钢框架结构抗连续性倒塌性能试验研究

Experimental study on progressive collapse resistance of steel framed structures

为了研究钢框架结构在中柱失效工况下的抗连续性倒塌性能,进行缩尺比为1∶3的单层三维钢框架结构准静态连续性倒塌试验.采用备用荷载路径法,对中柱施加竖向集中荷载直至结构体系发生钢材断裂等严重破坏,以模拟结构的倒塌过程.观测结构失效模式以及分析中柱竖向位移与所施加集中荷载的关系,研究结构体系的抗连续性倒塌性能.利用试验数据探讨2种抗连续性倒塌力学机制,即弯曲效应和悬链线效应对钢框架结构鲁棒性的贡献.试验结果表明,结构体系表现出良好的延性和较高的承载力,在中柱突然失效的情况下并没有发生连续性倒塌的风险.在加载初期,弯曲效应是结构抵抗连续性倒塌的主要力学机制;尽管随着中柱竖向位移的增大,悬链线效应对结构竖向抗力的贡献逐渐增大,并在加载后期超越弯曲效应,成为主要的抗连续性倒塌力学机制,但是弯曲效应对结构的抗倒塌能力的贡献始终显著.此外,梁柱节点形式对弯曲效应和悬链线效应的发展具有决定性作用.

An experimental study was conducted using a 1∶3 scale one-story bare steel moment frame substructure in order to study the collapse resistance of steel moment-resisting frame structures subjected to loss of an interior column.The alternate path method was employed in the test,which was carried out by increasing the concentrated load applied to the top of the interior column until extensive failure such as fracture of steel occurred.The resistance of the structural system against progressive collapse was investigated through observing the failure modes of the structure and analyzing the relationship between the vertical displacement of the interior column and the vertical load.Experimental data was used to explore the contributions of two types of collapse resisting mechanisms,including flexural action and catenary action,to the robustness of steel moment resisting frames.The experimental results reveal that the structural system exhibits remarkable collapse resistance and ductility,and progressive collapse can be prevented after the sudden loss of an interior column.In the early stage of loading,flexural action is the primary mechanism to resist progressive collapse.Although the contribution of the catenary action to the collapse resistance increases with the increase of the vertical displacement of the interior column and becomes the primary collapse resisting mechanism in the final stage of loading,the flexural action plays an important role in resisting progressive collapse along the entire loading process.Moreover,the type of connections has a determinant impact on the development of flexural action and catenary action.