钢梁腹板斜截面主拉应力幅超值疲劳机理研究  

Research on Fatigue Mechanism of Steel Beam Web Caused by the Exceeding Principal Tensile Stress Amplitude of Inclined Section

作　　者：马人乐[1] 张硕[1] 

机构地区：[1]同济大学建筑工程系,上海200092

出　　处：《特种结构》2013年第5期52-56,共5页Special Structures

摘　　要：钢梁腹板纵向纤维受压区和中性轴附近纯剪区疲劳裂缝的出现很难用正截面疲劳应力幅是否超标来判别。本文对受疲劳荷载铜梁腹板中部纯剪区、上部受压区及下部受拉区的应力单元进行了分析,揭示了因轮压滚动引起单元体剪应力变号,从而引起主应力面拉、压应力突变,造成很大的疲劳应力幅。因而,对于腹板剪应力水平较高的梁,存在较大的危险性。同时,本文说明了因剪应力变号而发生的腹板疲劳裂缝,其扩展机理不同于因拉应力幅而引起的翼缘疲劳裂缝的扩展机理,前者属于渐进型,后者属于扩张型。It is difficult to use fatigue stress amplitude of normal section to decide whether fatigue fracture occurs in longitudinal fiber compressive zone and pure shear zone near neutral axis. In this paper, pure shear zone, upper pressure zone and lower tensile zone near stiffener of steel beams under fatigue load were analyzed. It reveals that the changes of shear stress caused by rolling wheel pressure cause changes of tensile and compressive stress on principal stress plane and fatigue stress amplitude. Beam web under high shear stress will have big risk. At the same time, this paper illustrates that web fatigue crack extension mechanism due to shear stress changes is different from flange crack extension mechanism caused by tensile stress amplitude. The former is gradual type and the latter is expanding type.

关 键 词：钢梁 腹板 疲劳 主拉应力幅 

分 类 号：TU391[建筑科学—结构工程]