Results of full-scale fire tests of the monolithic reinforced concrete slab as part of a fragment of a frame building

Abstract

Purpose. To develop methods and conduct force tests under loading, full-scale fire tests of a reinforced concrete monolithic slab as part of an experimental fragment of a framing building, to obtain experimental data on relative deformations and displacements during force tests, temperature distribution in the fire chamber, in structural sections, slab displacements during fire exposure and to assess the damage.

Methods. Force tests of reinforced concrete slab using inventory loads, a set of deflection meters and strain gauges; full-scale fire tests of a reinforced concrete monolithic floor under load using a hydrocarbon fire load, a complex of thermoelectric converters and a displacement measurement system.

Findings. A methodology has been developed and strength tests of a reinforced concrete cast-in-place slab as part of an experimental fragment of a frame building under a load of 675 kg / m² have been carried out. The slab deflection in the span was no more than 1/1000. The relative compressive strains of concrete in the maximum values did not exceed 0.36 ‰, the relative tensile strains of concrete in the maximum values were 0.89 ‰, which indicates the elastoplastic work of the structure. A technique was developed and full-scale fire tests of a cast-in-place slab as part of an experimental fragment of a frame building under a load of 675 kg / m² were carried out. With the use of 2405 liters of waste engine oil and 1.8 m³ of wood, a thermal fire rate close to the standard was created. The temperature on the heated surface reached 1000 °С, while on the unheated side the temperature was not higher than 40 °С, which led to significant deformations of the slab, in total between the center and the console edges it was about 300 mm, or 1/30th of the slab geometric length. As a result of tests on the 69th minute from the beginning of the flashover fire, unexpected destruction of the reinforced concrete centrifuged columns occurred. After the fragment collapsed, two linear plastic hinges were found in the span at a distance of 1.5 m from each support at the point where additional reinforcement has been cut.

Application field of research. The research results can be used to assess the fire resistance of reinforced concrete cast-in-place flooring, in the development of design methods and in the modeling of reinforced concrete cast-in-place structures under force loading and at fire, as well as in the development of methods for full-scale fire tests of reinforced concrete structures.