Civil Engineering Reference
In-Depth Information
Simply supported beam; 35% upgrade in live load
Bonded Steel Plate
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Member Enlargement
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2 #8 rebar,
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100mm. grout
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1110kg dead load
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Formed and cured
FRP Sheet
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6mm bolted plate
1 layer resin bonded
110kg dead load
1.5kg. dead load
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6 men to lift and place
Placed by hand
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34% of the UK's waste is derived from construction and demolition
activities.
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The USA has 594,000 bridges - 28% of them are structurally deficient
or obsolete.
As previously mentioned, a good example of strengthening using
composites would be a highway structure, where vehicles from the continent
are delivering goods to the UK, and the strength and weight limits of our
bridge structures are lower than those in parts of Europe. Over the last 15
years or so, local agencies have undergone a programme of strengthening
the UK's bridge structures to meet the demands of European transport
legalisation.
The technology and application techniques used to strength these structures
have improved dramatically over those 15 years. The UK was using steel
plates and larger sections of concrete to strengthen such structures. Today
these methods are rarely used, favouring advanced lightweight composite
materials such as carbon fibre, glass fibre and aramid fibres. The use of FRPs
has progressed from using simple pultruded plates and wraps to the use of
ultra high modulus systems and unique profiles.
The strength of the fibres that are in use today can be up to 10 times that
of mild steel, while possessing a similar stiffness. For specialist applications,
where stiffness is a concern, such as cast iron structures, fibres up to four
times stiffer than steel are now available.
This chapter will examine some of the more intricate and interesting
applications, where the engineers involved have designed and promoted the
use of these very exciting materials. Where perhaps in the past they would
