A Study on the Unstable Behavior of H-Shaped Steel Beam-Columns Subjected to Multi-Dimensional Loads

在地震作用下，多层框架的梁柱在两个方向上受到水平力的作用而产生双轴弯矩。h型钢梁柱在双轴弯矩作用下的失稳行为有许多不明确之处。相对较小长细比的构件在屈服后可以吸收塑性能并逐渐增大侧向扭转变形，但目前对这种情况的研究试验较少。本研究旨在通过明确h型钢梁柱的倒塌类型以及确定h型钢梁柱吸能能力的基本参数，获得建立定量估算h型钢梁柱吸能能力方法所需的基础数据。在实验中，弯矩是通过与截面主轴成一定角度的水平力来加载的。角度设置为0度（强轴弯矩）、30度、60度、90度……More es（弱轴弯矩）。试验变量设置为长细比、轴比、水平力加载方向（角度）和加载方式（离子紧压加载或循环加载）。本研究的结果可以概括为：1)分析结果与实验结果吻合较好。验证了本研究所用分析方法的有效性。2)对于极限阶段构件的变形情况，观察到三种侧向变形和扭转变形模式。3)所有试件在受斜荷载（角度为30、60度）作用时，均处于腹板轴向与构件纵向中心加载方向成直角方向的扭转垮塌状态。4)强轴弯矩作用下试件（角度=0度）的循环加载曲线得到的正、负两侧骨架曲线低于单调加载曲线。其他试件的骨架曲线（角度分别为30、60、90度）与单调加载曲线基本一致。5)得到了试件和加载条件与能量吸收量之间的关系。少

Beam-columns of multi-story frames are subjected to biaxial bending moment due to horizontal forces acting on the columns in two directions during an earthquake. There are many unclear points on unstable behavior of H-shaped steel beam-columns subjected to biaxial bending moment. Members with a relatively small slenderness ratio can absorb plastic energy while gradually increasing lateral torsional deformation after yielding, but there have been few study experiments on such a case. This study aims at obtaining the basic data required to establish a method for quantitatively estimating the energy absorption ability through making clear the type of collapse for H-shaped steel beam-columns as well as basic parameters determining the energy absorption ability.In the experiments, the bending moment was loaded by acting a horizontal force in a direction with an angle from the principal axis of the section. The values for the angle were set as 0 (strong axis bending moment), 30, 60, 90 degre … More es (weak axis bending moment). The experiment variables were set as slenderness ratio, axial ratio, horizontal force loading direction (the angle) and loading method (nionotonic loading or cyclic loading).The results of this study can be summarized as follows :1) The results of analyses correspond well to the experiment results. The validity of the analytical method used in this study was confirmed.2) With regard to the member deformation condition at the ultimate stage, three patterns for the lateral deformation and torsional deformation were observed.3) All specimens subjected to an oblique load (the angle=30, 60 degrees) torsionally collapsed in such a state as the web axis approaches a direction at a right angle to the loading direction at the longitudinal center of the member.4) The skeleton curve on positive and negative sides obtained from the cyclic loading curve for the specimen (the angle=0 degrees) subjected to strong axial bending moment was lower than the monotonic loading curve. The skeleton curve for the other specimens (the angle=30, 60, 90 degrees) was almost equivalent to the monotonic loading curve.5) The relationship between the conditions for both the specimen and the loading and the amount of the energy absorption was obtained. Less