Attempt to estimate fire damage to concrete building structure

Depending on fire duration, fire temperature (reaching several hundred degrees centigrade) leads to a damage (in varying degrees) to concrete. A structural damage assessment based on an inspection is highly unreliable, particularly when concrete heated up during a fire was rapidly cooled down with cold fire-fighting water. Because of this thermal shock the surface of concrete cracks heavily. The load-bearing capacity of such a building component can be estimated based on the strength of the fire-damaged concrete and the thickness of the cracked layer. However, the temperature affecting the structure is different at different places and therefore the decrease anticipated in concrete strength is different in different elements and also varies within them. For this reason, among others, a building structure after a fire must be examined in many places in order to properly determine its technical condition. For in situ investigations nondestructive methods are most suitable. The example provided shows that such methods can successfully be used to test fire damaged concrete and reinforced-concrete structures.