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The Structural Engineer

The term ‘hyperstatic effects due to creep’, as used in ENV 1994:2 (the draft Eurocode for composite bridges’), may be unfamiliar Its interpretation in global analysis is explained. A two-span beam is analysed using two modular ratios, as in the UK Bridge Code, and using three, as in the Eurocode. A method of numerical analysis, using current software, is explained. The methods are applied to a beam of mixed construction, a beam prestressed by jacking at a support, and to efsects of shrinkage. The extent to which the simpler method (current practice in the UK) could be unsafe is usually small for the first subject, but may not be for the other two. Professor R.P. Johnson and Professor Dr Ing G. Hanswille

The Structural Engineer

Adjudication The Housing Grants Act affects the professional indemnity insurance arrangements of those professional firms on whom it impacts. The response of the insurance market to date has been inconsistent, to say the least: many insurers are placing extremely onerous conditions on their policies which have to be complied with if cover is not to be prejudiced. Andrew Bowyer

The Structural Engineer

On 1 May 1998 Part II of the Housing Grants, Construction and Regeneration Act 1996, better known as the Construction Act, finally came into force. Some 4 years after publication of the Latham Report Constructing the team the Construction Act is intended to address a range of problems which have bedevilled the industry for years. Not all of Sir Michael’s proposals have been adopted, but those that have include: - the abolition of ‘pay when paid’ clauses - the compulsory notification of an intention to set-off -the right to interim or periodic payment for work executed under construction contracts, which will generally include consultants’ appointments adjudication - the right to refer any dispute to Each of these areas is worth Andrew Rawstron

The Structural Engineer

Micropiles were fiist introduced into Malaysia in the late 1970s by French contractors to support to a new RC framed structure constructed inside a 100-year-old building supported by masonry spread foundations that were in turn supported by bakau timber piles. Since then, the development and application of micropiles have progressed by leaps and bounds. The first piles were 150mm in dimeter but rapid development in the last 2 decades has resulted in the present generation of piles of up to 300mm in diameter. The piles are presently applied in underpinning work as well as new foundations. Chan & Ting presented a state-of-the-art report. This paper seeks to highlight the main features of the piles. W.H. Ting and L.Y. Tai

The Structural Engineer

Usually, structures are considered to be elastic at the serviceability limit state. Evidence collected from previously reported large-scale experiments, supplemented by analysis, is used to show that plasticity can sometimes be developed in composite beams before the beam deflection reaches the serviceability Code limit. This phenomenon does not accord with the traditional concept of the serviceability limit state, for which elastic behaviour is assumed and elastic analysis methods are adopted in design Codes when predicting deflections. In order to limit plasticity at serviceability, tighter limitations on beam span/deflection ratios are required. The derivation of such limitations is presented herein. The beam span/deflection ratio corresponding to first yield of the beam is shown to be dependent on the steel grade, neutral axis position, and beam spaddepth ratio. Ifa small degree of plasticity is allowed at serviceability, a multiplication factor is needed to adjust the deflection obtained from an elastic analysis so as to allow for the efect of plasticity. The derivation of the multiplication factor is also presented. Professor D.A. Nethercot, T.Q. Li and B. Ahmed