山区高墩矮塔斜拉桥结构与美学设计

洪溪特大桥为跨越峡谷的山区桥梁,采用(150+265+150) m的双塔双索面预应力混凝土矮塔斜拉桥,桥塔横桥向为Y形,顺桥向塔柱截面从塔底往上逐渐线性收缩,到达上塔柱斜拉索锚固段后再线性渐变加大,塔梁固结,索面向外倾斜。通过强化桥面以上的结构体量,实现高墩矮塔斜拉桥桥面上下比例的协调匀称。采用MIDAS Civil进行空间有限元分析,整体计算结果表明结构满足规范要求。进行了塔梁固结部位局部分析和上部结构横向计算,采取了加大加腋尺寸和增强配筋的措施,改善应力集中效应,主梁横隔板内配置预应力钢束以平衡斜拉索的横桥向水平分力。采用规范简化公式法和欧拉临界荷载公式法计算塔柱计算长度系数,实现塔柱结构设计的经济性和美观性。     

Ultimate strength assessment of simply supported pitted platings: A new stochastic approach based on Monte Carlo simulation

The ultimate strength assessment of platings affected by random corrosion wastage is a key factor for the reliable design of new ships and the structural health monitoring of aged structures, as pitting corrosion wastage significantly affects the ultimate capacity of platings under compression. In this respect, significant efforts have been undertaken in the last decade to assess the ultimate strength drop-off of pitted platings under compression and several interpolating design formulas, based on a large number of FE simulations, have been developed. Nevertheless, current Rules and guidelines don't provide any explicit strength check criterion for pitted platings. Hence, the main aim of current research is the development of a new framework for the ultimate strength assessment of pitted platings, based on a stochastic approach and the endorsement of Monte Carlo simulation. A new formula, which allows evaluating the statistical properties of the plating ultimate strength in presence of random corrosion wastage, is developed. Subsequently, a benchmark study is carried out, to compare the new formula with the existing ones available in literature and a wide set of FE simulations, carried out by Ansys APDL. Current results are discussed, and the effectiveness of the new formula is verified.