Experimental Study And Finite Element Analysis On Hysteretic Behavior Of Buckling Restrained Dog-Bone Steel Beams

In view of the outward movement of the plastic hinge of the dog-bone steel beam,the problem of local buckling is likely to occur in the weakened area.In this paper,a buckling restraint steel sleeve for restraining local buckling in the weakened area of dog-bone steel beams is proposed.Relevant experimental studies and finite element analysis were carried out.In order to study the effects of three kinds of arrangement of buckling restraint steel sleeves on the seismic performance of dog-bone steel beams,such as failure mode,local buckling degree,bearing capacity and ductility,a dog-bone steel beam specimens and four dog-bone steel beams with different arrangement of buckling restraint steel sleeves were designed and manufactured,and their pseudo-static tests were carried out.The test results show that:(1)The plastic hinges of steel beams with three kinds of steel sleeve arrangement move out,and the main deformation and failure occur in the weakened area.(2)The influence of three kinds of steel sleeve arrangement on the peak load capacity of steel beams is less than 5%.(3)The ductility and energy dissipation of steel beam with steel sleeve on flange is increased by 31.67% and 31.81%,respectively.The specimens has good deformation and energy dissipation capacity.(4)The ring stiffness of steel beams with steel sleeves on both flanges and webs is the largest near the peak displacement.The ring stiffness decreases slowly in the later stage of loading,and the specimens can still maintain large bearing capacity under the condition of large deformation.Using ANSYS finite element software,the finite element analysis of steel beams without steel sleeves and steel beams with steel sleeves on flanges is carried out.After verifying the correctness of the finite element model,the thickness of flange and web is changed and the parameters are analyzed under the condition that the width of flange and the height of cross section remain unchanged.The results show that the bearing capacity of steel beams decreases rapidly after the width-thickness ratio and height-thickness ratio increase.The decrease speed of bearing capacity and energy dissipation are improved in different extent after the steel sleeve is installed on the flange.After the steel sleeve is installed on the flange of the specimens with large width-thickness ratio and high thickness ratio,the decrease speed of bearing capacity becomes slower and the energy consumption increases more obviously.In order to further study the seismic behavior of the joint,such as failure mode,bearing capacity,ductility,etc.,when the dog-bone steel beam with steel sleeves installed on both flange and web is applied to the joint.A side joint and a middle joint of a buckling restrained steel beam with end plate bolts are designed and manufactured,and the quasi-static test is carried out.The test results show that when the steel beam yields,the concrete beam,column longitudinal reinforcement and stirrups do not yield.The plastic deformation of the joint mainly occurs on the steel beam,and the plastic hinge moves out,which meets the requirements of "strong joint and weak member" in seismic design.