METHOD FOR ASSESSING FIRE RESISTANCE OF STEEL FRAME OF A BUILDING Russian patent published in 2016 - IPC G01N3/60 G01N25/00 

FIELD: fire safety.

SUBSTANCE: invention relates to fire safety of buildings and structures. Essence of the invention: at first technical inspection is performed; it is followed by instrumental measurement of geometric characteristics of truss elements in their dangerous sections; conditions for resting and fixing truss elements are determined; heating circuits of their cross sections are determined; truss steel grade is determined, metal resistance characteristics for compression and tension are determined; load value of assessment tests on steel frame are determined, circuits of load application are determined; intensity of load stress on metal at hazardous sections of elements of steel frame is determined; time of onset of marginal state on the basis of loss of carrying capacity of elements of steel frame under test load of assessment fire tests is determined. Assessment of fire resistance of steel frame of a building is carried out without natural fire exposure of non-destructive test methods using a complex of single quality properties of steel structures. Number and location of sections in which the single quality parameters are determined are established, wherein the technical inspection is complemented by determining a group of single-type steel frames. Single quality parameters are geometrical characteristics of truss elements, a degree of metal resilience and metal yield point; then the following integral design parameters are determined: intensity of normal power stresses in cross section of elements of steel frame under assessment fire test conditions; reduced thickness of metal of cross-section of steel frame elements, and, factoring in the above, the design time resistance of each element of the steel frame to thermal power action at loss of carrying capacity using an analytical expression is determined. Design limit of fire resistance of steel frame (F_ur, min) is defined by duration of resistance to loss of carrying capacity of the weakest element in terms of fire-resistance (τ_{us, min}, min) in conditions of assessment fire tests.

EFFECT: technical result is possibility of determining the fire resistance of steel frame of a building without natural fire action, higher reliability of statistical quality control and non-destructive testing, reduced metal consumption for fabrication of steel frame, reduced time of testing, low costs.

16 cl, 1 tbl, 4 dwg