In building codes, the fire resistance rating “non-combustibility 1.5h””

Fire resistance limit – Criterion for determination: Loss of stability. The component loses its capacity to support weight or resist deformation during the test. (1) Visual inspection: Such as wall collapse ； Beam and slab deformation exceeds L/20 ； The column collapses or its axial deformation exceeds h/100 (mm), or the rate of axial compression deformation is greater than 3h/1000 (mm/min) ； (2) Temperature change of the main stress-bearing bars: 16Mn steel, 510°C. Loss of integrity applies to partition elements such as floor slabs and partition walls. Signs of loss of integrity: the appearance of penetrating cracks or holes through which fire can pass. Loss of thermal insulation applies to partition elements such as walls, floors, etc. Signs of loss of adiabatic properties: Either of the following two conditions – the average temperature rise at the temperature measurement point on the backside of the specimen reaches 140℃ ； The temperature rise at any point on the backfire side of the test specimen reaches 220℃ ； There are three criteria for determining the fire resistance limit of building components, and specific cases need to be analyzed on a case-by-case basis in practical applications: (1) Partitioning components (partition walls, ceilings, doors, and windows): loss of integrity or insulation ； (2) Load-bearing members (beams, columns, roof trusses): loss of stability ； For details, refer to GB/T9978 (3): Load-bearing partition elements (load-bearing walls, floor slabs): Loss of stability, integrity, or insulation.