Abstract

Masonry structure is one of the oldest building constructions built in several parts of the world. Many developing and least developed nations still use masonry buildings as their basic housing shelter options, among which several countries lie in seismically active zones, increasing structural vulnerability. Several methods of strengthening/ retrofitting the masonry structures are available, but they could be inaccessible, expensive, and non-sustainable. The research study on understanding the traditional practice is limited, and countries cannot focus on the research just after the disaster event. A similar scenario was observed in Nepal after the 2015 Gorkha earthquakes (7.8 Mw main shock occurred on 25th April followed by  two major aftershocks 6.7 Mw on 26th April and 7.3 Mw on 12th May), during which more than 775000 buildings completely collapsed. The reconstruction work started with the help of the donor agencies, INGO, NGO, and the Government of Nepal, but the quality of work was not maintained as observed in the field. During the reconstruction phase, the government of Nepal had recommended the use of the horizontal seismic band, a traditional seismic strengthening technique practiced since 3000 BC. People were randomly using different materials for seismic bands in the same house. The actual seismic behavior of such bands using those materials is not quantified in the guidelines.  Therefore, in this study, we tried to quantify the performance of the two most commonly seismic band materials, which are timber and reinforced concrete.
A multi-scale approach is used for the experimental campaign to study the behavior of two types of materials when used as a seismic band. The materials used for the test are adobe, extruded adobe, and mud mortar. The material properties are characterized experimentally. Five wallets are tested under quasi-static cyclic loading- three walls using adobe and two using extruded adobe brick. Finally, three 1:2 reduced scale models are tested with dynamic shake table tests.
The results from quasi-static cycle tests provide the fundamental structural behavior properties of the masonry wall, with and without a seismic band. Three reduced scale dynamic tests on the house model highlight the benefit of having the seismic band and comparing the behavior using two materials as a seismic band regarding the natural frequency, damping, energy dissipation, crack propagation control, and others. The structural behavior is enhanced with the application of the seismic band, and there are some advantages in the performance of the RC band structure over the timber seismic band.  
 
Keywords: masonry structure; seismic band; Digital Image Correlation; traditional construction; experiment

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Jury   

Doctoral school: I-M EP 2
Jean-Claude MOREL, Professeur, ENTPE (Rapporteur)
Jean-Emmanuel AUBERT, Professeur, Université de Toulouse (Rapporteur)
Rohit JIGYASU, Project Manager, ICCROM (Rapporteur)
Dina D’AYALA, Professeur, University College London (Examinateur)
PremNath MASKEY, Professeur, Tribhuvan University (Examinateur)
Yannick SIEFFERT, Maître de Conférences HDR, UGA (Directeur de thèse)
Philippe GARNIER, Chargé de Recherche, ENSAG (Encadrant)
Florent VIEUX-CHAMPAGNE, Maître de Conférences, UGA (Encadrant)