Reliability Engineering 8 (1984) 85-100 Proof Loading and Structural Reliability Tzyy Shan Lin Department of Civil Engineering,Johns Hopkins University, Baltimore, Maryland, USA and Andrzej S. Nowak Department of Civil Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA (Received: 8 June, 1983) ABSTRACT Structural reliability depends on uncertainties in resistance and loads. In many practical cases the resistance dominates and a reduction of uncertainty about resistance is an effective way of increasing safety. It can be accomplished by proof loading. A truncated distribution is considered and reliability indices are calculated for various proof load levels. The structural reliability is sensitive to proof loading for larger coefficients of variation of resistance. A Bayesian approach is applied to develop a posterior distribution for resistance, after proof loading. Reliability indices are calculated for various ratios of the coefficients of variation of load and resistance. NOTATION hi F f P Parameter in Bayesian formula Cumulative distribution function Probability density function Probability 85 Reliability Engineering 0143-8174/84/$03-00 © Elsevier Applied Science Publishers Ltd, England, 1984. Printed in Great Britain