Single lap shear tests of masonry curved pillars externally strengthened by CFRP strips

Abstract

The paper presents an experimental study concerning the bond behaviour of Carbon Fiber Reinforced Polymers (CFRP) sheet reinforcements applied to curved masonry surfaces. Such strengthening technique is more and more used in structural rehabilitation and retrofitting of existing buildings. Its effectiveness has been demonstrated by several studies published in the literature, mostly devoted to flat bonded surfaces. Seeing that CFRP are extensively applied on arches and vaults but only few research activities concern curved bonded surfaces, the experimental study described in this paper is aimed to contribute to fill this gap. The experimental program was carried out on portions of masonry arches, reinforced by CFRP sheets bonded at extrados or intrados, tested by a single lap shear test. The experimental results allowed to analyse the effectiveness of such reinforcements, loaded by actions tangent to an end of the reinforcement itself, with respect to its position (intrados or extrados) and to the curvature of the bonding surface. As expected, the results highlight that the bond behaviour strongly depend on the position of the reinforcement. In particular, the capacity of reinforcements bonded at the extrados increases with the curvature, while decreases with the curvature for those bonded at intrados.

Coupled interface-based modelling approach for the numerical analysis of curved masonry specimens strengthened by CFRP

“…The case studies here accounted for the validation of the proposed modelling approach are derived from the current literature [33]. They consist of single shear-lap bond tests involving masonry pillars externally strengthened by CFRP strips.…”

“…The failure of the substrate was observed for all tested specimens. The bond strength was evaluated for each specimen by dividing the maximum pull-off force by the cross section area of the partial core: an average value equal to 1.15 MPa was obtained [33].…”

“…The single lap shear tests were performed in [33] by pulling the top edge of the carbon fabric left unbounded.…”

“…In addition, the steel wedge was equipped with an additional steel plate to constrain the specimen toward its rotation. Further details can be found in [33].…”

“…Two novel modeling strategies are proposed and critically compared, denoted respectively as approach (A), where the presence of mortar joints is neglected and approach (B), where mortar joints are specifically taken into consideration. The validation of the proposed approach is made by considering ad-hoc experimentation carried out by the authors [33] consisting of shear-lap bond tests involving curved masonry specimens with different radius values and different strengthened configurations. Finally, a comparison with FE advanced numerical models [34] and theoretical formulas [32], both deduced from the current literature, is also presented.…”