Exploring the long-term performance of welded details in composite trapezoidal corrugated web (TCW) girders is a significant focus for the service life of these structures exposed to atmospheric environment and traffic flow. The majority of the present studies have been conducted without accounting for thermal stresses induced by temperature differences and accurately reflecting internal force transfers for the composite girders in flexural bending. The fatigue behaviour of the welded details in these girders under coupled thermal-structural loading is investigated herein through experimental and numerical methods. The results indicated three stages for the structural degradation from the test performance and justified a proper allowance of the cross-sectional stress in coordination with the flexural curvature in the derivation of S-N relations comparable to similar details in related design codes. A sub-modelling procedure is implemented to capture the thermal gradient, the local stress concentration, and the crack distribution in global modelling while replicate the semi-elliptical surface crack at the external side of the fillet weld toe in local modelling. The fatigue lives predicted from the proposed analytical model match reasonably well with experimental and numerical results, indicating its good applicability incorporating characteristic geometric correction factors into classical theoretical calculation for fatigue evaluation.

中文翻译：

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热-结构耦合载荷下复合梯形波纹腹板梁焊接细节的基于子建模的疲劳评估


探索复合梯形波纹腹板 （TCW） 梁中焊接细节的长期性能是这些暴露在大气环境和交通流中的结构使用寿命的重要重点。目前的大多数研究都是在没有考虑温差引起的热应力的情况下进行的，并且没有准确反映复合材料梁在弯曲弯曲中的内力传递。本文通过实验和数值方法研究了这些大梁中焊接细节在耦合热结构载荷下的疲劳行为。结果表明，测试性能存在结构退化的三个阶段，并证明了在推导 S-N 关系时，与弯曲曲率相协调的横截面应力的适当允许是合理的，这与相关设计规范中的类似细节相当。实施了子建模程序，以捕获全局建模中的热梯度、局部应力集中和裂纹分布，同时在局部建模中复制角焊趾外侧的半椭圆形表面裂纹。根据所提出的解析模型预测的疲劳寿命与实验和数值结果相当吻合，表明其将特征几何修正因子纳入经典疲劳评估理论计算具有良好的适用性。