Influence of heating rate and thermal incompatibilities on the test results of concrete cylinder specimens with polypropylene fibres under heating

Thermal analyses for a 60-cm-thick concrete element subjected to ISO curve and a 60-cm-element exposed to ZTV-ING curve are performed. The results show that the maximum heating rate of the first layer, having 1 cm distance to the fire exposed side, is approximately 29 and 86 K/min for these two elements respectively. Using high heating rates in tests might cause thermal incompatibilities for transient tests, especially under low level of preload (0.1 MPa to 0.2 f_ck ). To investigate the effect of thermal incompatibilities induced by temperature gradients within the concrete cylinder specimen with PP fibres, a cylinder specimen in laboratory simulated via Finite Element software packages SOFiSTiK and ANSYS. Further, a cuboid with a similar size is analysed using fibre enhanced quadrilateral elements. The results of stress analysis show the influence of using different heating rates on the test results under the preload of 0.1 MPa to 0.2 f_ck .