厦漳跨海大桥北汊主桥锚拉板锚下区域受力分析

Force Condition Analysis of Zone Under Anchor Tensile Plate of North Main Bridge of Xiazhang Sea-Crossing Bridge

厦漳跨海大桥北汊主桥为主跨780m的双塔双索面钢箱梁斜拉桥,斜拉索在主梁上的锚固采用锚拉板式结构。由于锚拉板锚下区域是应力集中最为明显的地方,为改善该区域结构受力,寻求该区域结构过渡最优方案,采用有限元软件ANSYS建立完整锚拉板结构的节段模型,分别采用弹性材料模型及理想弹塑性材料模型,对锚拉板锚下区域的不同过渡形式进行应力分析,并比较其塑性应变。结果表明,随着过渡区曲率半径的增大,应力集中区的最大应力值逐渐减小,塑性区范围也随之发生变化。根据比较分析结果,结合锚拉板结构的紧凑性要求,厦漳跨海大桥北汊主桥锚拉板过渡区选用了半径为40mm的1/4圆弧过渡形式。

The north main bridge of the Xiazhang Sea-Crossing Bridge is a steel box girder cable-stayed bridge with double pylons, double cable planes and with a main span 780 m. The anchorage for the stay cables of the bridge at the main girder is of the anchor tensile plate structure. For the zone under the anchor tensile plate is the place where the stress concentration is most notable, to improve the structural force condition of the zone and to find out the optimal scheme for the structural transition in the zone, the finite clement software ANSYS was used to build up the sectional models for the complete anchor tensile plate structure. The stress of the different structural transition types of the zone was analyzed and the plastic strain thereof was compared, respectively using the models of the elastic material and ideal elastoplastic material. The results of the analysis reveal that with the increase of the curvature radius of the transition zone, the maximum stress value of the stress concentration zone will be gradually reduced and the range of the plastic zone will accordingly change. In terms of the comparison and analysis and in regard of the requirement for tight arrangement of the anchor tensile plate structure, the 1/4 round arc transition type with a radius of 40 mm is selected for the transition zone of the anchor tensile plate for the north main bridge.