Ugo Tonietti

Experimental Study of Bond Behavior of CFRP-to-Brick Joints

AbstractCarbon fiber–reinforced polymer (CFRP) composite materials have been widely used to strengthen masonry constructions. The bond between CFRP and substrate strongly conditions the performance of reinforced masonry structures. Characterization of shear bond mechanical behavior of masonry-CFRP interface thus becomes a crucial factor. The paper presents the results of an extensive experimental investigation aimed at evaluating the bond between clay brick and CFRP sheet. Specimens with varying width and length of the bonded CFRP sheet were subjected to shear test by three different testing setups. Results allowed comparison of the effectiveness of the three types of setup and pointed out the influence of the dimensions of the bonded sheet on ultimate load and ultimate slip, load-displacement diagram, and failure modes. Measurement of local strain along the CFRP sheet also allowed an investigation on the transfer mode of the stresses from the reinforcement to the brick and the determination of the local ...

Integrated geological-architectural pilot study of the Biet Gabriel-Rufael rock hewn church in Lalibela, northern Ethiopia

We present a geological and architectural integrated pilot study, aiming at the preservation of the Biet Gabriel-Rufael church, located in Lalibela, the worldwide known Ethiopian rock hewn monumental site protected by UNESCO since 1978. The town developed since the Neolithic up to the medieval age, as inferred from the traces of three distinct architectural phases. Lalibela was built on a geological substratum made of rocks belonging to the Ethiopian Plateau suite, which is mainly composed of basalts of fissural origin or derived from shield volcanoes. The geological units are composed of alternating massive and scoriaceous basalts. The main scoriaceous basalt level, embedded within the massive basalts, is 30–40 m thick and corresponds to the horizon within which the Biet Gabriel-Rufael church all the other monuments of Lalibela have been carved. Therefore, the evolution of the town was strongly conditioned by the occurrence and extent of the softer scoriaceous basalt level. Many fracture systems of both natural (i.e. geological) and anthropic origin (these latter connected to the carving of the church), were recognized. The fracture pattern determined the subdivision of the church into different blocks that can behave independently, thus compromising the stability of the monument. A net of deformometers and fracture gauges was installed for the monitoring of the fracture system and a preliminary Finite Element analysis, following the approach used for underground excavations, was performed, with the aim of elucidate the mechanical behaviour of the rock. The integration between geo-mechanical approach to the rock mass and the architectural study of the critical situation due to the carving and connected to buildings, resulted in the precise individuation of future interventions devoted to the conservation of these monuments.

Structural Characterization and Seismic Performance of San Francisco Church, the Most Ancient Monument in Santiago, Chile

ABSTRACT The Church of San Francisco is the oldest religious building in use in Chile and an iconic and historical heritage landmark of the capital Santiago. The church, the result of joint work between the Spanish and local indigenous people, was built in stone and brick masonry and has been modified by additions and constructive changes since its construction in 1586. The building has shown a remarkable resilience, withstanding about 15 destructive earthquakes. As part of research whose goal is to discover the basis of the structural behavior of the church, in this article a safety assessment of the monument is carried out based on a multi-disciplinary approach. Main fields comprises historical research, in situ surveys, crack pattern analysis, physical and mechanical characterization of materials, and multi-level structural analyses. The results highlight the particularities of the building and the current seismic vulnerabilities in order to provide a robust knowledge basis on which possibly pivoting future consolidation and safeguarding strategies could be done.

The Saadian sugar refinery of Chichaoua (Morocco): constructive and structural investigations for conservation

The Saadian sugar refinery of Chichaoua (XVI century), located southwest of Marrakech, is a large rammed earth building of relevant architectonic value, abandoned with the fall of Saadian dynasty. A structural study was undertaken to characterize the materials, to understand the construction techniques and to identify the structural criticities and the surface decay. In particular, carrying out physical and mineralogical analysis on earth samples, the use of two types of material was found, a first one with only soil earth and a second one with added lime. Mechanical tests, carried out by sclerometer and in laboratory, highlighted that the lime added earth exhibits great strength, exceeding the values known for that kind of building material. This conclusion throw light on the sophisticated building culture of the Saadian period in Morocco, as the El Bedi palace in Marrakech testifies too. The study of crack patterns shows the most common mechanisms of damage and consequently appropriate consolidation strategies.

TRADITIONAL BUILDING TECHNIQUES OF THE DRÂA VALLEY (MOROCCO)

The present work reports the results of investigations carried out on earthen constructions in the villages of Tamnougault, Tissergat, Amzrou and Tamngrout, in the Drâa valley (Morocco). This study aims to illustrate the techniques characterizing the local building culture, in order to understand its origins and motivation. Constructions show the use of both rammed earth (pise) and adobe, used separately in different parts of the building. Floors and roofs are made with palm wood, canes and earth. The built heritage of the Drâa valley is an excellent example of high quality architecture, but also of how the local people and culture were able to respond in an excellent way to the environmental challenge, when the context was very poor in natural resources.

Adhesion Problems Between Frp Reinforcement and Masonry Support in Existing Building Strengthening

The technique of bonding with composite materials having a polymeric matrix reinforced with long carbon fibers (CFRP) has become very widespread in the consolidation of masonry structural elements.

Seismic Vulnerability Assessment of Unreinforced Masonry Churches in Central Chile

In the central region of Chile, the unreinforced masonry (URM) churches underwent extensive structural damage during the 2010 Maule earthquake (Mw 8.8), highlighting the importance of implementing seismic risk reduction plans. These religious buildings are characterized by profound typological and constructive peculiarities, originated by the combination of the local build culture with European architectural revivalisms(i.e., Neo-Baroque, Neo-Classic, Neo-Renaissance and Neo-Gothic)during the Spanish domination (1536–1818). The uniqueness of this heritage and the seismic risk of the Chilean territory lead to the need to define a systematic method to assess the seismic vulnerability of the Chilean URM churches. In this paper, some results of an in-depth investigation on a representative stock of churches are reported. The investigation was based on a database implementation with geometrical, constructive, and structural characteristics of 40 URM churches in the Metropolitan Region of Chile. A preliminary qualitative assessment of the seismic capacity of these churches is provided using a survey of geometric indices. Than specific damages observed after the 2010 earthquake have been related to the recurrent failure mechanisms of masonry structures, taking into account 21 local mechanisms involving the macro-elements of the churches. The average level of damage suffered by each church was calculated through the global damage index and a histogram of damage levels frequencies has been arranged. These results are preliminar suitable probabilistic tools to support seismic risk reduction plans.