基于三维有限元的工字钢下翼缘局部弯曲应力计算

摘要

Calculating of the local bending stress is an important part of the strength design of the I-shape girders which subject to the loads on the bottom flange.Firstly,the present calculating methods for the local bending stress of the bottom flange of the l-shape girders were introduced and their shortcomings were discussedSecondly, the fine 3D solid FEA mesh of the l-shape girder 30a model was constructed and two calculating conditions were designed.Based on their result,precise local bending stress values were ob-tained.Then ,the influenced areas and the distribution properties of the local bending stress were analyzed, which result was compared with that through the present method.The conclusion was drawn that simplifying the bottom flange of a plate with consistent thickness is not reasonable and the calculating result based on it will not be accurate enough.lt is suggested that it is better to use the 3D FEA method to calculate the local bending stress currently.%局部弯曲应力的计算是下翼缘受载的工字钢梁强度设计的重要内容.首先介绍了现有的工字钢下翼缘局部弯曲应力的计算方法,分析了其中存在的问题.然后构建了工字钢30a的精细三维实体有限元模型,设计了两种计算工况,并通过这两种工况的计算结果获取了较为精确的局部弯曲应力值.接着对局部弯曲应力的影响范围和分布特点进行了分析,并与现有方法的计算结果进行了比较,提出了“按照等厚板模型简化下翼缘是不合理的,基于该原则的计算结果也不够准确”的结论.最后给出了若干意见,建议在现有阶段,局部弯曲应力的计算宜直接采用三维有限元技术进行.