A Study on Development of Constitutive Equation for Structural Steel under Cyclic Loading and Application the Constitutive Equation to the Finite Element Method

提出了用单调加载曲线预测钢的循环性能的塑性应变与真应力关系的本构方程。采用引入本构方程的有限元方法，对钢结构的循环性能进行了分析。在轴向位移幅值不变的情况下，分析了方板的循环特性。结果表明，当宽厚比参数大于0.5时，箱形短柱的抗压强度降低。钢箱形短柱抗压和循环弯曲强度与延性分析结果表明，宽厚比参数是地震作用下局部屈曲的主要因素。限制宽厚比参数对提高强度和延性是有效的。钢管的抗震分析研究在2种轴压和3种循环荷载作用下进行了有限元分析。根据分析结果，提出了参数钢管在循环荷载作用下的极限半径厚比。用弹塑性有限元法分析了小古根-南部地震中钢管墩损伤的循环性能。本文介绍了一种超低屈服应力钢管滞回阻尼器的研制，并通过非线性地震反应分析，阐明了这种钢管阻尼器在桥梁地震反应控制中的作用。

The constitutive equation to express the relationship between plastic strain and true stress is proposed, which predicts cyclic behavior of steels, using a monotonic loading curve. By the finite element method in which this constitutive equation is introduced, the cyclic behaviors of steel structures are analyzed.Hystreretic Behavior of Steel Plates under Uniaxial Tension and Compression The cyclic behaviors of square plates are analyzed with constant axial displacement amplitude. It is shown that the compression strength reduces when width-to-thickness ratio parameter is greater then 0.5Strength and Ductulity of Steel Box Stub-Columns Subjected to Compression and Cyclic Bending Analysis results show that the width-to-thickness ratio parameter is main factor of local buckling under seismic loading. Restriction of whidth-to-thickness ratio parameter is effective to improve the strength and ductility.An Analytical Study on Earthquake-Resistance of Steel Pipe The finite element analyzes are carried out under 2 types of axial compression and 3 types of cyclic loading. The limiting radius-to-thickness ratio of parameter steel pipe under cyclic loading is suggested according to the results of analysis.Numerical Simulation on Dameged Steel Pipe Piers in Hyogoken-Nanbu Earthquake The cyclic behavior of damaged piers are analyzed by the elasto-plastic finite element method. Comparing with actual damage, the buckling mode and the yielded zone match the actual damageDevelopment of Steel Damper Device for Bridges A histeretic damper using ultra-low yield stress steel pipe is presented and it is clarified that this steel pipe damper is useful for the seismic-response-control for the bridge by non-linear seismic response analysis.