STATISTICS OF HIGH-STRENGTH CONCRETE CYLINDERS

The results of a statistical analysis on steam-cured, plant-produced h igh-strength concrete in compression based on about 2200 cylinders obt ained from several concrete producers in the United States is summariz ed. The statistical analysis considers the actual-to-specified concret e strength ratio, coefficient of variation, and probability distributi on function. The seasonal effect on the statistical properties of the strength is also included. The results of the analysis showed that bot h the mean-re-nominal and the coefficient of variation are higher for normal strength concrete than for high-strength concrete. The mean-to- nominal ratio varies between 1.078 and 1.255, whereas the coefficient of variation is in the range of 0.06528-0.1353, depending on the speci fied 28-day concrete strength. Also, the analysis showed that the mean -to-nominal ratio and the coefficient of variation for concrete produc ed in the cold season are both lower than the cor responding statistic s Sor concrete produced in the warm season. The study will help code d evelopers in generating probabilistic resistance models for concrete s tructures that can be used in the development of load and resistance f actor design codes.