Analysis Of The Coupled Characteristics Of Temperature And Force Of Shear Low Yield Strength Steel Damping Structure

Metal damper is widely used in seismic engineering as a passive energy dissipation and shock absorption structure component.Through plastic deformation to consume energy,so as to reduce or avoid the damage of main structures such as bridges and buildings.Compared with ordinary steel and aluminum,low yield point steel has the advantages of low yield strength,large deformation capacity and good low cycle fatigue performance.At the same time,the shear damping structure has the characteristics of moderate bearing capacity and strong variability.Based on these performance advantages,shear type low yield point steel damper is more and more widely used.The existing research mainly focuses on the mechanical properties of shear type mild steel damper,but its fatigue heat generation under large plastic deformation has not been paid attention to.Therefore,this paper studies the temperature structure coupling characteristics of shear type low yield point steel damper under cyclic load.The main research results are as follows:Through the unidirectional shear tests of low yield point steel at different temperatures,the effect of temperature induced stress softening is preliminarily discussed.The cyclic hardening and cyclic softening effects of low yield point steel at different temperatures were further studied.The plastic constitutive model of low yield point steel is built considering the temperature effect and fatigue characteristics.It lays a foundation for the study of the heat generation and heat dissipation characteristics of the damper in the process of large plastic deformation.By comparing the experiment with the finite element simulation,the error analysis of the constitutive model under cyclic loading is carried out.Then,the accuracy of the plastic constitutive model of the damper is further improved based on the temperature effect and fatigue softening characteristics.Based on the accurate constitutive model,the temperature rise phenomenon of the damper in the process of elastic-plastic deformation is analyzed,and the internal heat generation mechanism is explored.The evolution process of surface temperature rise of low yield point steel damper under constant amplitude dynamic load is analyzed,and the internal temperature transfer process and energy conversion law in fatigue process are explored.Based on the basic laws of thermodynamics and the theoretical equations of thermoelastic and inelastic effects,the functional relationship between temperature rise and cumulative plastic strain in the process of large plastic deformation of damper is derived.The temperature rise of the damper under random dynamic load is studied to verify the accuracy of the simulation model and theoretical model.In this paper,the shear mechanical properties of low yield point steel at different temperatures are studied,and the accurate constitutive model of damper considering temperature effect and fatigue softening characteristics is established,which can more accurately evaluate the mechanical properties and deformation behavior of damper during fatigue process.At the same time,the temperature evolution process of the shear type low yield point steel damper in the process of cyclic loading is deeply studied,and the prediction model of the temperature rise of the damper is obtained.The model can effectively evaluate the energy dissipation performance of the damper under seismic dynamic response,and provide more accurate evaluation basis for the lightweight,high-performance and miniaturization design of the damper.