钢框架梁开孔削弱效应及补强分析

Analysis on weakening effect and reinforcement of prefabricated steel frame beam

钢框架梁常因建筑需求在腹板不同位置开孔,梁的承载力和稳定性会有不同程度的削弱。本文基于非线性有限元分析方法,研究在均布荷载与侧向荷载作用下的5种常见高跨比HN型钢梁不同孔位的屈曲模式、结构失稳荷载及开孔削弱效应;据此讨论加劲肋和贴板补强的不同效果。结果表明:不同高跨比的梁开孔削弱效应相近,且结构失稳荷载随孔位靠向跨端而产生明显削弱;孔位变化影响梁的屈曲特征,孔位近跨端时易发生孔域附近的局部畸变屈曲,孔位近跨中时易发生近似实腹梁的整体弯扭屈曲。均布荷载作用下跨中腹板开孔的中长跨梁和侧向荷载作用下开孔梁采用贴板补强即可更好地实现节省钢材、简化加工的目的。

Prefabricated steel frame beams are often perforated in different positions of webs due to the requirements of construction,and the bearing capacity and stability of the beams will be weakened in different degrees.In this paper,based on nonlinear finite element analysis method,the instability modes,critical buckling loads and opening weakening effects of five kinds of HN steel beams with common height-span ratio at different hole positions under uniform distributed loads are studied.The different effects of stiffening rib and plate reinforcement are discussed.The results show that the hole weakening effect of beams with different height-span ratios is similar,and the critical buckling load weakens obviously with the hole position toward the span end.The instability of the beam is affected by the change of hole location.The local buckling and torsion instability of the beam near the hole area is easy to occur when the hole location is near the end of the span,and the overall buckling and torsion instability of the beam near the solid belly is easy to occur when the hole location is near the span.It is better to save steel and simplify the machining of open beam with mid-span web by using plate reinforcement.