鹤大高速红岭高架桥病害分析及加固设计研究

鹤大高速红岭高架桥为5跨预应力混凝土连续刚构箱梁桥,经过多年运营,检测发现该桥右幅出现了主梁跨中下挠、腹板斜裂缝、顶板纵向裂缝等病害。为了解病害原因及结构受力状态,对病害原因进行分析,并进行荷载试验,在此基础上进行维修加固设计研究。结果表明:弯剪作用引起腹板斜向开裂,横向弯矩过大引起顶板开裂,预应力径向作用过大造成底板开裂。该桥上部结构校验系数大部分大于或接近于1.0,正截面抗拉强度不满足设计荷载要求;采取顶板加厚、腹板加厚、底板增设横梁以及张拉体外预应力加固设计。数值模拟分析显示加固后箱梁顶、底板最大压应力有效降低,安全储备增加,主应力得到明显改善。加固后第3跨L/4、L/2、3L/4截面分别上挠14.34,0.34,12.61 mm,结构受力满足现行规范要求。

Deterioration Analysis and Retrofitting Design for Hongling Viaduct on Hegang-Dalian Expressway

The Hongling Viaduct on Hegang-Dalian Expressway is a prestressed concrete continuous rigid-frame box beam bridge with five spans.After years of operation,deteriorations have been observed on the bridge,including the midspan downwarping,oblique cracks on webs and longitudinal cracks on top slabs.To investigate the causes of deteriorations and the load bearing condition of the structure,the causes of deteriorations were analyzed,and load tests were conducted,based on which the retrofitting design was studied.The results show that the oblique cracks on the webs are induced by the bending and shearing action,oversized transverse bending triggers cracks on top slabs,and excessive radial effect of prestressing causes cracks on the base slabs.Most correction factors of the superstructure are greater than or close to 1.0,and the tensile strength of the normal cross-section cannot meet the design requirements.The retrofitting design focuses on increasing the thickness of the top slabs and webs,adding cross beams to the bottom slabs and adding external prestressing tendons.The numerical simulation demonstrate that the maximum tensile stresses in the top and bottom slabs of the box beams after strengthening are effectively reduced,the safety margin is enlarged,and the principal stress state is significantly enhanced.After strengthening,the cambers in the L/4,L/2 and 3 L/4 cross-sections of the third span are 14.34,0.34 and 12.61 mm,respectively,and the load bearing capacity of the viaduct meets the current code requirements.