3,884 research outputs found
Shear strength of the anchor embedded into masonry
No full textThis paper focuses on any straight bar, herein called “anchor”, inserted within a hole drilled into a masonry structure, installed orthogonally to the masonry surface, and bonded to the masonry either with an anchoring material or without (adhesive or mechanical anchors). The anchor is subjected to a transverse force applied at the end that protrudes from the masonry (i.e., a shear force having direction parallel to the masonry surface), while no appreciable axial force is applied to the anchor (shear anchor). In brief, the paper is devoted to the postinstalled horizontal anchor that transfers vertical loads from a horizontal structure to a vertical masonry structure.
On site experiments on real anchors allowed the author to establish the mechanical assumptions that govern the behavior of the shear anchor. Based on those assumptions, an analytical (closed form) model was created. The model is comprised of a function that gives the ultimate contact pressures, and a two-equation system whose solution is the maximum shear force that the anchor can bear, therefore called “shear strength”. The model also provides the elastic limit shear strength. The data to be entered into the model is composed of the geometry of the anchor and the strength of the masonry.
The paper presents the experimental campaigns, the model, the application of the model to case studies, and a comprehensive discussion. The results put forward the optimal technical solutions for the masonry shear anchor, which are described
Shear strength of an anchor post-installed into a hardened concrete member
No full textLiterature has recently provided the analytical model that predicts the shear strength of the anchor embedded into masonry. It is apparent that this model does not apply to the anchor embedded into concrete, as the ultimate contact pressures are different. A gap in the literature was hence filled, but there existed a remaining gap. In order to fill that last gap, further research was done. This paper is herein an account of that work. The paper deals with the anchor post-installed by drilling into an already compact concrete structure, used to transmit applied loads from an attachment to the concrete, subjected to a force acting at the end that emerges from the concrete and orthogonal to the anchor (shear force with no axial force), with large clearance from the edges, either alone or with large clearance from other anchors. Being post-installed, the embedded part of the anchor is a straight shaft with no hook at the embedded end, and with no nuts, washers, or plates attached to the shaft. The paper presents an analytical model absent in literature prior to this study that predicts the maximum shear force the anchor can carry, thus called “shear strength” of the anchor. The assumptions of the analytical model were established from the results of a non-linear numerical model specifically constructed by the author. The predictive capacity of the analytical model and accuracy of its results were assessed and verified by experimental tests of real anchorages specifically designed and performed by the author. This paper also presents the numerical model and the comparisons of the analytical predictions to those experimental results, as well as com parisons to experimental results borrowed from literature and code provisions
Structural layout that takes full advantage of the capabilities and opportunities afforded by two-way RC floors, coupled with the selection of the best technique, to avoid serviceability failures
No full textA recently cast two-way rectangular reinforced concrete floor with a span-to-thickness ratio equal to 34.1, which constituted the two stories above ground of an office building under construction, exhibited a totally unsatisfactory deflection performance. The static loading test performed at the end of the construction work demonstrated that the stiffness of the floor was too low. Furthermore, not only the floor that had been loaded for the test, but also the other floor, exhibited excessive increases in deflections with time.
The author was entrusted with the task of redesigning the floor, which had to constitute the stories of a further nine buildings of the construction lot, whose floors had been designed equal to the floor that had failed, and neither the spans nor the thickness could be changed. The author designed and constructed a test building whose story was made up of a floor with perimeter, spans and thickness equal to those of the floors that had failed, but with different structural conformation, boundary conditions, and both amount and configuration of steel reinforcement. The new floor was built using a different construction method as well. The loading test carried out on this floor measured very low immediate deflections. The load was left on the floor for three years and the deflections increased only moderately. The test results substantiated all the theoretical analyses that had been previously carried out and confirmed that the structural performance was adequate. On that account, the proposed floor was eventually employed for the nine buildings of the complex that remained to be built.
