本文认为GBJ7—73所订η公式,仅当杆件中点具有构造初偏心e_0情况下,方属适用。对于端部存在初偏心、变弯矩、变截面及裂缝等其他影响,引用α_e进行考虑的方法,理论上不够严密,所得设计弯矩一般偏大,亦可能偏小。从当前实用出发,根据杆系弹性稳定的能量准则,作者求得考虑裂缝和变截面影响的折算计算长度及弯矩沿杆长变化的纵向弯曲系数η,与GBJ7—73相较,本文所提方法安全合理,对弯矩变化情况有良好的经济效果。 In this paper, the η formula defined by GBJ7-73 is applicable only when the mid-point of the rod has the initial eccentricity e_0. For other influences such as initial eccentricity, bending moment, variable cross-section, and cracks at the end, the method cited by α_e is not strictly theoretical, and the resulting design bending moment is generally too large and may be too small. Starting from the current practicality, according to the elasticity and stability of the energy criterion of the rod system, the author obtained the calculated length of the calculation considering the influence of cracks and variable cross sections and the longitudinal bending coefficient η of the bending moment along the length of the rod, compared with GBJ7-73. The method is safe and reasonable, and has a good economic effect on the change of bending moment.