3.1 Experimental procedures
Several contributions from researches are focused on the experimental behaviour of structural elements and assemblages. The main aim is to characterize the mechanical behaviour of strengthened elements, in order to define simplified model for design and assessment. Very first contributions about application on masonry concerned general aspects, especially
related to the improvement of the flexural capacity and the behaviour in seismic area (Schwegler 1994, Saadatmanesh 1997, Triantafillou et al. 1997 and 1998, Borri et al. 2002, Corradi et al. 2002, Brencich et al. 2005, Shrive 2006). Then, more specialized literature has been proposed, dealing with specific experimental, analytical and numerical works on subassemblages: arches and vaults (Briccoli Bati et al. 2000 and 2001, Foraboschi 2001 and 2004, Lourengo et al. 2001, Luciano et al. 2001, Valluzzi et al. 2001, Barbieri et al. 2002, Basilio et al. 2004, Oliveira et al. 2006, Borri et al. 2007, De Lorenzis et al. 2005 and 2007, Baratta et al. 2007) (Figure 5.a); columns and piers (Micelli et al. 2004, Aiello et al. 2005 and 2007, Krevaikas et al. 2005, Nurchi et al. 2005, Corradi et al. 2007) (Figure 5.b); in-plane (Ehsani et al. 1997, Luciano et al. 1998, Valluzzi et al. 2002, Haroun 2003, Cecchi et al. 2004, De Lorenzis et al. 2004, Ascione et al. 2005, Hamid et al. 2005, El-Gawady et al. 2005, El-DAkhakhni et al. 2006) and out-of-plane (Albert et al. 1998, Gilstrap et al. 1998, De Lorenzis et al. 2000, Velasquez-Dimas et al. 2000, Hamilton et al. 2001, Hamoush et al. 2001, Kiss et al.
2002, Kuzik et al. 2003, Galati et al. 2004, Li et al. 2004,Foster et al. 2005, Turco et al. 2006, Mosallam 2007) behaviour of wall panels (Figure 5.c and d); and on bond (Ehsani et al. 1997, De Lorenzis et al. 2000, Briccoli Batiet al. 2001, Casareto et al. 2003, Tan et al.
2003, Savoia et al. 2003, Aiello et al. 2005 and 2006, Liuetal. 2005) (Figure 6).
Harmonization of experimental procedures is a urgent need that international bodies of standardization and related professional corporations should considered, in order to allow comparison among results.
Figure 6. Experimental tests on local mechanisms: pull-off tests on surface (a), brick-FRP adhesion test (b), adhesion on mortar joints (c), splitting of rods (d).
where M is the maximum moment at the section under consideration, V is the corresponding shear force, d the distance from the extreme compression fibre to the centroid of tension reinforcement, f^ is the compressive strength of masonry, An is the compressed area of masonry, Af is the reinforcement area, P is the axial load, ffe is the design strength of FRP, and s in the spacing of horizontal reinforcement in the vertical direction. For CNR DT/200, the analogy with the design formulas proposed for reinforced masonry beam, as in the Eurocode 6, is evident:
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