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Consistent inelastic design spectra: hysteretic and input energy
236A
PROPERTIES:DYNAMICS
saturated, its dynamic behaviour can be modelled by means of Blot's poroelastic theory. In this paper, the boundary condition is implemented in an irreducible finite element formulation for a compressible pore fluid. Spurious reflections for oblique incident waves on the absorbing boundary contribute to the solution errors. Therefore, a spectral element method is used to assess the accuracy of the finite element formulation. -from Authors 945096 Amplification of vertically propagating SH waves by multiple layers of Gibson soils R. Davis & B. Hunt, International Journal for Numerical & Analytical Methods in Geomechanics, 18(3), 1994, pp 205-212. Using the HaskeU-Thomson transfer matrix approach, an analytical solution is obtained for SH wave amplification by multiple layers of Gibson soils. Amplification spectra for typical soil and basement rock properties are calculated. A comparison of the Gibson soil response with that obtained for homogeneous soil models shows generally stronger amplifications associated with the Gibson soil. -Authors 945097 A model for cyclic shear strain of cohesionless soils Li Wanhong & Wang Wenshao, Shuili Xuebao/Journal of Hydraulic Engineering, 9, 1993, pp 11-17. Describes the development and application of a model for cyclic shear strain of cohesionless softs. This model is characterized by the hyperbolic relation between shear stress and shear strain for initial loading, and Mindlin relation between shear stress and shear strain for unloadingreloading instead of Musing relation. The parameters in the model have been determined by cyclic triaxial test and the model has been used in incremental elastic method for analysing seismic response of a riverbed deposit. -Author 945098 Velocity and attenuation of compressional waves in nearly saturated soils J. P. Bardet & H. Sayed, Soil Dynamics & Earthquake Engineering, 12(7), 1993, pp 391-401. Based on the two-phase theory of Blot, exact and approximate expressions for the velocity and attenuation of compressional waves within nearly saturated poroelastic media are presented. The approximate solutions are used to model the low-frequency compressional waves within nearly saturated soils. The model accounts for the effective stress, degree of saturation, and void ratio, and is capable of describing experimental results on Ottawa sand. The three-phase theory of Vardoulakis and Beskos and the twophase theory of Blot similarly describe the velocity and attenuation of compressional waves in most soils. However, the former theory breaks down for nearly saturated gravels and dense sands. -Authors 945099 Consistent inelastic design spectra: strength and displacement T. Vidic, P. Fajfar & M. Fischinger, Earthquake Engineering & Structural Dynamics, 23(5), 1994, pp 507-521. A procedure for the determination of inelastic design spectra (for strength, displacement, hysteretic and input energy) for systems with a prescribed ductility factor has been developed. All the spectra are consistent (interrelated and based on the same assumptions). This is, the first of two companion papers which deals with the classical' structurat parameters: strength and displacement. The input data are the characteristics of the expected ground motion in terms of a smooth elastic pseudo-acceleration spectrum. Simple, approximate expressions for the strength reduction factor R are proposed. The value of R depends on the natural period of the system, the prescribed ductility factor, the hysteretic behaviour, damping and ground motion. -from Authors 945100 Consistent inelastic design spectra: hysteretic and input energy P. Fajfar & T. Vidic, Earthquake Engineering & Structural Dynamics, 23(5), 1994, pp 523-537. This is the second of two companion papers of inelastic design spectra (for strength, displacement, hysteretic and
Ut energy) for systems with a prescribed ductility factor. ~ll the spectra are consistent (interrelated and based on the same assumptions). This paper deals with two quantities related to cumulative damage: hysteretic and input energy. The input data for the procedure are the characteristics of the expected ground motion in terms of a smooth elastic pseudo-acceleration spectrum and tlae time integral of the square of the ground acceleration Ja2dt. Simple, approximate expressions for two dimensionless parameters (the arameter y and the hysteretic to input energy ratio E,/E~) ave been proposed. Very good approximations to the-~ntlastic spectra for hysteretic and input energy can be derived from the elastic spectrum using the spectra for the reduction factor R, proposed in the companion paper, and the proposed values for y and EH/Ex. -from Authors
~
