Mechanical Properties And Design Method Of The New Integrated Connector Of Buckling Restrained Brace RC Frame

As an excellent type of metal hysteretic energy-dissipation device,buckling-restrained braces(BRB)are currently used in building structures.Add BRBs in the reinforced concrete frame(RCF)structures to develop a dual structure system(BRB-RCF).To ensure the energy consumption performance of BRBs,stability and reliability of the joints of the BRB-RCF must be guaranteed.Traditional anchored guesst are composed of guesst plate,end plate,anchor plate and ribs and the guesst plate are welded to the end plate.Which are many disadvantages,for example,many construction steps should be carried out,a large cost of steel,complex stress on the concrete beam-column joint area,beams in the gusset area are prone to disadvantages such as additional burden,etc.As a connection between steel members and the concrete,shear connectors are widely used in bridge engineering and composite structures.In this paper,two types of shear connectors are adopted,namely,perforated plate shear connector(PBL shear connector)and welding stub shear connector.The shear connectors are applied to BRB-RCF to form a new type of integrated connection joint.This paper mainly studies the mechanical properties of the new type of integrated joints through the quasi-static hysteretic loading test and examines the mechanical performance of the joint plate through finite element analysis.The main research contents are summarized as follows:(1)The connection form of PBL connector and welding stub connector of BRB-RCF is proposed.Further,the specific arrangement of PBL,welding stub board,PBL hole and welding stub were designed according to the maximum axial force of BRB and integrated PBL connector,and welding stub are formed.Starting from a typical BRB-RCF prototype structure and considering the test site conditions,a pseudo-static hysteretic loading test for the BRB-RCF subsystem was carried out.The seismic performance,energy dissipation capacity,beam-column failure mode,stress development law of plate parts,etc.of PBL joint and welding stub joint were investigated.What’s more,through the reciprocating loading of 2% inter-story drift ratio,the low-cycle fatigue performance of BRB,under the condition that the connection joints are guaranteed to be not damaged,is investigated.(2)The quasi-static hysteretic loading test of the BRB-RCF sub-system was analyzed by finite element simulation.To compare with the finite element and the test results,the stress development,the hysteresis performance and stress development of the steel plate of the PBL connector and the Stub connector were investigated.As well as,the effectiveness of the damage control in the initial design period was verified.(3)The finite element analysis of the the push-out test of PBL plate is carried out.It considered that the detailed setting of the interrelation of the perforated plate,the concrete hole,the penetration steel bar and the concrete block.To analyze the mechanical properties of the PBL plate,the failure mode of the concrete hole,the failure mode of the plate,and the simulation analysis results verify the effectiveness of the assumption that the PBL holes evenly bear the shear force during the design.By calculating the design load capacity of the single hole,the more accurate elastic load capacity of the PBL node plate can be obtained.Further,to implement the parameters analyzed,the effects of different layout methods,the thickness of the perforated plate,the diameter of the perforated hole and the length of the rebar were investigated.As a result,a formula for calculating the optimal thickness of the plate was proposed.