T型外部补强箱型节点加劲肋长度的确定

Determination for stiffener length of external T-stiffener box-column to I-beam connections

为研究T型加劲肋长度对箱型节点性能的影响规律并确定合理的加劲肋长度,对T型外部补强箱型柱—工字梁节点进行弹塑性分析.采用ANSYS有限元方法,分析了T型外部补强节点应力发展趋势,进行了加劲肋长度对箱形柱—工字梁节点性能影响的参数分析,根据节点的设计标准确定了T型外部补强节点合理的加劲肋长度.研究结果表明:采用T型加劲肋时,塑性铰外移到梁翼缘与加劲肋连接端部,节点初始刚度和极限承载力有很大的提高;节点的弯矩传递路径由梁翼缘中部逐渐向梁两侧的加劲肋传递,并通过加劲肋有一部分弯矩传递给柱,从而节点变形大大减小.增大加劲肋长度有利于梁端弯矩通过加劲肋向柱腹板传递,但加劲肋过长时,柱腹板承担过多的应力,梁柱翼缘连接处容易局部屈服,最终确定当加劲肋长度取腹板对角线与梁翼缘夹角在10°～15°时为合理的加劲肋长度.

To study the effects of T-stiffener length on the behaviors of box-column to I-beam connections and design the optimum stiffener length, the elastic-plastic analysis on models of external T-stiffener box-column to I-beam connection was carried out. The stress distribution of external T-stiffener connections was studied using the finite element method, and the parameters of stiffener length were researched. The optimum stiffener length was determined by stress distribution and the basic design criteria. Results indicate that when connections are stiffened by T-stiffener, the plastic -hinge appears in the end of stiffener on beam flange, which greatly improves the initial stiffness and bearing capacity. The transmission route of moment is from the middle of beam flange to T-stiffeners beyond beam gradually, while a part of moment is transmitted to column by T- stiffeners. Then the deformation of connection is decreased significantly. The longer is the T-stiffener, the more moment is transmitted from the end of beam to web of column. However, the connection of beam and column webs is easy to yield locally because of the excessive stress in column web when the length of T-stiffener is over-long. The length, whose angle γ made by the stiffener web diagonal and the beam flange is within 10° to 15°, is ultimately determined as the optimum stiffener length.