Variation of Structural Characteristics of Steel Members Caused by Variation of Steel Materials

本文研究了钢构件的材料变化对其结构特性的影响。为此，对若干钢梁柱进行了以材料性能为主要参数的试验研究。并进行了数值分析，统计分析了不同材料性能对钢梁柱强度和延性的影响。还开发了一个面向对象的数据库，其中载有以前实验室测试的结果，以协助进行统计评价。根据试验和分析，发现(1)结构特性在很大程度上取决于钢材料的应变硬化性能，特别是构件的延性受到应变硬化程度的强烈影响；(2)尽管屈服比（定义为屈服应力相对于最大强度）被认为是量化应变硬化程度的方便指标，这个指标还太粗糙，不能用于准确估计延性变化。考虑到商业上可用的钢材料的预期变化程度，钢梁柱的强度和延性可能分别在变异系数方面变化约10%至20%和50%至100%。

This report presents a study on the variation of structural characteristics of steel members induced by the variation of their materials. To this end, a number of steel beam-columns were tested with the material properties as the major parameter. Numerical analysis was also conducted, in which material properties of the steel were varied and their effects on the strength and ductility of steel beam-columns were examined statistically. An object-oriented database that contains results of previous laboratory tests was also developed to assist in statistical evaluation. Based upon the test and analysis, it was found (1) that the structural characteristics are largely dependent on the strain hardening properties of the steel material, and, in particular, the member ductility is strongly influenced by the degree of strain hardening and (2) that, although the yield ratio, defined as the yield stress relative to the maximum strength, is believed to be a handy index to quantify the degree of strain hardening, this index is yet too crude to be used for accurate estimation of ductility variation. Considering the degree of variation expected in the steel materials that are commercially available, the strength and ductility of steel beam-columns would likely to vary about 10 to 20 % and 50 to 100 % in terms of the coefficient of variation, respectively.