The following are summaries of papers published in other parts of ICE Proceedings during 2006 that readers of Bridge Engineering may find of interest. Summaries of all papers in ICE journals are freely available and fully searchable at the ‘journals on-line’ section of the ICE website. See www.ice.org.uk/journals for details.
On the ropes: civil engineers get closer to rail bridges
Chris James
Proceedings of the Institution of Civil Engineers, Civil Engineering, 159, No. 1, February, 24–31
Bridges and viaducts are an essential part of transport infrastructure, particularly on railway networks where the variety of structural type, size and age usually exceeds that of the highway network. Inspection and examination form a large part of the management of these structures, which are often high and in remote locations. This paper details how rope access techniques are being increasingly used for the inspection of such structures in the UK and argues the benefits for more civil engineers to be trained in rope-access work.
Union Chain Bridge: linking engineering
G. Miller
Proceedings of the Institution of Civil Engineers, Civil Engineering, 159, No. 2, May, 88–95
Civil and marine engineering have long been linked, but perhaps no more symbolically than by the Union Chain Bridge between Scotland and England over the River Tweed. It was built 186 years ago by Sir Samuel Brown, who made the transition from Royal Navy captain to designer of the world's longest iron suspension bridge in one single leap. This paper reports on his remarkable eight-year journey, from leaving the Royal Navy in 1812 to start an anchor-chain business to building the record-breaking Union Chain Bridge in 1820. He went on to design the Brighton Chain Pier and supply Isambard Kingdom Brunel with chains for his Great Eastern steamship, while his company remained the navy's sole chain supplier for over a century. Union Chain Bridge, which still carries road traffic today, thus serves as an inspiration to all engineers of the benefits of cross-disciplinary thinking.
Jane Coston Cycle bridge: a model for managing vibration
M. Black and G. Webster
Proceedings of the Institution of Civil Engineers, Civil Engineering, 159, No. 3, August, 120–125
The growing popularity of long-span slender footbridges, as key elements in schemes to encourage greater walking and cycling, has required design engineers to look much more closely at dynamic behaviour. Following high-profile problems with the London Millennium Bridge and Passerelle Solferino in Paris, designers of the 77 m span Jane Coston bridge in Cambridge studied dynamic effects of pedestrians particularly carefully. The study established the specific requirements for the structure and also a new general approach for future footbridge design. It suggests that slender footbridges can be designed for static loading, and that dynamic effects can be cost-effectively accommodated by making provision for possible damper installation after completion.
Briefing. Stress-lamination: utilising low-grade timber in construction
G. Freedman and A. Kermani
Proceedings of the Institution of Civil Engineers, Construction Materials, 159, No. 1, February, 7–10
Stress lamination of timber, as an engineering concept, has a useful future in construction, and should provide many opportunities to utilise UK timber–a readily available lightweight material, excellent in compression yet good in bending. That combination will particularly encourage its use.
Chloride ion penetration in bridge deck concrete
H. A. Ghanem, S. Phelan, S. Senadheera and Y. A. Daou
Proceedings of the Institution of Civil Engineers, Construction Materials, 159, No. 3, August, 129–136
During freezing temperatures, ice accumulates on exposed concrete slabs such as bridge decks. De-icing salts such as calcium chloride are applied to control this ice formation. These salts migrate down to the reinforcing steel and they can break down the passivation layer on steel, causing it to corrode. This paper is part of a broader research study, sponsored by the Texas Department of Transportation, to explore the possibility of opening the bridge decks to full traffic following construction/repair earlier than the 10 to 12 days as practised now in Texas. Seven concrete mixtures typically used in Texas bridge decks were evaluated for chloride permeability using the ponding test. The primary experimental variables were the curing duration, type and percentage of supplemental cementitious materials, type of coarse aggregate, duration of ponding, and the surface preparation of ponded concrete specimens. The results of this investigation indicated that chloride permeability decreased with increasing curing duration for the top 1 in (2·5 cm) layer of concrete. It was also observed that curing duration may be decreased for some concrete mixtures, as no apparent improvement was shown after a specific curing duration, which ranged from 2 to 8 days depending on the mix. In addition, increasing the amount of cementitious materials such as fly ash from 20% to 30% considerably reduced the chloride permeability.
Foundation design for a large arch bridge on alluvial soils
J. Monnet, D. Allagnat, J. Teston, P. Billet and F. Baguelin
Proceedings of the Institution of Civil Engineers, Geotechnical Engineering, 159, No. 1, January, 19–28
The Crozet bridge is located on the Grenoble-Col du Fau motorway, on the Grenoble-Sisteron route, 15 km south of Grenoble, France. It crosses a 350 m wide valley and the RN75 national road. The adaptation of the bridge into the landscape has involved an arch design with three bays (in the Grenoble-Sisteron direction) and one bay (in the Sisteron-Grenoble direction). The supports of the structure were difficult to build because of the huge horizontal force and the low displacement tolerance. The low stiffness and strength characteristics foreseen led to a geotechnical investigation by cyclic pressuremeter tests with a friction angle and cohesion interpretation. The foundation calculations were carried out by a finite element calculation using the CESAR-LCPC program to determine the support rigidity. The complete computation of the bridge was done with the calculated support rigidity, which showed that displacements of the arches were lower than the tolerance. The bridge is located in a low seismic area of France, and the design takes into account the maximum foreseeable magnitude, and analysis of the soil liquefaction risk. Monitoring carried out for completion of the bridge in 1999 and along the surveying shows displacements lower than tolerance values. Since 1999, the bridge has withstood huge service weights without any difficulty.
Vibration serviceability for pedestrian bridges
M. Kasperski
Proceedings of the Institution of Civil Engineers, Structures and Buildings, 159, No. 5, October, 273–282
The response of pedestrians to lively bridges is one of the problems that has to be addressed in the scope of analysing serviceability. The excitation process by walking and/or running and the sensitivity of the human receiver both have to be understood as random variables. The present paper analyses the expected scatter of the response of pedestrians based on today's available information. A discussion is then presented on a method of correlating observed reactions of pedestrians and measured vertical vibration amplitudes, which allow a serviceability criterion to be developed. A tentative limit value for serviceability is proposed based on the observations so far.
