RESEARCH OF THE FIRE RESISTANCE OF REINFORCED CONCRETE HOLLOW CORE SLAB

Abstract

The paper presents the results of evaluating the fire resistance of a reinforced concrete hollow slab using a refined method using the finite element method. The purpose of the work is to determine which limit state of fire resistance of the considered reinforced concrete hollow slab occurs first under the influence of the standard fire temperature regime. The creation of mathematical models of concrete and reinforcement materials was carried out taking into account the recommendations of Eurocode 2. Symmetry was used to reduce resource provision during calculations. A finite-element mesh of the studied reinforced concrete hollow slab was created using finite elements of the following types: SOLID186, CONTAL174, SURF154 and REINF264. Computational experiments were carried out in two stages, in the first stage a thermal engineering problem was solved, in the second stage a static calculation was conducted to assess the fire resistance of a reinforced concrete hollow slab. The calculations were carried out according to the specified method recommended by Eurocode 2 in the thermal and mechanical modules of the AYSYS WB software complex. In order to obtain the most reliable results of the behavior of the studied reinforced concrete hollow slab during the study of the results of the stress-strain state, hinged resting on the stand is provided.

The obtained results indicate that the onset of the limit state for the loss of entirety occurs earlier than for the loss of bearing capacity at 678 s, which poses threats to the life and health of people before the occurrence of critical deflection due to the penetration of smoke, toxic products of combustion and temperature through the cracks formed in the structure . Loss of heat-insulating ability at the time of loss of entirety was also not observed. According to the results of computational experiments, it was established that the fire resistance limit of the investigated reinforced concrete hollow slab is 40.83 min and does not correspond to the REI 45 fire resistance class under the condition of its load of 4 kPa.