Comparison Study of One-Dimensional Site Response Analysis Methods

2016 ◽  
Vol 32 (2) ◽  
pp. 1075-1095 ◽  
Author(s):  
Chi-Chin Tsai ◽  
Chun-Way Chen
Keyword(s):  
Amplification Factor ◽  
Site Response ◽  
Nonlinear Behavior ◽  
Response Analysis ◽  
Comparison Study ◽  
Soil Response ◽  
One Dimensional ◽  
Site Factor ◽  
Nonlinear Properties ◽  
Numerical Approaches

The ground responses computed via frequency domain (FD) equivalent linear (EQL) and time domain (TD) nonlinear (NL) methods can considerably differ because of the constitutional differences in numerical approaches, damping formulations, and modeling of nonlinear soil response. To systematically evaluate the TD-NL and FD-EQL approaches, this study performs TD-NL, TD-EQL, and FD-EQL site response analyses considering different input motions, intensities of input motions, depths of soil columns, and nonlinear properties. Results show that the differences in the site responses calculated by the two approaches are highly influenced by dynamic soil properties, the significant nonlinearities of which (e.g., sand) tend to magnify such differences and the high damping of which tend to mitigate the differences. An amplification factor by TD-NL exhibits more nonlinearity than that by FD-EQL but agrees well with the nonlinearity in the 2015 NEHRP site factor, indicating that TD-NL is a better method than FD-EQL for modeling soil nonlinear behavior.

scholarly journals Harmonic-Modal Hybrid Reduced Order Model for the Efficient Integration of Non-Linear Soil Dynamics

2020 ◽  
Vol 10 (19) ◽  
pp. 6778 ◽  
Author(s):  
Claudia Germoso ◽  
Jean Louis Duval ◽  
Francisco Chinesta
Keyword(s):  
Site Response ◽  
Laboratory Data ◽  
Nonlinear Behavior ◽  
Forced Response ◽  
Equivalent Linearization ◽  
Response Analysis ◽  
Damping Factor ◽  
Alternative Analysis ◽  
Soil Response ◽  
Non Linear

Nonlinear behavior of soils during a seismic event has a predominant role in current site response analysis. Soil response analysis, and more concretely laboratory data, indicate that the stress-strain relationship of soils is nonlinear and exhibits hysteresis. An equivalent linearization method, in which non-linear characteristics of shear modulus and damping factor of soils are modeled as equivalent linear relations of the shear strain is usually applied, but this assumption, however, may lead to a conservative approach of the seismic design. In this paper, we propose an alternative analysis formulation, able to address forced response simulation of soils exhibiting their characteristic nonlinear behavior. The proposed approach combines ingredients of modal and harmonic analyses enabling efficient time-integration of nonlinear soil behaviors based on the offline construction of a dynamic response parametric solution by using Proper Generalized Decomposition (PGD)-based model order reduction technique.

Significance of ground motion time step in one dimensional site response analysis

2012 ◽  
Vol 43 ◽  
pp. 202-217 ◽  
Author(s):  
Camilo Phillips ◽  
Albert R. Kottke ◽  
Youssef M.A. Hashash ◽  
Ellen M. Rathje
Keyword(s):  
Ground Motion ◽  
Site Response ◽  
Site Response Analysis ◽  
Response Analysis ◽  
Time Step ◽  
One Dimensional ◽  
Motion Time

Relative Differences between Nonlinear and Equivalent-Linear 1-D Site Response Analyses

2016 ◽  
Vol 32 (3) ◽  
pp. 1845-1865 ◽  
Author(s):  
Byungmin Kim ◽  
Youssef M. A. Hashash ◽  
Jonathan P. Stewart ◽  
Ellen M. Rathje ◽  
Joseph A. Harmon ◽  
...  
Keyword(s):  
Peak Velocity ◽  
Site Response ◽  
Practical Significance ◽  
Response Analysis ◽  
Site Conditions ◽  
One Dimensional ◽  
Equivalent Linear ◽  
Stable Continental Regions ◽  
Input Motion ◽  
Relative Differences

