Technical
NSC 25
Apr 20
Dry floor plates
The project considered the possibilities of completing floor
panels offsite and erecting completed floors. This approach is
common in light gauge construction – so could a similar concept
be used in orthodox multi-storey buildings? The concept
investigated comprised panels up to 12 m long and 2.4 m wide –
three panels would therefore result is a column grid of 12 m ×
7.2 m.
The floorplate itself could be orthodox composite
construction, or cross laminated timber (CLT). The latter is
immediately seen as more expensive, but it has obvious ‘green’
credentials, can be manufactured to precise tolerances and is
readily demountable. A CLT panel 135 mm deep could span a
panel width of 2.7 m, under a variable action of 3.5 kN/m2, so the
solution is relatively shallow.
Whether the floorplate is CLT or conventional deck and
concrete, the longitudinal and transverse junctions between
panels demand special attention. Adjacent panels would need to
be inter-connected, so that the floorplate forms a diaphragm,
meaning that edge members such as channels which can be
bolted back-to-back are a possible solution. The fire stopping and
acoustic barriers at joints between panels would also need
careful consideration – which are all possible if carefully
engineered, in addition to the normal considerations of
deflection and dynamic performance.
Conventional composite construction is hard to beat for a
shallow, economic solution, so the benefits of dry floor panels,
such as speed and early access for following trades would need
to be valued to make such a solution worthy of further
development.
Single storey columns
A P-DfMA approach favours simple components suited for several
applications – so single storey columns are worthy of
consideration, especially if associated with the prefabricated dry
floor panels described previously. Single storey columns are
easier to handle robotically, so may be an attractive solution for
fabrication. Composite columns (with concrete surrounding open
sections, or concrete within hollow sections) are currently not
common in the UK, but have clear advantages at both ambient
temperature and in fire. With some changes in the supply chain,
manufacturing single storey composite columns appears entirely
feasible.
Where next?
More details of the solutions outlined above are available in the
guides freely available from BSCA and SCI. The project team
never imagined that solutions would be adopted immediately
without further development. The objective was that solutions
which deliver benefits – which would have to be valued against
conventional construction – should be considered in the mix. It is
said that the Rainier Square building would not have progressed
without the shortening of the construction program resulting
from the use of a steel composite core. Those responsible intend
to use the system for several other structures. Encouragement,
perhaps, for the designers in the UK to consider the possibilities
for their own projects.
Figure 3 – Bi-steel core with connections for the surrounding steelwork
/Steel_construction_products#.27Light_steel.27_sections
/Concept_design#Floor_grids
/Steel_construction_products#Decking_for_floors
/Braced_frames#Horizontal_diaphragms
/Floor_vibrations
/Composite_construction
/Fabrication
/Steel_construction_products#Structural_hollow_sections
/Composite_construction#Composite_columns
/Construction
link
/www.rainhamsteel.co.uk