1,721,403 research outputs found
Logements en construction composite en bois dans la région des Apennins
No full textA l’époque des wood products, le projet de Master (PdM) propose un autre regard sur l’évolution de la construction en bois : un développement où celle-ci pourrait gagner davantage en pertinence face à la crise climatique actuelle. Plutôt qu’une approche de la construction en bois autoréférentielle et hermétique, le PdM explore, d’abord dans l’Enoncé théorique et ensuite dans des cas de figures de logements, sa capacité à intégrer des débris minéraux dans un système composite. Le site et le programme du projet ont été choisis comme cas d’application pour leur portée implicitement globale : après avoir été sinistré par deux séismes, le village de San Pellegrino (IT) se retrouve à devoir gérer une très grande quantité de débris. A cause de l’isolement et de la taille réduite du village, l’administration locale se voit dans l’impossibilité de désencombrer la totalité des débris du village. La construction composite en bois devient ainsi le point de départ du projet pour répondre à une nécessité claire de réemploi de déchets minéraux dans un site de projet fermé et isolé : des conditions que l’on pourrait plus généralement considérer comme des fondamentaux d’architecture durable où l’aspect constructif constitue la prémisse et non la finalisation du projet.IBOISSXLEESDSAR-DCote: 2020.126Archive: MEM.1/1 A4 vertical, archive_informatique_DDGroupe de suivi: Weinand, Yves (dir. pédagogique) ; Fivet, Corentin (prof.) ; Beyer, Katrin (maître EPFL) ; Davidovici, Irina (expert)Professeur responsable de l'Enoncé: Weinand, Yves (ENAC IIC IBOIS)Enoncé théorique de master: Constructions composites en bois. Récolte et analyse d'exemples de constructions vernaculaires en bois associé à d'autres matériaux minéraux
A database of shake-table tests conducted on unreinforced masonry buildings
No full text<p>To date, databases focusing on unreinforced masonry have primarily been developed exclusively at the element level, specifically for stone and brick masonry walls. However, despite the significance of understanding the seismic behavior of complete buildings, a database of experimental results at this structural level had not been developed to date. This repository provides an open-access database containing the results of 69 shake-table experiments on unreinforced masonry structures that have been tested over previous decades. The database is organized in a consistent format, allowing the engineering and research communities to access detailed information and results of each test conveniently.</p><p>This project seeks to play an important role in enhancing modeling techniques, model validation, and reducing uncertainties, thereby benefiting earthquake engineering researchers and practitioners and promoting improvements in design and retrofitting standards, particularly for unreinforced masonry buildings, by facilitating the search, exchange, and reuse of experimental data from shake-table tests.</p><p> </p><p>Please cite as: Haindl, M., Beyer, K., & Smith, Ian F. C. (2023). "A database of shake-table tests conducted on unreinforced masonry buildings". Submitted to Earthquake Spectra</p>
Estimates for the stiffness, strength and drift capacity of stone masonry walls based on 123 quasi-static cyclic tests reported in the literature
No full text<p>Database of 123 shear and compression tests on stone masonry walls reported in the literature. Test references, geometrical and typological data, loading and boundary conditions, mechanical characterisation data, and synthetic test results are collected. Such test results include failure mode, force and displacement capacities for different limit states and estimates of the elastic and effective stiffness. Hysteretic force-displacement curves, digitalised from the sources, and the derived envelopes are provided, when available, as .csv files.</p>Please cite as: Vanin F., Zaganelli D., Penna A., Beyer K. (2017). Estimates for the stiffness, strength and drift capacity of stone masonry walls based on 123 quasi-static cyclic tests reported in the literature. Submitted to Bullettin of Earthquake Engineerin
A case study in the capacity design of RC coupled walls
Full text linkIn the seismic design of structures, capacity design is typically employed to ensure that a desirable ductile response is obtained. In this paper three different capacity design approaches for reinforced concrete coupled walls are investigated. For a simple case study building, the expected capacity design shear forces and bending moments are calculated using the different approaches. The results are then assessed against the corresponding actions found from nonlinear time-history analysis. The performance of each approach is discussed, along with some of the difficulties associated with undertaking the capacity design of coupled walls.EES
Ductility reduction factor formulations for seismic design of RC wall and frame structures
No full textSeismic design of standard structures is typically founded on a force-based design approach. Over the years this approach has proven robust and easily applicable by design engineers and - in combination with capacity design principles - it provides a good protection against premature structural failures. However, it is also known that the force-based design approach as it is implemented in the current generation of seismic design codes suffers from some shortcomings; among these is the fact that the base shear is computed using a pre-defined force reduction factor, which is constant for a given structural system. Thus, for the same design input, structures of an identical type but different geometry are subjected to varying ductility demands and may perform differently during an earthquake. The objective of this research is to present an alternative formulation for computing force reduction factors for RC wall and frame structures, using simple analytical models which only require input data already available at the beginning of the design process. Such analytical models allow to link global to local ductility demands and therefore to compute an estimate of the force ductility reduction factors that lead to equal local ductility demands and expected damage levels. A series of pushover and nonlinear time history analyses are run on simplified numerical models of a set of wall and frame structures. The results show that the proposed alternative formulation yields a more accurate ductility reduction factor than the current Eurocode 8 design approach.EES
Modelling reinforced concrete coupling beams designed for low-to-moderate seismic regions Author: Lisa
