Concrete walls conduct under the fireinfluence investigationusing final elements method

Abstract

The main objective of the study is to improve the methods for calculating the fire resistance of reinforced concrete load-bearing walls to ensure the requirements of the relevant building codes. To solve these issues, the use of the finite element method is considered to be promising, since it has advantages over other methods. To study all aspects of the application of this method in solving the fire resistance problems of reinforced concrete walls, the elevator shaft block is reviewed. When solving a heat problem, a mathematical model of heat transfer is used according to the recommendations of Eurocodes. To solve the heat problem using this mathematical model, the finite element method is used. The article describes the main aspects of the implementation of the finite element method for solving the heat problem, the design scheme and temperature distributions in the wall section at different times of the fire. The article also presents the curves of the temperature dependence on the transverse coordinate of the cross section at different points in time and the heating temperature of different points of the cross section depending on time. In solving the structural problem, the finite element method is used. At the same time, the properties of concrete and reinforcing steel were adopted, according to the recommendations of Eurocodes. The article presents the algorithm and the results of solving the structural problem. After the calculation, the parameters of the stress-strain state of the wall for each minute of fire development were obtained. For the given wall with different levels of mechanical load, normal stresses and crack distributions at different points in time of the fire, as well as the positions of fragmented elements at different points in time of the fire are shown. It was revealed that the wall first bends towards the thermal effect of the fire, and then, after passing the initial equilibrium position, it bends in the opposite direction. As a result of the work, the dependence of the fire resistance limit on the bearing capacity of the wall on the value of the acting mechanical load is obtained.