高温下铝合金轴心压杆极限承载力实用计算

Practical Calculation for Buckling Resistance of Aluminum-Alloy Members under Axial Compression at Elevated Temperatures

随着温度升高,铝合金的名义屈服强度和弹性模量下降,进而影响其高温下的极限承载力。将这种影响归纳为两个方面:第一,温度升高引起轴心压杆相对长细比的变化,定义温度函数进行描述;第二,温度升高,在相对长细比相同的情况下,引起轴心压杆稳定系数的变化,定义变换函数进行描述。采用某工程中的工字形截面作为典型截面进行有限元计算,确定两类函数的实用计算公式,并引用我国铝合金结构设计规范中的柱子曲线作为常温下的柱子曲线从而近似考虑截面规格类型不同的影响。最后,对文献中97根试件试验结果与有限元结果进行对比,验证有限元模型的正确性;同时,实用计算方法与欧洲规范方法对比表明:该方法与欧规方法同样安全简便地计算出高温下极限承载力,并且200℃之后比欧规方法更接近试验结果。

The nominal yielding strength and modulus of elasticity of aluminum alloy decrease with the rise of temperature,and buckling resistance of members under axial compression is affected by elevated temperatures.This paper summarizes the changes into two main issues：firstly,the relative slenderness ratio changes with the rise of temperature;secondly,the stability coefficient under axial compression changes with the rise of temperature at the same relative slenderness ratio.Each change is described in a temperature function.I-shaped section in an aluminum reticulated spatial structure is utilized as a sample in numerical analysis using ABAQUS.Based on the analysis results,formulas are obtained for the two functions.The column curve in Chinese aluminum structure design code is adopted as the column curve at room temperature to calculate the one at elevated temperature.Therefore,the influence of various sections is considered.Finally,the finite element model is validated by comparing experimental results of 97 specimens with the results obtained from numerical model.The comparison on the results from proposed method with those from Eurocode 9 shows the proposed method can provide reliable results as Eurocode 9,but the predictions are closer to the experimental results,especially at the temperatures beyond 200 ℃.