Abstract: Based on mechanical behavior of strengthened composite main arch and practical strengthening projects，internal force of main arch bridge before and after reinforcement was calculated． Increase rate of the main arch cross-section strength and the overall“strength-stability”was expounded． Shear capacity of old and new arch ring combination surface and the impact of new structure on the original structure were checked． As a result，an increase overall effect reinforcing evaluation index based on increase rate of bearing capacity was proposed，which played a positive role in design options and quality assessment of arch bridge reinforcement．

Key words: composite main arch circle, stone arch bridge, mechanical behavior, capacity increase rate

摘要： 从复合主拱圈加固石拱桥加固前后力学性态的角度，结合具体的实际加固工程，对加固前后主拱圈截面内力 进行计算，阐述主拱圈截面强度和整体“强度－稳定”性提高率，验算新旧拱圈结合面抗剪承载力和新增结构对原 结构的影响，提出一项基于承载力提高率的加固增强总体效果评价指标，以期对石拱桥加固设计方案比选、加固质 量评定有一定的积极指导作用。

关键词: 复合主拱圈, 石拱桥, 力学性态, 承载力提高率