Experimental Study On Seismic Performance Of Rigid Rocking Frame With Buckling-Restrained Columns

The earthquake resilient structure that can restore the structural function after an earthquake without(or significant)repair is usually formed by the ways of adding prestressed self-centering members and replacing concentrated energy dissipation members,which has been a research hotspot in earthquake engineering.For the ordinary brace steel frame structure,some scholars replaced steel columns at the bottom story with buckling-restrained braces(BRBs).The BRBs firstly yield to dissipate energy under major earthquakes,and the other part of the system remains elastic and rotates around the bottom,which is similar to a rocking system controlling the deformation of the main structures.The structural function can be quickly restored by replacing the damaged BRBs after the earthquakes.This structure is called as the rigid rocking frame with buckling-restrained columns(BRCs)in this paper.However,some researches noted that the connection details between rocking system and basement is complex,and the various connection forms of a BRB also affect its energy dissipation capacity.Moreover,the research on the connection performance of rigid rocking frames with BRCs(RRFBs)is rarely reported.Therefore,the RRFB is taken as the research object in this paper,and the influence of connection form on the seismic performance of RRFB and the BRC capacity is primarily investigated through pseudo-static tests and numerical simulations.The main research contents are as follows:(1)Five pseudo-static tests of the RRFB structures with different BRC and support connection forms are completed and the deformation and failure mode of BRBs and RRFBs with pinned connection,bolted connection and welded connection are analyzed.The seismic performance differences among the RRFBs with different connection forms are analyzed,such as the structural hysteretic curves,the strength and stiffness degradation,the rotation angle at RRFB base and the energy dissipation of BRC.(2)Firstly,based on ABAQUS software,the reasons of the RRFB Out-of-plane deformation and the BRC failure mode in the pseudo-static tests are investigated.Secondly,this paper analyzes the hysteretic curves of RRFBs with different connection forms and the deformation and expected break location of BRCs after adding lateral restraint.The results show that the hysteresis curves of the structures are plumper after adding the lateral restraint,the bearing capacity of the structure in which a rigid connection is used for the support is higher than those of the others,and the deformation and expected break location of BRCs are different when BRCs used different connection forms.(3)The bearing capacity and energy dissipation capacity of RRFBs are depended on the design and performance of BRCs.Once the BRCs fail,the seismic performance will be reduced.A two-level yielding RRFB(TYRRFB)is proposed to improve the seismic performance of RRFB after the BRCs yielding and the pseudo-static tests and numerical simulations are conducted for the TYRRFB.The results show that the TYRRFB can further improve the seismic performance of RRFB,and does not affect the capacity of BRCs.