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

8 Elasto-plastic microplane formulationfor FRCCThis chapter deals with an elasto-plastic microplane formulation aimed at simulatingthe failure behavior of Fiber Reinforced Cementitious Composites (FRCCs) within a continuumapproach. This novel proposal, based on the microplane projections approachalready available in scientific literature, assumes an hyperbolic maximum strength criterionin terms of normal and shear stresses, evaluated on generally orientated planes(microplanes). Moreover, an elliptical CAP model is proposed in terms of microplanestresses in the compression range. The well-known “Mixture Theory” is employedwith the aim to characterize the fiber-to-concrete interactions. Such interactions aregenerally described by considering the two fundamental phenomena already referredas “bridging debonding effect” and “dowel action” (see Chapter 3). However, only thelatter is deemed relevant for “high compression” stress states, namely around the CAPregion. After describing the constitutive model, this chapter focuses on numericalanalysis of FRCC failure behavior. Particularly, the soundness and capabilities of thisapproach are assessed and discussed against experimental data on FRCC samples.After a short literature review discussed in section 8.1, the general basis of the microplaneassumptions are outlined in section 8.2. The methodology to describe thecomposite material failure in FRCC members is then described in section 8.3. Thewell-know “Mixture Theory” by Trusdell and Toupin [1960] is taken into account thereinto represent FRCC as a composite material made of plain concrete matrix and fibers.Then, sections 8.4 and 8.5 deal with the constitutive laws employed at the microplanelevel. Particularly, the fracture energy-based softening rules and the model descriptionof the fiber-to-concrete interaction (i.e., crack-bridging and dowel effects) are thereindiscussed. Finally, section 8.6 reports some numerical applications of the proposedconstitutive model. The proposed comparisons analyze significant information about153