【正文】 y transferring of energy among vibrating modes.The first method includes devices that operate on principlessuch as frictional sliding, yielding of metals, phase transformationin metals, deformation of viscoelastic solids or fluids,and fluid orificing. The latter method includes supplementaloscillators, which act as dynamic vibration absorbers.In what follows, advances in this area in terms of research,development of design guidelines, and implementation as documentedin recent publications are presented and discussed. Metallic Yield DampersOne of the effective mechanisms available for the dissipationof energy input to a structure from an earthquake isthrough inelastic deformation of metals. The idea of utilizingadded metallic energy dissipators within a structure to absorba large portion of the seismic energy began with the conceptualand experimental work of Kelly et al. (1972) and Skinner etal. (1975). Several of the devices considered included torsionalbeams, flexural beams, and Vstrip energy dissipators. Duringthe ensuing years, a wide variety of such devices has beenproposed (Bergman and Goel 1987。 Whittaker et al. 1991。 Tsaiet al. 1993). Many of these devices use mild steel plates withtriangular or hourglass shapes so that yielding is spread almostuniformly throughout the material. A typical Xshaped platedamper or added damping and stiffness (ADAS) device isshown in Fig. 1. Forcedisplacement response of an ADASdevice under constant amplitude displacement controlled cycleshas been examined by Whittaker et al. (1991). A typicalresult is displayed in Fig. 2, where the area within the hysteresisloops measures the amount of dissipated energy. OtherJOURNAL OF ENGINEERING MECHANICS / SEPTEMBER 1997/899J. Eng. Mech. :897971. Downloaded from by Henan University of Technology on 03/05/13. Copyright ASCE. For personal use only。 all rights reserved.20.39。2 0??Dlapl8cernent (Inch)1 0 1Dlapl8C8l1len1 (Inch)~.21 0Dlapl8C8111enl (Inch)2TMI TMI T..~~~./1011~..(a)1.10i ~ I~ 0 0..J ..III10112(b)1110i ~ I~ 0{..l ., JIII10.113(e)11i 10~ Imaterials, such as lead and shapememory alloys, have beenevaluated (Sakurai et aI. 1992。 Aiken and Kelly 1992). Someparticularly desirable features of these devices are their stablehysteretic behavior, lowcycle fatigue property, longterm reliability,and relative insensitivity to environmental temperature.Hence, numerous analytical and experimental investigationshave been conducted to determine these characteristicsin individual devices.Despite obvious differences in their geometric configuration,the underlying dissipative mechanism in all cases resultsfrom inelastic deformation of the metallic elements. Therefore,to effectively include these devices in the design of an actualstructure, one must be able to characterize their expected hystereticbehavior under arbitrary cyclic loading. Ideally, onewould hope to develop a model of any metallic device startingfrom the micromechanical theory of dislocations, which mustultimately determine its inelastic response. However, since adirect physical approach from first principles is not yet feasible,one normally accepts a phenomenological descriptionbased on observation of behavior at the macroscopic level.A mathematically consistent framework, such as plasticity orviscoplasticity theory, is then constructed to reproduce that behaviorand to predict response under general conditions (Ozdemir1976。 Bhatti et aI. 1978). This approach may reduce therequirements for ponent testing. Recently, Dargush andFIG. 2. Force Displacement Response of ADAS Device (Whittakeret al. 1991)Dlsplacement AmplitUde: (a) In.。 (b) In.。 (c) In.T!~+1o(b)o~t 0 0 ..:L~ I(a)I II I I ~ t ~ It r . . 39。 FIG. 1. XShaped ADAS Device (Whittaker et al. 1991)900 I JOURNAL OF ENGINEERING MECHANICS I SEPTEMBER 1997J. Eng. Mech. :897971. Downloaded from by Henan University of Technology on 03/05/13. Copyright ASCE. For personal use only。 all rights reserved. Numerical Results700...............,700.parameters, and determined ultimate displacements of the deviceswith various sizes based on experimental data obtainedfrom the hysteretic behavior and lowcycle fatigue propertytesting of about 100 devices.To utilize metallic dampers within a structural system, it isnecessary to formulate design guidelines and procedures basedon knowledge gained from theoretical and experimental studies.Since all metallic yield dampers are nonlinear devices, alinear system with such devices will bee nonlinear. Someresearch has been conducted in an effort to establish designmethodologies for metallic energy dissipation systems by puttingthe hysteretic forcedisplacement model of metallic devicesin the equation of motion of the structure to be designed.Response analysis under all intensity levels of earthquakes canthen be conducted and, on the basis of analytical results, adesign methodology for structures with metallic devices maybe established (Xia et aJ. 1990。 Xia and Hanson 1992。 Tsai etal. 1993。 Pong et aJ. 1994). Their analytical results show that,for Xshaped and triangular plate elements, parameters BID(ratio of bracing stiffness to device stiffness), SR (bracedeviceassemblage stiffness to that of corresponding structural story),and Xy (yielding displacement of the device) are key parametersin reducing seismic response. An alternative design procedurebased on the concept of equivalent viscous dampingcorresponding to metallic devices was outlined in Scholl(1993) and is used in the ongoing efforts to establish buildingcode requirements for passive en