1,720,972 research outputs found
Mechanical Characterisation of Multi-Wythe Masonry Bridge in the City of Amsterdam
No full textThis paper presents the results of an experimental campaign carried out to characterise the mechanical properties of multi-wythe masonry infrastructure in the city of Amsterdam. Samples were extracted from a 1.2 m thick bridge’s pillar constructed in 1882. For the characterisation of shear and compressive properties of masonry, tests on cores with a 100 mm diameter were performed at the Stevinlaboratorium of Delft University of Technology. Samples were extracted along different locations in the wall thickness to evaluate the effect of exposure to environment conditions. Overall, the study provides a first insight on the mechanical properties of multi-wythe masonry city infrastructure and knowledge regarding the sampling and testing strategy for these structures. In turn, this will increase the knowledge on multi-wythe masonry, which is limited in literature, and will support the assessment of many infrastructures in typical Dutch canal cities
A model for beam–column corner joints of existing RC frame subjected to cyclic loading
No full textBeam-to-column joints are commonly considered critic regions for RC frames subjected to earthquake actions. When designed for gravity loads only, beam-to-column corner joints strongly affect the global structural behaviour of a frame, and they can be cause of its collapse, as shown by recent earthquakes in Europe. In the paper, a component-based f.e. model for external beam-to-column joints is presented to simulate the seismic behaviour of r.c. existing structures designed without any capacity design criteria (smooth bars with hooked-end anchorages and with no transverse reinforcements in the joint). The joint deformation is modelled by means of two separate contributions, the shear deformation of the panel zone, and the rotation at the interface sections between the joint and the structural members, due to the reinforcing bars' slip within the joint core. The work focuses on the evaluation of the joint strength and stiffness, and it points out the importance of modelling the bar bond slip within the panel zone to describe the actual frame response. The component-based f.e. model is validated by experimental results of tests on beam-to-column corner joints realized according to the construction practice of the 1960s-1970s in Italy, thus confirming the effectiveness of the presented model for the assessment of existing structures
Experimental results on the retrofitting of hollow brick masonry walls with reinforced high performance mortar coatings
No full textMany masonry buildings in Europe were built after the Second World War during a booming economy when seismic risk was not properly considered and, as a consequence, seismic codes were not available yet. Several of these buildings are quite small since they are used by one or two families. Because of the huge developments in the knowledge on seismic actions, there is now a major concern for the vulnera- bility of these buildings under possible earthquakes.
The present work focuses on seismic strengthening of a masonry typology widely used for social hous- ing. It is based on hollow masonry bricks with horizontal holes and poor cementitious mortar. Results of quasi-static cyclic tests carried out on full-scale unreinforced masonry walls with different geometries, representing either a shear wall or a pier-spandrel assembly, are presented. The specimens were repaired or strengthened with a thin layer of high-performance mortar reinforced with light steel-mesh. The test results show the effectiveness of the proposed technique since it provides a remarkable enhancement of both lateral strength and displacement capacity
A numerical model for column to foundation joint with un-bonded high strength steel bars in grouted sleeves
No full textThe present work deals with the experimental and numerical results of an innovative column to foundation connection for precast concrete elements. The joint is characterized by the use of high strength steel threaded bars in grouted sleeves to allow the bending moment to be transferred from the column to the foundation. The connecting bars are wrapped with plastic duct to allow the system to develop the lateral displacement capacity required during the seismic event. Furthermore, the un-bonded length is able to reduce the strain rate in the bar which can cause the premature fatigue failure of the steel bars. The work aims at developing a simple fem model to describe the cyclic behavior of a precast column connected to a cast in situ foundation by means the tested joint, by setting the non-linear behavior of the assembly in a non-linear spring at the base of the joint. The model accurately approximates the specimen experimental behavior
Modelling of Connection Failure in Seismic Assessment of Masonry Structures
No full textIn recent years, numerical modelling is increasingly being used to assess the seismic capacity of
masonry buildings. In numerical models, the connections between structural walls are commonly considered
as rigid, but in some cases this assumption may be inaccurate. Especially, this research focuses on the terraced
houses built in the Netherlands after 1980s which are characterized by vertical glued joints between transverse
masonry walls. Since the premature shear failure of these connections may cause a significant reduction of
seismic capacity of the entire structures, different numerical approaches to represent the nonlinear behaviour
of the joint are investigated and compared. The results of this work show that the strength of the vertical
connection strongly affects the capacity of the structure, and the choice of constitutive law plays a crucial role
in the robustness and accuracy of the model. In addition, a comparison between the numerical and experimental
results is presented and discussed
Modelling of exterior beam to column joint in ’60-70s RC existing buildings
No full textBeam-to-column joints are commonly considered critic regions for r.c. frames subjected to high-magnitude earthquakes. When designed for gravity loads only, beam-to-column corner joints can not on- ly strongly affect the global structural behaviour of a frame, but also be a cause of its collapse. In the paper a component-based f.e. model of external beam-to-column joints is presented. The joint deformation is mod- elled by means of two unrelated contributions, the shear deformation of the panel zone, and the rotation at the interface sections between the joint and the structural members, due to the reinforcing bars’slip within the joint core. The first part of this work focuses on the evaluation of the joint strength and stiffness. Finally, the component-based f.e. model is validated by experimental results of tests on beam-column corner joint realized according the construction practice of the 60’s-70’s, confirming the effectiveness of the presented model for the assessment of existing structures
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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