I was asked to give advice, as a specialist sub-consultant, on several features of a new 105 m high office tower with a restaurant at the top to be built on an existing reinforced concrete substructure after the superstructure was demolished. It was clearly a very important project and another fire consultant was earlier engaged by the developer to guide on general fire precautions.
The existing basement structure was a waffle slab with a nominal concrete cover of 25mm. The question was whether or not the slab would provide the 90 minutes fire resistance needed in a basement. A basement is an area where fire can become very severe and smoke logging can make it difficult and hazardous for fire fighters. According to Eurocode 2 this slab would have only 60 minutes as the waffling increases the surface area and reduces the fire resistance. This period of fire resistance was of concern because the basement slabs would be acting as diaphragms to provide buckling restraint to the columns above. A BRE report, BR128 cited in ADB, of which I was a co-author, was also relevant.
I also gave second opinions on several other features as well: advice on the fire fighting shaft; advice on reduction of fire resistance of secondary steel beams, advice on escape routes from restaurants; advice on the boundary wall condition affecting fire spread between buildings; advice against the use of a PIR plastic insulation in the external wall; advice on means of escape from rooftop restaurant, etc.
Client: Building Control Approval LtdShare