Keywords: reinforcement, composite ring-beam, arch, wood beams, fiber reinforced polymers, steel reinforced grouts.

This paper presents in-situ applications of fiber reinforced polymers (FRP) and steel reinforced grouts (SRG) composites. Issues related to this type of application have been investigated in the last decade, mainly in Italy due to the growing need for repair or rehabilitation and conservation of the vast architectural heritage. The ten-year experience of the authors makes it possible to make some considerations and critical issues about first FRP-SRG applications on masonry construction. The aim is to show that cooperation between university research and enterprises may lead to an interesting and positive evolution of knowledge of technical solutions.

After initial applications in reinforcing masonry vaults, retrofitting works of historical buildings with FRP a wide number of issues (shear reinforcement of masonry walls, construction encirclements, floor reinforcements, etc.) have been considered. The most part of these analyses and results are reported in the technical document CNR DT200/2004 [1].

This paper briefly reviews three applications of structurally-deficient buildings with composite materials, with special emphasis on monumental and historic constructions. Accordingly, both composites, FRP and SRG, can be used with hollow or solid brick to form a new strengthening system, called a LATLAM ring-beam, that can be used to effectively construct the roof ring beams of a masonry structure. This is the first example application. This new system, that can be subject also to a pretension force, jointly with the SRG beams, represents a new coordinate system that can drastically improve the response of a masonry building to seismic actions [2].

Seismic retrofitting of structures belonging to the architectural heritage requires a meeting of constraints which are related to the preservation of artistic features. Such a philosophy was applied to the design process of the retrofitting intervention of a masonry arch, belonging to a 17th century portico built inside a Roman amphitheatre in the city of Spoleto (Umbria) [3]. This is the second example.

The last example presented concerns the reinforcement of an old timber beam floor with glass fibers reinforced polymers (GFRP) pultruded elements placed in the compression zone. An experimental program based on a four- and three-point bending test configuration is proposed to characterize the stiffness and strength response of wood beams reinforced with pultruded GFRP elements. This reinforcement method was applied to the 16th century old floors of the Palazzo Collicola in Spoleto (Umbria) [4].

1

CNR-DT 200/2004, "Design guidelines for the strengthening of reinforced concrete and masonry structures with FRP in Italy", 2004.

2

A. Borri, G. Castori, A. Grazini, "Performance of masonry elements strengthened with Steel reinforced grout", FRPRCS-8, University of Patras, Greece, July 16-18, 2007.

3

A. Borri, G. Castori, "Research on composite strengthening of historical housebuilding: retrofitting intervention for masonry arches and vaults", Structural Analysis of Historic Constructions, VI Intern. Conference, Bath, UK, 2-4 July 2008.

4

M. Corradi, A. Borri, "Fir and chestnut timber beams reinforced with GFRP pultruded Elements", Journal of Composites, part B, 38(2), 172-181, 2007. doi:10.1016/j.compositesb.2006.07.003

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