No full textReinforced concrete (RC) coupling beams are often used to transfer and resist the earthquake loads. Coupling beams can improve significantly the stiffness and the strength of the all lateral resistant structure. By performing inelastically they decrease the energy dissipation required by the walls piers granted a better seismic performance. Because of their importance, some experimental and modelling research has been conducted focusing on these important elements. While their behaviour is known to be different from that of conventional beams, in low-to–moderate seismic regions, such as Australia, coupling beams are often designed as an “ordinary beam” with standard longitudinal reinforcements and stirrups. This incorrect procedure may be potentially dangerous and lead to a premature and brittle failure in the event of an earthquake. A finite element modelling approach, which also considers the non-linear behaviour of the beam, is investigated, with the aim of obtaining a realistic and useful model for future research projects and new design procedures. This research presents the preliminary investigations for using finite element modelling to predict the response of coupling beams with ordinary detailing designed for low-to-moderate seismic regions. Some guidelines regarding the use and setting of different parameters of the model are given. A modelling for coupling beams designed for low-to-moderate seismic regions is proposed and compared with experimental model for validation.SGCEES
Application of a recently proposed displacement-based assessment procedure for asymmetric-plan RC wall buildings
Full text linkArchitectural layouts of reinforced concrete buildings often require structural walls, with varying dimensions, to be placed in an asymmetric plan configuration. During seismic excitation the asymmetry induces a torsional component of response, which can impact negatively on the performance of the building by increasing demands on both structural and nonstructural elements. Furthermore, the torsional response can render existing assessment procedures less effective at providing an accurate estimate of engineering demand parameters. In this paper a recently proposed displacement-based assessment procedure, developed specifically for asymmetric-plan RC wall buildings, is applied to a case study structure. The method is based on a combination of two existing approaches, with the first being used to predict displacement demands in symmetric reinforced concrete wall buildings, and the second being used to account for torsional response in 2D asymmetric-plan systems. One of the key aspects of the procedure is the concept of assigning effective stiffness properties to the walls. In doing so the method is able to account for the influence of not only stiffness eccentricities but also strength eccentricities, which have been shown to play the more important role during inelastic response. Higher-mode effects, which can have a strong influence on a number of engineering demand parameters, are accounted for using existing simplified expressions. The case study structure under consideration is an eight storey RC wall building designed in accordance with Eurocode 8. It is modelled using a lumped plasticity approach and then assessed using nonlinear response-history analysis over a range of increasing intensity levels to establish benchmark estimates of several relevant engineering demand parameters. The new displacement-based assessment procedure is then used to assess the building in an equivalent incremental framework. The analyses are then repeated with Modal Pushover Analysis to provide another point of reference for evaluating the new approach. Comparison of the results shows that the newly proposed procedure performs to a satisfactory level in predicting displacement demands and wall shear forces in the case study building. Discussion is given on the relative merits and drawbacks of the new approach. One of the most significant advantages is that it can deal with what is arguably a highly complex analysis problem without the need of a numerical model. Its major disadvantages are that it is iterative and in its current form cannot account for bidirectional eccentricities of bidirectional excitation. However, it is deemed that the good results obtained in reference to the case study building and its appealing theoretical basis warrant its further development.EES
Shake-Table Test of a Strengthened Stone Masonry Building Aggregate with Flexible Diaphragms
No full textA unidirectional shake-table test was performed on the half-scale prototype of a natural stone masonry building aggregate, to investigate the seismic performance of this type of historical construction and to assess the effectiveness of two retrofit solutions. The specimen represented a building aggregate with two adjacent three-storey units, connected along one side as if they were built at different times. Double-leaf stone masonry with undressed blocks and river pebbles was used for the walls. Timber floors constituted flexible diaphragms in their planes. Roofs with different timber truss configurations and heights covered the two units. Improved wall-to-diaphragm connections and tie rods were pre-installed, although initially not fastened, on the prototype. Both retrofit systems were activated after significant damage was reached testing the unstrengthened specimen. This paper describes the seismic behaviour of the prototype, focusing on the effects of the retrofit interventions on damage mechanism evolution, lateral displacement demand, hysteretic response, and dynamic properties degradation.EES
Natural stone masonry characterization for the shaking-table test of a scaled building specimen
Full text linkThis paper discusses the material characterization tests on stone masonry specimens, and the in-plane cyclic shear-compression tests on four half-scale unreinforced stone masonry piers, which complement a shaking-table test on a half-scale building aggregate prototype. Material characterization tests allowed defining a mortar composition suitable for satisfying the similitude relationships associated with the half-scale tests. Vertical and diagonal compression tests provided a complete description of the mechanical properties of masonry assemblies, while in-plane cyclic shear-compression tests allow determining the hysteretic behavior of masonry piers with different aspect ratios and axial compression levels. Strength and displacement capacities corresponding to the observed damage mechanisms and failure modes were also identified and associated with the specimens geometric and loading conditions. These activities are part of an experimental and numerical research project jointly carried by the University of Pavia, Italy, and the École Polytechnique Fédérale de Lausanne, Switzerland, which aims at assessing the seismic vulnerability of natural stone masonry building aggregates of the historical center of Basel, Switzerland
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