945101 Experimental observations of the elastic and inelastic behaviour of porous sandstones Y. Bernabe, D. T. Fryer & R. M. Shively, Geophysical Journallnternational, 117(2), 1994, pp 403-418. In order to investigate the mechanical behaviour of porous sandstones, mechanical tests, including creep tests, were run on eight sandstones ranging from 17 to 30% porosity, in both vacuum-dry and water-saturated conditions. To interpret the data it is essential to separate the elastic and inelastic parts of the total strain. The elastic constants increased significantly with increasing mean stress, but the magnitudes and pressure-dependence of the elastic constants were not consistent with presently proposed grain contact models. Knowning the elastic constants, the elastic and, by difference, the non-elastic parts of the deformation were computed. This study confirms that plasticity models such as those used in soil mechanics can account, at least qualitatively, for many features of the inelastic behaviour of porous sandstones. -from Authors
945102 A 2D coupled finite element and boundary element scheme to simulate the elastic behaviour of jointed rocks J. P. Carter & B. Xiao, International Journal for Numerical & Analytical Methods in Geomechanics, 18(1), 1994, pp 49-71. In this paper a coupled finite and boundary element formulation is developed for the analysis of excavation in jointed rock. The presence of joints in the rock mass has been included implicitly by treating it as an appropriate anisotropic elastic continuum. The boundary element formulation for an anisotropic medium is briefly discussed. Good agreement has been found between numerical and analytical solutions for several example problems, demonstrating the accuracy of the present formulation. Numerical solutions are also presented for the problems of a deep circular tunnel and a ~asement excavated in a variety of jointed rock masses. -Authors
945103 A semi-analytical method for the waveinduced seabed response M. S. Rahman, K. EI-Zahaby & J. Booker, International
Journal for Numerical & Analytical Geomechanics, 18(4), 1994, pp 213-236.
Methods
in
A general semi-analytical method is presented for the analysis of seabed res. ~ n s e under wave action during a storm. The seabed is tdealized as a poro-elastic medium nued with a single compressible fluid with anisotropic flow. The coupled process of fluid flow and deformation of soil skeleton is formulated in the framework of Blot's theory. The analysis for the response of hom?seneous seabed of finite thickness under a plane progresstve wave is developed first, followed by an extension ~or the case of a layered seabed. A generalization for t h r e e - ~ i o n a l response of seabed is also developed for a general wave field which provides the analyses for seabed response under short-crested or standing waves in the vicinity of a
PROPERTIES:DYNAMICS
saturated, its dynamic behaviour can be modelled by means of Blot's poroelastic theory. In this paper, the boundary condition is implemented in an irreducible finite element formulation for a compressible pore fluid. Spurious reflections for oblique incident waves on the absorbing boundary contribute to the solution errors. Therefore, a spectral element method is used to assess the accuracy of the finite element formulation. -from Authors 945096 Amplification of vertically propagating SH waves by multiple layers of Gibson soils R. Davis & B. Hunt, International Journal for Numerical & Analytical Methods in Geomechanics, 18(3), 1994, pp 205-212. Using the HaskeU-Thomson transfer matrix approach, an analytical solution is obtained for SH wave amplification by multiple layers of Gibson soils. Amplification spectra for typical soil and basement rock properties are calculated. A comparison of the Gibson soil response with that obtained for homogeneous soil models shows generally stronger amplifications associated with the Gibson soil. -Authors 945097 A model for cyclic shear strain of cohesionless soils Li Wanhong & Wang Wenshao, Shuili Xuebao/Journal of Hydraulic Engineering, 9, 1993, pp 11-17. Describes the development and application of a model for cyclic shear strain of cohesionless softs. This model is characterized by the hyperbolic relation between shear stress and shear strain for initial loading, and Mindlin relation between shear stress and shear strain for unloadingreloading instead of Musing relation. The parameters in the model have been determined by cyclic triaxial test and the model has been used in incremental elastic method for analysing seismic response of a riverbed deposit. -Author 945098 Velocity and attenuation of compressional waves in nearly saturated soils J. P. Bardet & H. Sayed, Soil Dynamics & Earthquake Engineering, 12(7), 1993, pp 391-401. Based on the two-phase theory of Blot, exact and approximate expressions for the velocity and attenuation of compressional waves within nearly saturated poroelastic media are presented. The approximate solutions are used to model the low-frequency compressional waves within nearly saturated soils. The model accounts for the effective stress, degree of saturation, and void ratio, and is capable of describing experimental results on Ottawa sand. The three-phase theory of Vardoulakis and Beskos and the twophase theory of Blot similarly describe the velocity and