Exploration For Controling Deflection Of Continuous Rigid Bridge In Service By Using Of External Transverse-tension Prestress Method

The effective prestress in service of large-span continuous rigid bridge is not easy to control, which leads to the deflection of midspan and the formation of structure crack.The conception of using External Vertically Tensioned Prestress to treat the diseases is proposed in this paper, some aspects of the new technology is also explored,such as the strand arrangement, calculation method,structural measures and so on.1. The principle and the successful cases in engineering practice of the Vertically Tensioned Prestress are introduced.2. Based on much literature review, the paper gives the summary of the diseases of the continuous rigid bridge,and analysis on cause of deflection of midspan and the formation of cracks, commonly used solutions are analyzed as well.3. The conception of using Vertically Tensioned Prestress to regulate the deflection in service of continuous rigid bridge is suggested which based on analyzing the disadvantages and advantages of conventional external prestress, the calculation formula of prestress loss and tensioning force's calculation formula of the external vertically tension in the continuous rigid bridge are also proposed.4. It explores strand arrangements of external vertically tensioned prestressed which used to regulate the late deflection of continuous rigid bridge. The proper plans can be chose according to the practical designs.5. It probes into the regulating opportunity of continuous rigid bridges from the qualitative and quantitative. A new plan which used to regulate the late deflection of continuous rigid bridge is put forward in theory, the main reason of midspan sag is that the internal prestress loss is too large. Using deflection changes to obtain the loss ration of single prestressed strand, then palcing it into the continuous rigid bridge model to calculate out the stress near mid-span base plate, setting the stress as controling value to determine the regulating opportunity.6. Reference to anti-corrosion of the conventional External Prestressing steel tendons, the construction of the shock absorber, and the construction of cable clamp which in suspension bridge, the construction of the External Vertically Tensioned Prestress is explored.