Studies of Elasto-Plastic Behavior of Steel Members under Cyclic Axial Force and its Fracture

在荷载迟滞的早期阶段，钢轴向构件有时会在其局部屈曲截面处断裂。本研究的目的是阐明钢构件在循环轴力作用下的结构特性及其在局部屈曲截面发生裂纹之前的应变迟滞性。试样是用冷轧成形方钢管制成的。实验变量为长细比、宽厚比、是否存在热处理（正态化）和试样长度。主要研究结果如下：试件断裂前的吸能能力受宽厚比的影响要大于受长细比的影响。假设支架的长细比在其正常范围内，其长细比越小，其到断裂前的吸能能力越大。长细比在其中间范围内能量吸收能力最差。

Steel axial members sometimes fracture at its local buckling section in an early phase of a load hysteresis. It the purpose of this study to elucidate a structural characteristic of a steel member under a cyclic axial force and its strain hysteresisi until crack occurs in its local buckling section. Specimen was made of a cold roll- formed steel square tube. Experimental variables were slenderness ratio, width-thickness ratio, existence of heat treatment (normalize), and length of specimen.Main findings were as follows.1. The energy absorption capacity up to fracture was influenced much more by width-thickness ratio than by slenderness ratio of a test specimen.2. Assuming a brace of which slenderness ratio is in its ordinary range, the smaller its slenderness ratio was, the greater its energy absorption capacity up to fracture was.3. There was a slenderness ratio of which energy absorption capacity was the worst in its intermediate range.