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

Chapter 1. Introductioncracking behavior of FRC. However, the bending test on prismatic specimens representsthe most popular and the widely used experimental technique for this purpose. Itis relatively simple to realize and may represent the boundary conditions of manypractical situations.jF jl = 500h = 125spall sizes in mmCrack Mouth OpeningDisplacement (CMOD)b = 150Figure 1.10: Experimental set-up and geometry details of the notched beams under three-pointbending test [fib Model-Code, 2010a].The fib Model-Code [2010a] considers residual flexural strengths determined by performing3-point bending tests (Figure 1.10) on notched prisms according to EN-14651[2005]. Particularly, the residual flexural strengths, f R,j , are defined asf R,j = 3F j l2bh 2 sp(1.1)being l and b the span length and width of the specimens, respectively, while h sp isthe distance between the notch tip and the top of the specimen; the j index refersto the considered Crack Mouth Opening Displacement (C MOD) while F j is the loadcorresponding to C MOD = C MOD j .Since the compressive strength is not particularly influenced by the presence of fibers(up to a volume fraction of about 1%), the fib Model-Code [2010a], as it is also suggestedby almost all worldwide guidelines, accepts that the compressive relations valid forplain concrete can be further applied to FRC.Post-cracking strength and classificationThe post-cracking residual tensile strength of FRC represents an important designparameter for members. It is mainly influenced by the fiber types and geometry,18