final-report-of-the-advisory-committee-on-falsework-bragg-report - Flipbook - Page 80
reference to falsework problems would help to inculcate in future designers of permanent works a
sympathy for falsework which might well lead to their
designing permanent works which were easier to" construct. In fact we suggest that the student asked to
prepare a design for any permanent structure should
at the same time be asked to produce his concept for
the associated temporary works.
Incidentally we were pleased to learn that falsework
designs are accepted by the professional institutions
on a par with designs for permanent works as evidence
of professional competence. However we would go
further and recommend that submissions based on
permanent ~orks must be accompanied by a brief
for the corresponding falsework and an outline
scheme of how it might be effected.
Several people have asked us to report particulars of
failures we have studied, and a selection is given in
the Appendix. We believe that much more use could
be made of case histories in educating engineers.
Although government departments will occasionally
issue reports on particular failures (e.g, Loddon Viaduct) it is the professional people closely involved
who have most of the information. Difficulties will
obviously arise when claims are sub judice and not all
information may be freely available. However, any
investigation brings to light faults which might have
caused collapse in other circumstances even if they
had no effect in the case considered: descriptions of
these faults are just as valuable for educational
purposes as description of the actual causes of failure.
We therefore recommend that the professional intitutions - perhaps through the newly formed Safety
Committee - commission the publication of failure
reports that could be used as case histories for study.
By the same token we recommend that information
derived from general investigations undertaken after
a failure - for example the tests at the Transport and
Road Research Laboratory after Lod.don - should always be made freely available.
Reference was also made during our discussion to the
increasing use of computers which result in the design
of permanent works becoming more and more
sophisticated. Service conditions may be modelled
accurately and very complicated theories may be employed. In contrast, falsework design is essentially
ad hoe and working conditions cannot normally be
tated precisely enough to justify complicated theoretical treatment. There is, therefore, a real danger
that the particular type of engineering expertise
required for practical falsework design in the field will
disappear from normal curricula. Our proposals that
all civil engineering courses should include reference
to falsework problems must be interpreted with this
practical point in mind.
One particular deficiency which has been highlighted
by our study of falsework failure is a blindness of
designers to what might be called three-dimensional
effects. It is easy to forget that deflections in one
direction may produce stress in others perpendicular
to it. This is particularly important in structures which
are not symmetrical e.g, bridges with skew spans
where deflections and compensating reactions can
be produced in both the directions at right angles to
the load. It is often forgotten that beams tend to twist
under load in practice, even though ideal beams do
not do so in normal two-dimentional theory. Nearly
all practical loads are applied eccentrically which
enhances such effects. We have discussed the question
of proper allowance for lateral loads in the earlier
paragraphs on horizontal instability. What needs emphasis here is the need for engineers to be trained to
think in three dimensions. They must never forget
of the effect of eccentricity of loading and the possibility of deflection out of the plane of the paper.
We referred in the section on 'Responsibility' (page 73)
to the lack of understanding between architects and
engineers. It was argued that the advance in building
technology has been such that no architect can afford
to be ignorant of the fundamentals of structural engineering and materials science. The shape and layout
of many modern buildings are determined to a large
extent by the structural requirements and by the need
to provide engineering services. So it is no longer
possible, except in the simplest and most traditional
projects, for the architect to act as sole creator with
the engineer merely :filling in structural details. Engineering and architecture must contribute as equal
partners to a project and further education courses in
both subjects must recognise this. In the context of
temporary works this would mean that courses on
falsework design should properly form part of the
training of architects.
Professional short courses
We have heard of a number of short courses which
include reference to falsework, for example those
given at Fulmer Grange by the Cement and Concrete
Association, but none specifically aimed at falsework
designers. Perhaps one of the problems is that the
number of experienced people available to teach is so
small. Certain organisations run their own courses
at which their experiences are shared. We have heard,
for example, of one-day 'teach-ins' organised by
British Rail for its staff.
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