METHOD FOR DETERMINING THE FIRE RESISTANCE OF A MONOLITHIC STEEL-REINFORCED CONCRETE FLOOR SLAB OF A BUILDING Russian patent published in 2023 - IPC G01N25/50 

FIELD: fire safety.

SUBSTANCE: assessing and ensuring fire safety of steel-reinforced concrete elements and construction structures of buildings and structures used to analyze methods and means of non-destructive testing of elements of structures. A method for determining the fire resistance of a monolithic steel-reinforced concrete floor slab of a building, according to which a preliminary technical inspection is carried out, namely, a survey, and instrumental measurement of the geometric dimensions of the existing floor slab under study as a construction element, the class of concrete and reinforcing steel, the thickness of the protective layer of reinforcement, the conditions of support and fastening plates are established and the bearing and heat-insulating capacity, fire resistance, the degree of fire protection of a monolithic steel-reinforced concrete floor slab are revealed. The fire resistance of a structure element is determined in advance at the stage of its design, therefore, at this design stage, the necessary parameters and requirements for the designed monolithic steel-reinforced concrete floor slab are set, and the fire resistance of the building element is determined in the process of surveying the existing steel-reinforced concrete floor slab under investigation, which is made in a fixed steel formwork. Moreover, at the design stage, the possible operational loads that affect the designed floor slab are calculated, at the same time, the possible effects of thermal shock and the heating circuits of the designed floor slab in fire conditions are considered, and the thermal strength of the power steel decking, the maximum heating temperature and the heating time of the surface designed floor slab and steel decking are calculated. Non-destructive control methods are used in the process of surveying an existing steel-reinforced concrete floor slab. For this purpose, analytical equations are used, which reveal the bearing and heat engineering capabilities, fire resistance and, ultimately, the degree of fire protection of the existing studied monolithic steel-reinforced concrete floor slab. After comparing the results of the degree of fire resistance obtained during the design and during the survey, the actual compliance of the degree of fire resistance and the fire resistance limit of a monolithic steel-reinforced concrete floor with the regulatory requirements for a particular building and structure is established.

EFFECT: exclusion of a full-scale fire test of the existing investigated monolithic steel-reinforced concrete floor slab of the building, establishment of controlled indicators for the limit of fire resistance of the floor, reduction of time and simplification of the conditions for testing the monolithic steel-reinforced concrete floor for fire resistance, increased accuracy and reliability of non-destructive thermal testing, simplification of the influence on the value of the fire resistance limit for overlapping features of fire protection of steel-reinforced concrete elements of overlapping and coating using steel decking as a fixed formwork.

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