final-report-of-the-advisory-committee-on-falsework-bragg-report - Flipbook - Page 72
Summary
The term falsework covers a very wide range of loadbearing temporary structures which vary not only in
complexity but also in the size and nature of the
understanding and in the consequences of an untoward
occurrence.
Our evidence suggests that all falseworks can be
hazardous, and in none is the risk of injury or death
so small that correct procedures can be disregarded. It
would however, be unrealistic to expect that the full
range of procedures and checks described above
should be applied in every situation.
The procedures may be simplified for certain routine
and standardised applications in the building industry
provided that they had been fully applied to the first
design. If a discrete range of standard building dimensions could be adopted, only the initial work of
designing and calculating adequate falsework for each
of the standard categories would be required. Thereafter, provided there was no significant variation, the
standard drawings, the standard detailing and the
standard checking would be built in and would need no
further checks. This would save manpower and other
resources so that there would be an incentive in terms
of cost for the client to purchase one of the standard
designed buildings.
In major civil engineering projects (which include
--
high bridges, wide-span bridges, viaducts and similar
structures where the cost of collapse is great and where
the risk to individuals working on the site and to
members of the public may also be high) we recommend the application of the full system of procedures
and checks. We advocate a Temporary Works Coordinator who must be a chartered engineer qualified
in civil or structural engineering. Where a project of
this nature involves untried methods or new materials
or is of a size outside previous experience, the check on
falsework design should, by mutual agreement
between engineer and contractor, be undertaken
by a qualified engineer who is not directly involved
with that particular project. We do not necessarily
rule out the possibility that the 'independent' design
check may be done by someone within the contractor's
organisation because the ultimate responsibility for
a design failure must rest with the contractor.
In the smallest operations involving falsework, such
For larger building units (which include power
stations and multiple column and slab buildings such
as offices, and hotels) the procedures may be slightly
relaxed. For example, the repetitive nature of the
column and slab reinforced concrete structure makes
it unnecessary to recalculate the loading and the falsework design at each level; a preliminary calculation
for each sequence of similar structure with a separate
calculation for variations and departures from the
standard is considered adequate. The overall design
must however still be checked by a competent engineer
in the contractor's organisation and must be submitted to the architect who will solicit the opinion of
an engineering consultant in cases where neither the
Architect not a member of the Architect's own organisation is qualified in structural engineering. This is
particularly important when the design involves a
novel concept or goes beyond existing experience in
the use of materials; or when the structure is larger
than has been built before.
Responsibility and liability
In advocating that the falsework proposals should be
as the repair and maintenance of buildings, most of
the work is undertaken by the 'good practical man'.
Undoubtedly much sound work is done safely by the
skilled craftsman working to the rules which he has
been taught as part of his trade. However, we consider that even in these instances, it is essential for a
drawing of the work to be made. This may only
amount to a freehand sketch with an estimate of
applied loads and the known or warranted strengths
of the support equipment used. Preparing such a
sketch can indicate to the skilled operative that a
margin of safety, which he had thought adequate,
does not in fact exist. It is appreciated that, for this
class of work, the operatives may work in units of two
or three persons and training, instruction and effective
supervision are all very important.
checked by the designers of the permanent works - or
by the structural consultants if the design responsibility
was vested in an architect - we were concerned only
with reducing the risk of collapse.
Many witnesses have impressed on us that although
such a procedure is desirable from the point of view
of safety, and is indeed practised in many areas, it
does tend to blur the lines of responsibility as between
contractor and engineer. Indeed it is quite impossible for anyone to check anything without being
blamed if an error, which he might have found, is subsequently manifested. In consequence a few engineers,
and apparently nearly all architects, take pains to dissociate themselves from considering falsework proposals in order to ensure that they can incur no
liability for damages if a failure occurs.
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