JEC COMPOSITES MAGAZINE - Issue #85 - November/December 2013 - 32

PFRP house

four soldiers. The second is a very light
roof deck of only 80 cm depth, which
will span 20 m. The absence of a moving
load greatly simplifies the design. By fine
tuning and inducing a modest camber,
the roof span will increase to 30 m.

Implications

Fig. 3: Spacelink: the lightweight, flat-pack bridge spans 10 m and supports a 3.5 tonnes vehicle

in the building relative to other components, its structural performance and
the approved means of handling and
installation within the construction.
The same tag could have maintenance
instructions written into it. A facilities
manager would pass a reader over the tag
every four years to find out what maintenance (if any) was due. The completion
of maintenance tasks would be entered
in the building's digitised maintenance
record. At end of life, the same tag would
contain information about re-cycling
options, "buyback" possibilities or, if
neither of these applied, safe and environmentally-responsible disposal routes.
Under current building construction
practice, it is difficult to see how this
elegant, time-saving and cost-reducing
method could be implemented satisfactorily. Building material procurement
routes are too convoluted and disjointed; also, contractual relationships are
too meandering and difficult to disentangle. However, a building construction
system based on one production process, a closely-related family of strong,
lightweight materials and straightforward procurement options for the
constituent materials could lend itself
very readily to rational and cost-effective
use of sophisticated computer technology, as described above.
Startlink is such a system. Its adaptation

to this kind of computer technology
would be relatively easy. Were the system to be brought into existence with
such an advantage built into it, Startlink
would sweep aside over-complicated and
labour-intensive conventional construction methods in less than a decade.

The Spacelink™ study
Spacelink is a TSB-funded study,
focused on joint design in composite trusses with the aim of eliminating bolted connections. An adverse
consequence of bolted joints is that the
walls of composite sections thus connected have to be thickened to ensure safe
load transfer. This greatly increases the
weight of the whole structure. Spacelink
puts the structure into compression as
much as possible. The ends of struts
are shaped so joints tend to tighten
as the load increases. The surface area
thus available for load transfer is at least
three times that of a bolted joint. Two
conditions are being tested. The first is
a de-mountable bridge spanning 10 m
to support a 3.5 tonnes vehicle. Moving
loads create stress reversals in struts as
the load passes over the bridge. Any risk
of failure is mitigated by ensuring that
tensile stresses are always low, similar
in all struts and never exceed 10 MPa.
The bridge is exceedingly light at 175 kg
and can be carried by seven workmen or

32 jec composites magazine / No85 November - December 2013

Spacelink arose from consideration of
space-frame structures which turn bending forces into tension and compression forces. PFRP is stronger than steel
in tension and compression but not as
stiff, so a space-frame makes the best use
of PFRP properties. The outcome of the
study is highly significant. Used in this
way, PFRP is actually cheaper than steel
to build equivalent roof structures, yet
has the added benefits of lighter weight,
improved thermal properties and corrosion resistance. For larger buildings
ranging from industrial and commercial
to leisure, PFRP surprisingly offers a
more effective and less costly alternative to steel roof structures. The weight
saving is substantial, saving money
both on the roof itself, supporting
structures and foundations. Demountability simplifies shipping and superior
thermal properties contribute to energy
efficiency. Most importantly, corrosion
resistance becomes a major advantage
for structures in ports and coastal areas
where protecting steel is both difficult
and expensive. Spacelink can be scaled
up for longer spans and offers a step
change in building technology through
the intelligent use of PFRP.

The future
The successful outcomes of both projects show that PFRP can have a significant impact on the construction market.
The advantages over more traditional
materials are considerable and cost-effective solutions using PFRP have been
described and demonstrated. Taking this
forward depends on further collaboration and the inventors welcome contact
from interested parties. n
More information:
mark@startlink.co.uk
johnhutchinson@feildenandmawson.com

JEC COMPOSITES MAGAZINE - Issue #85 - November/December 2013

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #85 - November/December 2013