Comparison of Methods for Computing Equivalent Viscous Damping Ratios
of Structures with Added Viscous Damping
Journal of Structural Engineering / Volume 134 / Issue 1
Submitted 22 February 2005; accepted 13 April 2006
Authors : Finley A. Charney, Ph.D., P.E.1 and Robert J. McNamara, S.E.2
Abstract:
Three analysis methods are compared for determining the equivalent viscous damping ratios in a simple one-story, one-bay system with three different added damping configurations. The analysis methods are modal strain energy using the undamped mode shapes, free vibration log decrement, and complex eigenvalue-eigenvector analysis. The damping configurations include a diagonal configuration, a horizontal configuration, and a toggle-braced system. For each of these systems, a variety of linkage stiffness and damper capacities are considered. In all cases the structure, exclusive of the dampers, is assumed to remain elastic. A brief discussion is provided for the behavior of systems with nonlinear viscous dampers. The results of the study show that significantly different values may be obtained for the effective viscous damping in the same system when different analysis approaches are used. For the toggle-braced system with relatively flexible linkages, it was shown that the modal strain energy approach consistently produced increasing effective damping with increased damper capacity, while the other two methods indicated the opposite results. Subsequent analysis of the toggle-braced structure using the complex eigenvalue-eigenvector approach showed that the effective system damping was indeed decreasing with an increased device damping constant, and that the behavior could be attributed to the axial flexibility of the toggle brace linkage. The analysis indicated that the greater the flexibility of the linkage relative to the damping constant of the device, the greater the phase difference between the deformational velocity in the device and the relative horizontal velocity of the story containing the device. While the phase shift is evident from response history analysis, the most efficient visualization tool is a plot of the damped mode shapes on a complex plane.
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This report presents the results of the soil investigation carried out from 06th of June to 23 rd of July 2011, for M/s DAR SSH International Engineering Consultants in connection with theConsultancy Services for the construction of New Houses in South Ahmadi, Kuwait.
The soil investigation was carried out in accordance to the request of the client to drill forty-four(44) boreholes, consist of forty-two (42) boreholes to a depth of about 10.0m and two (2)boreholes to a depth of 20.0m below the existing ground level (EGL). The locations of thedrilled borehole are shown on the provided Borehole Location Plan (Drawing No. KOC-ST-150) in Appendix C attached to this report.
The purpose of the study is to determine the surface and subsurface conditions at the proposedsite and physical, mechanical and chemical properties of the foundation ground in order toprovide the structural engineer with sufficient information for the design of the most suitableand safe foundation system. This report presents the works completed together with the resultsand recommendations on subsoil parameters, bearing capacities and other related geotechnical information to aid in the design of the foundations for the proposed construction.
All works for the soil investigation were carried out in accordance with applicable ASTM(American Society for Testing and Materials) Standards, BSi (British Standards Institute) andother acceptable geotechnical standards/guidelines. Brief descriptions of the methodology of the field and laboratory tests are likewise provided in this report.
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can someone please share those few articles with us:
Results of Recent E-Defense Tests on Full-Scale Steel Buildings: Part 1 — Collapse Experiments on 4-Story Moment Frames
by Keiichiro Suita, Satoshi Yamada, Motohide Tada, Kazuhiko Kasai, Yuichi Matsuoka and Eiji Sato
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Results of Recent E-Defense Tests on Full-Scale Steel Buildings: Part 2 — Collapse Simulation and Blind Analysis Contest
by Makoto Ohsaki, Kazuhiko Kasai, Yuich Matsuoka, and Jingyao Zhang
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Results of Recent E-Defense Tests on Full-Scale Steel Buildings: Part 3 — Experiments on Dampers and Frame Subassemblies
by Kazuhiko Kasai, Yoji Ooki, Shojiro Motoyui, Toru Takeuchi, Koichi Kajiwara and Eiji Sato
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Results of Recent E-Defense Tests on Full-Scale Steel Buildings: Part 4 — Experiments Utilizing of Multipurpose Test Bed
by Toru Takeuchi, Kazuhiko Kasai, Mitsumasa Midorikawa, Yuichi Matsuoka, Takeshi Asakawa, Iaso Kubodera, Yuji Kurokawa, Hirotaka Ando, and Shoichi Kishiki
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DESIGN OF A PEDESTRIAN BRIDGE CROSSING OVER COLISEUM BOULEVARD
Author: Renan Constantino Chris Ripke James Welch | Size: 3.1 MB | Format:PDF | Quality:Original preprint | Publisher: Civil Engineering Program-Department of Engineering Indiana University | Year: December 11, 2009 | pages: 106
A major obstacle for pedestrians south of the IPFW campus is Coliseum Boulevard: a main arterial for the city of Fort Wayne which has an average daily traffic (ADT) of 50,000 vehicles a day. With this high of an ADT value, crossing by foot can not only be challenging, but it also can be dangerous. Thus, the civil engineering senior design group has proposed to build a pedestrian bridge over Coliseum Boulevard which would allow for easy, safe travel over this busy roadway. Cohering to the innovative design concepts of both the Willis Family Bridge and the Venderly Family Bridge which already exist on the campus, the new structure should be designed so that it too can be transformed into a landmark for the IPFW campus as the other two bridges have become.
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Size: 1.85 MB | Format:PDF | Quality:Original preprint | Publisher: Washington State Department of Transportation | Year: 1994 | pages: 204 | ISBN: Unknown
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The size and number of water projects and other development activities which influence the hydrological cycle have reached such proportions that the majority of problems involved extend beyond the boundaries of the traditional disciplines of hydraulics, hydrochemistry, hydrology and hydrogeology. New scientific methods for the solution of the contemporary problems in water management include analogy, operation research, system analysis and cybernetics. The distinctive features of these methods are their emphasis on measurement and on the use of conceptual models described in quantitative terms, the verification of their theoretical predictions, and their awareness that concepts are conditional and subject to growth and continuous change. This new approach should be defined within the framework of water resources management, i.e. within a complex of activities whose objective is the optimum utilization of water resources with regard to their quality and availability and the requirements of society.
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