METHOD FOR DETERMINING FIRE RESISTANCE OF COMPRESSED PIPE-CONCRETE BUILDING ELEMENT Russian patent published in 2023 - IPC G01N33/38 

FIELD: fire safety.

SUBSTANCE: relates to the fire safety of buildings in relation to the classification of compressed pipe-concrete elements according to their resistance to fire. A method has been proposed for determining the fire resistance of a compressed pipe-concrete construction element, including carrying out a technical inspection, establishing the steel grade of the pipe, the type of structural concrete, its compressive strength class, identifying the conditions for supporting and fastening the element, identifying the area of concrete and metal of the pipe, the thermal diffusion coefficient of concrete, the degree of reinforcement of the main section of a compressed pipe-concrete element, determining the reduced thickness of the pipe metal, the duration of the fire impact of a standard fire before the onset of thermal fluidity of the metal of the steel pipe and the time of resistance to the thermal force effects of the metal pipe, conducting evaluation thermal tests without destruction according to a set of individual indicators of the compressed pipe-concrete element of the building, characterized in that first, the reduced standard resistances of structural concrete and pipe metal when they work together in the composition of pipe concrete are identified, then the intensity of force stresses in the main section of the compressed pipe concrete element and in structural concrete is determined without taking into account the pipe metal, the reduced standard compressive resistances of structural concrete and pipe metal are found in the composition of pipe concrete, the coefficient of longitudinal deflection of the compressed pipe concrete element of the building is determined, while the design fire resistance limit of the compressed pipe concrete element based on the loss of load-bearing capacity F_UR, min is calculated using analytical equation 1, where d_b is the diameter of the pipe concrete element, mm, J_δb is the intensity of force stresses in concrete; η_fpc is the coefficient of retardation of heating of the concrete surface of a compressed pipe-concrete element; φ₀ is the coefficient of longitudinal deflection of the concrete element; D_bm is the coefficient of thermal diffusion of element concrete, mm²/min; R_bp is the reduced standard compressive strength of concrete, MPa; τ_fpc is the time of fire protection to thermal effects of pipe metal, min; π = 3.14 is the irrational number.

EFFECT: elimination of full-scale fire testing when assessing the design fire resistance of a compressed pipe-concrete element of a building, simplifying the conditions and reducing the time required to test the compressed element for fire resistance; increasing the accuracy and efficiency of assessing the design fire resistance limit of a compressed pipe-concrete construction element.

10 cl, 2 dwg