scispace - formally typeset
Search or ask a question

Development of a new family of normalized modulus reduction and material damping curves

About: The article was published on 2001-08-01 and is currently open access. It has received 810 citations till now. The article focuses on the topics: Reduction (complexity).
Citations
More filters
Journal ArticleDOI
TL;DR: In this article, a new empirical ground motion model for PGA, PGV, PGD and 5% damped linear elastic response spectra for periods ranging from 0.01-10 s was presented.
Abstract: We present a new empirical ground motion model for PGA, PGV, PGD and 5% damped linear elastic response spectra for periods ranging from 0.01– 10 s. The model was developed as part of the PEER Next Generation Attenuation (NGA) project. We used a subset of the PEER NGA database for which we excluded recordings and earthquakes that were believed to be inappropriate for estimating free-field ground motions from shallow earthquake mainshocks in active tectonic regimes. We developed relations for both the median and standard deviation of the geometric mean horizontal component of ground motion that we consider to be valid for magnitudes ranging from 4.0 up to 7.5–8.5 (depending on fault mechanism) and distances ranging from 0 – 200 km. The model explicitly includes the effects of magnitude saturation, magnitude-dependent attenuation, style of faulting, rupture depth, hanging-wall geometry, linear and nonlinear site response, 3-D basin response, and inter-event and intra-event variability. Soil nonlinearity causes the intra-event standard deviation to depend on the amplitude of PGA on reference rock rather than on magnitude, which leads to a decrease in aleatory uncertainty at high levels of ground shaking for sites located on soil. DOI: 10.1193/1.2857546

1,112 citations

Journal ArticleDOI
TL;DR: The results of cyclic tests indicate that the Chinese criteria are not reliable for determining the liquefaction susceptibility of fine-grained soils as discussed by the authors, and the plasticity index (PI) is a better indicator of soil susceptibility.
Abstract: Observations from recent earthquakes and the results of cyclic tests indicate that the Chinese criteria are not reliable for determining the liquefaction susceptibility of fine-grained soils. Fine-grained soils that liquefied during the 1994 Northridge, 1999 Kocaeli, and 1999 Chi-Chi earthquakes often did not meet the clay-size criterion of the Chinese criteria. Cyclic testing of a wide range of soils found to liquefy in Adapazari during the Kocaeli earthquake confirmed that these fine-grained soils were susceptible to liquefaction. It is not the amount of “clay-size” particles in the soil; rather, it is the amount and type of clay minerals in the soil that best indicate liquefaction susceptibility. Thus plasticity index (PI) is a better indicator of liquefaction susceptibility. Loose soils with PI 0.85 were susceptible to liquefaction, and loose soils with 12 0.8 were systematically more resistant to liquefaction. Soils with PI>18 tested at low effective confining stresses ...

374 citations

Journal ArticleDOI
TL;DR: In this article, a modified hyperbolic model and a statistical analysis of existing Resonant Column and Torsional Shear test results for 122 specimens obtained from South Carolina, North Carolina, and Alabama are presented.
Abstract: Predictive equations for estimating normalized shear modulus and material damping ratio of Quaternary, Tertiary and older, and residual/saprolite soils are presented in this paper. The equations are based on a modified hyperbolic model and a statistical analysis of existing Resonant Column and Torsional Shear test results for 122 specimens obtained from South Carolina, North Carolina, and Alabama. Variables used in the equations for normalized shear modulus are: shear-strain amplitude, confining stress, and plasticity index (PI). The equations for damping ratio are expressed in terms of a polynomial function of normalized shear modulus plus a minimum damping ratio. It is found that the Quaternary soils exhibit more linearity than soils of the other two groups. Also, it is found that the effect of PI on dynamic soil behavior is not as significant as previously thought. Data from all three groups exhibit significant variations with confining stress, similar to the variations determined by Stokoe et al. The uncertainties associated with the equations for PI of 0 and mean effective confining stress of 100 kPa are quantified using the point estimate method. A case study from Charleston, S.C. is provided to illustrate an application of the equations to seismic response analysis and the importance of considering confining stress and geologic age.

