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Steel Designers' Manual - 6th Edition (2003)
of delay caused by bad weather or insufficient or inadequate construction resources
in the locality of the site are significantly reduced.
Structural steel frameworks should generally be capable of being erected without
temporary propping or scaffolding, although temporary bracing will be required,
especially for welded frames.This applies particularly to the construction of the concrete
slab, which should be self-supporting at all stages of erection. Permanent metal
or precast concrete shutters should be used to support the in situ concrete.
In order to allow a rapid start to construction, the structural steelwork frame
should commence at foundation level, and preference should be given to single
foundations for each column rather than raft or shared foundations (Fig. 2.12).
Speed of erection is directly linked to the number of crane hours available. To
reduce the number of lifts required on site, the number of elements forming the
framework should be minimized within the lifting capacity of the craneage provided
on site for other building components. For similar-sized buildings, the one with the
longer spans and fewer elements will be the fastest to erect. However, as has been
mentioned earlier, longer spans require deeper, heavier elements, which will
increase the cost of raw materials and pose a greater obstruction to the distribution
of building services, thereby requiring the element to be perforated or shaped and
hence increasing the cost of fabrication.
Columns are generally erected in multi-storey lengths: two is common and three
is not unusual. The limitation on longer lengths is related more to erection than to
restrictions on transportation, although for some urban locations length is a major
consideration for accessibility.
To provide rapid access to the framework the staircases should follow the erection
of the frame. This is generally achieved by using prefabricated stairs which are
detailed as part of the steel frame.
The speed of installation of the following building elements is hastened if their
connection and fixing details are considered at the same time as the structural steel
frame design. In this way the details can be either incorporated in the framework
or separated from it, whichever is the most effective overall: it is generally more
efficient to separate the fixings and utilize the high inherent accuracy of the frame
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Fig. 2.12 Columns on large diameter bored piles
Factors influencing choice of form 57