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Issue 23/24

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The Structural Engineer

Poorly maintained HACC roofs are generally in a weaker condition than protected internal HACC floors, and the matter of seriously defective HACC roofs does not seem to be widely understood.

The Structural Engineer

Since the Department of Transport launched the bridge rehabilitation programme in 1987, many thousands of bridges have been assessed to determine their safe loadcarrying capacities. Although the majority of structures have been found to be satisfactory, large numbers of bridges have ‘failed’ their assessments. C.R. Middleton

The Structural Engineer

Mr A. N. Beal (M) (Thomason Partnership) Dr Desai has presented an interesting paper on a proposition most engineers have probably not considered: the use of centrally-placed horizontal steel in a reinforced concrete beam as shear reinforcement. However, in the paper the derivation of the proposed design formula (1) is not explained clearly and it would be helpful to have some explanation of this, as it is not obvious that it is necessarily the most appropriate formula to assess the contribution of such reinforcement.

The Structural Engineer

A previously proposed design method for corner joints, subjected to opening moments and reinforced with only intersecting U-bars, is extended to include the influence of diagonal reinforcement across the reentrant corner. N. Jackson

The Structural Engineer

Part 3: Introduction This year’s examination was attempted by a total of 746 candidates, a small decrease of 17 compared with the previous year. Of those candidates, 394 took the examination in the UK, while there were 352 candidates outside the UK, 280 at the Hong Kong centre. The UK pass-rate was 44.9%, a welcome increase of 5.3% compared to the previous year. The passrate outside the UK was 25.8%, which is rather disappointing, and the Hong Kong centre produced a pass-rate of 27.5%, the lowest for some years. The overall pass-rate was 35.9%, 0.4% higher than last year, and it is hoped that it will climb to the 40%+ band by next year.

The Structural Engineer

Large-scale tests were carried out on 26 slender; reinforced concrete columns with 1ength:depth ratio in the range 15-31.7; the compressive strengths of concrete ranged from 31 -96N/mm². The pin-ended columns were subjected to short-term eccentric axial loads with load-eccentricity:depth ratio of 0.25 and 0.5. All the columns were reinforced with four high-yield deformed bars having a nominal strength of 460N/mm² ith steel ratio varying from 1.34%-3.35%. The test results were compared with the values predicted using ACI318: 1995, BS 8110:1985, and EC2:1992. These tests, which for the first time enabled the provisions for slender columns in the Codes to be checked against experimental values, have indicated that the Codes are safe design documents for concrete strength as high US 96N/mm². Compared with those of BS 811O, the slender-column recommendutions of EC2 are more conservative, closer to those of ACI, and more complex to use. P.H. Chuang and Professor F.K. Kong

The Structural Engineer

Despite the unpopularity of collateral warranties with architects, engineers and contractors alike, there can be little doubt that, for the time being at least, warranties are here to stay. This article seeks to explain why that is the case and identifies some of the key considerations which need to be addressed before parties sign up. A. Rawston

The Structural Engineer

The PFF's revised Code of practice for the safe erection of precast flooring has been written to help everyone involved in designing, planning, using or erecting these products to understand the practicalities. P.A. Harris

The Structural Engineer

Factors of safety in Codes Alasdair Bed, from Leeds, has returned to the fray and writes: Colin Taylor’s invitation (Verulam, 16 September) to a game of pingpong with him and Alan Weller is tempting (if we could find a suitably shaped table!), but the correspondence on the derivation of the BS 5950 safety factors had a rather more serious purpose.

The Structural Engineer

Most of us are aware of the various ways of resolving disputes (e.g. negotiation, mediation, adjudication, arbitration, litigation). Adjudication has grown in popularity in recent years; it involves the use of a third party (the adjudicator) who finds out the details of a dispute and decides what should be a fair settlement, in the light of the contract. Unlike litigation (and to some extent arbitration) there is normally no set procedure to be followed. A.L. Gilbertson