tesi A. Caggiano.pdf - EleA@UniSA - Università degli Studi di Salerno

1.3. Codes and Standards for Fiber-Reinforced Cementitious Compositestrilinear relationships [DBV, 2001, RILEM-TC162-TDF, 2003] and multilinear models[DBV, 2001, fib Model-Code, 2010a] (Figure 1.9). On the other hand, the main parameterswhose define the constitutive laws in each one of the above models are derivedby means of experimental tests which procedures are reported by others companioncodes. For this purpose, test recommendations of several countries such as Italy [UNI-11039-1, 2003, UNI-11039-2, 2003], USA [ACI-544.2R-89, 1996, ASTM-C-1018, 1998],Spain [UNE-83510, 1989], France [NFP-18409, 1993], Belgium [NBN-B-15-238, 1992],Japan [JSCE-SF4, 1984], Germany [DIN-1048, 1991], Netherlands [CUR, 1994], Norway[NB, 1993], EU standards [EN-14651, 2005] and the Rilem international test procedure[RILEM-TC162-TDF, 2002] can be taken as references.These codes have mainly been used as guides to experimentally obtain two principalquantities, alternatively adopted in design:• (i) the equivalent flexural strength (f eq ) otherwise• (ii) the residual flexural strength (f R ).The first one (f eq ) is related to the work capacity of the material, derived by means of thearea enclosed under the experimental force-crack tip/mouth opening displacements[Caggiano et al., 2012a], while the second parameter (f R ) corresponds to the stressassociated to the force at a certain deflection measures or crack opening values [Barroset al., 2005].The fib Model Code 2010Recently, the lack of the international guidelines and codes for Fiber-Reinforced Concrete(FRC) elements in structural applications has strongly been filled by the publicationof a new fib Model-Code [2010a]. This new document aims at updating andreviewing the previous CEB-FIP-90 [1993] recommendations. In this regard, FRC hasbeen introduced into the “Technical Groups fib TG 8.3” (Fibre reinforced concrete) and“fib TG 8.6” (Ultra high performance FRC). In this subsection the fundamental assumptionsand main design rules for FRCC, proposed into the fib Model-Code [2010a], arereported and discussed.Uniaxial behavior: compressive and tensile stress-strainOne of the most important aspects of the mechanical response of FRC is representedby its behavior in tension. Different test methods are proposed for assessing the post-17