Local buckling behavior and plastic deformation capacity of H-shaped beams under reversed axial forces
Local buckling behavior and plastic deformation capacity of H-shaped beams under reversed axial forces
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反向轴力作用下H形梁的局部屈曲行为和塑性变形能力
DOI：
10.1002/cepa.379
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
Kasai Kazuhiko
中科院分区：
文献类型：
--
作者：
Suzuki Atsushi;Kimura Yoshihiro;Kasai Kazuhiko
一般来说，在进行推覆或动力分析时，假定抗弯钢框架中带有混凝土板的梁是轴向刚性的。因此，在设计过程中没有考虑作用在梁上的轴向力。然而，当框架在地震期间具有屈曲约束支撑时，钢梁会受到轴向力。与无轴力梁相比，有轴力梁的极限强度、塑性变形能力和累积塑性变形能力下降，可能会发生严重损坏。本研究的目的是阐明交变轴力作用下H形梁的特性，模拟阻尼器的反向轴向力。首先，本文对梁进行了单调和循环加载试验，以了解不同轴力加载方案（无轴力、恒定压缩轴力和交变轴力）下的局部屈曲行为。其次，研究了轴向力加载方案对极限强度、塑性变形能力和累积塑性变形能力的影响。第三，检查由于轴向力的大小和循环次数而导致的容量差异。最后，总结了梁的宽厚比对交变轴力作用下的屈曲行为和性能的影响。结果表明，交变轴力作用下的梁在压轴力作用下表现出局部屈曲，在拉轴力作用下表现出夹紧效应。虽然交变轴力作用下梁的性能较无轴力作用下有所下降，但获得了比恒压轴力作用下更大的极限强度、塑性变形能力和累积塑性变形能力。这种在交变轴向力下性能的增强源于当对梁施加拉伸轴向力时，由于在压缩轴向力下局部屈曲而导致残余变形的拉伸。
In general, beams with concrete slabs in the moment resisting steel frames are assumed to be rigid axially when pushover or dynamic analyses are conducted. Consequently, axial forces acting on the beams are not considered in a design procedure. However, steel beams are subject to axial forces when a frame has buckling restrained braces during the earthquake. Ultimate strength, plastic deformation capacity, and cumulative plastic deformation capacity of beams with axial forces decrease and severe damage may occur to compare with beams with no axial force.The purpose of this research is to elucidate the characteristics of H‐shaped beams under alternating axial force, which models the reversed axial forces from the dampers. Firstly, this paper conducts monotonic and cyclic loading tests on beams to understand local buckling behaviors under different loading protocols of axial force (no axial force, constant compressive axial force, and alternating axial force). Secondly, influences of the loading protocol of axial force on the ultimate strength, plastic deformation capacity, and cumulative plastic deformation capacity are investigated. Thirdly, the differences of capacity due to the magnitude of axial force and the number of cycles are examined. Finally, the effects of the width‐thickness ratio of beams on the buckling behaviors and performances under the alternating axial force are summarized.As a result, beams under the alternating axial force show local buckling under the compressive axial force and the pinching effect under the tensile axial force. Although the performances of beam under alternating axial force degrade to compare with those under no axial force, larger ultimate strength, plastic deformation capacity, and cumulative plastic deformation capacity than those under the constant compressive axial force are obtained. This enhancement of performances under alternating axial force is originated by the stretch of residual deformation due to local buckling under the compressive axial force when tensile axial force is applied to the beam.