Disproportionately wide range of fire in a RC building during construction stage

Abstract

The article analyzes the effects of a fire that occurred in a small room of an electrical switchboard in the underground garage of a multi-storey residential building. The building was in the final stage of construction, but many of the ‘passages’ of the installation through the walls and ceilings were not yet fire-protected, ie., the fire integrity requirement was not met. It results that a spread of fire was much larger than could be expected.The research carried out in order to assess the condition of the structure after the fire were presented, in particular the selection of members that: (1) had to be dismantled, (2) required significant strengthening or repair, (3) could be used after only minor cleaning works. Due to the short time to carry out the assessment, it was mainly based on non-destructive tests (NDT) results.The conclusions from the conducted assessment and analyzes were presented. A small and seemingly easy to control fire, which started in the underground garage, spread up to 12 storeys above ground level. The fire was difficult to control due to incomplete works in the field of securing installation passages through the partitions. These works were to be carried out in the final stage of the construction of the building, while the electrical installation was already in use.Damage to reinforced concrete members had an unexpectedly large extent due to thermal spalling of the concrete. Significant intensification of this phenomenon was caused by the high moisture content in ‘relatively young concrete’ (short drying time from casting the members) and the close location of the burning electrical wires in relation to the structural members. The possibilities of estimating, but still sufficiently reliable, assessment of damage to members using NDT was pointed out.