上跨既有桥梁现浇箱梁悬挑支架设计及施工

Design and construction of cantilever support for cast in situ box girder of existing bridge

文章介绍了旧桥结构受力分析及上跨既有白沙河桥现浇箱梁悬挑钢管支架设计、受力分析、支架搭设过程控制及注意事项。通过对旧桥结构受力计算,分析其承载能力,确定合理的上跨现浇箱梁支架搭设形式。通过合理布置钢管间距,尽量减少靠近悬挑位置钢管柱受力。在靠近悬挑位置钢管柱内灌注混凝土提高钢管受力性能。条形基础底部设置钢筋网片,钢管柱间设置纵横向剪刀撑、焊接斜撑。进行支架基础预压,消除了不良地质钢管支架基础不均匀沉降易造成架体失稳和梁体混凝土受拉产生裂缝的情况,确保在不影响旧桥结构受力的条件下实现上跨现浇箱梁施工。

The article introduces the structure and force analysis on bridge across both the baisha river crossing cast-in-situ box girder cantilever steel pipe support design, stress analysis, support build-up process control and the matters needing attention. Through the bridge structure calculation, analysis its bearing capacity to determine the reasonable span cast in situ box girder support build-up on the form. By reasonable arrangement pole spacing, decrease as far as possible close to the bearing steel tube column cantilever position.Carry out pour concrete in steel tube column in close to cantilever position to improve steel mechanical performance. Bar foundation bottom set up reinforcement mesh. Vertical and horizontal diagonal braces and welded diagonal braces are set between steel pipe columns. The support foundation is preloaded to eliminate the situation that uneven settlement of the steel pipe support foundation in bad geology is easy to cause instability of the frame and cracks in the beam concrete under tension, to make sure it will not affect the bridge structure under the condition of cast-in-place box girder construction implementation.