Study On Seismic Performance Of Buckling Restrained Braces With Replaceable Energy Dissipating Angle Fuses

The Buckling-Restrained Braces(BRBs)overcome the disadvantages of concentrical Braces which buckle under compression.Besides,the BRBs offer the enhanced hysteretic energy absorption capacity,the reduced difference in the tension and compression resistances.Consequently,BRBs have been widely used in new buildings and seismic retrofit of existing constructions.At present,though various types of high-performance BRBs have been proposed,the existing types of ordinary BRBs still have some limitations.After a severe earthquake,damage detection for energy dissipating element or replacing damaged BRBs if necessary can be challenging and even destructive for the configuration of buckling-restraining element and the connection between the energy dissipating element and the frame.Besides,the buckling-restraining element of a well-designed ordinary BRB should remain elastic when damages develop in its restrained yielding segment.However,it is inconvenient to re-use the buckling-restraining elements of the ordinary BRBs,which does not help achieve the sustainable design objective.To overcome the above-mentioned limitations,this paper proposed a new type of BRB with replaceable energy dissipating angle fuses,which includes three key assemblages:the inner telescopic Buckling-Restraining Mechanism(BRM),the buckling-restrained angle fuses and the outer BRM.The proposed BRB offers the ease of post-earthquake examination on fuse damages,the convenient and prompt replacement of damaged fuses and the re-use of the buckling restraining elements.To investigate seismic behavior of the proposed BRB,seven brace specimens were tested.The test parameters varied in these specimens included fuse design,fuse material,debonding material,and loading protocol.Test results show that the proposed BRB can exhibit stable hysteretic behavior.The compression strength adjustment factors and the cumulative plastic deformations of the specimens were found to satisfy the requirements specified by AISC 341-16.Failure modes of the specimens were found to be ruptures of the angle fuses as expected.Further,it was found that rupture failures of the proposed BRB can be captured by the modified Park-Ang damage measure.The test demonstrated that the specimens repaired through fuse replacements remained satisfactory in the following tests.Response results obtained using the SteelBRB model are compared to the test results and show good predictions of the experimental behaviour.