ANALYSIS OF FIRE TEMPERATURE DISTRIBUTION INFLUENCE ON STRENGTH PARAMETERS OF STEEL STRUCTURES

The analysis of high-temperature steel structure behaviour requires time-related effects to be taken into. Besides the absolute temperature value, a significant role for a steel structure component behaviour within a high temperature field is played by the temperature-vs-time relation and the dT/dt heating rate as indicated by the authors research. The purpose of the authors' research was determining the heating rate effect for selected strength parameters for two steel grades: S235JRG2 low-carbon general application steel, and S355J2G3 low-alloy high-strength steel. The authors' performed tests for structural steel in an unstable temperature field. The tests were performed under a linear temperature rise at various heating rates and for a constant sigma/fy stress value. It has been proven that the heating rate plays a significant role for structural steel component strength at higher temperatures, and that the heating rate should be considered in the strength analysis of structures exposed to high temperatures.