Study on Shear Lag and Ultimate Strength of Corner Parts in Steel Rigid Framed Structures

本文研究了剪力滞和局部屈曲对钢刚架结构角部极限强度的影响。结论可以概括如下：(1)对4个直角和斜角角件试件进行了试验，研究了弹性和弹塑性范围内的剪切滞后现象。(2)根据上述结果，提出了考虑轴力、弯矩变化和梁柱结合部剪力变化的角部剪力滞应力的解析模型。(3)翼缘板的剪力滞法向应力和腹板剪切变形引起的位移的试验结果与剪力滞分析的数值结果吻合较好。(4)在此基础上，通过试验结果与分析结果的比较，提出了一种近似计算剪力滞附加法向应力的方法。(5)在此基础上，通过对箱形截面在轴力、弯矩和剪力作用下的极限状态分析，推导出梁柱结合部对应截面的全塑性相互作用曲线。(6)对于钢刚架结构角部设计，分别采用考虑剪力滞时翼缘板最大法向应力和不考虑剪力滞时的全塑性状态来校核其使用性能和极限极限状态。

This study is carried out to make clear of the influence of shear lag and local buckling on the ultimate strength of corner parts in steel rigid frame structures. The conclusions can be summarized as follows;(1)Four test specimens of corner parts with right and skew angles are tested in order to investigate the shear lag phenomenon in both elastic and elasto-plastic ranges.(2)From the above results, an analytical model for determining the shear lag stress of corner parts is proposed by considering the variation of the axial force and bending moment as well as shearing force applied to the junction parts of beam and column.(3)Test results on the normal stress of flange plate due to shear lag and the displacement due to shear deformation of web plate coincide well with the numerical results by the shear lag analysis.(4)Based upon these facts, an approximate method for evaluating the additional normal stress due to shear lag is proposed through the comparison of test and analytical results.(5)In addition to these researches, a fully-plastic interaction curve for the cross-section corresponding to the junction parts of beam and column is derived by the ultimate limit state analysis of box cross-section subjected to axial force, bending moment and shearing force.(6)For design of the corner part of steel rigid frame structures, it is concluded that the serviceability and ultimate limit states con, respectively, be checked by the maximum normal stress of flange plate due to shear lag and the fully-plastic state without considering shear lag.