Correlation between tensile and bending behavior of FRC Composites with scale effect

This paper describes the results of an experimental test program designed to correlate the tensile and bending response of fiber reinforced cement composites tested under the same conditions. Several objec- tives were sought: 1) to correlate tensile and bending behavior of specimens having about the same cross sec- tion; 2) to ascertain that a strain hardening composite in tension leads surely to a deflection hardening compos- ite in bending; 3) to observe scale effects on bending behavior; and 4) to verify if some theoretical correlation between post-cracking tensile strength and bending resistance (modulus of rupture) are validated by experi- ments. The final objective of this study is to provide hard data needed to determine if the tensile stress-strain response of fiber reinforced cement composites can be predicted from their load-deflection response, as cur- rently surmised in some test standards and in some finite element studies claiming that tensile response can be uniquely back-calculated from bending behavior. The test program included several parameters, among which 2 types of high strength steel fibers (hooked and twisted) with identical volume fractions of fibers (1%), and three different sizes of cross section for the beams, namely, 50×25 mm, 100×100 mm, and 150×150 mm. Key observations are described and conclusions drawn. 1 INSTRUCTIONS ing is more difficult to carry out, many researchers have investigated whether the third point flexural test Much research has been conducted to increase the can be used, as an alternative test method, to obtain ductility of cement based composites by adding short the tensile response of the composite. Note that the fibers, because cement based matrices have innate flexural response can be predicted analytically from weakness in terms of brittle failure under tensile and the tensile and compressive behavior of the material. flexural loading.