Assessment of Pre‐Stress Losses in Instrumented Pre‐Stressed Concrete Beams Using Stochastic Analysis

In this study, stochastic analyses of pre‐stress losses in two pre‐stressed concrete beams are carried out, and the results of the analyses are compared with those obtained from the laboratory experimental investigations. The deterministic models given in ACI 209 (with modelling error) are used for predicting the pre‐stress losses. The compressive strength of concrete, water–cement ratio, coarse aggregate–cement ratio, fine aggregate–cement ratio, cement content, initial stress in steel and relative humidity are considered as random variables. Monte Carlo simulation technique is used to determine the statistical properties of pre‐stress losses at different times. From the results obtained, it is noted that while the relaxation strain can be assumed to follow a normal distribution, the frequency distributions of creep and shrinkage strains are not uni‐modal. A relation for estimating total losses is also proposed in the article. The stochastic analysis approach presented in the article would be useful in the assessment of pre‐stress losses in existing pre‐stressed concrete members in a more rational way.