Structural steel and plane frame assemblies under fire action

By means of series of tests carried out on simply supported beams of standard rolled sections subjected to bending, fully analytically formulated calculation values were derived for the temperature-dependent stress-strain relationships of structural steel under fire action from normal temperature to 1000 °C.

Systematic series of investigations carried out on frame assemblies made up from rolled sections with high scale accuracy revealed the characteristic parameters influencing the critical temperatures. The analyses showed good-to-excellent agreement both for the temperature-displacement curves and for the critical temperatures, so that the integrity of the stress-strain relationships could also be verified for combined bending and compressive stress states and for stability-endangered assemblies.

The knowledge gained by the of experiment and computation furnished — in generalized terms — a basic concept for the simple and uniform assessment of the resistance to fire action of single elements and whole assemblies of structural steel subject mainly to bending stresses or endangered in stability. This allows the collapse temperatures of uniformly heated systems to be determined as a function of load utilization factor and system slenderness. These major parameters — load utilization factor and system slenderness ratio — are normal temperature design characteristics and can be determined using conventional methods.