Comparison of Equivalent Linear and Nonlinear Site Response Analysis Results and Model to Estimate Maximum Shear Strain

Carlton, Brian; Tokimatsu, Kohji

doi:10.1193/021215eqs029mr1

Cited by 25 publications

(9 citation statements)

References 22 publications

(41 reference statements)

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“…2020, 10, 2999 9 of 23 is 16.17%. The calculation results of the nonlinear dynamic constitutive model are generally smaller than those of the equivalent linear method, which is consistent with previous research [35,50,51] and is necessary to represent the actual behavior of the soil. In addition, the differences of peak responses and relative differences for five typical ground motions selected from different earthquakes are further calculated and listed in Table 2.…”

Section: Justification Of the Davidenkov Model In Ground Motion Propa...supporting

confidence: 88%

Energy Spectrum Study and Optimal Design of an Inerter-Based Structure Considering the Underlying Soil

2020

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As a classic inerter system, the tuned viscous mass damper (TVMD) has been proven to be efficient for vibration control. It is characterized by an amplification effect, where the deformation of the dashpot in the TVMD can be larger than that of a single dashpot, providing enhanced energy dissipation. However, the contribution of this system to the enhancement of the energy dissipation quantity and vibration control remains unclear. To deal with this, and considering the underlying soil, this study proposes a systematic energy spectrum analysis framework for the single-degree-of-freedom (SDOF) element controlled by a tuned viscous mass damper (TVMD) in order to reveal the energy characteristics of the TVMD and develop an optimal energy dissipation enhancement-based design. The proposed energy spectrum analysis includes ground motion propagation and energy balance analysis. Considering the underlying soil, energy balance analysis is performed for a series of SDOF elements connected to the TVMD, which yields a fitted input energy spectrum for optimal design of the TVMD. Extensive parametric analysis reveals energy characteristics of the TVMD compared with a single dashpot, yielding an optimal energy dissipation enhancement-based design. The findings of this study show that by considering the soil underneath the inerter-based structure, the developed energy spectrum analysis quantifies the degree of energy dissipation enhancement effect of the TVMD. The proposed design is effective in guaranteeing the target of displacement control, which optimizes the efficiency and quantity of the TVMD for energy dissipation, relieving the energy-dissipation burden on the primary element.

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Section: Justification Of the Davidenkov Model In Ground Motion Propa...supporting

confidence: 88%

Energy Spectrum Study and Optimal Design of an Inerter-Based Structure Considering the Underlying Soil

2020

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“…Besides these studies, others have focused on the predictions between equivalent-linear and nonlinear site response models (without comparisons to observations) for the purpose of developing recommendations for the thresholds at which these model types deviate (e.g., Rathje and Kottke [2011], Assimaki and Li [2012], Carlton and Tokimatsu [2016], Kim et al [2016], and Eskandarinejad et al [2017]; the thresholds in these latter three studies use a proxy for the maximum shear strain proportional to PGV / VS30, where PGV is the peak ground velocity and VS30 is the time-averaged shear-wave velocity in the upper 30 m of the subsurface). Additional studies have focused on the influence of site response model input parameters; for example, Assimaki et al (2006), Rathje et al (2010), and Griffiths et al (2016b) evaluated the effects of assumed shear-wave velocity profiles on site response predictions, and Afshari and Stewart (2017) evaluated the effect of small-strain damping using 21 downhole arrays in California.…”

Section: Introductionmentioning

confidence: 99%

Challenges in Predicting Seismic Site Response with 1D Analyses: Conclusions from 114 KiK‐net Vertical Seismometer Arrays

