Mechanical fracture parameters of concrete exposed to high temperatures related to approximation of temperature fields in experimental panels

conference paper

English

Experimental concrete panels (2300 × 1300 × 150 mm) were exposed to high temperatures using the fire test furnace according to the standard temperature-time curve (ISO 834). The panels were heated to a maximal nominal temperature of 550, 600, 800 or 1000 °C, and then this temperature was maintained for 60 minutes. When the heating processes were complete, the panels were left to cool down to the ambient temperature. After that, specimens (100 × 100 × 400 mm) were cut from the panels, provided with an initial central edge notch and tested in a three-point bending test configuration. The basic mechanical fracture parameters were determined using the Effective Crack Model and the Work-of-Fracture method. To obtain more correct relations between temperature and elastic modulus, fracture toughness and fracture energy, it was necessary to employ approximation functions in the estimation of concrete temperature. Time dependent functions of temperature at different depths within the panel were obtained via the nonlinear approximation of the temperatures measured by temperature sensors. The values recorded for the mechanical fracture parameters of the tested concrete specimens were related to the fire load temperatures in the fracture process zone, which were obtained by approximation functions

High temperature, Concrete, Approximation, Elastic modulus, Effective fracture toughness, Specific fracture energy

ROZSYPALOVÁ, I.; FRANTÍK, P.; VYHLÍDAL, M.; ŠIMONOVÁ, H.; DANĚK, P.; KAREL, O.; KERŠNER, Z.

1. 10. 2019

Fédération internationale du béton (fib)

Switzerland

978-1-877040-15-3

Proceedings for the 2018 fib Congress held in Melbourne, Australia

3399

3409

11