Bonding and anchoring of a CFRP reinforced render for the external strengthening of old masonry buildings (original) (raw)
Related papers
KSCE Journal of Civil Engineering, 2016
This paper demonstrates an analytical model to simulate a single story brick masonry in-filled frame strengthened by carbon-fiber reinforcement polymer (CFRP) to resist lateral loads. The paper is a part of a comprehensive research related to characterize the behavior of CFRP in retrofitting In-filled Frames. The pervious phase was an experimental program carried out on half scale specimens to study the effectiveness of different strengthening techniques for in-filled frame. The results of the pervious phase showed that the used strengthening methods were effective, with high increase in strength and ductility. In the current phase, an analytical model was presented and investigated. Based on this model, two design formulas were proposed to determine the required amount of FRP needed to resist lateral loads. The first formula represents the accurate solution while the second formula is a simplified empirical design equation. They showed good agreement with the experimental results of the first research phase.
Composites Part B: Engineering, 2018
This article presents the results of an extensive experimental programme investigating the structural performance for in-plane loads of old masonry walls strengthened using a specific technique that consisted of applying a CFRP mesh embedded within a shotcreted render. In this article the expression old masonry refers to rubble stone masonry with lime-based mortar but it is believed that the strengthening technique can also be applied to other types of old masonry (e.g. solid or almost solid clay or concrete brick masonry). The reinforcing composite material, called CFRP reinforced render (CFRP-RR), is characterized by the use of a CFRP mesh and the shotcreted pre-mixed mortar, lime-based, specific for the rehabilitation of old masonry load bearing walls. This material is applied to one or both faces of the masonry walls, thus improving both the inplane and out-of-plane behaviour for horizontal loads (the latter benefits are described in Ref. [1]). The experimental programme consisted of the in-plane testing of full-scale physical models of walls, herewith called specimens. These were subjected to reversed cyclic horizontal loads (simulating earthquake loads) with constant vertical loads (simulating gravity loads). The comparison between the experimental results of the nonreinforced with the reinforced (strengthened) specimens allowed the quantification of the inherent benefits in terms of structural performance under earthquake actions.
Strengthening of Old Masonry Walls for out-of-Plane Seismic Loading with a CFRP Reinforced Render
Experimental Techniques, 2018
This paper presents part of the results of an experimental campaign for the development of a strengthening technique, aimed at retrofitting old buildings by the application of exterior reinforcing render layers to their masonry walls. The experimental campaign comprised tests with out-of-plane loading on both strengthened and non-strengthened masonry walls. The strengthening layer material, hereby designated as CFRP (Carbon Fibre Reinforced Polymer) reinforcing render, is an innovative material for the seismic retrofitting of masonry walls. The reinforcing render material consists of a lime-based mortar reinforced with a carbon fibre mesh, applied on one or both facings of a masonry wall. This solution was developed to provide the masonry wall with improved mechanical properties, while respecting the main principles for a proper rehabilitation of old buildings.
One side strengthening of masonry walls with CFRP
Structural Studies, Repairs and Maintenance of Heritage Architecture XI, 2009
Masonry structures may exhibit inferior performance against lateral loads, such as those induced by earthquakes. In this context, it is crucial for such structures of historical value to increase their seismic performances in order to be protected against the earthquakes. This study deals with the empirical assessment of strengthening the masonry structures whose structural walls are constructed with bricks. In this study, conventional brick walls are strengthened using CFRP stripe and textile materials in different forms on one side and the target is to determine the effect of this strengthening on the behaviours and the strength of the walls on an empirical approach.
Combined Strengthening Techniques to Improve the Out-of-Plane Performance of Masonry Walls
2019
The purpose of this study is to improve the performance of walls under out-of-plane loads, particularly when subjected to the hammering action of the floors. The idea behind the paper is to provide the masonry walls with a device that behaves like a buttress, without having to build a traditional buttress. The solution presented here consists of a mechanical coupling between the three-dimensional net of steel ribbons of the CAM system and the CFRP strips. Since the steel ribbons of the CAM system have a pre-tension, the mechanical coupling allows the steel ribbons to establish a semi-rigid transverse link between the CFRP strips bonded on two opposite sides of a wall. Therefore, two vertical CFRP strips tied by the steel ribbons behave like the flanges of an I-beam and the flexural strength of the ideal I-beam counteracts the out-of-plane displacements of the wall. The experimental results showed that the combined technique inherits the strong points of both constituent techniques: ...
State of the Art for Strengthening Masonry with Fibre Reinforced Polymers
The Bulletin of the Polytechnic Institute of Jassy, Construction. Architecture Section, 2012
This paper addresses the modern strengthening techniques used for improving the earthquaqe behaviour of masonry structures, by aid of fibre reinforced polymers (FRP). These type of materials play an important role in the process of overtaking the tensile stresses which masonry by itself is not capable to resist. Also, they proved to have a very good bond strength, both for normal and tangential stresses, with respect to masonry units (fired clay bricks, concrete blocks) and mortar. Basically, the interventions on existing masonry may be concentrated in joints, starting with joints repointing or near surface mounted (NSM), reinforcing techniques, or may be applied on the entire wall or structure, mentioning here jacketing, post-tensioning or center core techniques. Even though structural repointing presents less influence in terms of strength to in and out-of-plane loading than overall applied techniques, their main advantage is represented by the possibility to preserve the original...
Single lap shear tests of masonry curved pillars externally strengthened by CFRP strips
Composite Structures, 2018
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.
Confinement of brick masonry columns with CFRP materials
Composites Science and Technology, 2007
In the 1980s, block masonry started to be widely used for new constructions in Italy's earthquake prone areas. However, recent seismic events demonstrated that block masonry buildings may need to be repaired after earthquakes due to cracking. Construction defects are the main cause for cracking of block work masonry. Carbon fiber reinforced polymer (CFRP) sheets have been used as a local repair method for non-defective and defective wall panels. An experimental program was formulated to investigate the shear behavior of block masonry walls repaired with CFRP sheets. A total of six wall panels were constructed in the laboratory and tested in shear (in-plane lateral loading). It was found that, although the control (non-defective) wall panels had a high ultimate load capacity, the use of CFRPs reduces the effects of construction defects and restores the lateral load capacity in non-defective walls. Overall, this research suggests that the use of epoxy-bonded CFRP sheets could be used for local repair of cracked wall panels.