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雁荡山桥是一座双线铁路系杆拱桥,属于繁忙高速路上的桥梁,由(90+90)m连续钢箱梁构成。由于自重大、倾角大、不对称和临时灵活布置的横梁,钢箱梁的顶推施工面临挑战。由于现场施工条件的限制,许多常见方法不适用于桥梁的顶推施工。采用有限元法模拟顶推过程,结果表明:如果不采取改进措施,梁腹板和底板将产生局部应力集中。对影响应力集中的因素进行研究。在实际工程中采取4种措施减小梁的局部应力:在每根墩柱上增设2个滑块;在钢箱梁前端的横隔板上焊接6个短钢导梁;在临时墩不同位置预提升6个滑块,以消除临时横梁的部分变形;在某跨使用特殊的可调滑块。监测整个顶推过程,应力和变形实测结果与有限元分析结果吻合。采用这4种改进措施,取得了很好的效果。最终,雁荡山桥的顶推施工顺利完成。
Yandangshan Bridge is a double-track railway tied arch bridge, belonging to a busy highway bridge, by (90 +90) m continuous steel box girder. Due to their heavy weight, large inclination, asymmetric and temporary flexible placement of beams, steel box girder push construction is facing challenges. Due to the restriction of on-site construction conditions, many common methods are not suitable for the push-to-bridge construction of bridges. The finite element method is used to simulate the thrusting process. The results show that if no improvement is taken, the local stress concentration will occur in the webs and slabs. The factors that affect the stress concentration are studied. In practice, four measures are taken to reduce the local stress of the beam: two additional sliders are installed on each pier; six short steel guide beams are welded to the diaphragm on the front end of the steel box girder; at different positions of the temporary pier Pre-lift 6 sliders to eliminate some of the temporary beam deformation; use a special adjustable slider at a span. Monitoring the whole thrust process, the measured results of stress and deformation are in good agreement with the results of finite element analysis. With these four kinds of improvement measures, and achieved good results. In the end, the push-yang construction of Yandangshan Bridge was successfully completed.