302 Collapsed structures Flashcards
What are the 2 main headings of collapse
Natural and Human
Natural Cause of Collapse
Natural: • Earthquake. • Hurricane. • Lightning. • Flooding. • Subsidence.
Human Cause of Collapse
Human: • Premises under renovation. • Accidental impact. • Arson. • Terrorist induced (aeroplane impact, vehicle impact. etc.). • Accidental gas explosion.
On many occasions the collapse will occur without warning, leaving casualties little or no time
to escape. This can result in a number of casualties being trapped under large amounts of
unstable debris.
When
considering structural damage, buildings may be divided into two classes
1) Framed buildings
A skeleton or frame of steel or reinforced concrete
supports the structural load in this type of building, i.e. the floors and roof. This type of construction is
generally encountered in modern public buildings, e.g. office blocks and hospitals.
Framed buildings have a greater resistance to collapse and, in general, failures that occur are more
localised.
2) Unframed buildings
In this type of building the walls carry the structural loads. This is the traditional form of construction in the UK and many countries abroad. Walls support floors and roofs, and typical brick and joist structure is usual. If the load bearing walls fail along with columns or floor beams, the result is an extensive collapse, with a large area of debris
The nature of collapse types
Collapse types can be categorised as being
Internal,
External
Total collapse
What are the types of internal collapse
1) Pancake collapse:
Pancake collapse is often mistakenly referred to as total collapse. This type of collapse occurs
when there is a failure of load bearing walls, or an upper floor fails. The floor falls horizontally, or
pancakes upon a lower floor and the added weight causes this and other floors to fall to a lower
level, but not always to ground level.
2) Lean-to collapse:
Lean-to collapse occurs when one of the supporting walls collapse and a beam fails at one end. A
triangle shaped void is formed where occupants may survive.
3) V” collapse
‘V’ collapse occurs when heavy loads or a collapse from above, place undue strain on the centre
of the floor, which causes it to fail in the middle
4) Tent collapse:
Tent collapse occurs when floor beams fail near the outer walls, but an interior load bearing wall
or girder remains intact.
What are the types of External collapse
1) 90o angle collapse:
9Oo angle collapse is the most dangerous form of external collapse as the wall falls outwards for a
distance at least equal to its height.
2) Curtain fall collapse:
Curtain fall collapse is where part of the wall comes straight down and debris piles up near the
base.
3) Inward/outward collapse:
Inward/outward collapse is where the wall cracks horizontally in the middle and causes the top
half to usually fall inwards and the lower half to fall outwards.
4)Total collapse
This is the most severe form of structural failure, where all the floors have collapsed to the ground
or basement level and all walls have collapsed onto the floors.
What are the Pre-planning considerations?
1) Operational intelligence should be gathered and recorded in accordance with Policy Number 800
- Management of operational risk information.
2) In line with this policy, watch officers should assess the hazards identified for a location and
determine the level of risk by reference to factors such as size, complexity and layout. The
contents, any processes carried out and occupancy should also be considered and the location must be included within the Operational Risk Database (ORD) as the Premises Risk Assessment score dictates.
What are The six stages of rescue
The Six Stages of Rescue
R Reconnaissance and survey. E Elimination of utilities P Primary surface search and rescue E Exploration of voids and spaces A Access by selected debris removal T Terminate by general debris removal
Non-Government Organisations (NGOs)
1) Several organisations exist that offer a capability in search and rescue. These organisations vary in
size and are not linked directly to the UK fire service or local authorities. Collectively, they are
known as Non-Government Organisations (NGOs).
2) Incident commanders should be aware that incidents of this type are likely to attract considerable
media attention from the early stages. As a result, there may be offers of assistance from NGOs,
either directly to the incident ground or to LOC.
3) All such offers of assistance should be referred to the Officer of the day (OOD), via LOC, who will
refer the offer to the duty Assistant Commissioner for consideration. NGOs should not take any
role in the incident until or unless approval has been given by the duty Assistant Commissioner.
What are the Operational considerations? 1 of 11
Local authorities have full powers to deal with structures which may become dangerous, whether
due to fire or any other cause. In the Greater London area the authorities concerned are
- The City Corporation
- The ‘inner’ London Borough Councils, acting through the Dangerous Structures Engineer
- The ‘outer’ London Borough Councils, acting through the Dangerous Structures Engineer
What are the Operational considerations? 2 of 11
If buildings become dangerous as a result of fire, or if information is received by the Brigade that a
building has become dangerous
A message is to be sent to London Operations Centre (LOC) and LOC will notify the Dangerous Structures Engineer of the district concerned. Pending arrival of
the Dangerous Structures Engineer, it may be considered necessary to take urgent safeguarding
action by cordoning off an area by the erection of barriers.
What are the Operational considerations? 3 of 11
The scale and causes of collapsed structure incidents can be varied. Incident commanders should
consider these and instigate procedures as necessary. The following are examples of procedures
that may be applicable:
- Major Incident Procedure.
- Terrorist related incidents.
- Fires and incidents involving hazardous substances.
- Civil disturbances.
- Fires and incidents involving radioactive substances.
What are the Operational considerations? 4 of 11
Collapsed structure incidents will, by their nature, require investigation by the police and the
Health and Safety Executive (HSE).
Consideration must therefore be given to the preservation of
evidence. It is important that close liaison is established and maintained with the police and other
agencies throughout the incident.
What are the Operational considerations? 5 of 11
It is recognised that, particularly in the early stages of an incident, crews may be subjected to
extreme pressures created by public expectation
It is vital therefore that any actions undertaken
in these circumstances remain in accordance with Command procedures, as detailed in Policy
Number 238 - Incident command procedures.
