Furthermore, emphasis Is given to descriptions of viscous, scholastic, metallic, and friction damping systems, Including recent applications of such systems. In the paper "Design Formulations for supplemental Viscous Dampers to Building Structures," Hang, Hung, Hi, and Ho examine the accuracy of existing design formulas for determining the damping coefficients corresponding to a specified added damping ratio.They conclude that the effect of flexural deformations of a building is as significant as the shear deformations and that neglecting flexural deformations leads to inaccurate damping ratios.
New design formulas are resented that account for both flexural and shear deformations, providing more accurate predictions of the damping ratio contributed by linear viscous dampers and ensuring a more conservative design for buildings that employ nonlinear viscous dampers.In "Comparison of Methods for Computing Equivalent Viscous Damping Ratios of Structures with Added Viscous Damping," Charley and Manager demonstrate that the approach used to compute modal damping ratios can have a significant influence on the computed values and that the axial flexibility of toggle- damper increases, a phenomenon that is readily observed through examining employ-valued mode shapes.In their paper "Seismic Protection of Frame Structures by Fluid Viscous Damped Braces," Source and Terrine present results from experimental testing of two three-story building frames, one constructed of steel and the other of reinforced concrete, each containing a bracing system employing fluid viscous dampers. The method by which the damping coefficient of the dampers was selected is discussed and evaluated by comparing the target response with the experimentally measured response.An analytical study entitled "Fluid Dynamics and Behavior of Nonlinear Viscous Fluid Dampers" is presented in the paper by Ho.
In this study, the dynamics of the fluid flow are evaluated through solving the Navies-Stokes equations, and the shear-thinning effect and vivisectionists of the fluid are considered. Comparisons with experimental data show that both the nonlinear viscous and restoring force behavior can be captured.The seismic response of a three-story reinforced concrete frame with viscous wall dampers is investigated by Lu, Chou, and Yang in their paper "Shaking Table Test and Numerical Analysis of RCA Frames with Viscous Wall Dampers. " In addition, the effect of the wall dampers on the seismic performance of a partially damaged reinforced concrete Ramee is examined. The test results demonstrate that the viscous wall dampers add significant damping while also providing some increase in stiffness, reducing the test structure displacements, and in some cases, increasing accelerations.
Blankets, Hoffman, and Itinerant and Itinerant, Blankets, and Shoshone study the application of vocalists materials to woodworker shear walls in their companion papers "Simplified Hysteretic Finite-Element Model for Wood and Vocalists Polymer Connections for Dynamic Analysis of Shear Walls " and "Experimental Cyclic Performance of Vocalists Gypsum Connections and Shear Walls," respectively. First, a simplified approach to modeling complex hysteretic behavior, such as is found in wood framing connections, is developed in which combinations of basic elements found in commercial finite-element analysis software are used.This approach is then used to model the behavior of a shear wall that employs a vocalists material between the wood framing and gypsum sheathing in lieu of conventional screw connections. Experimental tests demonstrate that shear walls that use the vocalists material have significantly larger nonrepresentational capacity and stiffness.
In the first of a set of companion papers, Christopher, Trembler, Kim, and Lacerate discuss the development of a new bracing system in "Self-centering Energy Dissipative Bracing System for Seismic Resistance of Structures: Development and Validation. The bracing system can undergo large deformations without damage while providing a flag-shaped hysteretic response with full registering capability. The experimental results validate the design and behavior equations that are developed. In their second paper, "Seismic Response of Multistory Buildings with Cloistering Energy Dissipative Steel Braces," Trembler, Lacerate, and Christopher valuate the seismic response of a series of steel-framed buildings containing the new bracing system and JOURNAL OF STRUCTURAL ENGINEERING CASE / JANUARY 2008/1 braces.GHz and Ghana, in their paper "Seismic Analysis of Concentrically Braced Frame Systems with Self-centering Friction Damping Braces," present a new bracing system that has cloistering capability and dissipates energy via friction.
Nonlinear dynamic analyses of steel-braced frames are performed, both with the new bracing system and with buckling-restrained braces. In the paper "Seismic Response Evaluation of Positioned Pretest Concrete Frames with Friction Dampers," Morgan ND Karma investigate the seismic response of unbounded positioned pretest moment frames that incorporate friction dampers at the beam-column Joint.Seismic response analyses show that the dampers provide significant energy dissipation to the frame while the positioning provides self-centering capability. Comparative studies are performed between frames incorporating the new friction damper system and framing having more conventional beam-column Joints.
Gosh and Bass examine the seismic performance of a liquid column damper in their paper "Seismic Vibration Control of Nonlinear Structures Using the Liquid Column Damper. The damper is modified from a conventional liquid column damper so that it has a broader range of applicability.Numerical simulations are performed to evaluate the effectiveness of the damper. In their paper "Experimental and Theoretical Investigation of Equivalent Viscous Damping of Structures with TOLD for Different Fluids," Colonel and Bass describe an experimental investigation of the damping characteristics of three different fluids that are utilized within a tuned liquid column damper. Numerical simulations are then performed to evaluate the effectiveness of the different fluids in oppressing the response of structures subjected to base excitation.
