A Study on Application of High Strength Steels for the Development of Structural Functions

近年来，日本钢铁企业相继开发了几种高性能结构钢。本课题围绕钢结构结构功能的发展，以低屈服比高强度钢(LYR钢)为研究对象，通过试验和数值研究，对LYR钢的材料性能和组织行为进行了研究，取得了以下成果：1.通过对钢厂的查询和大量的拉伸试验，建立了基于LYR钢材料性能的数据库。对静拉强度为60kgf/cm~2的LYR-60钢的材料性能进行了统计评价。用Dafalias-Popov两面塑性模型对包括LYR钢在内的几种结构钢进行了一系列的循环加载试验。通过引入边界线的移动、弹性范围的缩小和形状参数的适当修改，成功地模拟了试验结果的单轴循环行为。利用数据库中选取的代表LYR 60钢的应力-应变关系，进行了弹塑性有限位移分析的对比研究。在紧凑截面的情况下，可以观察到LYR钢在延性方面优于传统的高强度钢。对采用LYR钢和普通高强度钢建造的钢框架的箱形连接模型框架角部进行了反复荷载作用下的强度和延性试验。由于材料的不同，各模型的滞回性能没有明显差异，变形能力基本相同。

Recently, some kinds of high performance structural steel have been developed by the iron manufactures in Japan. In this research project concerning with the development on structural functions of steel structures the high strength steels with low yield ratio (LYR steel) were focused, and the material properties and structural behaviors of LYR steels were surveyed by the experimental and numerical investigations.The following results can be obtained :1. Material Properties of LYR SteelA data-base on the material properties such as yield ratio, uniform elongation, hardening strain, etc. of LYR steels was framed by the inquiries for steel manufactures and lots of tensile test. For LYR 60 steel which has 60kgf/cm^2 static tensile strength, the material properties were evaluated statistically.2. Hysteretic Performance of LYR Steel under Uniaxial Compression-TensionDafalias-Popov's two surface plasticity model was examined by a series of cyclic loading test for several structural steels including LYR steels. Introducing the movement of bounding lines, the reduction of elastic range and the appropriate modification of shape parameter, the uniaxial cyclic behavior of test results can be successfully simulated.3. Cross-Sectional Strength and Deformation Capacity of I-Section Beans Using LYR SteelUsing the stress-strain relation representating LYR 60 steel chosed by the data-base, the comparative investigations by elasto-plastic finite displacement analysis were conducted. In case of compact sections the superiority in ductility of LYR steel to the customary high strength steel can be observed.4. Strength and Ductility of Frame Corners Using LYR SteelBox to box connection models of steel frames made from LYR steel and customary high strength steel were tested under cyclic loading. The difference on hysteretic behavior due to material could not be observed, and each models have almost same deformation capacity.