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来预测钢材循环行为的本构方程，用以表示塑性应变与真实应力之间的关系。通过引入本构方程的有限元方法，分析了钢结构的循环性能，钢板在轴向拉压作用下的滞回性能，方板在轴向位移幅值不变的情况下的循环性能。结果表明，当宽厚比参数大于0.5时，钢箱形短柱的抗压强度和延性有所降低。分析结果表明，宽厚比参数是地震作用下局部屈曲的主要影响因素。限制宽厚比参数对提高钢管的强度和延性是有效的。在钢管抗震分析研究中，进行了2种轴压和3种循环荷载作用下的有限元分析。根据分析结果，提出了循环荷载作用下参数钢管的极限径厚比。利用弹塑性有限元方法对受损桥墩进行了弹塑性有限元分析。桥梁钢质阻尼器装置的研制提出了一种采用超低屈服应力钢管的阻尼器，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应用。

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.