76 research outputs found
Seismic testing of post-tensioned Pres-Lam core walls using cross laminated timber
No full textWith the increasing demand for multi-storey timber buildings in areas with high wind loads and high seismic activity, stiff lateral load resisting systems are becoming a crucial design component. Post-tensioned Pres-Lam mass timber lift shafts and stairwell core walls not only provide a strong and very stiff lateral load resisting system, but also damage limiting response in the case of a large seismic event. This paper describes the results of experimental tests on Cross-Laminated Timber (CLT) Pres-Lam core walls tested under bi-directional quasi-static seismic loading. In the first configuration the CLT wall panels were connected in the corners with screws, while in the second configuration, steel pivotal columns were introduced at the corners and the CLT wall panels were connected to the steel columns with dissipative U-shaped Flexural Plates (UFPs). Overall the testing showed that the Pres-Lam system, when used for structural timber core walls subjected to bidirectional loading regimes, sustains nominal damage after large drift demands. By adding ductile screw-connections or steel columns with UFPs at the corners additional strength and dissipation capacity is obtained. Friction between the CLT panels improved the seismic performance of the structure, which in Serviceability Limit State (SLS) conditions led to rigid behaviour of the splices between the panels. Displacement incompatibilities between the floor diaphragm and the core walls were accommodated by locating the connections at the centre of the walls, or by pinned connections in the corner pivotal columns. Relative displacements between orthogonally running connector beams were accommodated by using flexible connections out-of-plane. Under low axial forces there was horizontal sliding of the walls at the foundation level, but this was not observed when larger post-tensioning forces were applied
Lateral performance of a Pres-Lam frame designed for gravity loads
No full textThis paper analyses the lateral load performance of a post-tensioned timber (Pres-Lam) frame which was designed with the primary function of supporting gravity loading. A full scale, two bay frame was used and subjected to quasi-static horizontal displacement. A total of four tests were performed, one with only the post-tensioning cables to resist horizontal loading and three with the addition of sacrificial steel elements externally attached and acting as dissipative reinforcing. This external reinforcing increased the moment capacity of the frame connections and the ability of the frame to release energy through hysteretic damping. Following a description of the test setup the results show that although the primary functions of the post-tensioning is to reduce section height and increase bay length under gravity loading it will also provide a significant contribution to the lateral resistance of the structure. Finally, a simplified design procedure is presented which allows assessing the magnitude of this contribution
Diaphragm connections in structures with rocking timber walls
No full textTall timber structures require lateral load-resisting elements which are very stiff and strong without complex connections. Post-tensioned timber (Pres-Lam) walls provide such properties and can also limit damage in case of extreme seismic events. Low damage can only be guaranteed if the connections between the walls and the diaphragm can transfer the horizontal loads and accommodate the displacement incompatibilities from the seismic rocking of the walls. This paper describes an experimental program on a post-tensioned timber wall specimen with ten different wall-to-diaphragm connections. The test results show that the degree of decoupling between rotational and translational deformations can significantly affect the strength and stiffness of the overall wall-beam system. A cost analysis showed that the higher the degree of decoupling, the more expensive the connection. If the wall-to-diaphragm interaction is not eliminated by decoupling at the connection, both the strength and stiffness of the wall-beam system are increased. The level of enhancement can be determined by an iterative procedure which is based on equilibrium equations and the stiffness of the floor beams and the connection
SEISMIC DESIGN OF CROSS-LAMINATED TIMBER BUILDINGS
No full textThe increasing interest in cross-laminated timber (CLT) construction has resulted in multiple international research projects and publications covering the manufacturing and performance of CLT. Multiple regions and countries have adopted provisions for CLT into their engineering design standards and building regulations. Designing and building CLT structures, also in earthquake-prone regions is no longer a domain for early adopters, but is becoming a part of regular timber engineering practice. The increasing interest in CLT construction has resulted in multiple regions and countries adopting provisions for CLT into their engineering design standards. However, given the economic and legal differences between each region, some fundamental issues are treated differently, particularly with respect to seismic design. This article reflects the state-of-the-art on seismic design of CLT buildings including both, the global perspective and regional differences comparing the seismic design practice in Europe, Canada, the United States, New Zealand, Japan, China, and Chile
The Biologically Crucial C Terminus of Cholecystokinin and the Non-peptide Agonist SR-146,131 Share a Common Binding Site in the Human CCK1 Receptor
No full textInternational audienceThe cholecystokinin (CCK) receptor-1 (CCK1R) is a G protein-coupled receptor, which mediates important central and peripheral cholecystokinin actions. Our aim was to progress in mapping of the CCK1R binding site by identifying residues that interact with the methionine and phenylalanine residues of the C-terminal moiety of CCK because these are crucial for its binding and biological activity, and to determine whether CCK and the selective non-peptide agonist, SR-146,131, share a common binding site. Identification of putative amino acids of the CCK1R binding site was achieved by dynamics-based docking of the ligand CCK in a refined three-dimensional model of the CCK1R using, as constraints, previous results that identified contact points between residues of CCK and CCK1R (Kennedy, K., Gigoux, V., Escrieut, C., Maigret, B., Martinez, J., Moroder, L., Frehel, D., Gully, D., Vaysse, N., and Fourmy, D. (1997) J. Biol. Chem. 272, 2920-2926 and Gigoux, V., Escrieut, C., Fehrentz, J. A., Poirot, S., Maigret, B., Moroder, L., Gully, D., Martinez, J., Vaysse, N., and Fourmy, D. (1999) J. Biol. Chem. 274, 20457-20464). By this approach, a series of residues forming connected hydrophobic clusters were identified. Pharmacological and functional analysis of mutated receptors indicated that a network of hydrophobic residues including Cys-94, Met-121, Val-125, Phe-218, Ile-329, Phe-330, Trp-326, Ile-352, Leu-356, and Tyr-360, is involved in the binding site for CCK and in the activation process of the CCK1R. Within this hydrophobic network, the physico-chemical nature of residue 121 seems to be essential for CCK1R functioning. Finally, the biological properties of mutants together with dynamic docking of SR-146,131 in the CCK1R binding site demonstrated that SR-146,131 occupies a region of CCK1R binding site which interacts with the C-terminal amidated tripeptide of CCK, i.e. Met-Asp-Phe-NH(2). These new and important insights will serve to better understand the activation process of CCK1R and to design or optimize ligands
Ein Wörterbuch für die Bedürfnisse der Habsburgermonarchie des frühen 19. Jahrhunderts. Der Supplement-Band zu jedem italienisch-deutschen und deutsch-italienischen Wörterbuch von Johann Ritter von Vogtberg (1831)
No full textThis article deals with the Supplement-Band zu jedem italienisch-deutschen
und deutsch-italienischen Wörterbuch, the supplementary volume to every
Italian-German and German-Italian dictionary, published in Vienna in 1831 by
the imperial-royal Rechnungsrath, “accountant”, Johann Ritter von Vogtberg.
The volumewas developed in the context of the Habsburg Monarchy and was an
auxiliarytool for civil servants and tradesmen who had to solve language-mediating
tasks in the field of administration, trade or navigation in the Italian territories. For
them, the larger German-Italian dictionaries of the time did not provide the necessary terminology. After an introduction to the teaching of Italian and German in the historical context under analysis and an overview of the situation of the German-Italian dictionary, the author Johann von Vogtberg is introduced. Furthermore, the most important notes on his approach are reconstructed from the preface to the supplementary volume. The conclusion is a random analysis of his four glossaries
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