Statistics for concrete and steel quality in Saudi Arabia

This paper presents results of an experimental program designed to develop the probabilistic models of compressive strength of concrete and 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 were randomly collected from the construction sites for strength testing. Results indicate that ready-mixed concrete types are well modeled by the normal distributions whereas site-mixed concrete is well represented by log-normal distribution with low mean-to-nominal ratio and high coefficient of variation. Variation in the yield strength of reinforcing steel is modeled by normal distribution with high mean-to-nominal ratio. The models are verified by the Chi-square and Kolmogorov-Smirnov goodness-of-fit tests at 5 percent significance level. The models developed in this paper is useful for prediction of the performance of structural elements and assessment of their reliability levels. They are also essential for calculating resistance factors for limit state design code.This paper is part of a study sponsored by King Abdul-Aziz City for Science and Technology under grant numbers AR-9-34