The behaviour of prestressing steel tendons under fire and post-fire conditions is investigated numerically employing the ABAQUS package and its user-defined material subroutine UMAT which allows comprehensive constitutive relationships to be implemented. Based on an existing thermal creep model, a new set of parameters are proposed and calibrated against available test results in the literature. The proposed numerical model is versatile in predicting thermal creep, isothermal response and transient thermal relaxation of prestressing steel tendons. Moreover, parametric studies are conducted to investigate the effects of heating rate, heated length ratio, initial stress and various boundary conditions on the thermal relaxation of prestressing steel tendons. Besides, transient state analyses are carried out with constant heating rate and initial stress to investigate the rupture properties of prestressing steel tendons.
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