Theoretic Calculation And Control Methods Research In Deflection Upward Of Prestressed Concrete Beam

Prestressed concrete beam is applied widely with strong rivalrousness lately. But in the recent years of constructions, a harmful deflection upward exceeding reasonable value, which is caused by prestress, creep of concrete, and so on, is found. The deflection affects normal use of bridges. Therefore, the precise calculation of reversed arch is important for practical projects.The main aim of this thesis is to solve the problem of determining the value of deflection and to seek the control methods of over-deformat i on.With abroad data and rational analysis, the major work is described as follows: (1) Influencing factors of reversed arch in prestressed concrete beam is analyzed at length. (2) The deflection upward is calculated and programmed. (3) Effective methods in design and construction are provided to control over-deformation.The wok lucubrated in this paper is generalized as follows: (1) The reversed arch caused by prestress is computed by solving differential equations. (2) Creep coefficient is simulated and programmed. (3) The deflection of simple supported beam is calculated by the means that unites elastic and plastic analysis into Finite-Element theory. (4) The deflection of continuous beam is computed by the Finite-Element method. (5) The reversed-arch of a bridge under construction is worked out and the change of value is presented in different circumstances.The deflection of prestressed concrete beam can be predicted much accurately than before and mastered effectively through the massive work of this paper.