Luisa Rovero

Structural Behavior of Arch Models Strengthened Using Fiber-Reinforced Polymer Strips of Different Lengths

The authors address the structural behavior of masonry arches strengthened through carbon-fiber-reinforced polymer (CFRP) strips at intrados or extrados surfaces and subjected to horizontal forces. The paper reports and compares results from experimental tests on 1:2-scale arches and from an analytical model that considers no-tensile strength, infinite rigid, and infinite compressive strength material. Under the assumption that the structure fails because of the formation of a four-hinge collapse mechanism, the model allows the calculation of the collapse load and the evaluation of the load-displacement diagram. The model is based on the equilibrium conditions and considers finite displacements. Results provide an evaluation of the dependence of arch structural behavior on the length of CFRP strengthening. In particular, the postpeak behavior is evaluated in the perspective of performance-based seismic design criteria, which regard the ultimate displacement as a key parameter for seismic capacity. The evaluation shows that, for the considered case study, an increase of intrados reinforcement length produces an increase of maximum load but a decrease of the ultimate displacement.

Time-Dependent Behavior of Laminated Glass

This research deals with the mechanical characterization of laminated glass beams (glass-interlayer-glass) subjected to bending, with the main purpose of evaluating the coupling that the interlayer is able to establish between the glass sheets; in fact, the interlayer provides the glass plies with the ability to work more or less jointly. Four-point-bending tests (constant load) were performed on glass beams laminated with different interlayer plastic sheets. Shear tests (constant load) were performed on laminated glass specimens to determine the viscosity properties of the interlayer, when laminated between glass sheets. The parameters of viscosity, determined by the shear tests, make it possible to reproduce the time-dependent behavior of the composite beam, both numerically and by means of a closed-form procedure. The experimental results were compared with those obtained with the theoretical model and with the numerical simulation. The comparison among the different polymer interlayers shows that they are able to influence differently the mechanical behavior of the laminated composite and that their performance degrades at different rates as a function of time.

Experimental Investigation on Bond Behavior of Cement-Matrix–Based Composites for Strengthening of Masonry Structures

AbstractFabric-reinforced cementitious matrices have raised a great interest for the external strengthening of historical masonries, representing a valid alternative to fiber-reinforced polymers. As the effectiveness of an external reinforcement firstly depends on the bond performance, this paper presents an experimental investigation, through double-shear tests, on the bond behavior of cement-matrix-based composites reinforced with three different textiles, namely, carbon, polybenzoxazole (PBO), and glass. Textiles and matrix specimens were experimentally tested to correlate mechanical properties of the constituent materials with the global response of the composites. The results of bond tests highlighted that PBO-fiber- and glass-fiber-based composites better exploit the mechanical properties of the textile. Observation of the failure mechanisms highlighted that debonding phenomena occur at the fiber–matrix interface. Furthermore, the effective anchorage lengths were estimated. The values of fracture en...

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.

Equilibrium analysis of masonry domes. on the analytical interpretation of the Eddy-Lévy graphical method

ABSTRACT The 19th century graphic method of Eddy-Lévy is analyzed and proposed in an analytical form as an assessment tool for masonry domes. The method determines the neutral hoop that separates the upper part of the dome that behaves as a compressed membrane from and the bottom that behaves as independent arches, due to the presence of vertical cracks. This method allows determining a no-tension equilibrated solution, accounting for the natural behavior of masonry domes of fracturing along meridian planes. Six case studies were investigated, considering spherical and pointed dome, complete, with hole and with hole and lantern. A modified version has been studied to model the biaxial stress of upper part properly through the membrane theory, and compared to the solution obtained by a numeric discrete block model. Limit thickness-to-radius ratio was identified, and a parametric analysis was carried out to investigate the extension of meridian fracture varying dome shape and thickness.

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.

Ancient stone masonry constructions

Abstract A very large part of the vernacular built heritage consists of masonry buildings. This heritage needs to be protected and enhanced as it participates in preserving the cultural identity of a community and contributes to extending the value of stone resources for sustainable and eco-friendly new buildings. In this chapter, the masonry construction is analyzed at different scale levels: compositional and mechanical characterizations of materials, descriptions of wall types, mechanical performance of masonry structures, environmental performance of masonry constructions, and innovative applications in modern architecture.

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.