A Softened Membrane Model for UHPC (SMM-UHPC)

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Understanding the shear behavior of Ultra-High-Performance (UHPC) is crucial to prevent undesired responses that could be induced by diagonal shear cracks. Hence, the ability of analytical models to predict shear responses of UHPC members is of paramount importance. This issue is addressed in this thesis by utilizing the Softened Membrane Model (SMM). Since the SMM is a two-dimensional shear modeling framework developed for normal concrete, a parametric investigation was performed to assess its suitability for UHPC, namely SMM-UHPC. Through this assessment, a softening coefficient for the biaxial behavior of UHPC was derived and new constitutive laws were integrated into SMM. It was also found that the decomposition between biaxial and uniaxial strain fields, commonly used in SMM, may be of less significance for UHPC. Comparisons with shear panel tests were used to evaluate the accuracy of SMM-UHPC and quantify the significance of key model parameters. Combining analytical and experimental data, this thesis shows that statistical determination of the localization strain is key for predicting the shear behavior of UHPC.

Ultra-High-Performance Concrete (UHPC), Softened Membrane Model (SMM), Concrete Shear, Membrane Elements, Universal Panel Tester