外包钢壳混凝土拱形桥塔节段拼装几何姿态预测研究

Research on Geometric Attitude Prediction of Prefabricated Segmental Steel-Clad Concrete Arch During Assembly

赣州市集结大桥主桥为外包钢壳混凝土拱形桥塔斜拉桥,为确保钢混组合拱形桥塔节段拼装精准合龙,采用MIDAS Civil软件建立拱形桥塔空间几何模型,分析外包钢壳和混凝土湿重对桥塔变形的影响,采用切线初始位移法对桥塔施工阶段位移进行预测,通过求解制造线形对桥塔待拼装节段进行预偏修正,并与实测数据进行对比。结果表明:外包钢壳能显著减小桥塔变形;施工阶段桥塔变形主要由混凝土湿重引起,临时支撑能有效减小混凝土浇筑产生的横向变形。基于切线初始位移法的几何姿态预测方法能有效预测桥塔拼装全过程几何姿态,实测成桥阶段桥塔各节段最大偏位为6 mm,小于施工控制要求,具有较高的实施精度,可保证成桥状态下桥塔几何姿态的准确性。

The main bridge of Jijie Bridge in Ganzhou City is a cable-stayed bridge with an arch-shaped pylon that consists of steel-clad concrete segments.The assembly of the arch segments were numerically simulated in MIDAS Civil,to analyze the influence of steel shell and wet concrete on the pylon deformation.The initial tangential displacement method was used to predict the displacement of pylons during the construction process.Furthermore,the pre-offsets of pylon segments waiting for assembly were corrected via calculating the manufacturing geometry,and the predicted values were compared with the measured data.It is shown that the external steel shell effectively suppresses the deformation of the pylon,but the wet concrete is the main cause of the pylon deformation during construction,and adding temporary supports is an effective way to reduce the transverse deformation of the pylon structure during concrete casting.The geometric attitude prediction method developed from initial tangential displacement method is able to effectively predict the geometric attitude of the pylon during the whole assembly process.After completion of the bridge,the measured maximum bias of each pylon segment is 6 mm,smaller than the allowable value,indicating great implementation precision.The required geometric attitude of the pylon after completion of the bridge can be ensured.