Effect of soil-structure interaction on damping and frequencies of base-isolated structures

146A Static stiffness and damping coefficients for circular, rectangular and embedded footings in half-spaces with hysteretic damping are represented graphically and these results used to estimate stiffness and damping coefficients for an equivalent elastic half-space. Comparison between estimation and theory shows limitations for the theory for relaxed conditions at dimensionless frequencies greater than 3. 883341 F.~ect of soil-structure interaction on damlJng and frequencies of bme-imlated m'uemres Constantinou, M C; Kneifati, M C

Proc Tkird US Natiomd Couference on Eartkqtmke E q i ~ e r f ~ , Clmrleston, 24-28 August 1986 V1, P671-681. Pubi El Cerrito: Earthquake Engineering Research Institute, 1986 Damping of the response of a base-isolated structure to seismic excitation, by dissipation of energy in the elastomeric bearings or by radiation damping in the soil, has been evaluated using two approaches. One, a complex eigenvalue approach, is mathematically correct: the other is a simple but less accurate energy method. The results are compared and the accuracy of the energy method is evaluated. 883342 Validity of modal saperposttion technique in soil structure

t m r a e t ~ mudy~s Vaidya, N R; Bazan-Zurita, E; Rizzo, P C Proc Tkird US NoMomd Conf~.mce oa Eartkcuake Es~g, e r ~ , Ckarleston, 24-28 A ~ t 1956 V1, P683-693. Publ E! Cerrito: Earthquake Engineering Research Institute, 1986 The relatively simple and cheap modal superposition method of seismic analysis, based on combining the seismic response in each orthogonal mode in accordance with the modal participation factors, is compared to the more exact direct integration method. Sources and magnitudes of errors in the superposition method are examined, the validity of the technique is assessed, and the conditions under which it provides reasonable results are discussed. 883343 Fxthquake evaluation of existing earth dams with earth foondatfom Stone, S D; Spearman, E L

Pro¢ Tkird US Nmimai Co~eremce on F.artlqmke ~ , Clm4nto~, 24-28 Amgnst 1986 V1, P695-702. Publ El Cerrito: Earthquake Engineering Research Institute, 1986 A deterministic decision-tree model for the seismic evaluation of earth dams with earth foundations is presented. It involves a series of progressive evaluations, ranging from simple empirical evaluations to complex analyses, and allows for results to be modified according to site conditions and information gained from a previous section. A case study of the Kentucky Dam, Tennessee, USA, is illustrated. 8833~ S e t m ~ stability aml strem mmiyJis for Blmmone Dam Hribar, J A; Mozer, J D; W'nnberly, P M; Yost, R E Proc Tkird US Natitmai Coq~z~e on FArtkcmke F~~, Ckarkston, 24-28 Ae~ut 1#86 Vl, P703.714. Publ E1 Cerrito: Earthquake Engineering Research Institute, 1986 The seismic stability of the Bluestone Dam, a concrete gravity dam in West Virginia, USA, has been evaluated for maximum credible and operating basis earthquakes. Appropriate parameters were selected for the concrete and foundation rock, and

foundation drain efficiencies. The safety of the dam against sliding failure and unacceptable bearing capacities is calculated, taking into account dam-reservoir interaction. 883345 Analysis of strong-motion emqh~uke records from a wellinstrumented earth dam Fedock, J J

Proc Third US N a 6 o ~ Co.create on F~rt&luke Esqineed~, Ckar&stom, 24-28 A ~ IM6 V1, P729-740. Publ El Cerrito: Earthquake Engineering Research Institute, 1986 During the Mammoth Lakes earthquake sequence of 1980, high quality, long-duration records of motion of the Long Valley Dam, California, USA, were obtained for 22 embankment and bedrock sites. A valuable data set for studies of seismic response of earth dams was collected. Analysis of accelerometer records shows trausverse, longitudinal, and vertical motions, and rocking behaviour. Further work to better understand the dam's reaction is already underway. 883346

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Chopra, A K Proc Tkird US National Co~¢~mce oR Eartl~u~e Eugineeri~, C ~ , 24,28 Agput I ~ VI, P741-75Z Publ El Cerrito: Earthquake Engineering Research Institute, 1986 Using recently developed dynamic analysis procedures, the linear response of a gravity dam and an arch dam to Oatthquakes has been analysed for a variety of conditions. It is demonstrated that the following factors should be taken into account: dam-water interaction; d a m - f o ~ rock interaction; reservoir boundary absorption; and water compressibility 883347

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Proc Tkird US Nadowd Cm~re~e on Eqineeriq, C ~ , 24-28 Aglmt 19~ VI, P797-808. Publ El Cerrito: Earthquake Engineering Research Institute, 1986 The probability of failure of offghore piling due to ~ y induced axial loading is exa~'~_~. Premmt ~ ~ ~ng a deterministic philosophy and incorporaliag a factor o f u f e t y concept are compared to probabiti~c methods. The ~ v i t y of failure probabilities is reviewed as a function of loadinsand capacity for various pile capacity algorithms in a silty clayclayey silt soil. Piling adequacy for expected environmental and seismic loads is discussed. 883348 Dyuamk mmlyds of tke Paramt Medfe i)mm Pardini de Corzo, M E; Platino, D E; Giral, J J Proc 5tA l m ~

P863-87~. Publ Rotterdam: A A Baikema, 1986 The dynamic analysis of an embankment dam of hydraulic fill over cohesive soil and sand foundations is ~emnlted. Both simplified semi-empirical methods and analytical methods using finite element analysis and laboratory ~ soil properties were used. Although some areas of silty sand and sands with low density were seen to have low liquefaction resistance, these zones were still safe under the worlt pomible conditions of the design earthquake. Results from both analytical approaches were in good agreement,

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