Suitability of shear tension code requirements for the assessment of existing structures build-up with Prestressed I- and t-shape girders

Abstract

For existing structures, it is of interest to know if codes are conservative. If this is the case, it can be useful to examine if more accurate assessment methods are feasible. This paper addresses this topic for shear tension code requirements. Shear tension failure is of importance for prestressed structures with thin webs such as I- T- and Box girder structures. The studied codes are the fib Model Code (2010) (MC2010), the ACI building codes (ACI) and Eurocode 2 (EC2). These code requirements are based on the concept that the principle tensile stresses are limited to the concrete tensile strength. For that reason the resistance to web shear cracking is studied in this paper. To examine the suitability of the code requirements, 51 single span specimens are gathered. In the associate literature, shear cracks were reported, originating from the web. The experimental found shear capacity is compared with the predicted mean resistance to web shear cracking based on the code requirements. For the specimens uncracked in bending the predictions appear to be accurate and the level of approximation approach suitable. For the specimens cracked in bending, on the other hand, the predictions appear to be conservative. This is caused by the conditions within which the formulas for shear tension are applicable. Not the shear tension formulas but the formulas for flexural shear are applicable for a considerable part of the specimens. This is the case despite the observation that shear cracks in the specimens originated from the web instead of from the flexural cracks in the flange. The application conditions within which the shear tension formulas are applicable appear to be the most relevant topic for future research and offers the best possibility to improve the accuracy of shear tension code requirements.