In-plane behaviour of clay brick masonry wallettes retrofitted with single-sided fabric-reinforced cementitious matrix and deep mounted carbon fibre strips

Ö S Türkmen,B T De Vries,A T Vermeltfoort,S N M Wijte

doi:10.1007/s10518-019-00596-2

Ö S Türkmen, B T De Vries + Show 2 more

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https://doi.org/10.1007/s10518-019-00596-2

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Abstract

The in-plane shear behaviour of a new seismic retrofit concept which combines two standalone retrofit measures for in-plane and out-of-plane strengthening of masonry walls was investigated. The in-plane reinforcement consists of a single-sided carbon fabric-reinforced cementitious matrix (FRCM) overlay, while the out-of-plane reinforcement consists of deep mounted carbon fibre reinforced polymer strips embedded in a viscous-elastic epoxy. An experimental program was undertaken in which clay brick masonry wallettes were subjected to the diagonal compression test to assess the effectiveness of the strengthening system on the in-plane behaviour. The obtained results showed that the single-sided carbon FRCM overlay increased the shear capacity with 80%, compared to the unstrengthened control specimens. Moreover, by testing two different FRCM overlay thicknesses it was found that a thicker matrix layer does not increase the shear capacity of wallettes. However, wallettes provided with a thicker FRCM overlay did show a higher level of ductility. Furthermore, the obtained experimental results showed that the presence of only the aforementioned out-of-plane reinforcement does not affect the in-plane strength of masonry wallettes loaded under shear, and even prevented the disintegration after reaching the failure load compared to the unstrengthened control specimens. Finally, an existing analytical model as well as the Eurocode 8 design provisions were compared to the found failure mechanisms and failure loads. The analytical model developed showed good correspondence with the experimental values for both the failure mechanism and failure load, with an experimental/model ratio left( varphi right) of 0.98, while Eurocode 8 proved to lead to conservative values.

Highlights

In Groningen, an area in the Northeast of the Netherlands, earthquakes occur because of gas production from the Groningen field
The in-plane shear capacity of unstrengthened walls were determined using two approaches: the analytical model developed by Li et al (2005) and the design provisions according to Eurocode 8-3 (2005a, b)
An experimental program was undertaken to assess the effectiveness of a combined retrofit method to improve the in-plane behaviour of clay brick Unstrengthened Masonry (URM) walls

Summary

Introduction

In Groningen, an area in the Northeast of the Netherlands, earthquakes occur because of gas production from the Groningen field. A broad range of strengthening techniques for enhancing the capacity of Unstrengthened Masonry (URM) walls are available nowadays Traditional strengthening methods such as reinforced concrete jacketing and steel frames, add considerable mass to the structure, are labor intensive, and generally alter the esthetics of a building (Triantafillou 1998). In this method firstly the surface of the substrate is prepared by removing contamination and weak surface layers, after which a FRP sheet is adhesively bonded to the substrate by means of an organic resin This strengthening system has proven to be highly effective in enhancing both the shear capacity, the flexural capacity and the ductility of masonry walls. The main disadvantages of this method were found to be vulnerability to environmental influences, vulnerability to fire, high cost of epoxies, lack of vapor permeability, inability to install the system on damp substrate and inability to install the system at low temperatures (Papanicolaou et al 2008; Petersen 2009; Banijamali et al 2015)

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