This study investigates the conditions for which one-dimensional (1-D) nonlinear (NL) site response analysis results are distinct from equivalent-linear (EL) results and provides guidance for predicting when differences are large enough to be of practical significance. Relative differences in spectral accelerations and Fourier amplitudes computed from NL and EL analyses are assessed for a range of site conditions and for suites of input motions appropriate for active crustal and stable continental regions. Among several considered parameters, EL/NL differences are most clearly dependent on shear strain index ( I γ), defined as the ratio of input motion peak velocity to time-averaged shear-wave velocity in the top 30 m of the soil profile. For small I γ (generally under 0.03%), EL and NL results are practically identical, whereas at larger strains, differences can be significant for frequencies >0.3 Hz. Frequency-dependent I γ values are recommended for conditions above which NL analyses are preferred to EL.

κ0 for soil sites: Observations from KiK-net sites and their use in constraining small-strain damping profiles for site response analysis

2019 ◽  
Vol 36 (1) ◽  
pp. 111-137 ◽  
Author(s):  
Boqin Xu ◽  
Ellen M Rathje ◽  
Youssef Hashash ◽  
Jonathan Stewart ◽  
Kenneth Campbell ◽  
...  
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Site Response ◽  
Strong Motion ◽  
Small Strain ◽  
Site Amplification ◽  
Site Response Analysis ◽  
Response Analysis ◽  
One Dimensional

Small-strain damping profiles developed from geotechnical laboratory testing have been observed to be smaller than the damping inferred from the observed site amplification from downhole array recordings. This study investigates the high-frequency spectral decay parameter ( κ0) of earthquake motions from soil sites and evaluates the use of κ0 to constrain the small-strain damping profile for one-dimensional site response analysis. Using data from 51 sites from the Kiban-Kyoshin strong motion network (KiK-net) array in Japan and six sites from California, a relationship was developed between κ0 at the surface and both the 30-m time-averaged shear wave velocity ( V s30) and the depth to the 2.5 km/s shear wave velocity horizon ( Z2.5). This relationship demonstrates that κ0 increases with decreasing V s30 and increasing Z2.5. An approach is developed that uses this relationship to establish a target κ0 from which to constrain the small-strain damping profile used in one-dimensional site response analysis. This approach to develop κ0-consistent damping profiles for site response analysis is demonstrated through a recent site amplification study of Central and Eastern North America for the NGA-East project.

Evaluation of One-Dimensional Multi-Directional Site Response Analyses Using Geotechnical Downhole Array Data in California and Japan

2018 ◽  
Vol 34 (1) ◽  
pp. 349-376 ◽  
Author(s):  
Gangjin Li ◽  
Ramin Motamed ◽  
Stephen Dickenson
Keyword(s):  
Site Response ◽  
Ground Motions ◽  
Soil Column ◽  
Response Analysis ◽  
Engineering Practice ◽  
Backbone Curve ◽  
One Dimensional ◽  
Strain Behavior ◽  
Linear Elastic ◽  
Downhole Array

This study presents a comprehensive investigation of one-dimensional (1-D) site response analysis (SRA) to predict the dynamic response of soil deposits under earthquake loading utilizing the recordings at selected borehole arrays. Seven instrumented downhole arrays in California and Japan were studied using 41 recorded ground motions that cover a broad range of intensities. The arrays were initially assessed in terms of effectiveness of 1-D SRA using taxonomy screening. Furthermore, LS-DYNA, an advanced Finite Element (FE) program, was employed to develop the 1-D soil column models for the SRA of these arrays. The soil stress-strain behavior was characterized with three different models including one linear elastic and two nonlinear backbone curve formulations. All predictions were compared to the measured ground motions to quantify the model biases and uncertainties. Lastly, the practical limitations of 1-D SRA models considered herein are identified, and recommendations are provided to assess the usefulness of the predictions in engineering practice.

