Study On The Construction Control Of The Critical Item Of Extradosed Cable-stayed Bridge

Extradosed cable-stayed bridge is a new kind of bridge between the cable-stayed bridge and continuous beam bridge. It has a beautiful appearance and has been quickly developed at home and abroad. On the basis of the control theory and method of cable-stayed bridge construction, relying on the construction process of Nanping extradosed cable-stayed bridge, the construction control method and construction monitoring has been done. At the same time, the finite element simulation of the whole construction process has been established, and the stress and linear control targets has been obtained ultimately. The conclusions are as follows:(1)The construction control of cable-stayed bridge is a cycle process,which is "Prennouncement-Measure-Recognition-Modifying-Prennouncement". The adaptive control method,which is measuring the cable-stayed bridge actual stress and deformation and continuous modifying the design parameters, can ensures that the calculation results are in good agreement with the actual construction.In this way, the stress and linear controled targets can be achieved.(2)Proposing control scheme of Nanping bridge construction and establishing the monitoring target, which were the elevation control, stress control and the control of cable force. The ultimate goal was to make the construction of the structure in the best condition, ensuring construction safety and the finished bridge state (including the internal force and alignment) could meet the design requirement and specification requirement.(3)Establishing the finite element model of Nanping bridge, analysising the stress of the main girder and the cable tower in each stage.The analysis showed that the maximum tensile stress, the maximum compressive stress of the main girder and the tensile stress of the cable tower were on the control of the specification limits; the maximum tension stress of the cable force were in the safety requirements.(4)The implementation of the linear monitoring of the cable-stayed bridge during construction, monitoring data showed that the measured values were close to the theoretical value and the deviation were in the specified control range; the offset deviation of two cable towers were also in the specification limits.(5)The measured stress and cable force of Nanping bridge during construction were close to theoretical calculation values,meeting the control requirements stage.The main girder alignment were within the control.