正交异性钢桥面横向焊接接头的疲劳寿命估算

来源期刊:中南大学学报(自然科学版)2015年第9期

论文作者:陈世鸣 陆云 周聪 顾萍

文章页码:3461 - 3468

关键词:正交异性钢桥面;疲劳试验;疲劳寿命;应力强度因子;子模型技术

Key words:steel orthotropic decks; fatigue tests; fatigue life; stress intensity factor; sub-modeling technique

摘    要:针对正交异性铁路钢桥面构造细节,设计2个足尺钢桥面构件进行静载和高周疲劳承载试验。在试验研究的基础上,建立钢桥面有限元模型,并进行分析计算,计算结果与试验值基本吻合。在1阶段模型的基础上,采用子模型技术建立纵肋焊缝位置带半椭圆表面裂纹的2阶段模型,用退化奇异单元模拟该部位裂纹尖端应力场,通过位移外推得到不同裂纹深度下裂纹尖端的应力强度因子K。基于初始裂纹尺寸的合理判定,对Paris公式积分推导得到纵肋焊接接头裂纹扩展曲线并估算疲劳寿命,计算结果解释了试验中裂纹的萌生和发展规律。建议钢桥面纵肋焊接接头按EC33中的71级或铁路桥梁钢结构设计规范中IX细节进行疲劳设计。

Abstract: Based on detailing of railway bridges, two full scale steel orthotropic decks with butt welds in the longitudinal ribs were designed and fabricated. Then static and fatigue tests (FE) were conducted. Based on the test results, the FE model of the decks was established and the analytic computation was carried out. The FE results were found in agreement with the fatigue tests results. The second-level models with consideration of pre-existing semi-elliptic crack were developed using the sub-modeling technique and singular element to simulate the stress field of the crack front. The stress intensity factors of different initial crack depths in the butt welds of the longitudinal ribs were obtained by displacement extrapolation. Based on reasonable determination of the initial crack depth, the crack propagation was simulated and the fatigue life was predicted by numerical integration of the Paris formula. The results explained how the crack initiated and grew. It is suggested that fatigue detailing of the butt-weld in longitudinal ribs of the steel orthotropic decks be designed in accordance with detailing grade 71 of EC3, or with the detailing IX of the Chinese Design Code of the Steel Railway Bridge.

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