This paper aims at investigating the optimum positions and the required flexural rigidity (γ_rq) of a single and two longitudinal web stiffeners of unsymmetric plate girders subjected to pure bending by using gradient-based optimization algorithms. The optimization procedure is performed into two steps: The first step is to maximize the bend-buckling coefficient k_b generated from eigenvalue buckling analyses, and then the second step aims to minimize the flexural rigidity of the stiffeners (γ). This procedure is implemented using the Abaqus2Matlab toolbox which allows for the transfer of data between Matlab and Abaqus and vice versa. Based on this research, the optimum locations of the stiffeners are recommended for the unsymmetric plate girders under pure bending. Additionally, equations are suggested to determine γ_rq of the longitudinal web stiffeners of the unsymmetric plate girders. These proposed equations are more realistic in the practical designs than those recommended by AASHTO LRFD specifications and several works in the literature in which γ_rq of the longitudinal web stiffeners is determined based on the simply supported plates but not the unsymmetric plate girders under bending.

本文旨在调查最佳位置和所需的弯曲刚性（γ _RQ单个的），并通过使用基于梯度的优化算法进行纯非对称弯曲板梁的两个纵向腹板加强筋。优化过程分为两个步骤：第一步是最大化特征值屈曲分析生成的弯曲屈曲系数k _b，然后第二步旨在最小化加劲肋的抗弯刚度（γ）。此过程是使用Abaqus2Matlab工具箱实现的，该工具箱允许在Matlab和Abaqus之间传输数据，反之亦然。根据这项研究，建议在纯弯曲下对非对称板梁进行加劲肋的最佳位置。此外，方程建议，以确定γ _RQ的不对称板梁的纵向腹板加强筋。所提出的这些方程是在小于所建议通过AASHTO LRFD规格，并且在文献几个作品，其中实际设计更加逼真γ _RQ下弯曲的纵向腹板加强筋的是基于所述简支板来确定，但不是非对称板梁。