刚架拱桥病害分析及上部和基础结构优化设计

Analysis of Deterioration and Optimal Design of Superstructure and Foundation Structure of Rigid-Frame Arch Bridge

刚架拱桥在使用过程中微弯板、拱肋、横梁及大、小节点处均出现了不同程度的开裂现象。结合定型设计图分析认为,病害的产生与构件尺寸、刚度偏小以及接头构造形式相关。通过适当增加构造尺寸、改进计算分析方法、更改钢板接头为现浇接头、优化基础方案、改善横梁与拱肋的连接方式、加强施工控制等优化措施可避免相关病害的出现,采用这些优化措施在黄土地区设计了一座主跨50 m的刚架拱桥。地下连续墙基础具有承载力高、刚度大、工程量小和施工难度低的优点,将其作为优化的基础形式用于该桥。后期监测数据表明该桥运营状况良好,未出现病害。

The deterioration of cracking of different degrees occurred in the slightly bent plates, arch ribs, cross beams, small and large joints of rigid-frame arch bridge in the service period. In the light of the analysis of the standard design drawings of the bridge, it was concluded that the occurrence of the deterioration was related to the relatively small sectional dimensions and low rigidity of the structural members and also to the structural formation of the joints. However, the deterioration could be avoided by a series of measures of appropriately increasing the dimensions of the members, improving the calculation and analysis methods, changing the steel plate joints into the cast-in-situ concrete ones, optimizing the foundations, improving the connection between the cross beams and arch ribs and reinforcing the construction control. With these measures, a rigid-frame arch bridge with a main span 50 m to be built in loess region was designed. As an optimized foundation type, the underground diaphragm walls were used for the bridge since the foundation type had the advantages of strong carrying capacity, great rigidity, less engineering quantity and little construction difficulty. The late period monitoring data of the bridge showed that the bridge was in good operation state and no deterioration like the cracking occurred in the bridge.