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PRESS
RELEASE
Improvements
to the safety of tall buildings post-11th September 2001
– publication of recommendations
“For
the future, it has to be assumed that there may be more severe and
different extreme events in tall/large buildings than have occurred to
date.”
The
safety of tall buildings in the wake of the extreme events of
September 11th 2001 must be improved to take account of the
increased risks such structures now face, according to a new report
published today [Wednesday 10th July].
The study has been conducted by an international working group,
which was convened by the Institution of Structural Engineers
(IStructE), the world’s leading professional body for structural
engineering.
‘Safety
in tall buildings and other buildings with large occupancy’
examines what can be learnt from those events for
the future design of new buildings and the appraisal of existing ones.
The report, which is the result of collaboration between a
number of agencies involved in the construction process, makes wide
ranging recommendations about future structural design; fire
protection; means of escape; building security and third-party
inspection.
Chairman of the
working group, John Roberts, commented, “The recommendations made in
the report seek to address the current reality of threats to the
safety of tall and large buildings following the events at the World
Trade Center and the Pentagon. Before
9/11 none of these buildings were considered unsafe by any credible
criterion. This is a
situation that has clearly changed irrevocably.
“Methods
of reducing the probability of a recurrence of extreme events do not
lie within the gift of building owners and construction professionals. The Report, nevertheless, seeks to contribute to public
safety by providing recommendations to assist building owners and
their professional advisers to provide buildings and infrastructure
better able to sustain any future malicious attacks with a reduced
risk of loss of life.”
Summary
of recommendations
Vulnerability
to progressive collapse
•
Raise the ‘trigger’ threshold, i.e. increase the capability of the
structure to limit damage and to bridge over damaged parts by
provision of alternative load paths. For this purpose, use structural
elements with robust, ductile and energy absorbing properties and tie
them together with strong ductile connections, recognising the
directions of potential extreme event forces.
•
Give specific consideration to elements that are fundamental to the
survival of the structure.
Passive
and active fire protection
•
Provide robust, resilient and durable passive fire protection.
•
Treat active fire protection, e.g. sprinklers, as an addition to, and
not a substitute for, passive fire protection, and do not consider it
for extreme events.
•
Ensure compartments are gas tight and seals are sound on building
completion by inspection, testing and certification.
•
Provide protection to compartments and mitigate spread of smoke.
•
Design buildings to survive complete ‘burn out’ of contents.
•
Require independent approval, as a part of licensing and periodic
third-party audit of life-safety systems, of modifications to passive
and active fire protection.
Escape,
its management and the emergency services
•
Provide protection to escape routes from ingress of smoke.
•
Protect vulnerable parts of building services systems and incorporate
redundancy.
•
Provide separate stand-by power for vital building services and for
lighting of escape routes.
•
Provide robust adequately-sized escape routes and diverse locations
for them and provide protection for final exit routes.
•
In addition to phased evacuation for emergencies, plan for timely
simultaneous evacuation of a large proportion of floors in major
emergencies, including use of lifts as well as staircases.
•
Be prepared for extreme event emergencies through development and
trial use of emergency response strategies that guide decisions on
evacuation, communication with occupants and the emergency services.
•
As part of preparedness, make sure that: plans of the building are
deposited in a remote accessible location; engineering advice can be
obtained quickly during an extreme event; communication systems with
floors, stairwells and lifts are in place and functioning; training
for the management team, emergency services and occupants is given;
and evacuation procedures are practised at regular intervals.
•
Require independent approval, as a part of licensing and periodic
audit of life-safety systems, of modifications to escape routes.
Other
issues
Safety
of cladding, including glazing
•
Use laminated and/or toughened glass with fixings designed to take
account of potential explosion loading/impact/fire.
Security
and safety of building services
•
Use a broadly-based strategy involving design and building management
to reduce the risks.
Security
against unauthorised entry
•
Reduce the probability of occurrence of extreme man-made events with
potential to cause progressive collapse, where practicable. For this
purpose, use incident prevention or limitation measures, e.g. provide
barriers to protect the base of the building from vehicle impact or
explosion, and provide security against unauthorised entry.
•
Use both design and management provisions to deter and protect against
extreme man-made events taking place in or near the building.
Inspection
of design and construction
•
Reduce the risk of the building performance being compromised during
the design and construction processes by appropriate use of
independent third-party inspection, testing and certification of
safety-related structure and systems.
-ENDS-
Copies
of ‘Safety in tall buildings and other buildings with large
occupancy’ are available from the Institution of Structural
Engineers.
The
international working group comprises representatives from the
Institution of Structural Engineers, the Institution of Civil
Engineers, the Royal Institute of British Architects, the Chartered
Institution of Building Services Engineers, the Royal Institution of
Chartered Surveyors, the Institution of Fire Engineers, and the
initiative is supported by the Construction Industry Council.
An observer from the Department for Transport, Local Government
and the Regions was also present.
Members of the working body include professional engineers from
New York, Hong Kong, Australia and New Zealand as well as from the
United Kingdom.
The
Institution of Structural Engineers is the world’s leading
professional body for structural engineering.
It is the appropriate source of relevant and considered opinion
on all structural engineering and public safety issues in the built
environment. The
Institution has 22,000 members in 101 countries around the world, and
is recognised internationally for the technical and professional
competence of its members. Its
image is one of safety, efficiency and excellence both of its
operations and in the standards of its members.
The Institution qualifies its members by examinations that test
professional competence in structural engineering design, and operates
using the phrase
“Working
together to promote world-class standards of safety, efficiency and
excellence in structural engineering.”
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