Research Into Prestressing Landslip Of Curved Box Girder Bridges By Tensioning Of Steel Wires

With the rapid development of expressway and main road, more and more interchanges and fly-over crossing will be built. The curved box girder bridges have been adopted more and more in the bridge project of interchanges and fly-over crossing because of good performance of structure and features of economy, beauty and utility.Curved box girder bridge is a space structure. Due to the influence of the radius of curvature, the mechanical characteristic of the curved box girder bridge is differ to those of the straight bridges. The tensioning of the steel wires is the key step in the construction process. To the curved girder bridge's prestressed reinforcement "side direction landslip" phenomenon that some experts put forward in resent years, this dissertation makes a systematical research about prestressed reinforcement side direction landslip of prestressed concrete continuous curved box girder bridge which is relied on a Bridge of NeiMeng Province.The dissertation use emulation analyse method which is based on space finite-element method to analyze curved box girder bridge is different from the grillage structure theory which is rifeness used on curved box girder bridge design. The finite element model which analyzes the stress of the beam section in tensioning is established through stimulating the construction process.Compared with crack and landslip part which is effected by tensioning, the rational methods which is used to prevent prestressed reinforcement side direction landslip are given.A brief introduction of the deduction of Valsov equation about curved beams is given in this paper at first. Second, the space prestressing effect analytical theory and method was formulated. Then, according to the latest highway bridge design standards, the prestressing loss calculation and the prestressing design of the curved girder bridge was discussed. Based on coordinating relations of steel and concrete method and the finite-element theory of ANSYS, the prestressing effect analytical method was introduced Prestressed reinforcement side direction landslip of prestressed concretecontinuous curved box girder bridge was checked computations according to the latest highway bridge design standards. Finally, making use of the finite element model, the example of the NeiMeng Bridge were analyzed by use reduce temperature to simulate the tensioning of the steel. Then, when inner force and deformation are calculated in the analysis of bridges, shrinkage of concrete can be considered automatically, so the part loss of prestressing force can be calculated. Then computational efficiency and precision are increased. The final date can be used for reference on the curved box girder bridge design.The research to prestressed concrete crack and landslip which is created by the tensioning of the steel is material nonlinearity research. The concrete constitutive model is based on Willam-Wamker destroy that need five parameter which can simulate concrete crack and landslip efficiently and exactly.