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Numerical modelling and experimental tests for the characterization of composite materials

Keywords: FRP, FRCM, bond slip, fire, pultruded materials
Fig. 1. Experimental set-up for bond tests on FRP and FRCM strengthening systems (Carloni).
Numerical modelling and experimental tests for the characterization of composite materials - Fig. 2
Fig. 2. Analysis of the out-of-plane behaviour of reinforced masonry walls (Mazzotti).

The research group carried-out several experimental tests concerning FRP-concrete and FRPmasonry bond behaviour and is currently focused on the analysis of FRCM bond on different substrates (mainly concrete and masonry). FRP plates and sheets, FRCM composites with different numbers of layers, of several widths and lengths and with different substrate surface preparations have been studied, together with different test set-ups using traditional instrumentation as well as innovative optical techniques (Digital Image Correlation).

The effectiveness of composite strengthening was analyzed by testing full-scale structural elements such as concrete beams, masonry columns and masonry walls and by investigating their behaviour under different load conditions (e.g. in- and out-of-plane behaviour of reinforced masonry walls).

The research group also developed several numerical models in order to better understand and describe the obtained experimental results.

The effects of aggressive agents and long-term loads have been considered investigating the FRP-concrete interface creep behaviour. The problem of fire resistance has also been addressed, by testing the effectiveness of different methods of protection. Within the ReLUIS research project, the effect of cyclic loads was studied in order to verify the effectiveness of the strengthening on RC elements subjected to seismic loads. As for the FRCMs, the group has worked on the definition of test standards and on the identification of failure mechanisms (for various types of fibers and matrices). The research group was involved in different national and international Round Robin Tests on bond and components of the group are part of the Committee which drafted the Guidelines CNR DT200/2004 on FRP. Prof. Carloni is member of Technical Committees ACI 440 (FRP), ACI 549 (Thin Reinf.rced Cementitious Products and Ferrocement), and ASTM D30.10 (Composite Materials).

The group has studied also pultruded elements, addressing problems related to the development of computational models for the descriptions of the behavior of cellular and thin wall beam sections and has investigated both experimentally and numerically the long-term behavior of pultruded elements. Professor Savoia was part of the Committee which drafted the DT205/2007 “Istruzioni per la Progettazione, l’Esecuzione ed il Controllo di Strutture realizzate con Profili Pultrusi di Materiale Composito Fibrorinforzato (FRP)”, of National Research Council (CNR).

The research group is currently involved in the definition of guidelines for the standardization of qualification procedures for FRPs and FRCMs (with an approach focused also on environmental durability) and took part in the current FRP qualification process for several producers following the current Italian guidelines.

Main publications

Kwiecień A., de Felice G., Oliveira D. V., Zając B., Bellini A., De Santis S., Ghiassi B., Lignola G. P., Lourenço P. B., Mazzotti C., Prota A. (2016). Repair of composite-to-masonry bond using flexible matrix. Mat. and Structures 49, 2563-2580.

de Felice G., Aiello M. A., Bellini A., Ceroni F., De Santis S., Garbin E., Leone M., Lignola G.P., Malena M., Mazzotti C., Panizza M., Valluzzi M. R. (2016). Experimental characterization of composite- to-brick masonry shear bond. Materials and Structures 49, 2581-2596.

D'Antino T., Sneed L.H., Carloni C., Pellegrino C. (2016). Effect of the inherent eccentricity in single-lap direct-shear tests of PBO FRCMconcrete joints. Composite Structures 142, 117– 129.

Carloni C. and Focacci F. (2016). FRP-Masonry Interfacial Debonding: An Energy Balance Approach to Determine the Influence of the Mortar Joints. European Journal of Mechanics A/Solids 55, 122–133.

Sneed L.H., D'Antino T., Carloni C., Pellegrino C. (2015). A comparison of the bond behavior of PBO-FRCM composites determined by single-lap and double-lap shear tests. Cement and Concrete Composites 64, 37-48.

Mazzotti C., Ferracuti B., Bellini A. (2015). Experimental bond tests on masonry panels strengthened by FRP. Comp. Part B: Eng. 80, 223-237.

Mazzotti C., Murgo F. S. (2015). Numerical and experimental study of GFRP-masonry interface behavior: Bond evolution and role of the mortar layers. Comp. Part B: Engineering 75, 212-225.

Mazzotti C., Sassoni E., Bellini A., Ferracuti B., Franzoni E. (2015). Strengthening of masonry elements by FRP: influence of brick mechanical and microstructural properties. Key Engineering Materials 624, 330-337.

Iovinella I., Prota A., Mazzotti C. (2013). Influence of surface roughness on the bond of FRP laminates to concrete. Construction and Building Materials 40, 533-542.

Carloni C., Subramaniam K. V., Savoia M., Mazzotti C. (2012). Experimental determination of FRP–concrete cohesive interface properties under fatigue loading. Composite Structures 94, 1288- 1296.

Mazzotti C., Savoia M. (2009). Stress redistribution along the interface between concrete and FRP subject to long-term loading, Advances in Structural Engineering, 12(5), 648-658.

Mazzotti C., Savoia M. (2009). Experimental tests on intermediate crack debonding failure in FRP-strengthened RC beams, Advances in Structural Engineering, 12(5), 625-637.

Bottoni M., Mazzotti C., Savoia M. (2008). A finite element model for linear viscoelastic behaviour of pultruded thin-walled beams under general loadings. International Journal of Solids and Structures, 45(3-4), 770-793.

Mazzotti C., Savoia M., Ferracuti B. (2008). A new single-shear set-up for stable delamination tests on FRP-concrete joints. Construction and Building Materials, Volume 23, Issue 4, April 2009: 1529-1537.

Research projects

RILEM TC 234-DUC Committee “Design procedures for the use of composites in strengthening of reinforced concrete structures”: members Proff. Savoia and Mazzotti.

RILEM TC 223-MSC Committee “Masonry Strengthening with Composite materials”: member Prof. Mazzotti

Research project with ARDEA and BASF for the study of crisis mechanisms of fiber-reinforced systems.

2010-2013: Research project funded by the Department of Civil Protection - Reluis tasks 1 and 3: “Reinforced Concrete Structures”; “Development and analysis of new materials for seismic retrofit (including new concretes)”. Coordinators: Proff. G. Manfredi, L. Ascione