Control Methods And Experiment Research In Deflection Upwards Of P.C. Beams

In recent years, with the rapid development of large span prestressed concrete bridge in our country, the time dependent factors are becoming more and more important for engineering personnel, especially the shrinkage, creep of concrete and the relaxation of prestressed reinforcing bar, which depend on the time. And these changes will affect the stress and strain of the structure, then the deflection. The deflection upwards exceeding reasonable value will bring difficulty for high speed running and increase the impact effect, causing the intensive shake of the bridge.Therefore, the precise estimate for deflection upwards of prestressed concrete bridge, from which searching for the reasonable design and construction method, is very important for practical projects. The theme of this paper is to solve the problem about how to determine the deflection upwards precisely and to seek the control methods of over-deformation.Regard background as practical construction project, with abroad and rational analysis, the major work is described as follows: (1) Influencing factors of deflection upwards in prestressed concrete beam is analyzed in detail. (2) Deflection upwards is programmed and estimated precisely on the concise calculation model. (3) Effective methods in design and construction are provided to control over-deformation.The work lucubrated in this paper is generalized as followers: (1) Creep coefficient of each creep model is simulated and programmed. (2) The deflection upwards caused by prestress is simulated by differential equations. (3) The deflection upwards of simple supported beam is calculated by the means of unites elastic and plastic analysis into Finite-Element theory. (4) By this programme the deflection upwards of several bridges on the Wuhan Outer Circumferential Highway are calculated, through which to find out the main effective factor.The deflection upwards of prestressed concrete beam can be predicted much accurately than before and mastered effectively through the massive work of this paper.