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Rigid foundations subjected to seismic waves
342A
896428 Rigid foundations subjected to seismic waves Pais, A L; Kausel, E Earthq Engng Struct Dynam V18, 174, April 1989, P475-489 The kinematic (wave scattering) component of soil structure interaction, which occurs because the foundation is much stiffer than the soil and cannot accommodate its distortions, is analysed using an approximate solution based on a simple algorithm of Iguchi (1982). Inertial effects are not considered. Comparison is made with accurate numerical solutions, which require considerable computational effort, for the cases of cylindrical and prismatic foundations. Accuracy is seen to be suitable for engineering purposes.
896429 Prediction of amplitude of vibration of machine foundations Sridharan, A; Prasad, B R Indian Geotech J V18, N1, Jan 1988, P54-76 Previously reported work on the vibration of machine foundations has concentrated on amplitude and frequency at resonance. No work is yet found for elastic half space theory considering effects at the operating frequency at which the machine is constantly used. Simple charts are presented to predict displacement and amplitude at any frequency using the elastic half space theory for both vertical and horizontal vibration. Results are presented for rigid base, uniform and parabolic pressure distributions, for weighted average displacement condition, and for constant force and rotating mass excitations.
896430 Performance of flexible retaining walls supporting dry cohesionless soils under cyclic loads Siddharthan, R; Maragakis, E M lnt J Num Anal Meth Geomech V13, N3, May-June 1989, P309-326 Finite element analysis of seismic response of flexible wall/soil systems is presented, which takes into account nonlinear hysteretic soil behaviour and increase in lateral stress and settlement related to grain slip caused by cyclic loads. Predicted response is in reasonable agreement with results of centrifuge model tests. Influence of wall flexibility and fill density is evaluated. Maximum bending moments from current design practices are seen to be nonconservative for stiffer loads. Flexible walls holding medium density sands suffer greatest deflections.
896431 Rocking stiffness of arbitrarily shaped embedded foundations Hatzikonstantinou, E; Tassoulas, J L; Gazetas, G; Kotsanopoulos, P; Fotopoulou, M J Geotech Engng Div ASCE Vl15, N4, April 1989, P457-472 A boundary element formulation is used in a comprehensive and systematic study of the static and dynamic rocking stiffness of an arbitrarily shaped foundation in a homogeneous half space. Closed-form algebraic expressions and dimensionless charts are produced. A numerical example illustrates use of the method and results are compared with an equivalent circle approximation.
896432 Rocking damping of arbitrarily shaped embedded foundations Fotopoulou, M; Kotsanopoulos, P; Gazetas, G; Tassoulas, J L J Geotech Engng Div ASCE Vl15, N4, April 1989, P473-490 A simple analytical method for estimation of rocking radiation damping coefficients of arbitrarily shaped embedded foundations in an elastic homogeneous half space. The model
is based on physical approximations representing fundamental principles of dynamics and wave propagation, and is calibrated using numerical results from boundary element and finite element formulations. Comparisons with numerical data are presented for a variety of basemat shapes and a range of embedment depths. The method is illustrated by estimating the damping coefficient for a hypothetical embedded foundation.
896433 Impedance functions and input motions for embedded square foundations Mita, A; Luco, J E J Geotech Engng Div ASCE Vl15, N4, April 1989. P491-503 Tables of impedance functions and effective input motions for rigid square foundations embedded in a uniform elastic halfspace are presented. The tables include numerical results obtained by a hybrid approach for embedment to half-width ratios ranging from 1/3 to 3/2 and by a boundary element method for surface foundations. Media characterised by Poisson's ratios of 1/4, 1/3 and 0.4 are considered. The impedance functions include vertical, torsional, horizontal, rocking, and coupling terms. Effective foundation input motions for vertically incident P and SH waves and for horizontally incident SH waves are also listed. Auth. 896434 Seismic response analysis of offshore seabed with depthproportional shear modulus Akai, K; Tamura, T Mere Fac gngng Kyoto Unit V50, N3, July 1988, P188-200 An analytical model to obtain seismic response of an offshore sea bed with a depth-proportional shear modulus is described. Using data from PS logging in Osaka Bay, an equation of motion for vibration of a semi-infinite layer subjected to horizontal seismic motion at its base is derived. A closed-form solution of seismic responses in the form of a Duhamel integral for acceleration, velocity, displacement, shear strain and shear stress is developed. The model is illustrated for a seabed subjected to irregular seismic excitation.
896435 Dynamic subsoil-coupling between rigid, circular foundations on the hnifspaee Triantafyllidis, T; Prange, B Soil Dynara Earthq Engng V8, N1, Jan 1989, P9-21 The dynamic behaviour of a group of rigid circular foundations on the surface of a homogeneous, isotropic, linear-elastic half space is described in terms of influence functions. The distance between circular and rectangular foundations below which dynamic subsoil-coupling cannot be ignored is also evaluated. The method may be applied to problems of passive screening or to the solution of interaction problems in the case of far-field excitation.
896436 Soil-structure interface effects on dynamic interaction analysis of reinforced concrete lifelines Krauthammer, T; Chert, Y Soil Dynam Eartlul Engng I/8, N1, Jan 1989, P32-42 Soil structure interaction for rectangular reinforced lifelines (utilities conduits) is analysed using the finite element code ADINA. Effects of various interface structures and embedment conditions are evaluated. The interface model is represented by the relations between shear and bulk moduli and volumetric strains which can be obtained by triaxial tests.
