Determining Specimen Size Influences on FRC Response Using the Digital Image Correlation Technique

摘要

The global response of FRC members is known to be influenced by the force transfer mechanisms occurring at cracks, including the contributions from bridging fibers. These transfer mechanisms depend in part on the width of the cracks, which can vary with overall specimen size. This paper reports the response in flexure for notched specimens fabricated using normal weight concrete containing 1% volume fraction of hooked end steel fibers. Nominal specimen dimensions that varied by a factor of up to 2 were used to allow for the quantification of size dependent influences on the response. Instrumentation based on the digital image correlation technique allowed for a detailed study of the variation of crack width over the member depth, and its relation to the specimen size and loading. Companion tests were conducted on cylinders in compression using a size factor of 1.5. The results showed that the flexural strength decreased in relation to the overall specimen depth. From the crack width analysis, it was possible to develop relationships between the crack width and mid-span deflection.