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Steel Designers' Manual - 6th Edition (2003)
31.3.4 Lift shafts for elevators
The deviations from verticality that can be tolerated in the construction of guides
for ‘lifts’ or elevators are commonly more stringent than those for the construction
of the building in which they operate. In low-rise buildings sufficient adjustment can
be provided in association with the clearances, but in tall buildings it becomes necessary
either to impose ‘special’ tolerances on column verticality or else to impose
‘particular’ tolerances on those columns bounding the lift shaft.
In agreeing the limits to be observed with the lift supplier, it should not be overlooked
that the horizontal deflections of the building due to wind load also have
implications for the verticality of the lift shafts.
31.4 Fabrication tolerances
31.4.1 Scope of fabrication tolerances
The description ‘fabrication tolerances’ is used here to include tolerances for all
normal workshop operations except welding. It thus covers tolerances for:
(1) cross sections, other than rolled sections,
(2) member length, straightness and squareness,
(3) webs, stiffened plates and stiffeners,
(4) holes, edges and notches,
(5) bolted joints and splices,
(6) column baseplates and cap plates.
However, tolerances for cross sections of rolled sections and for thicknesses of
plates and flats are treated as manufacturing tolerances. Welding tolerances (including
tolerances on weld preparations and fit-up and sizes of permitted weld defects)
are treated elsewhere.
31.4.2 Relation to erection tolerances
Fabrication tolerances 923
An overriding requirement for accuracy of fabrication must always be to ensure
that it is possible to erect the steelwork within the specified erection tolerances.
Due to the wide variety of steel structures and the even wider variety of their
components, any recommended tolerances must always be specified in a very
general way. Even if it were possible to specify fabrication tolerances in such a way
that their cumulative effect would always permit the specified erection tolerances
to be satisfied, the resulting permitted deviations would be so small as to be unreasonably
expensive, if not impossible, to achieve.