Ronan Point Collapse

Group 1Michael Day Jean GiblinChris MaguireJames Wilkinson

22 storey apartment block built in 1960s to provide cheap housing in London.

Larsen-Neilson method of construction.

Ronan Point

The Problems

A recent change in national policy that “allowed the density of occupancy to double”.

Unskilled construction workers. Larson-Neilson method:

• “…composed of factory-built, precast concrete components designed to minimize on-site construction work.  Walls, floors and stairways are all precast.  All units, installed one-story high, are load bearing”

• Relies on skilled and precise construction.• Every wall is load bearing.

Flaws in Larson-Neilson Method

Only designed for buildings up to 6 stories.

All units load bearing. No secondary load path. Poor construction methods.

The Collapse

Gas explosion sparked by a match lit in the South-East corner of the 18th floor.

Load supporting walls were blown out, causing the four floors above to collapse onto the floors below, which in turn gave way under the additional load resulting in a progressive failure.

The Explosion

A faulty connection allowed gas to leak slowly into the apartment.

Explosion was so small that the woman that lit the match didn’t damage her hearing.

Car Tyre 20psi

Bicycle Tyre 100psi

Air in lungs 1.5psi

Gas explosion in Ronan Point <10psi

Conclusions

Government investigation concluded “a gas explosion had triggered the collapse of a building that was structurally unsound”.

The report also found that the building was highly susceptible to fire loading.

http://www.youtube.com/watch?v=J96Fzk1OdBQ

Positives

Only four fatalities. Encouraged massive development in

building regulation codes. Highlighted the importance of on site

monitoring of workmanship.