Effects of transient creep strain on post-tensioned concrete slabs in fire

The effects of transient creep strain of concrete on post-tensioned concrete slabs in fire were investigated by means of numerical modelling. Employing the commercial package Abaqus, three-dimensional non-linear finite-element (FE) models were established. The thermal creep strain of prestressing steel tendons was explicitly incorporated into the FE models. Three concrete constitutive models were considered – a basic model without considering transient creep strain, a transient model explicitly considering transient creep strain and the Eurocode 2 (EC2) model, implicitly considering transient creep strain taken from BS EN 1992-1-2. Through comparing the numerical results with those obtained from available tests in the literature, excellent agreement was achieved. Based on this, the basic model was verified at ambient temperature and both the EC2 model and the transient model were also verified in test fire scenarios. A main conclusion from this study is that transient creep strain should be considered either explicitly or implicitly in numerical modelling for its positive contribution to the fire resistance of slabs.