Structural Assessment of a Bridge with Transversal Cracks

Abstract

To estimate the influence of cracks on the mechanical behaviour of a bridge, these discontinuities are assimilated to a series of elastic or plastic hinges, alternating with sound beam segments and jointly setting up a new system in equilibrium. The main difficulty resides in the calculation of the hinge residual flexural stiffness, which is a function subject to various parameters and assumptions. To offer a practical solution and facilitate realistic modelling, we developed an experimental method based on the relationship between bending moment and resulting curvature. Under a test load the measured curvature redistribution reflects the new mechanical response of the structure and leads to the actual stiffness functions of the hinges. These are introduced into a program of structural analysis. The new statical system, thus defined, enables the real stresses and residual strength to be estimated. In the technological field, prototype inclinometry instruments of high accuracy had to be developed. This method was tested in the laboratory then successfully applied on site.