scholarly journals Does the One-Dimensional Assumption Hold for Site Response Analysis? A Study of Seismic Site Responses and Implication for Ground Motion Assessment Using KiK-Net Strong-Motion Data

2019 ◽  
Vol 35 (2) ◽  
pp. 883-905 ◽  
Author(s):  
Marco Pilz ◽  
Fabrice Cotton
Keyword(s):  
Ground Motion ◽  
Site Effects ◽  
Site Response ◽  
Three Dimensional ◽  
Strong Motion ◽  
Site Response Analysis ◽  
Response Analysis ◽  
One Dimensional ◽  
Ground Motion Variability ◽  
The One

The one-dimensional (1-D) approach is still the dominant method to incorporate site effects in engineering applications. To bridge the 1-D to multidimensional site response analysis, we develop quantitative criteria and a reproducible method to identify KiK-net sites with significant deviations from 1-D behavior. We found that 158 out of 354 show two-dimensional (2-D) and three-dimensional (3-D) effects, extending the resonance toward shorter periods at which 2-D or 3-D site effects exceed those of the classic 1-D configurations and imposing an additional amplification to that caused by the impedance contrast alone. Such 2-D and 3-D effects go along with a large within-station ground motion variability. Remarkably, these effects are found to be more pronounced for small impedance contrasts. While it is hardly possible to identify common features in ground motion behavior for stations with similar topography typologies, it is not over-conservative to apply a safety factor to account for 2-D and 3-D site effects in ground motion modeling.

Nonlinear Site Amplification Factors for Constraining the NGA Models

2008 ◽  
Vol 24 (1) ◽  
pp. 243-255 ◽  
Author(s):  
Melanie Walling ◽  
Walter Silva ◽  
Norman Abrahamson
Keyword(s):  
Site Response ◽  
Linear Method ◽  
Site Amplification ◽  
Parametric Models ◽  
Imperial Valley ◽  
Soil Response ◽  
Amplification Factors ◽  
Nonlinear Properties ◽  
Ground Motion Model ◽  
Equivalent Linear Method

Amplification factors computed from the equivalent-linear method using the program RASCALS are used to develop constraints on the nonlinear soil response for possible use by the NGA ground-motion model developers. The site response computations covered site conditions with average VS30 values ranging from 160 to 900 m/s, soil depths from 15 to 914 m, and peak accelerations of the input rock motion ( VS30=1100 m/s) between 0.01 g and 1.5 g. Four sets of nonlinear properties of the soils are used: EPRI, Peninsular Range, Imperial Valley, and Bay Mud. The first two soil models are used for VS30≥270 m/s and the later two are used for VS30≤190 m/s. Simple parametric models of the nonlinear amplification factors that are functions of the PGA on rock and VS30 are developed for the EPRI and Peninsula models.

scholarly journals Linear One-dimensional Site Response Analysis in the presence of stiffness-less free surface for certain power-law heterogeneities

2020 ◽  
Author(s):  
Joaquin Garcia-Suarez ◽  
Domniki Asimaki
Keyword(s):  
Free Surface ◽  
Power Law ◽  
Site Response ◽  
Small Strain ◽  
Site Response Analysis ◽  
Response Analysis ◽  
Physical Explanation ◽  
One Dimensional ◽  
Soil Deposits ◽  
Heterogeneous Soil

We revisit previous results in small-strain One-dimensional Site Response Analysis of heterogeneous soil deposits. Specifically, we focus on sites whose shear modulus distribution is described by means of a power law that yields zero stiffness at the free surface. First, we show that in some cases (which we characterize in detail) considerations of energy finitude should prevail over considerations of vanishingtractions at the free-surface, as these may pose acuter constrains. We re-evaluate previous contributions in light of this result. Second, we analyze the previously-reported occurrence of “energy accumulation in upper layers”, providing a physical explanation for it. In passing, we supply estimates of the natural frequencies, and compare these with our previous results.

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