Abstract: A scale-down RC structure model of the arch rib from an old bridge in Xinjiang province was designed and fabricated, then the model was tested and numerically simulated under the loading of structural self weight, respectively with or without the strengthening process by means of a prestressing hinged piecewise steel arch (PHPSA). The variation conditions of indicators, such as the stress, the deflection of controlling cross-sections and the bending energy of the arch model, were comparatively investigated before and after strengthening. The test results indicate that, the overall normal stress levels on the controlling cross-sections of the arch model after strengthening decrease a lot compared with those before strengthening; the PHPSA method could effectively modify the deformed axis of the arch model under the structural self weight; furthermore, the bending energy of the arch model after strengthening goes down by 81%. In general, the PHPSA used to strengthen the arch model effectively shares the structural internal forces and optimizes the structural stress condition under self weight, thus it greatly promotes the compressive carrying capacity of the arch under live load. This strengthening technique has a significant effect on those spandrel arch bridges with poor shapes of arch axes or in undue stress conditions under structural self weight loadings, so it makes a good choice for the technical decision on the rehabilitation of worn arch bridges.

Key words: bridge engineering, arch bridge strengthening, prestressing hinged piecewise steel arches (PHPSA), internal force optimization, arch axis modification, bending energy

摘要： 以新疆某旧拱桥为工程背景，建立其主拱圈缩尺模型，对比分析了缩尺模型在模拟自重荷载作用下，采用预应力折线形铰接钢拱加固前后主要控制截面的应变、挠度及拱圈弯曲能等指标的变化。缩尺模型经加固后，拱圈控制截面的应力水平总体比加固前明显减小；加固对拱轴线形可起到明显的调整作用，且加固后拱圈弯曲能量减少了81%。实验结果表明，预应力折线形铰接钢拱能够有效分担和改善拱肋的自重内力，从而显著提高其抗压承载力。该加固技术对改善类似拱轴线形不佳或自重内力条件不利的上承式拱桥的承载力和使用性能效果显著，可作为拱桥加固的备选技术方案。

关键词: 桥梁工程, 拱桥加固, 预应力折线形铰接钢拱, 内力优化, 拱轴线调整, 弯曲能量