РОЗРАХУНКОВА ОЦІНКА МЕЖІ ВОГНЕСТІЙКОСТІ ЗАЛІЗОБЕТОННОЇ БАЛКИ ЗА РЕЗУЛЬТАТАМИ ВОГНЕВИХ ВИПРОБУВАНЬ БЕЗ МЕХАНІЧНОГО НАВАНТАЖЕННЯ
This work reveals the method of evaluation of the fire resistance limit of the reinforced concrete beam according to the results of fire tests without mechanical load and considering it at the stage of calculation.
The algorithm for evaluation of the fire resistance limit of the reinforced concrete beam according to the results of fire tests without mechanical load, which forms the basis of the general method, has been developed and described. It consists of the interpolation of temperature distributions and further calculation of the limit of fire resistance with the combined effect of temperature and force loads on a real size beam. The scheme and type of reinforcement are taken into account, as well as the characteristics of changes in the strength of materials during heating.
The method of interpretation of the temperature indicators of the heating of a reinforced concrete beam has been developed and substantiated, heating of the beam fragments was carried out in a small-sized furnace according to the standard fire temperature regime, which made it possible to practically estimate the limits of its fire resistance and can serve as a part of the experimental and calculation method of fire resistance assessment.
The scheme for the location of control points is described, where the temperatures that are necessary and sufficient for data interpolation will be determined. A diagram of their arrangement is presented in graphic form.
Temperature distributions in cross-sections of reinforced concrete beams are determined. Their dimensions and characteristics corresponded to the characteristics of the studied sample and the heating temperatures of its layers during the experiment data on the length of the product and the distributed load designed during the operation of the structure in the building were additionally input. Thus, by changing them, it is possible to determine the limit of fire resistance for columns of other dimensions and with a different workload. It has been demonstrated that when the working load on a reinforced concrete beam increases, its fire resistance limit decreases.