Shear behaviour and analysis of partially prestressed i-girders

Six large, pretensioned concrete girders of I-shape cross-section were tested to failure. Two parameters were introduced, i.e. shearspan-to-effective-depth ratio and partial prestressing ratio. The test results are timely and useful, as, to the authors' knowledge, there is no current Code provision for the design of prestressed deep girders. A strut-and-tie approach is also proposed, and the failure criteria are based on Mohr-Coulomb's equation for biaxial compression-tension stress state and Kupfer's equations for biaxial compression-compression stress state. The accuracy of the method is verified by experimental results from six girders. Comparison study shows that the model predictions are in good agreement with test results.