Study On Seismic Behavior Of Restorable Steel Circular Tubular Piers

Steel piers are widely used in viaducts,pedestrian overpasses and other bridge structures,as well as other large public buildings such as airports,high-speed railway stations,and load-bearing structures of green energy power generation facilities such as wind power and solar energy,duo to its high strength and light weight.In earthquake-prone zones,plastic damage is easy to occur at the roots of steel piers,which leads to the destruction of the main structure.The steel circular tubular pier was selected as the study objects in this paper and the plastic damage control reinforcement method is used to reinforce the root of the steel circular tubular pier,so as to effectively improve its seismic performance.Considering the stress characteristics of steel circular tubular piers,this thesis designed a detachable energy dissipation area at the base of the piers.Some common steel panels in the energy dissipation area are replaced by low yield point steel panels,and stiffened steel plates connected by high strength bolts are set on both sides of the low yield point steel panels.When the pier is subjected to seismic action,low yield point steel panels play the first role,and restrains its buckling deformation through the stiffened steel plates on both sides,thus improving its strength and energy dissipation capacity.At the same time,the energy dissipation area of the pier is easy to replace and has strong recoverable ability.The main purpose of this paper is to study the effects of axial compression ratio,eccentricity,panel strength,panel thickness,slenderness ratio and other parameters on the seismic performance of such piers under vertical pressure and cyclic lateral loading.The main contents of this paper are as follows:(1)This test is conducted about seven circular tubular steel specimens under pseudo-static experiment.The failure mechanism of the specimens was analyzed and the load-displacement curve,load-strain curve,skeleton curve,displacement ductility coefficient,bearing capacity,stiffness degradation characteristics,strength degradation characteristics,energy dissipation capacity and restorability of thespecimens were obtained.The influence of the axial compression ratio and eccentricity on the seismic performance of piers is analyzed(2)The finite element model of the scaled specimens is established by using ANSYS,and the accuracy of the finite element simulation is verified by the test.On this basis,28 full-scale specimens were designed to study the influence of eccentricity,panel thickness,panel strength and slenderness ratio on the seismic performance of piers.(3)The formulas for calculating the bearing capacity of steel circular tubular piers under lateral repeated loading are obtained by fitting,and putting forward some reasonable design suggestions for the piers.The results show that the buckling load and failure load of the specimens increase,the bearing capacity and energy dissipation capacity increase,and the seismic performance of the specimens is improved after the low yield point energy dissipation panels is installed.Axial compression ratio has less influence on the buckling load and failure load of the specimens,and has greater influence on the failure mode of the specimens.With the decrease of the axial compression ratio,the strength and stiffness degradation of the specimens in the later stage slows down,and the bearing capacity and ductility of the specimens under axial compression decrease,while the bearing capacity and ductility of the specimens under eccentric compression increase.The results of parameter analysis show that the eccentricity,panel strength and thickness,slenderness ratio have great influence on the seismic performance of specimens.With the increase of eccentricity,the forward bearing capacity increases while the reverse bearing capacity decreases;with the increase of panel thickness and strength,the bearing capacity and hysteretic performance of the specimens increase;with the increase of slenderness ratio,the ductility of the specimens is better,but the bearing capacity decreases.