Title:
Statistical Analysis of the Compressive Strength of Concrete in Structures
Author(s):
F. Michael Bartlett and James G. Macgregor
Publication:
Materials Journal
Volume:
93
Issue:
2
Appears on pages(s):
158-168
Keywords:
compressive strength; concrete cores; concretes; cylinders; evaluation; load factors; Materials Research
DOI:
10.14359/1353
Date:
3/1/1996
Abstract:
The relationship between the in-place compressive strength of concrete in structures and specified strength f c is investigated through the use of Factors F 1 and F 2. Factor F 1, the ratio of the average strength of standard 28-day-old cylinder specimens to the specified strength, is evaluated using data from 3756 cylinder tests representing 108 concrete mixes produced in Alberta, Canada, between 1988 and 1993. Factor F 2, the ratio of average in-place strength to average cylinder strength, is evaluated using core and cylinder data representing 108 concrete mixes with strengths less than 55 MPa that were investigated by others. A statistical description of the compressive strength of concrete in structures is derived that accounts for the inherent randomness of Factors F 1 and F 2 and also the typical strength variation within a specific structure. The probability of the in-place compressive strength of concrete in a 28-day-old column being less than f c is approximately 13 percent. It is likely that a recalibration of the load and resistance factors for the design of new structures in Canada based on these findings would yield greater factored concrete strengths than are currently in use.