same time.While the change of the gap between the web and the restraining plate under the bidirectional force state has almost no effect on its performance.(4)The hysteresis performance of BRSPD under multi-directional forceWhen the damper is under multiaxial loading state,as the loading angle increases,the flange will crack earlier due to excessive shear force,which will lead to a reduction in the ultimate load and ultimate displacement.Besides,the stiffness and energy consumption will also be significantly reduced with increasing loading angle.For the specimens loaded with variable axial force,the bearing capacity begins to decline due to the cracks of the flange,and the larger the axial force of the specimen,the lower the load at each level,the lower the cumulative energy consumption.However,the magnitude of the axial force has little effect on the stiffness of the damper. |
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