九江长江大桥主桥公路桥改造设计

Retrofitting Design of Roadway Bridge of Main Bridge of Jiujiang Changjiang River Bridge

针对九江长江大桥主桥公路桥存在的两方面问题(原设计标准低于现在的运营要求;桥面系结构出现的病害使整个结构存在安全隐患且影响结构的耐久性),分析病害原因并进行结构检测评估,在此基础上提出加固改造方案。在不改变原有结构受力体系的前提下,采用较轻的正交异性钢桥面板整体更换原公路桥面系,所有纵向构件全联连续,取消原桥一联中间设置的小型伸缩缝;将原横梁加劲板的上、下两端分别与横梁的上、下翼缘固定,同时在原加劲板两侧增设加劲板改善支座附近横梁腹板的受力状况;对原公路托架采取安装新增构件和更换部分节点板及杆件的措施进行加固。改造方案提升了公路桥的技术标准,并且修复了存在的病害。

In view of the problems of the two aspects existing in the roadway bridge（i.e.the original design criterion of the bridge was below the current operation requirement and the deteriorations occurring in the floor system structure of the bridge caused the whole structure to have the potential safety hazard and affected the durability of the structure）of the main bridge of Jiujiang Changjiang River Bridge,the causes leading to the deteriorations were analyzed,the structure was inspected and assessed and the retrofitting scheme for the roadway bridge was correspondingly proposed.On the premise that the original structural force system of the bridge was not changed,the original floor system structure of the bridge was integrally replaced with the relatively light orthotropic steel bridge deck.All the longitudinal components in the whole continuous unit of the bridge were made continuous and the small-size expansion joints originally arranged in the continuous unit were removed.The upper and lower ends of the stiffening plates of the original cross beams were respectively fixed at the upper and lower flanges of the cross beams and at the same time,the new stiffening plates were added to the both sides of the original stiffening plates in order to improve the force conditions of the webs of the cross beams close to the bearings.The original roadway brackets were strengthened by the measures of installing the new components and replacing parts of the gusset plates and members.With the proposed retrofitting scheme,the criterion of the bridge was improved and the existing deteriorations were well repaired.