Experimental Assessment of Cyclic Shear Response of Brick Masonry Walls Retrofitted with TRM

Abstract

As one of the main historical construction materials, masonry is abundant among the architectural heritage of earthquake-prone areas of the Mediterranean countries. Earthquake mitigation approaches are now focusing on strengthening solutions based on compatible and environmentally friendly repair materials. These solutions should efficiently improve the in-plane lateral strength and displacement capacity, which are the two most significant parameters considered in the seismic assessment of masonry buildings. This paper reports an experimental programme on masonry walls composed of handmade solid clay brick and hydraulic lime mortar, a recurrent typology for historical buildings. Tests under cyclic in- plane forces were carried out on unreinforced and retrofitted walls. The unreinforced walls were repaired and retrofitted after being damaged in the first test and were then tested again to investigate the recovery of strength. The repair consisted in filling the open cracks and replacing the damaged bricks by following the so-called “scuci-cuci” technique. The retrofitting consisted of externally bonded textile reinforced mortar (TRM). The investigated TRM system was a continuous bidirectional grid of basalt embedded in hydraulic lime mortar. The experimental results show the suitability of the proposed solutions for seismic retrofit and post-earthquake repair of existing masonry buildings. The research results highlight the effectiveness of the investigated systems in increasing the resistance and ductility of unreinforced brick masonry. In addition, the results allow a better understanding of the behaviour of masonry walls subjected to cyclic horizontal displacement.

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References

[1] American Concrete Institute, ACI 549.4R-13 - Guide to Design and Construction of Externally Bonded Fabric-Reinforced Cementitious Matrix (FRCM) Systems for Repair and Strengthening Concrete and Masonry Structures, (2013).

[2] CNR - Consiglio Nazionale delle Ricerche, DT 215/2018 - Istruzioni per la progettazione, l’esecuzione ed il controllo di interventi di consolidamento statico mediante l’utilizzo di compositi fibrorinforzati a matrice inorganica (in Italian), (2018).

[3] European Standard, Eurocode 8 : Design of structures for earthquake resistance — Part 3: Assessment and retrofitting of buildings., 3 (2004).

[4] Ministero delle Infrastrutture e dei Trasporti, DM 17/01/2018 - Aggiornamento delle “Norme Tecniche per le Costruzioni” (in italian), (2018) 1–198.

[5] J. Segura, D. Aponte, L. Pelà, P. Roca, Influence of recycled limestone filler additions on the mechanical behaviour of commercial premixed hydraulic lime based mortars, Constr. Build. Mater. 238 (2020). doi:10.1016/j.conbuildmat.2019.117722.

[6] CEN, EN 772-1, Methods of test for masonry units. Part 1: Determination of compressive strength, Com. Eur. Norm. Brussels. (2011).

[7] CEN, EN 772-6, Methods of test for masonry units. Part 6: Determination of bending tensile strength of aggregate concrete masonry units., Com. Eur. Norm. Brussels. (2002).

[8] M. Santandrea, I.A.. Imohamed, C. Carloni, C. Mazzotti, S. de Miranda, F. Ubertini, A study of the debonding mechanism in steel and basalt FRCM masonry joints, Brick Block Mason. - Trends, Innov. Challenges. (2016) 433–440.

[9] C. Knox, Assessment of Perforated Unreinforced Masonry Walls Responding In Plane, The university of Auckland, 2012.

[10] G. Magenes, G.M. Calvi, Cyclic behaviour of brick masonry walls, in: Balkema (Ed.), Proc. Tenth World Conf. Earthq. Eng. 19-24 July 1992 Madrid, Spain, 1992: pp. 3517–3522.

[11] Applied Technology Council, Interim Testing Protocols for Determining the Seismic Performance Characteristics of Structural and Nonstructural Components - FEMA 461, (2007).

[12] G. Magenes, G.M. Calvi, In-plane seismic response of brick masonry walls, Earthq. Eng. Struct. Dyn. 26 (1997) 1091–1112.

[13] M. Tomaževič, Earthquake-Resistant Design of Masonry Buildings, Imperial Collage Press, 1999. doi:10.1142/9781848160835.

[14] F. Vanin, D. Zaganelli, A. Penna, K. Beyer, Estimates for the stiffness, strength and drift capacity of stone masonry walls based on 123 quasi-static cyclic tests reported in the literature, Bull. Earthq. Eng. 15 (2017) 5435–5479. doi:10.1007/s10518-017-0188-5.

[15] M. Godio, F. Vanin, S. Zhang, K. Beyer, Quasi-static shear-compression tests on stone masonry walls with plaster: Influence of load history and axial load ratio, Eng. Struct. 192 (2019) 264–278. doi:10.1016/j.engstruct.2019.04.041.