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

本文研究了钢构件因材料变化而引起的结构特性变化。为此，以材料性能为主要参数，对多根钢梁柱进行了试验。数值分析中还进行了不同的材料性能的钢和钢梁柱的强度和延性的影响进行了统计检查。还开发了一个包含以前实验室测试结果的面向对象的数据库，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的应变硬化特性，特别是构件的延性受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，虽然被认为是一个量化应变硬化程度的简便指标，但该指标过于粗糙，不能用于精确估计延性变化。考虑到市售钢材的预期变化程度，钢梁柱的强度和延性可能分别在变化系数方面变化约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.