Trial prevention system for concrete panel tower block collapse
A new solution to prevent the collapse of pre-cast concrete Large Panel System (LPS) buildings in the event of a gas explosion is to be trialled on up to three Birmingham City Council-owned buildings this year.
It has been devised by consultant Curtins, which specialises in assessing and repairing low-, medium- and high-rise housing.
LPS buildings do not have a structural frame and are constructed using interconnected concrete panels supporting the concrete floors. As a consequence, they are considered at risk of disproportionate collapse in the event of an explosion within part of the building, if they were not originally designed to withstand the forces from such an event.
The risk that such explosions pose to LPS buildings was highlighted by the partial collapse of the 22-storey Ronan Point tower block in Newham, east London, in 1968, only two months after it opened, which resulted in the death of four people.
Curtins was invited to design a retrospective solution to prevent disproportionate collapse to the LPS buildings owned by for Birmingham City Council. The innovative design involves the installation of a steel brace on the outside of the tower block that ties the external loadbearing concrete walls, and the upper internal loadbearing walls, to the floors. This brace enables those components of the building to act together to withstand the forces in the event of explosion, with the building remaining structurally stable. The steelwork is insulated with a non-combustible external wall Insulation and clad with a more attractive render.
Curtins claimed that the solution would result in minimal disruption to residents because only certain floors need to be decanted, rather than the entire block.
John Healey, an associate at Curtins said: “We’re pleased to be introducing this new solution for LPS buildings.
“The lack of a structural frame in LPS towers means that these buildings are potentially at risk of disproportionate collapse. Piped gas heating has therefore been banned to minimise the possibility of a gas explosion. However, the buildings are still susceptible to non-piped gas explosions and their concrete façade means they’re thermally inefficient.
“Primarily, our solution will ensure that in the event of an explosion, tenants will be able to vacate the building safely. The introduction of our innovative galvanised steel frame and cross stitching on the upper levels will prevent deflection of the loadbearing walls, which can cause them to collapse. The second major benefit is that the non-combustible external wall insulation and cladding will make the buildings much warmer, which is great news for the tenants and the environment.
“Many Local Authorities in the UK have one or more LPS buildings, so our future strategy will be to introduce the solution across the UK to improve safety nationwide.”