Kaklamanos

Bradley

2018

Bulletin of the Seismological Society of America

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Nonlinear soil behavior often exhibits a strong influence on surficial ground motions, and seismic site response models attempt to quantify these effects. However, site response models exhibit large uncertainties and can on occasion poorly replicate observed ground motions. In this study, nonlinear total-stress site response model predictions for 5626 ground motions at 114 KiKnet vertical seismometer arrays are calculated and compared to observed ground motions and predictions from linear and equivalent-linear analyses. Using this large database of onedimensional (1D) site response model predictions, a variety of statistical analyses are performed to quantify model bias and precision, and these statistical analyses are paired with physical insights into site and ground-motion behavior. As expected, there are deviations between the linear, equivalent-linear, and nonlinear site response constitutive models at large shear strains. When using cumulative Arias Intensity to assess the temporal evolution of model uncertainty, the equivalent-linear model is shown to have excessive bias early in the ground motion record, but this bias is obscured when the entire record is considered. Another less intuitive result is that on average, across the entire dataset, all models-linear, equivalent-linear, and nonlinear-tend to underpredict high-frequency ground motions in the aggregate. A number of physical hypotheses are explored to provide insights into these persistent biases. The use of a depth-dependent shear-wave velocity gradient, in particular, has a significant impact on the model bias, even more so than changing the constitutive model for dynamic soil behavior. Using an unprecedented number of sites and ground motions, the results of this study provide insights for the present limitations of, and potential improvements to, 1D site response model predictions.

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“…This study compared the differences between parameters calculated from site response analyses using different SR values with standard deviations from GMPEs. The differences are defined as non-negligible when they are greater than one quarter of the standard deviation calculated by a GMPE for the same parameter, similar to Carlton and Tokimatsu (2016). According to this criterion, the value of SR has a non-negligible effect on the predicted values of γ max , T m , and Sa at short and long periods (see Table 1 and Figure 5).…”

Section: Discussionmentioning

confidence: 99%

“…Figure 2 shows the shear wave velocity profiles. Carlton and Tokimatsu (2016) give more details on the sites and ground motions used in the site response analyses.…”

Section: Site Response Analysesmentioning

confidence: 99%

“…To help put the magnitude of the differences in perspective, this section compares the absolute value of the predicted loess lines (the general trend of the δ values) found in this study with standard deviations calculated from ground motion prediction equations for similar parameters ( σ GMPE ). This study defines the non-negligible δ value ( δ nn ) as one-quarter of the σ GMPE value for a similar parameter, which is the same criterion used in Carlton and Tokimatsu (2016) to measure the difference between equivalent linear and nonlinear analyses.…”

Section: Comparison Of Differences With Standard Deviations From Gmpesmentioning

confidence: 99%

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Ground Motion Parameter Sensitivity to Shear Strain Ratio in Equivalent Linear Analyses

Carlton

2016

Earthquake Spectra

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This paper compares 5,715 equivalent linear analyses to examine the sensitivity of the results to the shear strain ratio ( SR). The results show that as SR increases, equivalent linear analyses predict larger values of maximum shear strain ( γ max), peak ground displacement, mean period ( T m), and spectral acceleration ( Sa) at long periods, smaller values of peak ground acceleration ( PGA), Arias intensity, significant duration, and Sa at short periods, and similar values of peak ground velocity and Sa at middle periods. SR has a non-negligible effect on predicted values of γ max, T m, and Sa at short and long periods. This study also compares measured values from 80 ground motions and six vertical arrays with the results of equivalent linear analyses conducted using two methods to calculate SR. The results show that using SR = 0.65 gives a 2–10% better fit than using SR = ( M − 1)/10, where M is the earthquake magnitude.

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Comparison of Equivalent Linear and Nonlinear Site Response Analysis Results and Model to Estimate Maximum Shear Strain

Cited by 25 publications

References 22 publications

Energy Spectrum Study and Optimal Design of an Inerter-Based Structure Considering the Underlying Soil

Energy Spectrum Study and Optimal Design of an Inerter-Based Structure Considering the Underlying Soil

Challenges in Predicting Seismic Site Response with 1D Analyses: Conclusions from 114 KiK‐net Vertical Seismometer Arrays

Ground Motion Parameter Sensitivity to Shear Strain Ratio in Equivalent Linear Analyses

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