【摘要】 门式启闭机是水利水电工程中的重要启闭设备，工程设计中支腿通常采用变截面替代等截面的形式，其结构计算结果为近似解，为了在工程中得到更精确的计算结果，总结研究了5种变截面支腿折算惯性矩计算方法，按照原理将其分成三类，并通过方程式展开推导与讨论得到了折算惯性矩以I_Zmin、I_Zmax与系数乘积的关系式；通过工程实例与有限元计算结果对比分析得到5种方法结果的精度。结果显示：主梁跨中弯矩结果都与有限元结果接近，而对于支腿与主梁交接处弯矩、主梁跨中挠度，则几种方法都存在一定误差，《水工建筑物的启闭机械》的方法精度更好；并指出对于门机主框架，评判折算惯性矩方法的精度时，仅考虑主梁跨中弯矩是不够全面的，对于重要的门机，建议应进行有限元计算。更多还原

【Abstract】 Gantry hoist is an important equipment in water conservancy and hydropower engineering. In engineering design, the leg usually adopts the form of variable cross-section instead of equal cross-section, and the structural calculation result is an approximate solution. In order to obtain more accurate calculation results in engineering, five methods for calculating the converted moment of inertia of variable cross-section legs are summarized and studiedanalyzed. According to the principle, it is divided into three categories, and the relationship between the converted moment of inertia and the product of I_Zmin、I_Zmax and coefficient is obtained through the derivation and discussion of the equation. The accuracy of the results of the five methods is obtained by comparing the engineering examples with the finite element calculation results. The results show that the mid-span bending moment results are close to the finite element results. There are some errors in several methods for the bending moment at the junction of the leg and the main beam and the deflection of the main beam. The method of “Opening and closing machinery of hydraulic structures” has better accuracy, and pointed outproved that for the main frame of gantry crane, it is not comprehensive enough to only consider the mid-span bending moment of main girder when evaluating the accuracy of the converted moment of inertia of variable cross-section legs. For important door machine, it is suggested that finite element calculation should be carried out.更多还原