Визначення закономірності втрати цілісності ребристими пластинами в умовах пожежі

Abstract

This paper reports a study aimed at assessing fire resistance of reinforced concrete ribbed slabs at the onset of integrity loss limit state. EN 1992-1-2 lacks calculation methodology for deter-mining the limit of fire resistance of rein-forced concrete slabs when the limit state of integrity loss occurs. Scientific works are focused on two limit states of fire resistance: load-bearing capacity and heat-insulating capacity. Experimental tests are criticized because of difficulties in registering signs of the onset of the limit state of loss of integrity, in particu-lar due to the need to control the unheat-ed surface of the ribbed plate during a fire under the action of mechanical load. Therefore, there is no calculation methodology for assessing the fire resis-tance of reinforced concrete ribbed slabs upon the onset of the limit state of loss of integrity. At the same time, to ensure the safe evacuation of people in the event of a fire, to prevent the spread of fire, as well as to carry out the effective work of rescuers, it is necessary to use building structures with guaranteed fire resis-tance classes.The paper reports the results of solv-ing thermal engineering and static prob-lems, which relate to the temperature distribution and stress-strain state of the investigated ribbed plate. Conducting research into the fire resistance of rein-forced concrete ribbed slabs, taking into account the onset of the limit state of loss of integrity, made it possible to establish the dependence of the fire resistance limit of these structures on the loss of integrity on the level of applied mechanical load. The resulting dependence plot makes it possible to evaluate reinforced concrete ribbed slabs according to the criteri-on of the onset of the limit state of loss of integrity, which provides an oppor-tunity to determine fire resistance more objectively