This study uses an integrated experimental and numerical approach to assess the use of the forcebased design (FBD) methodology presented in Eurocode 8 (EC8) for multi-storey steel concentrically-braced frames (CBFs). In the EC8 approach, the design seismic action is defined by first generating an elastic response spectrum. This spectrum is reduced to create the design spectrum by applying an appropriate behavioural factor (q) to account for energy dissipation. The value of q chosen depends on the form of the lateral-load resisting structure, the structural material(s) to be used, the ductility class and the degree of irregularity in the structural layout. The design base shear force calculated from the design spectrum is used to estimate the seismic forces on the structure and hence determine the final member cross-section sizes. In this study, the FBD approach to the design of structures presented in Eurocode 8 is described and applied to 4-and 8-storey CBF structures. Both dissipative (Ductility Class High -DCH) and nondissipative (Ductility Class Low -DCL) design is considered for each structure. A numerical modelling approach developed using the OpenSees seismic analysis software and validated from a series of full-scale experimental tests of single-storey CBFs is outlined. The twodimensional reference model assigns appropriate out-of-plane rotational stiffnesses to the ends of the bracing members based on the strength and geometry of gusset plates specified. The experimental work used to validate the model, carried out as part of the BRACED transnational research project funded by the European Commission's Seventh Framework Programme (FP7) is briefly described. The experimental observations support model validation at different levels of earthquake ground motion including elastic, inelastic and ultimate response conditions. The validated numerical modelling approach is used to perform a series of non-linear time history analyses (NLTHA) of the designed 4-and 8-storey frames by subjecting them to appropriately scaled simulated ground motion accelerations. The key recorded responses of the NLTHA of the modelled frames (displacements, drift, brace forces and ductility demands) are compared, and the implications of the assumed energy dissipations are discussed.
The international Large Coil Task (LCT), involving EURATOM, Japan, Switzerland, and the United States, is developing competing concepts of superconducting toroidal field coils.Six different coils will be tested together in the Large Coil Test Facility (LCTF). All Participants are collaborating in planning and will share all test data. FUSION MAGNET DEVELOPMENTBecause of the importance of performance, reliability, and cost, and the magnitude of the development required, superconducting magnets have been widely recognized as a critical element of fusion technology. Superconducting coils have been used in a few plasma confinement experiments (e.g., Baseball II and Tokamak-7), but fusion reactor magnets will be huge in comparison with these small devices. For example, the toroidal field (TF) magnet in INTOR would operate at two to three times the field strength of Toka.itak-7 and the storad energy (a measure of mass and cost) wouH be several thousand times as great. To cross the associated wide technology gap, fusion programs have chosen two distinct approaches:a. Intermediate size confinement experiments using superconducting coils are built.and operated. Development efforts focus on a single design, meeting actual constraints of the specific device. Coil testing is incidental to device operation. b. Intermediate size test coils of various designs, meeting constraints typical of envisioned reactors, are built and tested over extreme ranges of conditions. Well-known examples of the first approach are MFTF-8 in the United States, Tokamak-15 in the U.S.S.R., and Tore Supra in Europe. When development for these devices began about 1977, quite different configurations of conductor and coolant were chosen for their coils. MFTF-3 coils employ NbTi superconductor, cooled by a bath of helium at atmospheric pressure (4.2 K). Tokamak-15 designers went to NbjSn superconductor, cooled by forced flow of twophase helium. Tore Supra coils will use . M .bTi, cooled by supprfluid helium at 1.8 .<. The second approach is represented by the Large Coil Task (LCT), which is developing competing concepts of superconducting TF coils through the testing of coils about 0.4 the size of those in INTOR /!/. Three LCT coils are bath-cooled, and three are cooled by forced flow of helium at supercritical pressure. Five coils use NbTi, one uses .'ib.Sn. IEA LARGE COIL TASKThe LCT stems from several separate national programs of development that were drawn together because of the availability of the Large Coil Test Facility (LCTF) /2/. Research sponsored by the Office of Fusion Energy, U.S. Department of Energy under contract No. W-740S-eng-26 with the Union Carbide Corporation.i DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States mlfl\. I t|J Government. Neither the United States Government nor any agencv aiereof, nor any or their iBiltf I tGfl employees, makes any warranty, express or implied, or assumes sny legal liability or rcsponsi-b ility for the accuracy, completeness, or usefulness of any in...
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