Statistics for concrete and steel quality in Saudi Arabia

This paper presents the results of an experimental programme designed to develop probabilistic models for the compressive strength of concrete and the yield strength of reinforcing steel produced in Saudi Arabia, as a first step towards the development of a national design code for reinforced concrete buildings. A total of 955 concrete samples and 434 samples of steel bars weve randomly collected from construction sites for strength testing. The results indicate that ready mixed concrete is well modelled fly the normal distributions, whereas sire mixed concrete is well represented by the log-normal distribution with a low mean/nominal ratio and a high coefficient of variation. Variation in the yield strength of reinforcing steel is modelled by the normal distribution, with a high mean/nominal ratio. The models are verified by the chi(2) and Kolmogorov-Smirnov goodness of fit tests at the 5% significance level. The models developed in this paper are useful for predicting the performance of structural elements and assessing their reliability levels. They ave also essential for calculating resistance factors for a limiting state design code.