Advanced Materials Research Vols. 133-134

Abstract: In this paper, an analytical and numerical analysis on the collapse mode of circular masonry arches is presented. Specific reference is made to the so-called Couplet-Heyman problem of finding the minimum thickness necessary for equilibrium of a masonry arch subjected to its own weight (Heyman 1977). The note reports the results of an on-going research project at the University of Bergamo. First, analytical solutions are derived in the spirit of limit analysis, according to the classical three Heyman hypotheses and explicitly obtained in terms of the unknown angular position of the intrados hinge at the haunch, the minimum thickness to radius ratio and the non-dimensional horizontal thrust (Colasante 2007, Cocchetti et al. 2010). Results are then compared to Heyman solution. Though only the first of these three characteristics is perceptibly influenced in engineering terms, especially at increasing opening angle of the arch, the treatment settles an important conceptual difference on the use of the true line of thrust, along the line of Milankovitch work. Second, numerical simulations by the Discrete Element Method (DEM) in a Discontinuous Deformation Analysis (DDA) computational environment are provided, to further support the validity of the obtained solutions, with good overall matching of the obtained results (Rusconi 2008, Rizzi et al. 2010).

Abstract: To verify the conditions and the possible use of the historical buildings, it is fundamental to individuate structural patterns really near to each particular configuration. The calculation of a double warp ceiling usually supposes that the secondary warp structure simply leans upon the principal beams. Principal beams, on their turn, can lean or seldom be lodged into the walls. These conditions are usual in the most simple ceilings, but they cannot merely be transferred to the most riches and complex constructions. In the case of Palazzo Pallavicino in Cremona were inserted on some beams between the joists wooden blocks, forming a veritable reinforced beam. Verification to calculation of these reinforced beams gave load values eligible for the new public destination. The old system has served as a model for consolidation, and allowed minimal intervention and avoided the introduction of incongruous materials.

Abstract: Several historical constructions in Croatia have permanent column problems, particularly at connections with capitals and bases, characterized by specific fractures. Experimental and numerical analysis of traditional column connections were conducted. Distinct fractures concentrated around the connections, as well as the traces of previous restorations noted by the chronicles, intrigued us to conduct research of the possible fundamental deficiency of the structural system. Traditional connections can be described as carefully smoothed stone contact areas, joined with centrally placed iron dowel fixed with a lead infill in a slightly larger hole. The comprehensive numerical and experimental efforts have shown that even a small imperfection in the construction process or a disturbance of bearing system have consequence, the contact leans to one side. As the joint has a very limited ability to compensate rotations, the relative rotation between column elements causes high local stresses at the edge of a column, which eventually results in numerous fractures. Ignoring or not fully appreciating the real nature of connections leads to significantly different stress distributions and orientations of thrust lines which may grossly overestimate the safety factor. This usually leads to inadequate rehabilitation, but also if no action is taken continuous fracture propagation can endanger local or global stability of the structure. Laboratory tests were performed on stone samples provided from traditional quarries and we tried to restore a rather similar level of stress and stress distribution caused by eccentric forces. Although some results will be presented, final objective will be to obtain the value of rotational stiffness and stress – strain diagram for connections, which is crucial for understanding of the load carrying mechanism, numerical treatment of connections and adequate retrofit strategies. In order to ensure serviceability and durability, we have started to test the possible retrofit concept with a layer of lead placed between two connected areas. The material such as lead enables small rotations and protects connected areas from large stress concentrations. Lead has already been used to fill the dowel holes and the additional horizontal thin layer appears to be an appropriate and almost invisible intervention.

Abstract: Diagnostic analysis, required to characterize materials and mechanical parameters of ancient masonry, needs a systematic collection and a careful reading of data results, as well as the cross-check of results of the different samples collected. This work assumes that diagnostic is part of the knowledge phase of existing buildings: knowledge level is fundamental to evaluate the state of conservation, as prescribed also in italian Technical Standards for Construction (2008). This paper describe some characteristics of a database system, M.A.I.D.A - Masonry Analysis Interpretation and Data Archive, performed to contain diagnostic analysis results of traditional materials and constituted by interactive analysis cards. Cards nomenclature and method follow UNI Normal rules for the construction materials: stones, bricks, mortars. Some tests on M.A.I.D.A system were carried out in a cooperation project between University of Parma and University of Rome ‘La Sapienza’. The project comprehends analysis of the Carolingian masonry and mortars from some buildings in Rome: SS. Quattro Coronati ecclesiastic complex, S. Francesca Romana Church and a Carolingian part of the Aurelian Walls in Rome. In order to enforce the data archives and to share the results M.A.I.D.A system will be put in a internet server.

