The Structural Engineer > Archive > Volume 73 (1995) > Issues > Issue 16 > Correspondence on Partial Safety Factors for Reinforcement by Professor A.W. Beeby
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Correspondence on Partial Safety Factors for Reinforcement by Professor A.W. Beeby

Mr A. N. Beal (M) (Thomason Partnership) Reducing safety factors in design Codes is rather like tiptoeing towards the edge of an overgrown cliff. Initially, it is safe, but beyond a point there is danger and no one knows exactly where that is. The more that the safety factor is reduced, the greater is the risk that the danger line will be crossed, but we may not know that it has been crossed until many years after the decision, when buildings have ‘matured’ a little and had chance of being subjected to their full design loads. Unfortunately, by that time many thousands of buildings might have been constructed to the new standard, so the possible costs of a mistake are considerable. It should also be borne in mind that, although the risk increases as the safety factor is reduced, there are diminishing returns on the cost-saving side, as nominal reinforcement, defection limits, etc., increasingly govern design.