This paper provides a simplified design approach for estimating the lateral–torsional buckling (LTB) strength of the pultruded glass fiber-reinforced polymer (GFRP) composite I-beams. A detailed finite element (FE) model based on ABAQUS incorporating more realistic parameters for pultruded GFRP I-beam is developed and verified against the test results available in the relevant literature. After achieving a reliable FE model (through high degree of accuracy in the numerical validation), detailed parametric studies were undertaken by varying the section geometries as well as the span of pultruded I-beams. The selection of the sectional dimensions was based on the composite manuals available in the market, to ensure ease in the practical application of the outcomes of this study. In this analysis, simply supported beam with a uniform bending moment is considered. In accordance with the results of the FE parametric analysis, the accuracy of the theoretical LTB strengths predicted by the equations proposed for pultruded GFRP beams available in the literature is assessed. This comparison indicates that the existing method results in an over-conservative LTB strength estimates for pultruded GFRP I-beams, especially in the low and medium slenderness range. This is primarily due to a comparatively lesser impact of section imperfections on LTB resistance than high slenderness range. Therefore, to address this shortcoming, new simplified design formulations were proposed to have high accuracy of the LTB strength predictions for pultruded GFRP I-beams especially in the low and medium slenderness range. The proposed equations have been provided that might aid the structural engineers in economically designing the pultruded GFRP I-beams in the future.

本文提供了一种简化的设计方法，用于估算拉挤玻璃纤维增​​强聚合物（GFRP）复合工字梁的横向扭转屈曲（LTB）强度。开发了基于ABAQUS的详细有限元（FE）模型，该模型结合了拉挤GFRP工字梁的更多实际参数，并根据相关文献中提供的测试结果进行了验证。在获得可靠的有限元模型后（通过高度精确的数值验证），通过改变截面几何形状以及拉挤工字梁的跨度进行了详细的参数研究。截面尺寸的选择是基于市场上可用的复合手册，以确保易于实际应用本研究的结果。在此分析中，考虑具有均匀弯矩的简支梁。根据有限元参数分析的结果，评估了文献中针对拉挤GFRP梁提出的方程式所预测的理论LTB强度的准确性。这种比较表明，现有方法导致拉挤的GFRP I型梁的LTB强度估算值过于保守，尤其是在中低纤度范围内。这主要是由于截面缺陷对LTB抵抗力的影响要比高细长范围的影响要小。因此，为了解决这一缺点，提出了新的简化设计公式，尤其对于中低纤度范围的拉挤GFRP I型梁，其LTB强度预测的准确性很高。