Construction Monitoring and Control of Steel Truss Girder Cable-Stayed Bridge of Huanggang Changjiang River Rail-cum-Road Bridge

The main bridge of Huanggang Changjiang River Rail-cum-Road is a steel truss girder cable-stayed bridge with double pylons and double cable planes.To ensure that the completion status of the bridge could meet the design requirements,the spatial model for the whole bridge was established and the corresponding calculation and analysis were made,using the bridge special finite element analysis software 3D-bridge.Two target status of closure and completion of the bridge were set and the construction monitoring and control of the bridge were carried out according to the target status,using the unstressed state control method.The construction of the pylons of the bridge was controlled by way of pre-raising the padding courses of the bearings and the elevation of the stay cable anchoring points.The cantilever erection and the geometric shapes of the steel truss girder were controlled,using the relative coordinate method through adjusting the installation procedures of the members of the girder after the temperature influences were filtered according to the consecutive construction survey.The stay cables of the whole bridge were tensioned in place in two times and the precision of the initially tensioned stay cable forces were effectively controlled,using the cycling iteration method of pulling-out amount.The steel truss girder of the central span of the main bridge was closed,using the active closure method and the precision of the closure was ensured through adjusting the rotation angles,elevation,longitudinal and transverse positions of the girder at the closure gap.After the construction of the ballast trough slabs was completed,the stay cable forces of the whole bridge were then adjusted for the second time.