CFRP sheets bonded to natural stone: interfacial phenomena

The effectiveness of the reinforcing technique consisting of fiber reinforced polymer sheets bonded to the structural elements depends on a good connection at the joint. This has to be able to ensure the transfer length of the shear stress in order to avoid a premature failure due to debonding. In this paper, the bond phenomenon at the interface is examined with reference to the calcarenite stone and carbon fiber reinforced polymer (CFRP) sheets in order to evaluate the possibility of utilizing this technique on masonry structural members, consisting of calcarenite ashlars and mortar. An experimental investigation is carried out on nine specimens obtained by applying unidirectional CFRP she…

Strengthening of masonry walls subjected to out-of-plane loads using CFRPs

This paper presents an experimental investigation carried out on masonry panels subjected to axial load and bending moment in the plane of minor inertia. The masonry type consist of calcarenite ashlars and mortar joints; the reinforcement is made of Carbon Fibres Reinforced Polymer (CFRP) strips applied with the wet-lay-up system. Tests are carried out with controlled displacements. Results have been recorded at each step in terms of: horizontal force and corresponding displacements; moment and curvature at the base of the wall; strains on the CFRP strips near the base of reinforced specimens in order to observe the delamination phenomen. Comparison between the results relative to unreinfor…

Stress transfer at the interface of bonded joints between FRP and calcarenite natural stone

Interface behaviour of bonded CFRP-Calcarenite stone joints

This paper presents the results of an experimental study investigating the interface behaviour between calcarenite stone and Carbon Fibre Reinforced Polymer (CFRP) reinforcement. The analysis of the results has allowed to deduce the local behaviour at the interface, which can be modelled by means of a bi-linear shear stress-slip law, according to several codes. The experimental investigation was carried out on specimens subjected to double shear pulling tests by varying the bond length of the CRFP strips. Tests enabled determination of the bond strength of the joint and the effective bond length. The parameters of the stress-slip law were calibrated on the experimental results in order to c…

Debonding Phenomena in CFRP Strengthened Calcarenite Masonry Walls and Vaults

In this paper the results of an experimental investigation on full-scale reinforced masonry elements like vaults and walls are presented. The masonry type is constituted by calcarenite ashlars and bed joint mortar and the reinforcement is constituted by Carbon Fibre Reinforced Polymer (CFRP) strips. Preliminary experimental results obtained in a previous research by the authors on the local behaviour at the interface CFRP-calcarenite are summarized. Tests with controlled displacement are carried out on out-of-plane loaded walls and cylindrical vaults loaded at a quarter of the span. Results of tests carried out before and after the application of the reinforcement made it possible to evalu…

Digital image correlation analysis of interfacial debonding properties and fracture behavior in concrete

The use of digital image correlation (DIC) as a fracture mechanics tool is described, for two projects currently underway. The goal of the first project is to examine the bond between carbon fiber reinforced polymers (CFRP) and concrete substrates. The second project involves the interfacial transition zone (ITZ) of plain concrete, and the softening and fracture behavior of this region. For both projects, DIC allows for precise measurement of the surface displacements of the deforming materials. The resulting strain data are higher in resolution than is possible with other experimental techniques. For both projects, the DIC results are being used to determine bond constitutive laws, which w…

Nonlinear FE analysis of out-of-plane behaviour of masonry walls with and without CFRP reinforcement

Abstract The out-of-plane behaviour of unreinforced and CFRP reinforced masonry wall is studied by means of experimental investigation and numerical FE modelling. The latter is based on a linear constitutive law both for ashlars and mortar joints constituting masonry and the lines of potential delamination are taken into account by means of an interface element with bi-linear law, reproducing the opening failure mode. When reinforcement is introduced, an interface element with bi-linear law is also used, reproducing sliding failure mode. Comparison between numerical and experimental results show the reliability of the modelling. Moreover, a parametric analysis is carried out in order to inv…

Uno strumento di pianificazione per la salvaguardia degli edifici storico-monumentali. Un caso di studio: la chiesa del SS. Salvatore a Naro

Il patrimonio storico, e in particolare gli edifici monumentali, sono i manufatti tra i più vulnerabili nei confronti degli eventi sismici, e spesso determinano anche gravi ripercussioni su quello che comunemente è definito ”rischio urbano”. Per la conservazione e la tutela del patrimonio culturale nei riguardi dell’azione sismica è necessario disporre di strumenti di analisi in grado di permettere la valutazione della vulnerabilità e del rischio, nonché la progettazione degli interventi di miglioramento sismico. Le Linee Guida per la valutazione e riduzione del rischio sismico del patrimonio culturale – allineamento alle nuove Norme tecniche per le costruzioni, G.U. 26.02.2011, n°47 (di se…

Bond behavior between CFRP strips and calcarenite stone

CFRP flexural strenghtening of masonry walls: experimental and analytical approach