attenuation of compressional waves in most soils. However, the former theory breaks down for nearly saturated gravels and dense sands. -Authors 945099 Consistent inelastic design spectra: strength and displacement T. Vidic, P. Fajfar & M. Fischinger, Earthquake Engineering & Structural Dynamics, 23(5), 1994, pp 507-521. A procedure for the determination of inelastic design spectra (for strength, displacement, hysteretic and input energy) for systems with a prescribed ductility factor has been developed. All the spectra are consistent (interrelated and based on the same assumptions). This is, the first of two companion papers which deals with the classical' structurat parameters: strength and displacement. The input data are the characteristics of the expected ground motion in terms of a smooth elastic pseudo-acceleration spectrum. Simple, approximate expressions for the strength reduction factor R are proposed. The value of R depends on the natural period of the system, the prescribed ductility factor, the hysteretic behaviour, damping and ground motion. -from Authors 945100 Consistent inelastic design spectra: hysteretic and input energy P. Fajfar & T. Vidic, Earthquake Engineering & Structural Dynamics, 23(5), 1994, pp 523-537. This is the second of two companion papers of inelastic design spectra (for strength, displacement, hysteretic and
Ut energy) for systems with a prescribed ductility factor. ~ll the spectra are consistent (interrelated and based on the same assumptions). This paper deals with two quantities related to cumulative damage: hysteretic and input energy. The input data for the procedure are the characteristics of the expected ground motion in terms of a smooth elastic pseudo-acceleration spectrum and tlae time integral of the square of the ground acceleration Ja2dt. Simple, approximate expressions for two dimensionless parameters (the arameter y and the hysteretic to input energy ratio E,/E~) ave been proposed. Very good approximations to the-~ntlastic spectra for hysteretic and input energy can be derived from the elastic spectrum using the spectra for the reduction factor R, proposed in the companion paper, and the proposed values for y and EH/Ex. -from Authors
~
945101 Experimental observations of the elastic and inelastic behaviour of porous sandstones Y. Bernabe, D. T. Fryer & R. M. Shively, Geophysical Journallnternational, 117(2), 1994, pp 403-418. In order to investigate the mechanical behaviour of porous sandstones, mechanical tests, including creep tests, were run on eight sandstones ranging from 17 to 30% porosity, in both vacuum-dry and water-saturated conditions. To interpret the data it is essential to separate the elastic and inelastic parts of the total strain. The elastic constants increased significantly with increasing mean stress, but the magnitudes and pressure-dependence of the elastic constants were not consistent with presently proposed grain contact models. Knowning the elastic constants, the elastic and, by difference, the non-elastic parts of the deformation were computed. This study confirms that plasticity models such as those used in soil mechanics can account, at least qualitatively, for many features of the inelastic behaviour of porous sandstones. -from Authors
945102 A 2D coupled finite element and boundary element scheme to simulate the elastic behaviour of jointed rocks J. P. Carter & B. Xiao, International Journal for Numerical & Analytical Methods in Geomechanics, 18(1), 1994, pp 49-71. In this paper a coupled finite and boundary element formulation is developed for the analysis of excavation in jointed rock. The presence of joints in the rock mass has been included implicitly by treating it as an appropriate anisotropic elastic continuum. The boundary element formulation for an anisotropic medium is briefly discussed. Good agreement has been found between numerical and analytical solutions for several example problems, demonstrating the accuracy of the present formulation. Numerical solutions are also presented for the problems of a deep circular tunnel and a ~asement excavated in a variety of jointed rock masses. -Authors
945103 A semi-analytical method for the waveinduced seabed response M. S. Rahman, K. EI-Zahaby & J. Booker, International
Journal for Numerical & Analytical Geomechanics, 18(4), 1994, pp 213-236.
Methods
in
A general semi-analytical method is presented for the analysis of seabed res. ~ n s e under wave action during a storm. The seabed is tdealized as a poro-elastic medium nued with a single compressible fluid with anisotropic flow. The coupled process of fluid flow and deformation of soil skeleton is formulated in the framework of Blot's theory. The analysis for the response of hom?seneous seabed of finite thickness under a plane progresstve wave is developed first, followed by an extension ~or the case of a layered seabed. A generalization for t h r e e - ~ i o n a l response of seabed is also developed for a general wave field which provides the analyses for seabed response under short-crested or standing waves in the vicinity of a