Study On Stiffness Model Of Cracked Pre-stressed Concrete Beams

With the development of transportation, millions of bridges are built. The pre-stressed concrete bridge is widely accepted due to its taking full advantage of high-strength materials, light structure, saving steel and good durability. With the increasing of the using time, a large part of the pre-stressed concrete bridge suffers different degrees of disease which is cracking and deflection. Scholars and engineers who studied the pre-stressed concrete bridge mainly concentrated on the causes of cracking and deflection, the main impact factors of them; they also proposed the corresponding treatment measures. But the study on the using state of the pre-stressed concrete bridge with damages is still blank. How to assess the stiffness of the pre-stressed concrete in using simply and effectively is an important problem which needs to be solved urgently.This article starts from the actually measured damage parameters which are the actually measured pre-stress of the steel strands and the statistical bending crack feature. In this paper, with considering the nonlinear characteristics of concrete and steel bars and with using the section analysis method, the cross-section balance equation based on measured damage parameters is derived; the damage stiffness analysis method of pre-stressed concrete beam based on measured damage parameters is presented. In this paper, the assessment method about the stiffness of cracked pre-stressed concrete bridge in using is explored.In this paper, how to express the effective stiffness of pre-stressed concrete beam is presented. Using an example of a T beam, the differences of the stiffness between different constitutive models are compared; the stiffness is also compared with the norm in using. By changing the amount of ordinary steel bars, the amount of the pre-stressed steel strands, the pre-stress of the strands and the elastic modulus of the concrete, the parameters about the stiffness are analyzed.