Abstract: The Bell Tower of the Basilica de la Merced de Lima is a monument with its own personality in itself, was built by master masonry Alonso de Morales as contract signed May 12, 1589 whose original is in the General File Nation of Peru. Until now has been repaired several times due to damage to large earthquakes that destroyed the city of Lima in more than one occasion. The Bell Tower of the Basilica de la Merced de Lima is the construction of unreinforced brick masonry higher and that has continued for over four centuries in the same location and is without doubt one of the famous monuments of the city of Lima. For structural analysis, the monument was modeled and analyzed by finite element method, models were developed to adjust and show impressive results and consistent with the records of damage were made in the year 2005 date when the monument was established structurally. An important historical record supports the technical scope of the investigation. Interesting comments on its formidable seismic capacity, and their significant contributions in knowledge of construction techniques of the builders of the sixteenth century in Lima, reveal a building that surprises with its apparent simplicity but it saves a lot of knowledge about engineering techniques applied to the great monuments that have survived from the years in which Lima was the largest metropolis in South America.

Abstract: Experiments may be used to verify numerical and analytical results, but large-scale model testing is associated with high costs and lengthy set-up times. In contrast, small-scale model testing is inexpensive, non-invasive, and easy to replicate over several trials. This paper proposes a new method of masonry model generation using three-dimensional printing technology. Small-scale models are created as an assemblage of individual blocks representing the original structure’s geometry and stereotomy. Two model domes are tested to collapse due to outward support displacements, and experimental data from these tests is compared with analytical predictions. Results of these experiments provide a strong understanding of the mechanics of actual masonry structures and can be used to demonstrate the structural capacity of masonry structures with extensive cracking. Challenges for this work, such as imperfections in the model geometry and construction problems, are also addressed. This experimental method can provide a low-cost alternative for the collapse analysis of complex masonry structures, the safety of which depends primarily on stability rather than material strength.

Abstract: Failure of masonry structures are generally studied in terms of the formation of unstable mechanisms and the thrust line approach is considered to be the most useful tool for this. Thrust line analysis is a simple technique for studying the stability of masonry structures, although its applicability is limited to specific types of structures because of various implicit assumptions. Finite element analysis, on the other hand, is versatile but computationally more intensive. This paper presents a linear elastic finite element analysis based method of obtaining the thrust line of a masonry structure. The proposed method allows the application of the thrust line analysis to structures with any complicated geometry while retaining the simplicity of this approach for studying the stability of a masonry structure. The proposed method is applied to various case study structures and the sensitivity of the results to the adopted material property data in the finite element analysis is studied. The proposed method also allows a structural engineer, who is usually familiar with the finite element analysis, to easily migrate to the stability analysis of masonry systems.

Abstract: The study compares ancient composite beams, located in northen Italy, with the models drawn in Treatises from XVI century to XIX century in order to define structural characteristcs of this tecnology.

Abstract: We have many difficulties in the modeling and analysis of masonry stone pagoda structure because this structure has the discontinuum behavior characteristics, compared with the general continuum structures. Also, we need to consider the inner construction types of stylobate for the reasonable analysis of structural mechanism of masonry stone pagoda. Most masonry stone pagoda structures built in Korea are largely classified into three parts such as top part, body part and stylobate. Specifically, the stylobate takes a very important structural part, performing the role of foundation in ordinary structures, and the reduction of stylobate’s bearing capacity has great influence on the safety of structure. As for stylobate, the construction types of inner Jeoksim result in the different structural behaviors. Therefore, this study selects three-story stone pagoda in Goseon-sa temple site that shows the typical type of stone pagoda structure in Korea. Also, this study investigates the construction types of stylobate and evaluates the structural and mechanical behaviors of masonry stone pagoda structure according to many application variables of stylobate’s Jeoksim forms. To this end, we considers the contact surface and block modelling for the discontinuum elements through the discrete element method and finite element method. Through the comparison of analysis results, we can find out the load transfer mechanism according to the inner Jeoksim types of stylobate.

Abstract: In this paper, the preliminary study of intervention on puddle iron and cast iron Hydraulic crane, situated in the “Arsenale” of Venice is described. The crane was built by Armstrong, Mitchell & Co. in 1885. It is one of the most important and the last remaining example of XIX century innovation of English engineering, after the disposal of other Armstrong Company cranes. Thanks to the interest of the Superintendency of Venice and The Venice in Peril Fund UNESCO Committee, the crane is now undergoing restoration works. To design and execute the restoring interventions of the crane, a preliminary study was necessary. The first fundamental step consisted on performing a detailed historical research, focused in particular of the past interventions and on identifying the most important causes of damage.