双曲拱桥主拱圈外包混凝土加固

Construction Techniques for Strengthening Main Arch Rings of a Two-Way Curved Arch Bridge by Covering Concrete

南渡大桥是一座运营了42年的双曲拱桥,已出现多处病害且原设计荷载等级低,为满足目前的使用要求,对其进行加固。采用外包混凝土的方法增大主拱圈截面,同时提高拱肋配筋率;加大横系梁截面,使其变成横向连接墙;增加L/8跨处系梁截面。施工中在主拱圈上植筋设置吊点,通过钢丝绳吊住拱下的吊架平台,拱下搭设施工吊架,采用吊架作为施工平台,模板采用拉杆吊挂系统进行支承,通过导流管完成自密实混凝土的浇注。加固后的南渡大桥满足设计和规范要求。

The Nandu Bridge is a two-way curved arch bridge that has been in operation for 42 years. Owing to the deteriorations found in a number of parts and the low original designed load level of the bridge and to satisfy the current operation requirement, the bridge was strengthened. The cross sections of the main arch rings were enlarged by the method of covering concrete outside the arch rings and at the same time, the reinforcement ratio in the arch ribs was increased. The cross sections of the cross tie beams were enlarged to make them the transverse connection walls and the cross sections of the tie beams at L/8 span were also enlarged. In the construction, the reinforcement were set in the main arch rings and the lifting points were set there. A suspended platform under the arches was lifted by the steel ropes, the scaffolding that would serve as the working platform was set up under the arches. The formwork were supported by the tensile members and suspension system and the self-compacting concrete was cast via the ducts. The bridge after it was strengthened can meet the design and code requirements .