用能量法分析变截面梁的稳定极限承载力

ANALYZING ULTIMATESTRENGTH FOR TAPERED BEAMS BY THE ENERGY-METHOD

本文提出了用直接能量变分方法对变截面钢梁在弹塑性阶段的稳定极限问题进行分析的方法；并根据这一方法编制了分析变截面工型梁的计算程序，进行了相应的实验研究，以验证理论分析结果，实验结果肯定了理论分析的结论．实验和理论分析都表明，在长细比λ接近于１的附近，变截面工型梁与跨中相同高度的等截面工型梁相比，其稳定极限承载力有较大提高，特别是在变截面梁的端部高度较小时，提高比较明显．根据理论分析结果，本文提出了供设计使用的简化公式。

In this paper,the direct- energy - variational technique is used to obtain the ultimate locads of the tapered beam-columns.A FORTRAN program is developed to analyse the tapered I-beams.Experiments have been carried out to verity the theory;It's found that the theoretical results have a agreement with the experimental tata.Both the tests and the theoretical analyses show that,when the relative slendemess ratio (λ) is near to one,the maximum strength of the tapered I-beam is greated than that of the uniform I-beam whose section is the same with the mid-span section of the tapered one, and especially when the end-height of the tapered beam is small. Based on theoretical analytical result , a simplified formula is recommended for use in practice.