This paper – which is directed at analyzing a structural failure, helping reduce the incidence of serviceability failures, and extending the operating horizons of thin RC floors – explains why the original version of the floor failed, describes the new version of the floor, including the loading test on the prototype and on the nine new buildings, and provides a useable and reproducible recipe for designing and assessing high span-to-thickness ratio rectangular RC floors
Optimal Design of Seismic Resistant RC Columns
No full textAlthough the author is well aware that it is nothing special, presented here is the method that he uses to design the columns of a seismic resistant reinforced concrete structure, in hopes that this could be of use to someone. The method, which is directed at satisfying the capacity design requirements without excessively large sections, consists of proportioning the column so that the seismic action effects shall be resisted by the maximum of the bending moment–axial force interaction curve. That design condition is defined by two equations whose solution provides the optimal aspect ratio (or, alternatively, the optimal section side length) and the maximum feasible reinforcement ratio. The method can be used directly to determine the optimal column for given beam spans and vertical loads, or indirectly to determine the optimal beam spans and vertical loads for given cross-sectional dimensions. The paper presents the method, including its proof, and some applications together with the analysis on the optimality of the obtained solutions. The method is intended especially for the practicing structural engineer, though it may also be useful for educators, students, and building officials
Appunti per una inedita epistemologia dell’ingegneria strutturale = Suggestions for a New Epistemology of Structural Engineering
No full textIl criterio che maggiormente caratterizza la scienza moderna è la probabilità, ampiamente introdotto con mirabile chiarezza da Jakob Bernoulli e Pierre-Simon Laplace attorno al 1712, colpendo e contraddicendo l’ordine rigidamente deterministico della fisica e meccanica classiche. La probabilità ha introdotto l’incertezza: anche ammettendo l’esistenza della causalità naturale non si può parlare di certezza di un evento ma soltanto di una più o meno grande probabilità del suo verificarsi. Tale osservazione è sintetizzata dalla lapidaria affermazione di Bernoulli nella sua storica opera Ars Conjectandi del 1713 (postuma): “La probabilità è un grado della certezza” (“probabilitas enim est gradus certitudinis”).---The tutorial makes a parallelism between structural engineering of today and in the past. First, the article analyz-es how the most important principles that have characterized modern physics affect structural engineering. Then, the author questions how the great structural engineers would be if they lived and worked now and attempts at offering an answer. Finally, the author gives his suggestion about what changes must be made in the relationship between society and engineers of today in order for the latter to have the same tremendous impact on the world as they did in the past
Specific structural mechanics that underpinned the construction of Venice and dictated Venetian architecture
No full textThis paper demonstrates that Venetian architecture was the result of specifically conceived structural mechanics, novel failure analysis, and specially devised construction techniques, which allowed structural design to take full advantage of materials. Venice witnessed the creation of ‘structural art’ that drastically reduced the incidences of failure caused by extremely soft soils and aggressive environment, which extended the operating horizons of masonry and timber structural materials to the extent that very bold structures were obtained also before the pre-eminent materials of modern structures.
A further aim of this paper is to promote a greater knowledge and understanding of the attributes and capabilities of traditional engineering materials in the context of structural design, thereby contributing to the prevention of failures of cultural buildings in the future.
While normal masonry constructions can be governed by Euclidean geometry, Venetian buildings are far more complex and elusive in form. Venice and its architecture can be interpreted and comprehended only in the remit of structural engineering, which played a central role in enabling the construction of the city. The fundamental determinants of Venetian building morphology — the underlying logic of form in architecture — entailed a tectonic form midway between the masonry construction and the skeletal structure
L’architettura di Venezia l’unica possibile per la Laguna: gli edifici veneziani non “sulla” ma “della” Laguna veneta
No full textComposite beam: non-linear analytical exact fully-developed model
No full textThe contribution is split into two papers.
(1) The full version, which presents the model for predicting the ultimate load of composite beam (load-carrying capacity of composite beam that fails due to the connection, whose behavior is elasto-softening).
(2) A two-page-paper, which presents the application of the model to two steel-concrete composite beams
Bending load-carrying capacity of reinforced concrete beams subjected to premature failure
No full textThis paper investigates the ultimate flexural strength of reinforced concrete beams when affected by premature failure due to a rotational capacity of the first plastic hinge being consumed before the last plastic hinges reach their maximum possible moment. The paper provides a simple formula for predicting the ultimate load of a hyperstatically supported beam, taking into account the available ductility. The proposed formula is the result of calibration against the ultimate loads from a non-linear analysis on a variety of beams, with a wide spectrum of configurations and with concrete grades from 10.0 to 60.0 N/mm2. The formula in based on the plastic hinge model, making it easy to apply, and the ultimate bending moments allow for the actual rotational capacity, making predictions accurate. © 2019 by the authors
Analytical modeling to predict thermal shock failure and maximum temperature gradients of a glass panel
No full textThe research has tackled thermal cracking distress in glass from a design perspective. The paper addresses a novel modeling framework, and provides closed-form solutions to predict thermally-induced stresses and the temperature profiles that cause glass to crack. The analytical formulation applies to monolithic glass and to plies of laminated glass or insulating glass.
Results and discussion prove that the ratios between maximum thermal stress and temperature gradient have an upper bound, which is given, show that empirical approaches are largely inaccurate, and establish evidence that some code stipulations are wrong and some recommendations misleading
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