Analysis Of Performance And Research On Design Of Non-fully Restrained Buckling-restrained Braces

In the traditional buckling-restrained braces,the kernel is completely wrapped by constraint components.This design can effectively restrain the lateral deformation of the core,so that the BRB has a stable mechanical performance.However,when the core section is complex form,the structure of the full constraint requires a lot of materials.In this paper,a new type of BRB structure is proposed,which is called non-fully restrained structure,by using the characteristics of H-section kernel's good stability and its large difference of inertia moment between the strong axis and weak axis.This paper introduces the design concept of non-fully restrained BRB and puts forward the preliminary design scheme.The effect of clearance,constraint ratio and other factors on the energy dissipation performance was studied.The influence of the structure form of non-fully restrained on the force and deformation of BRB was studied,and design methods were proposed according to the analysis results.The main research contents are as follows:(1)In this paper,a new type of H-section non-fully restrained BRB structure was proposed and the preliminary design scheme was given.Then its stability was checked according to the existing theoretical research results.(2)Based on ABAQUS platform,the parameter optimization analysis of H-section non-fully restrained BRB was carried out,and the influence of clearance,kernel defect,constraint ratio and other factors on its hysteretic performance and mechanical deformation was studied.(3)By comparing the fully restrained BRB and the non-fully restrained BRB,it is found that the hysteretic performance of the latter has defects,which the hysteretic curve has slippage and stiffness degradation.Then,based on the results of the comparative analysis of the stress and deformation cloud images,the causes of the slippage and stiffness degradation were explained.(4)Based on the analysis of the reasons for the defects in the hysteretic performance of non-fully restrained BRB,two design methods for improving the hysteretic performance of non-fully restrained BRB were proposed from the perspective of determining the reasonable non-restrictive length and adjusting the materials of different parts of the kernel.The improved non-fully restrained BRB has the mechanical properties of symmetrical tension and compression and full hysteretic curve.