Theoretical And Experimental Research On Deflection Control Of Simply-supported-continuous Girder Bridges

Simply-supported-continuous system with reasonable force structure, less expansion joints for high-speed driving, and can improve construction quality and accelerate the construction schedule by way of pre-lifting construction, are widely used at home and abroad. However, this system exist a widespread problem in practice that is very difficult to control the deflection of the structure, and therefore, affecting the quality of construction and normal use.In order to control the deformation of simply-supported-continuous system, take Fujin - Suibin Songhua River Bridge construction project as background, combine theoretical analysis with actual measurement to calculate deflection regulation and stress distribution of structure and analysis of various factors that are affective, and recommend effective methods to control deflection.At first, research elasticity and plasticity calculation theories of deflection control of simply-supported-continuous girder bridge. In elastic calculation, mainly consider prestress loss and calculate the deformation of the structure with principle of virtual work. In plastic theory, focuses on concrete creep mechanism, influencing factors and prediction models, and compare forecasting models to choose a suitable prediction model.Secondly, through User Programmable Features based on ANSYS, select the 04 standard creep model and make this creep equation for exponential fitting, establish a creep strain increment equation that can be used by Fortran programming languages.Next, at the construction site, observed the transient deformation of 94 pieces of T beams and 6 months long-term deformation of 29 pieces of T beam after tension. Grasp the situation of structure's short-term and long-term deflection, and find that the deflection control problems are really existed. Through using the ANSYS and Doctor Bridge to simulate pre-T beam and compare the calculated values with measured values, analyze the deflection regulation and stress distribution of pre-T beams. In the ANSYS simulation, explore considering and not considering the role of ordinary steel bar how to affect the long-term deformation and long-term stress of the structure, and further study of the impact in the perspective of ordinary steel bars'rate. Then, simulate the whole process of simply-supported-continuous girder bridge, analysis of the structural's deflection and stress distribution, and compared the simply-supported-continuous girder with the pre-T girder, and brought forth the key point of the way to control deflection. Explore the interaction affect of prestress, second internal force and stress redistribution to the structure.Finally, by calculating the elastic deformation of pre-T girder after tension, modify the coefficient values of variety factors, comparative analysis of its impact on the structural deformation, combined the affecting factors of plastic deformation, and therefore, proposed effective measures to control deflection.