斜拉桥锚拉板易损细节设计优化

研究目的:郑北大桥索梁锚固结构采用锚拉板结构形式,该区域构造复杂,焊缝交错,部分位置存在明显的应力集中现象,恒载作用下易发生塑性破坏,反复荷载作用下易产生疲劳破坏。通过建立精细化有限元模型,分析锚拉板式索梁锚固结构的易损部位,对局部细节进行设计参数优化,从而改善其恒载和活载下的受力性能。提取疲劳易损部位热点应力,通过热点应力S-N曲线和线性累积损伤理论计算其疲劳寿命,验证参数优化效果。研究结论:(1)在原设计的基础上适当优化锚拉板厚度能有效改善锚拉板式索梁锚固结构恒载下受力性能,防止材料塑性破坏;(2)经热点应力法计算疲劳寿命验证,在原设计的基础上适当优化圆形过渡区半径、锚拉板厚度、锚筒厚度能提升锚拉板的疲劳寿命;(3)本文研究结论可运用于今后的斜拉桥锚拉板式索梁锚固结构的设计中,以供相关设计人员参考。

Optimization of Vulnerable Structural Details of the Anchor Plate of Cable-stayed Bridge

Research purposes: The cable-to-girder anchoring structure of Zhengbei Bridge adopts anchor plate structure. The structure in this area is complicated with welds staggered. There is obvious stress concentration at some locations. Constant load can lead to plastic failure while the fatigue failure is likely to occur under live load. By establishing a refined finite element model,we analyze the anchor plate on which parts are easily damaged,and optimize the design parameters of the regional geometric details,consequently improving its performance under constant and live load. The hot spot stress of fatigue vulnerable part is extracted,and the fatigue life is calculated by a hot spot stress S-N curve and the Miner linear cumulative damage theory to verify the effect of parameters’ optimization.Research conclusions:( 1) Appropriate optimization of the thickness of the anchor plate on the basis of the original design can effectively improve the mechanical performance and prevent damages of the cable-to-girder anchoring structure under constant load.( 2) Appropriate optimization of the radius of the circular transition zone,the thickness of the anchor plate and the thickness of the anchor tube on the basis of the original design can improve the fatigue life of the anchor plate,which is verified by the hot spot stress method.( 3) The research conclusion can be applied to the design of anchoring plate-type cable-to-girder anchorage structures for cable-stayed bridges in the future for reference by related designers.