武汉长丰大道高架桥不平衡重称重试验

Unbalanced Weighing Test for Changfeng Avenue Viaduct in Wuhan

武汉长丰大道高架桥为(55+90+90+55)m预应力混凝土连续刚构桥,位于曲线上。38号、39号墩上部箱梁采用先支架浇筑后平转的施工方法,转体重量分别约155000kN、135000kN。为指导该桥正式转体,采用球铰竖向转动法进行不平衡重称重试验。首先通过理论分析称重过程中球铰受力,推导球铰处于静、动摩擦状态之间的极限状态时最大静摩阻力矩、不平衡力矩、重心偏心量及静摩擦系数公式;然后分析顶升力与位移试验结果,确定极限状态时的顶升力并代入公式,推算转动相关参数值。该桥横向、纵向重心偏心量分别设置为0m、0.050m;根据不平衡力矩,设置纵横向配重;试转时38号、39号墩转动体启动牵引力实测值分别为674kN、531kN,与计算值较接近,满足平转牵引要求。

The Changfeng Avenue Viaduct in Wuhan is a curved, prestressed concrete continuous rigid-frame bridge with four spans of 55, 90, 90 and 55m. The box girders over the pier No.38 and pier No.39 were first cast on scaffoldings and then swinged into position, the two parts rotated weighed up to 155 000 kN and 135 000 kN, respectively. To guide the formal rotation of the viaduct, the spherical hinge vertical rotationmethod was used to carry out the unbalanced weighing test. First, the load bearing condition of the spherical hinges were theoretically analyzed, to deduce themaximum static frictionalmoment, unbalancedmoment, eccentricity of gravity center and static frictional coefficient when the spherical hinges were in the ultimate state between the static and dynamic friction states. Then, the jacking forces and the results of displacement test were analyzed to determine the jacking force in the ultimate state, the latter was substituted into formula to deduce the values of related parameters to rotation. The transverse and longitudinal eccentricities were set at 0m and 0.050m, respectively. Longitudinal and transverse counterweights were added in accordance with the unbalancedmoments. During the trial rotation, themeasured starting traction forces of the rotated parts of pier No.38 and pier No.39 were 674 kN and 531 kN, respectively, which were closer to the computed values andmet the requirements for the swing traction.