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Issue 23/24


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The Structural Engineer

The premature corrosion of steel reinforcement in concrete structures can be a major problem, particularly in aggressive environments. The increasing cost of repair to corrosion-damaged structures has resulted in the development of alternative non-ferrous materials such as fibre-reinforced plastic (FRP) composites. This paper describes an innovative reinforcing system for concrete columns using purpose-made prefabricated FRP-filament-wound tubes. The FRP composite provides a barrier to the ingress of chlorides and atmospheric gases, and acts as structural reinforcement for the column. The triaxial confinement of the concrete core due to the FRP composite results in significant increases in both the strength and ductility of the composite columns. Additionally, the filament-wound tube has suficient rigidity to act as permanent formwork. To determine the short-term behaviour of such FRP compositely-reinforced concrete columns, 121 fullscale concrete columns have been tested to failure. D. Lillistone and C.K. Jolly

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The Structural Engineer

Peter Flynn is Technical Director of Techrete’s Irish office at Howth, near Dublin, a company which offers specialist technical and manufacturing skills in architectural precast concrete cladding. A structural engineer, he heads the drawing office team of more than 40 engineers/draftsmen. He spent 12 years working with architects in multi-disciplinary practices such as BDP and RMJM prior to joining the company. He now works on behalf of the manufacturer with top architects such as Foster & Partners, Terry Farrell and many others, to develop the precast products they need to achieve their design intentions. Cladding is a complex process and demands a lot of time and energy. Projects may be prestigious, in sensitive locations where high-tech solutions need to look traditional, and often involve innovative ideas. He delights in his work, particularly in sitting down with fellow professionals Kathy Stansfield

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The Structural Engineer

Good ground engineering involves maintaining a balance between a number of key activities including ground exploration, laboratory and field measurements, appropriate predictive modelling, and empirical procedures based on ‘well-winnowed experience’. A number of cases involving interactions between ground and structure are presented to highlight the importance of all these activities and of keeping them in balance. In all of the case histories the importance of understanding the patterns and basic mechanisms of ground movement becomes apparent. The parallel is drawn between the approach of the geotechnical engineer and that of the structural engineer working on an ancient historic building. Professor J.B. Burland

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The Structural Engineer

Part 3 report This year’s examination was attempted by a total of 849 candidates, a slight increase in comparison with last year. Of those candidates, 375 took the examination in the UK while there were 474 candidates in international centres. There were a record 400 candidates at the Hong Kong centre.

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The Structural Engineer

The highly publicised closure of the London Millennium Footbridge owing to excessive lateral vibration at its opening on 10 June 2000 has highlighted a potentially critical loading effect not currently considered in international bridge design codes. The purpose of this update is to alert designers to the phenomenon, to disseminate information about it, and to identify what further research is necessary before definitive design rules can be developed. Pat Dallard, Tony Fitzpatrick, Dr Anthony Flint, Angus Low, Roger Ridsill Smith and Michael Willford

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The Structural Engineer

Eighteen large-scale reinforced concrete columns, with concrete compressive strength (fcu) of 55.24N/mm² or 76.15N/mm², were tested under short-term loading. The effective-length-to-depth ratios Le/h) of the columns are 26.2,28.7 or 30.4, load-eccentricity-to-depth ratio (e/h) is 0.25 or 0.50, and steel ratio (p) is 3.35% or 5.24%. The experimental behaviour of the columns is presented and discussed. P.H. Chuang, S.K. Kong and Emeritus Professor F. K. Kong

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The Structural Engineer

This paper describes the civil work involved in the demolition of Tsing Yi Power Station in Hong Kong, during 1998. The work included the use of explosives to safely demolish the five, up to 150m-tall, reinforced concrete chimneys. This was one of the first and largest uses of explosives in demolition in Hong Kong. Demolition methods adopted in Hong Kong and the UK are compared and contrasted. T.J. Dishman

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The Structural Engineer

Eurocodes Roger Pope writes: Following Joe Locke’s letter published on 5 September 2000, you raised several questions about the impact of Eurocodes on design. My response to your queries based on my experience as an active player in the process concerning Eurocodes 0,1,3 and 4 is as follows: (1) Very few complete trial designs were ever undertaken using solely the ENV versions of the Eurocodes. Nearly all experience at ENV stage was with the NAD version in each country, often with pre-existing national loading codes not the actions specified in ENV 1991. As the NADs had been ‘calibrated’ to give the same design outcomes as pre-existing national codes it was hardly a surprise if trial designs undertaken with the ENV and NAD together resulted in design outcomes similar to that from pre-existing national codes! As an example, the UK NAD for ENV 1993-1-1 reduced the gamma factor for steel to 1.05 from a boxed value of 1.1 which eliminated 5% of the uncompetitiveness in the bare ENV.

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