Abstract

VAN SCHALKWYK, F  and  KEARSLEY, E P. The influence of concrete compressive strength and specimen size on the compression stress block parameters of reinforced concrete. J. S. Afr. Inst. Civ. Eng. [online]. 2018, vol.60, n.4, pp.34-44. ISSN 2309-8775.  http://dx.doi.org/10.17159/2309-8775/2018/v60n4a4.

This paper describes the influence of concrete compressive strength and specimen size on the fundamental characteristics of the flexural compressive stress-strain distribution. The main variables were specimen size and cylinder compressive strength. A total of 27 concrete specimens were subjected to flexural tests, with specific reference to analysis of the compression stresses, produced by varying two independent loads in a configuration aimed at controlling the strain distribution. These loads generated a condition of zero strain on the one face of the specimen, and a condition of maximum flexural compression strain on the opposite face. From the strain distribution, the stress-strain curves and stress block parameters were determined, and the influence of specimen size on the stress block parameters described using the Modified Size Effect Law (MSLE). Using a modified form of the moment-axial force (M-N) interaction diagram the BS 8110-1 (1997), SANS 0100-1 (2000), ACI-318 (2014) and EN 1992-1-1 (2004) codes of practice were compared for the design of reinforced concrete beams containing South African materials.

Keywords : stress block parameters; rectangular stress block; size effect; SANS 0100-1; EN 1992-1-1.

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