ASSET, the innovative structural system based on advanced composite profiles, has started laboratory tests in Spain in readiness for the installation of a prototype highway bridge in the UK during mid-2002 to carry vehicles of up to 40 tonnes.
This is part of the ASSET (Advanced Structural System for Tomorrow’s infrastructure) research programme being carried out by a European consortium led by Mouchel experts in composite structures. The four-year project is part-funded with £1.5M from the EU under the Industrial & Materials Technologies Brite-EuRam III programme.
The aim is to develop a complete lightweight structural system of high-strength standardised profiles, lengths of which can be rapidly assembled for small bridges and other structures or used as heavy duty decking and flooring. Low whole-life costs will result from the material’s superior resistance to fatigue and corrosion, and minimal maintenance requirements.
During the first two years of the project, Mouchel has optimised a fibre-reinforced polymer profile of prismatic multi-cell design for mass production by pultrusion techniques. This patented profile makes best use of the composite’s properties and does not mimic structural shapes used by traditional materials. ASSET consortium partner Fiberline Composites A/S of Denmark has perfected the pultrusion die and is now precision-producing a two-cell version of the profile, 225mm deep and 520mm width (including overlapping sections), in lengths exceeding 30 metres.
Mouchel’s design incorporates mating and overlapping sections so that lengths of the two-cell profile can be factory-bonded together side-by-side to form a high-strength deck structure, repeatable in 300mm widths and able to carry concentrated wheel loads. Specialist knowledge on the joining of composite materials came from Swedish university KTH, another partner in the ASSET consortium.
Parallel work by ASSET partner HIM Chemie BV of the Netherlands has identified an epoxy-based surfacing system and polymer concrete that will bond securely on the profile to provide high-grip low-wear action for traffic and pedestrians.
Reported Dr Sam Luke, Mouchel’s head of advanced engineering: “We are at the stage where Spanish research institute IETCC (another ASSET partner) has started a programme of 150 large-scale tests on 2.2m and 4.4m lengths of the profile. Single, double and triple profiles will be subjected to static and dynamic loads, including four-point bending and the study of hogging, sagging, shear and local wheel effects.”
Mouchel is now working with ASSET client partner Oxfordshire County Council, Skanska Teknik AB of Sweden and contractor Skanska UK (both ASSET partners) to design and gain planning permission for a prototype composite bridge at West Mill in SW Oxfordshire. This ten-metre single span structure, seven metres wide, will carry two traffic lanes and footpaths over a river to replace an 1870s bridge that can only take a single traffic lane with its 3.5 metres width.
Explained Sam Luke: “Oxfordshire’s involvement with this innovative new-build project follows substantial development work we have carried out with the County’s bridge engineers on plate bonding of composites for structural strengthening over the past six years. The current project should prove ASSET’s great advantages over traditional construction methods — lower weight, easy handling and rapid installation.
“Our plan is to produce seven-metre sections of the two-cell ASSET profile and bond 34 of these side-by-side to form a rigid deck structure 10m long. We will then bond and mechanically fix four composite box-section beams beneath the deck to span the river.”
This prefabricated composite structure, together with its concrete upstands, diaphragms and parapets, will weigh just 27 tonnes — a load that Skanska can economically crane into position on new abutments. An equivalent concrete structure would be around 95 tonnes and prove far more time consuming to construct.
State-of-the-art instrumentation will continuously monitor key elements of the bridge for immediate use by Oxfordshire’s engineers, and a web-camera will provide real-time views of traffic action. All performance data will be displayed on the ASSET web-site for academic research and public information.
“We have rigorously designed the profile to European and British codes of practice, which are among the world’s most conservative,” confirms Mouchel director Malcolm Taylor. “The longterm monitoring is designed to prove the technology and confirm the system’s outstanding strength and fatigue resistance.
“Armed with our experience of structural strengthening with advanced composites, and the knowledge already gained through the current research programme, we will soon be ready to market the ASSET system globally.”
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