厚边U肋正交异性钢桥面的疲劳性能

Fatigue Performance of Orthotropic Steel Decks with Thickened Edge U-Ribs

新型厚边U肋正交异性钢桥面的应用有望提高顶板与U肋连接焊缝的抗疲劳寿命.为研究其实际疲劳性能和具体提升机理,对该类钢桥面中顶板与U肋连接焊缝开展了疲劳试验和数值分析.通过足尺模型疲劳试验,采用名义应力法和热点应力法对常规等厚U肋钢桥面和新型厚边U肋钢桥面进行了对比;在疲劳试验的基础上,建立了精细化有限元模型并通过试验数据验证了其有效性;通过该模型对厚边U肋钢桥面顶板与U肋焊缝的疲劳性能提升机理进行了分析.结果表明:厚边U肋的使用有效地提高了顶板与U肋连接焊缝的疲劳强度;在焊接负公差存在的情况下,厚边U肋试件对未熔透厚度的变化相对不敏感,从而保障了顶板与U肋连接焊缝疲劳性能的稳定性.厚边U肋正交异性钢桥面在北京三元桥新桥和成都凤凰山高架桥等工程项目中的应用验证了其抗疲劳的有效性.

The fatigue performance of rib-to-deck(RD)joints is expected to be enhanced by the application of the orthotropic steel deck(OSD)with thickened edge U-ribs(TEUs).To investigate its actual fatigue performance and the mechanism of enhancement,the RD joints in the OSD with TEUs using the fatigue test and numerical analysis was evaluated.Through the fatigue model test of full-scale specimens,comparative analysis was performed on the OSD with conventional U-ribs(CUs)and the OSD with TEUs,in the test,both the nominal stress and hot spot stress approaches were incorporated.A refined finite element(FE)model was established based on the test,and validated by the test data.Using the model,numerical analysis was carried out to study the mechanism of the enhancement in RD joints by the application of TEUs.The results show that:the use of TEUs improve the fatigue strength of rib-to-deck joints effectively;in the presence of negative welding errors,the specimens with TEUs are relatively insensitive to the variations in unpenetrated thicknessthat leading to the robustness of the fatigue strength of rib-to-deck joints.The fatigue performance of the OSD with TEUs has been further validated through its application in several engineering projects such as New Sanyuan bridge in Beijing and Fenghuangshan Viaduct in Chengdu.