Study On Hysteretic Behavior Of Sub-Assembled Self-Centering Buckling Restrained Brace With Disc Spring

Reasonable designed buckling restrained brace(BRB)has good ductility and energy dissipation ability,but the residual deformation is larger after being subjected to the large axial yielding displacement.Therefore,a new type of brace,so-called self-centering buckling restrained brace with disc spring,is designed in this dissertation.A quasi-static test and numerical simulation are carried out to explore its seismic performance.The main research contents are as follows:(1)A new configuration of the self-centering buckling restrained brace(SCBRB)is proposed.The detailed structure of SCBRB is given,and the stress characteristics(mechanical properties)are analyzed.According to the configuration,the SCBRB test specimens are designed.The self-centering ability of the designed SCBRB is provided by a combination of pre-compressed disc springs,which facilitates in reducing the residual deformation of the BRB.The BRB is composed of the steel core,the circular steel tube filled with mortar using as the restraining member,and the debonding material between the core and the restraining member.(2)By quasi-static tests,a self-centering specimen(SC),a buckling restrained brace specimen(BRB)and two self-centering buckling restrained brace specimens(SCBRB)were tested.The test results show that,compared with BRB,the SCBRB presents a flagshape hysteretic performance while its residual deformation decreases significantly.The hysteretic curve of the SC is also a stable flag-shape.The combination of disc springs in SC exhibited small energy dissipation capacity under axial compression.According to constructional details,both SC and BRB were tested with the upper and the lower pushpull blocks.Under horizontal cyclic loads,it was found that the interaction between the upper and lower push-pull blocks(the lower push-pull block’s controlling tube is inserted into the tube of upper push-pull block)provide extra energy dissipation,along with horizontal resistance.Under horizontal loads,the interaction of push-pull blocks is mainly from bending actions and friction actions between the tubes.Therefore,when subjected to horizontal loads,the SC specimen has certain energy dissipation ability and the BRB specimen still presents a certain horizontal resistance after tensile failure of the core.(3)The mechanical properties of SC,BRB and SCBRB specimens were analyzed by Abaqus finite element software and compared with the tests.The rationality of the analysis was verified.In order to strictly embody the structural details supporting each component,the finite element model is established by using the solid element.Considering some actual conditions in the tests,the influence of the actual conditions on the hysteretic performance of the specimens is investigated.These conditions include initial tilted position of test rig,which leads to initial horizontal displacement of 42 mm,and the interaction between the push-pull blocks,which are fixed with 45° angle in each brace,with different friction coefficients under horizontal loads.Based on both the test and analysis results,the causes of the testing phenomenon and some design suggestions of SCBRB are given.