Civil Engineering Reference
In-Depth Information
(1968)
The need to provide replacement housing for homes destroyed in World War II
prompted European development of innovative prefabricated construction techniques.
One such design involved the erection of multi-story apartment buildings using
factory made concrete components. The structural system comprised load bearing
walls, with each level of apartments stacked directly on the one below (Figure 5-2).
Floor on wall and wall on floor joints were grouted bearing surfaces (Figures 5-3 and
5-4). This was termed “system building.” A high-rise apartment building at Ronan
Point, Canning Town, U.K. was constructed using one such system.
On May 16, 1968 an undetected gas leak resulted in an explosion in the
kitchen of a unit on the eighteenth floor when the occupant attempted to light the
stove. The corner walls of this unit blew out, causing the wall above to collapse.
This, in turn, impacted on the floors below and destroyed the whole corner of the
building. Fourteen people were injured, three fatally.
Analysis of the event revealed that there were no alternative load paths when
one part of an external wall at one level was removed. Demolition of the building
also confirmed that deficiencies existed in the quality of the grouted joints between
the prefabricated components.
Due to the failure of Ronan Point Tower authorities questioned the safety of
other apartment towers using similar structural systems. Many were demolished well
in advance of their expected life expectancy. Progressive collapse, in which local
failure is followed by a chain reaction producing widespread collapse, certainly was
not unknown prior to the Ronan Point event. Structures are particularly susceptible to
this domino effect during of the construction process. What was unusual in the case
of Ronan Point was that a relatively minor gas explosion triggered the collapse of a
significant portion of a completed building.
Lessons Learned
The experience of Ronan Point reemphasized the need to be aware of the possibility
of progressive collapse of constructed facilities, the desirability of providing
redundancy - or fail safe possibilities - in structural systems, and the necessity of
ensuring quality control in the construction process. Also, the system building
technology had never been intended for buildings of this height, and had been pushed
well past the limits of safety. It was disturbing that the building conformed to the
codes in effect at that time in the U.K., which led to revision of those codes.
References
Allen, D.E. and Schriever, W.R. (1972). “Progressive Collapse, Abnormal Loads and
Building Codes,”
Structural Failure: Modes, Causes, Responsibilities,
ASCE,
New York, NY.
