Cast-in-place reinforced concrete plate construction as a part of a frame experimental building for fire resistance research
Purpose. Based on the results of comparative numerical finite element modeling, to develop and consruct a structure of a cast-in-place reinforced concrete slab with a theoretical fire resistance rate REI 150 as part of an experimental fragment of a frame building, including precast centrifuged columns, and to study fire resistance in the framework of full-scale fire tests, close to the standard temperature fire curve. Methods. Analysis of the existing research results and methods. Numerical finite element modeling of reinforced concrete structures using LIRA-SAPR 2013 R5 software. Analogy method. Assessment of fire resistance by the limiting equilibrium method. Measuring the concrete cover thickness by magnetic method. Geometry measurements by laser leveling. Findings. Cast-in-place frame reinforced concrete systems of buildings are currently the most common in the construction of multistory buildings; such systems have a high potential fire resistance, but due to the complexity of reconstruction of real conjugation and loading conditions experimental studies have not been carried out in practice. To solve this problem, the numerical finite element modeling of a plain reinforced concrete cast-in-place 200 mm thick slab as part of a 2-storey frame building with 6×6 m columns grid and 10 kN / m2 load has been estimated. The required reinforcement of concrete cast-in-place slab has been calculated based on the stresses and design practice, as well as loadings combinations. A fragment of a reinforced concrete slab of 3×9 m size from the central part of the 1st floor of the frame was transferred by analogy into an experimental fragment, including two centrifuged reinforced concrete columns with 6.0 m span as supports and linked to them. The fire resistance rate of the slab, determined by the limit equilibrium method, taking into account the potential of redistribution of forces, was estimated higher than REI 150. On the basis of the design, a fragment of a frame building was construcred to study fire resistance within the framework of full-scale fire tests, close to the standard temperature fire curve. Application field of research. The research results can be used for full-scale fire tests of the constructed fragment, design and construction of similar reinforced concrete cast-in-place, combined precast/cast-in-place flooring, in the development of methods for assessing the fire resistance of reinforced concrete structures.