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

Chapter 1. Introductionfor structural members are those able to guarantee minimum mechanical performancemainly measured in terms of appropriate experimental monitored parameters, such astoughness indexes, post-cracking strength values, etc.Several constitutive models have been proposed in the current national and internationalcodes in order to design FRCC structures. These constitutive proposals mainlydeal with the tensile characterization of the FRCC behavior through either stress-strain(σ-ɛ) or stress-crack opening displacement (σ − w) curves [Blanco et al., 2013].This section is aimed at reviewing and classifying the main proposals highlighted bystandards and recommendations available in literature. Particular focus is given insubsection 1.3 to the fib Model-Code [2010a] which is largely considered as the mostadvanced worldwide reference for FRCC in structural applications.a) rigid-plastic b) elasto-hardening/softening c)σ σ σcrack-hardeningcrack-hardeningf Ftuf Ftutrilinearf Ftsf Ftucrack-softeningf Ftsf Ftucrack-softeningσ 1σ 2σ 3ε Fuεε Fuεε 1 ε 2 ε 3εσf ctd)σ Α σ Αε Bε Bmultilinearf Ftsf Ftuε Cε SLS ε ULSεεε A SLS ε ULSεcase 1 case 2 case 3ε Aσ Cf Fts fFtuσf Ftuf ctσσ Αε Af Ftsf Ftuε SLSf Ftuε ULSεFigure 1.9: Constitutive σ−ɛ laws for the tensile behavior of FRCC: a) rectangular and b) bilinearshapes [CNR-DT-204, 2006], c) trilinear law [RILEM-TC162-TDF, 2003] and d) multilinear rules[fib Model-Code, 2010a].The post-cracking tensile behavior and the parameters which identify such a relationshiprepresent the key “ingredients” to design FRCC members. On the one hand, thereare several guidelines which propose a different type of σ − ɛ diagram to be used fordesign purposes: i.e., the rectangular shapes by DBV [2001], CNR-DT-204 [2006], EHE08[2008], fib Model-Code [2010a], the bilinear proposals [DBV, 2001, CNR-DT-204, 2006],16