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An application of damage mechanics for seismic analysis of concrete gravity dams
SURFACE STRUCIURES:DAMS interior space caused the delay. A conventiooal load test was considered. However, loading pile from the top was not an option because of the limited space in the concourse. Engineers suggested performing a relatively new load test using a system called the Osterberg Load Cell. The O-Cell could be used to test the pile’s capacity. As they discovered it could also improve the foundations by preloading the pile to consolidate and stiffen and soils at its base. This meant the piles could be shortened and remain as effective as the original design. (Authors)
956248 NonBnear lateral interaction in pile dynamics M. H. El Naggar & M. Novak, Soil Dynamics & Earthquake Engineering, 14(2), 1995, pp 141-157. A model for pile lateral response to transient dynamic loading and to harmonic loading is presented allowing for nonlinear soil behavior, discootinuity conditions at the pile-soil interface and energy dissipation througb different types of damping. The approach is used to establish equivalent linear stiffness and damping parameters of single piles as well as dynamic interaction factors for approximate nonlinear analysis of pile groups. The dynamic stiffness of pile groups is greatly affected by both the nonlinear behavior of the soil and the slippage and gapping between the pile and soil. For a basic range of soil and pile parameters, equivalent linear stiffness and damping parameters of single piles and interaction factors for approximate nonlinear analysis are provided. (Authors)
956249 ReIiabiIity ?? naIysIs of a pile design P. F. Hansen, H. 0. Madsen & T. I. Tjelta, Structures, 8(2), 1995, pp 171-198.
Marine
This paper presents a stochastic pile design for a wellhead platform designed for Danish waters. The relevant failure modes for both ultimate and serviceability limit states are defined. Failure modes for the pile as well as failure in the soil are thereby considered. An uncertainty modeling for the environmental cooditions, the response and the soil stiffness and strength is suggested. The effects of spatial variation of soil properties are assessed both in terms of varying positions of layer boundaries and in terms of spatially varying soil properties. The model uncertainty in the soil strength for axial compressive and tensile loading is quantified. (Authors)
956250
Bitumen coating verses plastic sheeting for redwing negative skin friction K. S. Tawiiq & J. A. Caliendo, Journal of Material in Civil Engineering - ASCE, 7(l), 1995, pp 69-81. The plastic sheeting approach for negative skin friction reduction in end-bent piles behind proprietary mechanically stabihxed earth walls was investigated along with the conventional bitumen coating method. Test results showed that wrapping concrete piles with polyethylene sheets reduced the skin friction by 78%. Additional reduction was achieved by lubricating the polyethylene sheets with oil. The effectiveness of oil-lubricated polyethylene sheets in reducing skin friction was about 94%. Factors that aBect the shearing behavior of bitumen coating did not influence the friction CharacWstics of the polyethylene sheeting. Based on the results of this study, two formulas were suggested for estimating the shearing resistance of the bitumen-soil matrix and lubricated sheets. (Authors)
& EMBANKMENTS
283A
Dams and embankments 956251 Internatinal wafer power and dhn comtruction kaadbook 1995 ed J. Osborne, (Reed Business Publishing), ISBN (paperback) 0 617 00564 8, 1995,248 pp. This annual handbook was produced by the publishers of the journal International water power and aivn construction. Details of hydropower projects around the world are summarixed. The handbook is divided into seven sections: regional reviews; hydromachinery; an international address database; hydro resources; pumped storage; dams and hydro plants; and a buyers’ guide for products and services associated with the hydropower industry. (S.E.Brown) 956252 Threedimensional vibrations of inflatable dams C. M. D. Moorthy, J. N. Reddy & R. H. Plaut, Thin- Walled Structures, 21(4), 1995, pp 291-306. Intlatable dams am used for various purposes, such as controlling flood-waters, diverting water for irrigation, impounding water for recreation, raising the height of existing spillways, and preventing beach erosioo. They are flexible, cylindrical structures attached to a rigid, horixontal base. The vibrations of such dams are investigated in this paper. The dam is modelled as an elastic shell intlated with air and anchored along two of its generators. Both inftitely-long dams and dams of ftite length are considered. The ftite element method is applied, first to determine the equilibrium shape of the dam and then to analyze small vibrations about that conBguration. For the numerical examples, the lowest six vibration frequencies and corresponding mode shapes are obtained. The results are compared to those when no external water is present. (Authors) 956253 An application of damage mechanics for eeismic eaalysis of concrete gravity dams F. Ghrib & R. Tinawi, Earthquake Engineering & Structural Dynamics, 24(2), 1995, pp 157-173. This paper discusses the local approach of fracture using damage mechanics concepts to evaluate the seismic response of concrete gravity dams. A constitutive model for plain concrete, subjected to tensile streams, is presented. A 60 m concrete gravity dam is selected and subjected to ground motion typical of eastern North America. Five scenarios of initial damage are presented and the results confirm the importance of accounting for the initial state for the seismic safety evaluation of an existing dam. (from Authors) 956254 InveatIgation of stress and seepage stability at the conjoined section of concrete dirpimgm ad core of rockfill dam (in Cbineae) Liu Jie, Miao Liangjuan & Fu Yu, Shuili Xuebao/Joumal of Hy&aulic Engineering, 12, 1994, pp 47-54. This paper addresses stress and seepage control behaviour in a dam core directly inset by a concrete diaphragm. The characteristics of stress-strain in the core at the top of diaphragm and the probability of seepage failure along the shear face, as well as the interface between the wall and the core after core shear failure of the core is explored. The result shows that there is no concentrated leakage in the shear face of the core at the top of diaphragm. The conjunction of concrete diaphragm with the core is so strong that 00 contact seepage erosion will take place. (English summary)
956248 NonBnear lateral interaction in pile dynamics M. H. El Naggar & M. Novak, Soil Dynamics & Earthquake Engineering, 14(2), 1995, pp 141-157. A model for pile lateral response to transient dynamic loading and to harmonic loading is presented allowing for nonlinear soil behavior, discootinuity conditions at the pile-soil interface and energy dissipation througb different types of damping. The approach is used to establish equivalent linear stiffness and damping parameters of single piles as well as dynamic interaction factors for approximate nonlinear analysis of pile groups. The dynamic stiffness of pile groups is greatly affected by both the nonlinear behavior of the soil and the slippage and gapping between the pile and soil. For a basic range of soil and pile parameters, equivalent linear stiffness and damping parameters of single piles and interaction factors for approximate nonlinear analysis are provided. (Authors)
956249 ReIiabiIity ?? naIysIs of a pile design P. F. Hansen, H. 0. Madsen & T. I. Tjelta, Structures, 8(2), 1995, pp 171-198.
