final-report-of-the-advisory-committee-on-falsework-bragg-report - Flipbook - Page 34
which were to support other falsework. The collapse
of the slab floors of the Skyline Plaza in Fairfax
County, Virginia in March 1973 was one such case.
Conclusions
A falsework constructed from the most carefully
manufactured, properly selected and well maintained
materials can be no safer than is allowed by the
expertise employed during its erection. Whereas we
have been impressed in some instances by high standards of methodical workmanship, the results of
training and experience, we have also seen examples,
particularly on the medium and small building operations, of deplorable standards. The working there
appeared to lack the method, system, orderliness and
tidiness which are essential for good working condiions and good workmanship.
Indeed it would not be a great exaggeration to say
that we have seen examples of errors in almost every
element where errors can occur. Some common
eatures are: absence of effective bracing and lacing;
inadequate ties; lack of verticality; inadequate base
plates for standards; defective sole plates; props
pinned by pins of the wrong type, size and grade of
steel; eccentric loading in forkheads; failure to use
centralising wedges; failure to secure wedges; failure
to ensure a safe angle for cut wedges; over-extension
of screw heads without additional bracing; inadequate
bearings for the ends of telescopic centres; failure to
brace together the individual towers of a multitower support system; failure to tie back to a fixed
structure; failure to use temporary props and stays
to counter instability during the construction of the
falsework; failure to reinforce around vehicular
openings; failure to provide traffic fenders or, in their
absence, to provide sufficient redundancy in vehicular
openings liable to dislodgment; lack of connection
between units in vertical tiers; the mounting of rolled
steel sections in grillage-type forms without the interconnections, web stiffeners or plan and cross-bracing
which were called for in the design; and many others.
Some of these unsatisfactory features are illustrated
in this report, as are examples of the high quality
workmanship also found.
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