钢框架梁下翼缘削弱型组合节点的滞回性能研究

Study on hysteretic behavior of composite joints with weakened beam bottom flanges in steel frame

针对带混凝土楼板的钢框架节点延性性能差,在梁下翼缘焊缝处易于发生破坏的不足,本文提出一种采用上窄下宽且仅梁下翼缘削弱的单轴对称钢梁截面的新型组合节点形式,运用有限元软件ABAQUS对其进行滞回性能研究。结果表明:梁翼缘的削弱方式以及钢梁上、下翼缘宽度比对组合节点的滞回性能有明显影响。合理的组合节点形式可有效缓解组合梁截面的中和轴上移,实现梁上塑性铰外移,提高组合节点的延性;随着梁上、下翼缘宽度比的减小,组合梁截面中和轴逐渐下移,节点的承载能力以及延性有所提高,建议钢梁上、下翼缘宽度比的取值为:(0.6~0.9)。

The steel frame beam column joint with concrete floor slab has poor ductility,and the weld of the lower flange of the beam is prone to brittle failure.In view of the above shortcomings,this paper proposes a novel connection form of uniaxial symmetric composite joint with narrow upper flange and wide lower flange of the beam,which only weakens the lower flange of the beam.The finite element software ABAQUS was used to analyze the hysteretic performance of the proposed connection.Results show that the weakening form of beam flange and the size of upper and lower flanges have a great impact on the hysteretic performance.The reasonable form of composite joints can effectively alleviate the upward movement of the neutral axis of the composite beam section,realize the outward movement of the plastic hinge on the beam,and improve the ductility of the composite joints.With the decrease of the width ratio of the upper and lower flanges of the beam,the neutral axis of the composite beam section moves down gradually,and the bearing capacity and ductility of the composite connection can be improved.It is suggested that the width ratio of upper and lower flanges be 0.6~0.9.