Energy Dissipation Performance Study On A New Mild Steel Damper Of Ⅱ Type

At present,the known mild steel dampers are single in form,and there are three problems.Firstly,when the mild steel damper is applied in the plane,it is easy to result in local stress concentration.Secondly,most of the mild steel dampers studied at this stage are confined to in-plane forces,and the phenomenon of out-of-plane instability,residual stress and strain are sill not solved.Thirdly,if the metal dampers are damaged after the earthquake,they need to be replaced completely,which is not economical.In this paper,a new type Ⅱ mild steel damper is proposed,and the mechanical properties of the Ⅱ-shaped mild steel damper under monotonic static load and low-cycle reciprocating load are studied.The damper performance is simulated by using finite element software ABAQUS,and the results of simulation and test are compared and analyzed.The specific research contents and results are as follows:(1)Stress and strain tests of the material were carried out,and the mechanical properties and constitutive relationship of the material were determined by monotonic tensile tests of three groups of test Q235 steel.By applying a one-way horizontal loading method to the first group of dampers,the yield load of the Ⅱ-shaped mild steel damper is determined to be 130 kN.Then,the cyclic reciprocating loading method is used to compare the local buckling Ⅱ character after the aftershocks after the strong earthquake.The type of mild steel damper still has better energy consumption.By cyclic loading the second group of Ⅱ-shaped mild steel dampers,the corresponding hysteresis curve is obtained,the failure process of the dampers during the test is recorded,the failure mode of the energy consuming device is recorded,and the hysteretic curves and skeleton curves are analyzed.The strain distribution of the damper during the test was observed.(2)The finite element analysis model of mild steel damper is established by ABAQUS,and the finite element analysis of the top release unidirectional loading simulation and reciprocating loading is carried out.The hysteresis curve,maximum horizontal force,bearing capacity degradation coefficient and stiffness degradation of the mild steel damper are obtained.The simulation results are compared with the test results.The comparison between the simulation and the test results shows that the mild steel damper has good energy dissipation capacity and has high application value in practical engineering.(3)Aiming at the problems in the test of the Ⅱ-shaped mild steel damper,the improvement scheme is put forward.The optimization of the Ⅱ-shaped mild steel damper is mainly included,and the hysteretic curve,skeleton curve,ductility coefficient and energy dissipation parameters of the optimized energy dissipation capacity are compared with those of other displacement dampers,and the reasons for the difference between the test and simulation are summarized.The experimentalsimulation results show that the yield capacity and ultimate bearing capacity of the optimized double ten-type mild steel damper are 294.8 kN and 836 kN,and the finite damping ratio is 0.74,and the ductility coefficient is 6.02.Out-of-plane instability,low stiffness,poor ductility can be solved by the improved damperThe new type Ⅱ mild steel damper designed in this paper has better energy consumption ability.After further research and improvement,it can be applied in practical engineering,and reffered to the affairs for the country anti-earthquake.