322 citations

Journal ArticleDOI
TL;DR: In this article, the authors presented two new soil damping formulations implemented in nonlinear one-dimensional site response analysis for small and large strains, which were used separately and simultaneously in non-linear site response analyses.

260 citations

Journal ArticleDOI
TL;DR: In this article, exact linear frequency-domain solutions for body wave propagation through an elastic medium are used to establish guidelines for two issues that have long been a source of confusion for users of nonlinear codes.
Abstract: One-dimensional nonlinear ground response analyses provide a more accurate characterization of the true nonlinear soil behavior than equivalent-linear procedures, but the application of nonlinear codes in practice has been limited, which results in part from poorly documented and unclear parameter selection and code usage protocols. In this article, exact (linear frequency-domain) solutions for body wave propagation through an elastic medium are used to establish guidelines for two issues that have long been a source of confusion for users of nonlinear codes. The first issue concerns the specification of input motion as “outcropping” (i.e., equivalent free-surface motions) versus “within” (i.e., motions occurring at depth within a site profile). When the input motion is recorded at the ground surface (e.g., at a rock site), the full outcropping (rock) motion should be used along with an elastic base having a stiffness appropriate for the underlying rock. The second issue concerns the specification of viscous damping (used in most nonlinear codes) or small-strain hysteretic damping (used by one code considered herein), either of which is needed for a stable solution at small strains. For a viscous damping formulation, critical issues include the target value of the viscous damping ratio and the frequencies for which the viscous damping produced by the model matches the target. For codes that allow the use of “full” Rayleigh damping (which has two target frequencies), the target damping ratio should be the small-strain material damping, and the target frequencies should be established through a process by which linear time domain and frequency domain solutions are matched. As a first approximation, the first-mode site frequency and five times that frequency can be used. For codes with different damping models, alternative recommendations are developed.

193 citations

References
More filters
Journal ArticleDOI
TL;DR: In this paper, an equation and graph for the determination of shear modulus and damping of soils for use in design problems involving repeated loading or vibration of soils, are presented.
Abstract: Equations and graphs for the determination of shear modulus and damping of soils, for use in design problems involving repeated loading or vibration of soils, are presented. These equations and graphs are based on numerous laboratory tests on both remolded and undisturbed cohesive soils and on clean sands. Comparison of the measured and computed values shows good agreement. An example problem showing how these equations and curves are used is given.

1,710 citations


"Development of a new family of norm..." refers background in this paper

  • ...…various equipment on companion soil samples (from Stokoe et al., 1999) .................... 102 xxiii Figure 5.1 Hyperbolic soil model proposed by Hardin and Drnevich (1972b) ........................................................................................ 110 Figure 5.2 The normalized…...

    [...]

  • ...…107 5.1 Introduction ....................................................................................... 107 5.2 Hardin and Drnevich (1972) Design Equations ................................ 107 5.3 Empirical Relationships…...

    [...]

  • ...105 Table 5.1 Parameters that control nonlinear soil behavior and their relative importance in terms of affecting shear modulus and material damping (Hardin and Drnevich, 1972b) ....................... 108 xv Table 7.1 Prior information provided in the discrete example.................... 160 Table…...

    [...]

