The aim of this study focuses on torsional centre position of the cross section of a complex section stocky beam (CSSB), a new type of model for structural members with arbitrary noncircular cross-sectional shapes and with arbitrary elastic material properties and with length-to-height or length-to-width ratio no more than 3 encountered in modern civil engineering structures. The nodal-line method is utilized to describe the shapes of the out-of-plane warpages of all cross sections of a CSSB under restrained torsional conditions by employing n unknown displacement functions of nodal lines, together with n quadratic interpolation functions inspired and evolved by the shape of Prandtl’ membrane. The governing ordinary differential equations are established by employing the principle of energy in elasticity. Based on the fact that the torsional stiffness of cross section of the same CSSB stays unchangeable with the change of the torque modes exerted to it, and on the computational results of the change rate of torsional angle due to the individual action of each torque corresponding to three torque modes, a formula for calculating two coordinates of the torsional centre position of the cross section is formulated. The computational results of numerical examples are demonstrated to verify the rationality and correctness of the formula.

这项研究的目的集中在复杂截面马鞍形梁截面的扭转中心位置（CSSB），一种新型模型，用于具有任意非圆形横截面形状，具有任意弹性材料特性且长高比或长宽比不超过3的现代土木工程结构中的结构构件。通过使用节点线的n个未知位移函数以及n个受启发和演化的二次插值函数，节点线方法用于描述约束扭转条件下CSSB所有横截面的平面外翘曲的形状。 Prandtl膜的形状。利用弹性能量原理建立了控制常微分方程。基于同一CSSB横截面的扭转刚度随施加的扭矩模式的变化而保持不变的事实，并且，针对与三个转矩模式相对应的各转矩的个体作用所引起的扭转角变化率的计算结果，推导了计算截面的扭转中心位置的两个坐标的公式。通过数值算例验证了该公式的合理性和正确性。