新型铝合金耗能支撑屈曲约束条件研究

Buckling Restraint Conditions for Innovative Aluminum Alloy Energy Dissipation Braces

摘要:

在国外已进行的相关铝合金材料及其屈曲约束支撑(BRB)试验基础上，对铝合金耗能支撑(ALBRB)的受力性能进行了进一步的数值分析。主要目的是对ALBRB进行参数化研究，找出影响其整体及局部屈曲的关键因素。结果发现利用约束比设计BRB的传统方法不能充分考虑偏心距、初始缺陷的影响，采用安全系数法能克服这一问题。为开发适用于空间结构减震的新型ALBRB，设计了一种质量更轻、构造更简单、性能更稳定的ALBRB，并对其防屈曲性能进行了理论推导和数值模拟。结果表明新型ALBRB单调加载下稳定性能良好，循环加载下其滞回曲线饱满稳定具备良好的耗能能力，对于大跨空间结构抗震应用具有积极意义。

Abstract:

The concept of structural damage control，introduced in the seismic retrofitting area in the late 1980s，has become popular in its applications for engineering bridges and buildings.Under strong or severe earthquake excitations，plans are made such that damage is expected to take place in energy dissipation devices and the primary structure can be kept away from the damage.Among many types of damping devices，increasing attention is being paid to hysteretic dampers，because the inelastic deformation capacity of metallic substances presents an effective approach in transferring seismic energy to other forms of energy at a low cost.Buckling-restrained braces （BRBs），as an axial-type hysteretic damper，are widely studied through their component behavior and system applications in civil engineering.Aluminum has drawn our attention for improving the durability of high-performance BRBs.Usually，aluminum and its alloys need no protection against atmospheric or chemical corrosive agents，because aluminum oxide，which is naturally generated on the surface of the metal，protects the body of the metal against corrosion.Because of the advantages of aluminum and its alloys，such as its light weight，corrosion resistance，ease of production，and economic and environmental benefits，aluminum alloy is selected for the manufacture of BRBs in this paper.Further numerical analysis of the mechanical behaviors of the aluminum alloy BRB （ALBRBs） was conducted based on aluminum alloy material tests and corresponding BRB tests，which were performed abroad.The objective of the analysis is to conduct a parametric study of BRBs with different gap widths（between the core and the restraining member）and initial imperfections to investigate the buckling behavior of the brace.The core plate and BRM were modeled using 8-node C3D8R linear brick elements with reduced integration.Large displacement static cyclic analysis was performed using the ABAQUS 6.10 general purpose finite element program.The results showed the conventional BRB design method does not consider the effect of initial imperfections and eccentricities，but the safety factor method can solve this problem.In order to enhance the aseismic ability of space structures，a new type of ALBRB was developed.The characteristics of the new ALBRB showed more reliable performance and simple construction，as well as decreased mass.Analysis of the buckling restraint conditions of the new ALBRB was completed.Results show that the stability of the ALBRB was good under monotonic loading and that it completed the full hysteresis loop and had preferable ductility and dissipative capacity under cyclic loading. The new ALBRB performs well and can be used in the aseismic design of space structures.One of the underlying requirements of BRBs is avoiding both overall and local buckling until the brace member reaches the target displacement and ductility.This required performance becomes important as the weight of the BRB and the strength and rigidity of the restraining member are reduced.Further experimental and analytical investigation is necessary to examine the overall buckling prevention conditions of ALBRBs，taking into consideration different gap sizes，BRM types，and frictional response effects in ALBRBs.