Journal ArticleDOI
TL;DR: In this article, a study on the influence of the plasticity index (PI) on the cyclic stress-strain parameters of saturated soils needed for site response evaluations and seismic microzonation is presented.
Abstract: A study on the influence of the plasticity index (PI) on the cyclic stress‐strain parameters of saturated soils needed for site‐response evaluations and seismic microzonation is presented. Ready‐to‐use charts are included, showing the effect of PI on the location of the modulus reduction curve G/Gmax versus cyclic shear strain γc, and on the material damping ratio λ versus γc curve. The charts are based on experimental data from 16 publications encompassing normally and overconsolidated clays (OCR=1-15), as well as sands. It is shown that PI is the main factor controlling G/Gmax and λ for a wide variety of soils; if for a given γc PI increases, G/Gmax rises and λ is reduced. Similar evidence is presented showing the influence of PI on the rate of modulus degradation with the number of cycles in normally consolidated clays. It is concluded that soils with higher plasticity tend to have a more linear cyclic stress‐strain response at small strains and to degrade less at larger γc than soils with a lower PI. ...

1,608 citations


"Development of a new family of norm..." refers background or methods or result in this paper

  • ...239 Figure 9.13 Empirical (a) normalized modulus reduction, and (b) material damping curves proposed by Vucetic and Dobry (1991)............ 240 Figure 9.14 Comparison of the effect of soil plasticity on nonlinear soil behavior predicted by the calibrated model and empirical curves proposed by…...

    [...]

  • ...It is also called the nonlinearity threshold by Vucetic and Dobry (1991) and...

    [...]

  • ...13 Empirical (a) normalized modulus reduction, and (b) material damping curves proposed by Vucetic and Dobry (1991)............ 240 Figure 9.14 Comparison of the effect of soil plasticity on nonlinear soil behavior predicted by the calibrated model and empirical curves proposed by Vucetic and Dobry (1991).....

    [...]

  • ...1 1 Shearing Strain, γ , % Vucetic and Dobry (1991) Non-Plastic PI = 15 % PI = 30 % PI = 50 % PI = 100 % PI = 200 % (b)...

    [...]

  • ...This trend agrees with all empirical curves presented in the literature, which show the effect of PI on normalized modulus reduction and material damping curves, (e.g., Sun et al., 1988; Idriss, 1990; Vucetic and Dobry, 1991; and Ishibashi and Zhang, 1993)....

    [...]

Journal ArticleDOI
TL;DR: In this article, a simple relationship is proposed to relate the shear modulus of a cohesionless soil to a modulus stiffness coefficient, which is a soil property and depends on the characteristics of the soil, and the effective mean principal stress at any point in the soil.
Abstract: Data are presented concerning the shear modulus and damping ratios of sands and gravelly soils as determined by laboratory and field tests. A simple relationship is proposed to relate the shear modulus of a cohesionless soil to a modulus stiffness coefficient, which is a soil property and depends on the characteristics of the soil, and the effective mean principal stress at any point in the soil. Values for the modulus coefficient at low strains are suggested, and it is shown that these values for sands can be estimated from the standard penetration resistance of the sand. Values for gravels are generally greater than those for sands by factors ranging from 1.35–2.5. Suggestions are also made for determining the variation of shear modulus with shear strain and the damping ratios for both sandy and gravelly soils.

945 citations


"Development of a new family of norm..." refers background or methods in this paper

  • ...10, the empirical curves proposed by Seed et al. (1986) are presented....

    [...]

  • ...%) predicted by the calibrated model and empirical curves proposed for sands by Seed et al. (1986) .......................................................................................... 299 Figure 12.2 Comparison of the effect of soil plasticity on nonlinear soil behavior predicted by the…...

    [...]

  • ...10 Empirical (a) normalized modulus reduction, and (b) material damping curves proposed for sands by Seed et al. (1986) .......... 236 Figure 9.11 Comparison of the effect of confining pressure on nonlinear soil behavior of sand (PI = 0 %) predicted by the calibrated model and empirical curves proposed for sands by Seed et al. (1986) ....

    [...]

  • ...1 Comparison of the effect of confining pressure on nonlinear soil behavior of sand (PI = 0 %) predicted by the calibrated model and empirical curves proposed for sands by Seed et al. (1986) ....

    [...]

  • ...116 Figure 5.6 Empirical (a) normalized modulus reduction, and (b) material damping curves proposed by Seed et al. (1986).............................

    [...]