Study Of Seismic Performance Of GFRP-aluminium Alloy Buckling Restrained Brace

Buckling restrained bracing(BRB)is considered to be an excellent performance energy dissipating and vibration damping element and is widely used in construction projects.However,traditional Buckling restrained bracing suffers from high self-weight,high wet work,susceptibility to corrosion and high post-maintenance costs.Therefore,a new GFRP-aluminium alloy buckling restrained brace(GABRB)is proposed,which combines two new materials,aluminium alloy and GFRP(Glass Fiber Reinforced Plastics),to give full play to their respective advantages.Based on the working mechanism of the brace and the stress state of the inner core aluminium tube,a theoretical analysis of the overall stability of the brace and the stability of the core was carried out to obtain the conditions for the design parameters.Four GABRB test specimens were designed and subjected to pseudo-static test to investigate the effect of core weakening and end reinforcement on the performance of the brace.Using ABAQUS software,a finite element analysis model of the GABRB was developed and the simulation results were compared with the test results for verification.The influence of the key dimensional parameters of the brace on the brace performance was analysed and the reasonable values of the brace dimensional parameters were determined.An optimisation model of the GABRB was established using MATLAB and a multi-objective multi-parameter optimisation analysis of its construction cost,constraint stiffness and key parameters was carried out using genetic algorithms to obtain the variation pattern of the member dimensions.Finally,the GABRB was arranged in the frame structure to evaluate its practical working effect in the project.It was found that the 4 GABRB specimens did not have integral buckling,and the failure form was pulled off at the welding of the inner core aluminum tube end.The hysteresis curves were full and showed stable hysteresis characteristics.All performance indexes are in line with the standard requirements,showing excellent energy consumption performance.For the size parameters of GABRB,it is recommended that the support gap be 1 mm ～ 2 mm.GFRP cross-winding is better than one-way winding,and the recommended winding angles are 0° ～ ±60° and 0° ～ 45°.The diameter to thickness ratio of the inner core tube should not be greater than 27.After optimization,it is recommended that the diameter to length ratio of the inner core tube ranges from0.025 to 0...055;The diameter to thickness ratio is between 12 and 20;The minimum wall thickness of the inner core tube is 3mm.The results show that the new GFRP-aluminium alloy buckling restrained brace has a good seismic damping effect.As the first line of defence of the structure,it can take up a large part of the shear force of the structure,enhancing the seismic capacity of the structure,reducing the inter-storey displacement angle of the structure,lowering the seismic damage level and ensuring the stability of the structure.