Marine
This paper presents a stochastic pile design for a wellhead platform designed for Danish waters. The relevant failure modes for both ultimate and serviceability limit states are defined. Failure modes for the pile as well as failure in the soil are thereby considered. An uncertainty modeling for the environmental cooditions, the response and the soil stiffness and strength is suggested. The effects of spatial variation of soil properties are assessed both in terms of varying positions of layer boundaries and in terms of spatially varying soil properties. The model uncertainty in the soil strength for axial compressive and tensile loading is quantified. (Authors)
956250
Bitumen coating verses plastic sheeting for redwing negative skin friction K. S. Tawiiq & J. A. Caliendo, Journal of Material in Civil Engineering - ASCE, 7(l), 1995, pp 69-81. The plastic sheeting approach for negative skin friction reduction in end-bent piles behind proprietary mechanically stabihxed earth walls was investigated along with the conventional bitumen coating method. Test results showed that wrapping concrete piles with polyethylene sheets reduced the skin friction by 78%. Additional reduction was achieved by lubricating the polyethylene sheets with oil. The effectiveness of oil-lubricated polyethylene sheets in reducing skin friction was about 94%. Factors that aBect the shearing behavior of bitumen coating did not influence the friction CharacWstics of the polyethylene sheeting. Based on the results of this study, two formulas were suggested for estimating the shearing resistance of the bitumen-soil matrix and lubricated sheets. (Authors)
& EMBANKMENTS
283A
Dams and embankments 956251 Internatinal wafer power and dhn comtruction kaadbook 1995 ed J. Osborne, (Reed Business Publishing), ISBN (paperback) 0 617 00564 8, 1995,248 pp. This annual handbook was produced by the publishers of the journal International water power and aivn construction. Details of hydropower projects around the world are summarixed. The handbook is divided into seven sections: regional reviews; hydromachinery; an international address database; hydro resources; pumped storage; dams and hydro plants; and a buyers’ guide for products and services associated with the hydropower industry. (S.E.Brown) 956252 Threedimensional vibrations of inflatable dams C. M. D. Moorthy, J. N. Reddy & R. H. Plaut, Thin- Walled Structures, 21(4), 1995, pp 291-306. Intlatable dams am used for various purposes, such as controlling flood-waters, diverting water for irrigation, impounding water for recreation, raising the height of existing spillways, and preventing beach erosioo. They are flexible, cylindrical structures attached to a rigid, horixontal base. The vibrations of such dams are investigated in this paper. The dam is modelled as an elastic shell intlated with air and anchored along two of its generators. Both inftitely-long dams and dams of ftite length are considered. The ftite element method is applied, first to determine the equilibrium shape of the dam and then to analyze small vibrations about that conBguration. For the numerical examples, the lowest six vibration frequencies and corresponding mode shapes are obtained. The results are compared to those when no external water is present. (Authors) 956253 An application of damage mechanics for eeismic eaalysis of concrete gravity dams F. Ghrib & R. Tinawi, Earthquake Engineering & Structural Dynamics, 24(2), 1995, pp 157-173. This paper discusses the local approach of fracture using damage mechanics concepts to evaluate the seismic response of concrete gravity dams. A constitutive model for plain concrete, subjected to tensile streams, is presented. A 60 m concrete gravity dam is selected and subjected to ground motion typical of eastern North America. Five scenarios of initial damage are presented and the results confirm the importance of accounting for the initial state for the seismic safety evaluation of an existing dam. (from Authors) 956254 InveatIgation of stress and seepage stability at the conjoined section of concrete dirpimgm ad core of rockfill dam (in Cbineae) Liu Jie, Miao Liangjuan & Fu Yu, Shuili Xuebao/Joumal of Hy&aulic Engineering, 12, 1994, pp 47-54. This paper addresses stress and seepage control behaviour in a dam core directly inset by a concrete diaphragm. The characteristics of stress-strain in the core at the top of diaphragm and the probability of seepage failure along the shear face, as well as the interface between the wall and the core after core shear failure of the core is explored. The result shows that there is no concentrated leakage in the shear face of the core at the top of diaphragm. The conjunction of concrete diaphragm with the core is so strong that 00 contact seepage erosion will take place. (English summary)