© 1989 Pergamon Press plc. Reproduction not permitted
896428 Rigid foundations subjected to seismic waves Pais, A L; Kausel, E Earthq Engng Struct Dynam V18, 174, April 1989, P475-489 The kinematic (wave scattering) component of soil structure interaction, which occurs because the foundation is much stiffer than the soil and cannot accommodate its distortions, is analysed using an approximate solution based on a simple algorithm of Iguchi (1982). Inertial effects are not considered. Comparison is made with accurate numerical solutions, which require considerable computational effort, for the cases of cylindrical and prismatic foundations. Accuracy is seen to be suitable for engineering purposes.
896429 Prediction of amplitude of vibration of machine foundations Sridharan, A; Prasad, B R Indian Geotech J V18, N1, Jan 1988, P54-76 Previously reported work on the vibration of machine foundations has concentrated on amplitude and frequency at resonance. No work is yet found for elastic half space theory considering effects at the operating frequency at which the machine is constantly used. Simple charts are presented to predict displacement and amplitude at any frequency using the elastic half space theory for both vertical and horizontal vibration. Results are presented for rigid base, uniform and parabolic pressure distributions, for weighted average displacement condition, and for constant force and rotating mass excitations.
896430 Performance of flexible retaining walls supporting dry cohesionless soils under cyclic loads Siddharthan, R; Maragakis, E M lnt J Num Anal Meth Geomech V13, N3, May-June 1989, P309-326 Finite element analysis of seismic response of flexible wall/soil systems is presented, which takes into account nonlinear hysteretic soil behaviour and increase in lateral stress and settlement related to grain slip caused by cyclic loads. Predicted response is in reasonable agreement with results of centrifuge model tests. Influence of wall flexibility and fill density is evaluated. Maximum bending moments from current design practices are seen to be nonconservative for stiffer loads. Flexible walls holding medium density sands suffer greatest deflections.
896431 Rocking stiffness of arbitrarily shaped embedded foundations Hatzikonstantinou, E; Tassoulas, J L; Gazetas, G; Kotsanopoulos, P; Fotopoulou, M J Geotech Engng Div ASCE Vl15, N4, April 1989, P457-472 A boundary element formulation is used in a comprehensive and systematic study of the static and dynamic rocking stiffness of an arbitrarily shaped foundation in a homogeneous half space. Closed-form algebraic expressions and dimensionless charts are produced. A numerical example illustrates use of the method and results are compared with an equivalent circle approximation.
896432 Rocking damping of arbitrarily shaped embedded foundations Fotopoulou, M; Kotsanopoulos, P; Gazetas, G; Tassoulas, J L J Geotech Engng Div ASCE Vl15, N4, April 1989, P473-490 A simple analytical method for estimation of rocking radiation damping coefficients of arbitrarily shaped embedded foundations in an elastic homogeneous half space. The model
is based on physical approximations representing fundamental principles of dynamics and wave propagation, and is calibrated using numerical results from boundary element and finite element formulations. Comparisons with numerical data are presented for a variety of basemat shapes and a range of embedment depths. The method is illustrated by estimating the damping coefficient for a hypothetical embedded foundation.
896433 Impedance functions and input motions for embedded square foundations Mita, A; Luco, J E J Geotech Engng Div ASCE Vl15, N4, April 1989. P491-503 Tables of impedance functions and effective input motions for rigid square foundations embedded in a uniform elastic halfspace are presented. The tables include numerical results obtained by a hybrid approach for embedment to half-width ratios ranging from 1/3 to 3/2 and by a boundary element method for surface foundations. Media characterised by Poisson's ratios of 1/4, 1/3 and 0.4 are considered. The impedance functions include vertical, torsional, horizontal, rocking, and coupling terms. Effective foundation input motions for vertically incident P and SH waves and for horizontally incident SH waves are also listed. Auth. 896434 Seismic response analysis of offshore seabed with depthproportional shear modulus Akai, K; Tamura, T Mere Fac gngng Kyoto Unit V50, N3, July 1988, P188-200 An analytical model to obtain seismic response of an offshore sea bed with a depth-proportional shear modulus is described. Using data from PS logging in Osaka Bay, an equation of motion for vibration of a semi-infinite layer subjected to horizontal seismic motion at its base is derived. A closed-form solution of seismic responses in the form of a Duhamel integral for acceleration, velocity, displacement, shear strain and shear stress is developed. The model is illustrated for a seabed subjected to irregular seismic excitation.
896435 Dynamic subsoil-coupling between rigid, circular foundations on the hnifspaee Triantafyllidis, T; Prange, B Soil Dynara Earthq Engng V8, N1, Jan 1989, P9-21 The dynamic behaviour of a group of rigid circular foundations on the surface of a homogeneous, isotropic, linear-elastic half space is described in terms of influence functions. The distance between circular and rectangular foundations below which dynamic subsoil-coupling cannot be ignored is also evaluated. The method may be applied to problems of passive screening or to the solution of interaction problems in the case of far-field excitation.
896436 Soil-structure interface effects on dynamic interaction analysis of reinforced concrete lifelines Krauthammer, T; Chert, Y Soil Dynam Eartlul Engng I/8, N1, Jan 1989, P32-42 Soil structure interaction for rectangular reinforced lifelines (utilities conduits) is analysed using the finite element code ADINA. Effects of various interface structures and embedment conditions are evaluated. The interface model is represented by the relations between shear and bulk moduli and volumetric strains which can be obtained by triaxial tests.
© 1989 Pergamon Press plc. Reproduction not permitted