Resistance of prestressed bridge girders to diagonal tension cracking

Diagonal tension cracking is the governing failure mode for bridge girders with a thin web that are highly prestressed and contain little shear reinforcement. When assessing existing bridge girders using the Eurocode 2 [1], it often turns out that it is not possible to demonstrate sufficient resistance to diagonal tension cracking. This paper evaluates the method to determine the maximum principal tensile stresses as used in the Eurocode 2 [1] and investigates how flexural cracks affect the principle tensile stresses in the regions without flexural cracks. This paper also investigates how the tensile strength of the web is affected by the presence of compressive stresses and by the size of the area subjected to high tensile stresses. Based on the results of these investigations, an improved model is proposed to determine the resistance to diagonal tension cracking.