Effect of transient strain on strength of concrete and CFT columns in fire – Part 1: Elevated-temperature analysis on a Shanley-like column model

This paper presents elevated-temperature analysis on a Shanley-like column model, as part of a study on the effect of transient strain on the strength of concrete and concrete-filled tubular columns in fire. Three high-temperature concrete material models are applied and the structural behaviours of the Shanley-like model using these three material models are compared. The effects of transient strain of concrete have been investigated by comparing the results of the analyses with and without considering this property, under the assumption that the temperature distribution within the model is uniform. The model has been evaluated against the tangent-modulus and reduced-modulus critical buckling loads at elevated temperatures. Numerical analyses have been carried out under both steady-state and transient heating scenarios, in order to investigate the influence of each on high-temperature structural analysis of the type described in this paper. It is seen that considering transient strain causes a considerable reduction of the buckling resistance, irrespective of the concrete material models and loading–heating schemes used.

► Considering transient strain (TS) causes a reduction of the predicted buckling capacity.
► Ignoring TS in structural modelling may lead to unsafe predictions.
► This reduction is caused by the stress and strain re-distribution due to TS.
► This reduction is shown when using three different high-temperature concrete models.