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.

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.

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

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.

The effect of soil nonlinearity on high-frequency spectral decay and implications for site response analysis

2021 ◽  
pp. 875529302098199
Author(s):  
Boqin Xu ◽  
Ellen M Rathje
Keyword(s):  
Shear Strain ◽  
High Frequency ◽  
Site Response ◽  
Small Strain ◽  
Site Response Analysis ◽  
Response Analysis ◽  
Large Strains ◽  
Soil Nonlinearity ◽  
Equivalent Linear ◽  
Generate Surface

This study uses recorded ground motions at soil sites over a range of shaking intensities to investigate the effects of soil nonlinearity on the high-frequency spectral decay, as quantified by the parameter [Formula: see text]. Equivalent-linear site response analyses indicate that [Formula: see text] should increase significantly with increasing shear strain and ground motion intensity due to increases in soil damping. However, using more than 2500 motions from 32 sites, this study shows that [Formula: see text] does not vary systematically with the induced shear strain but instead remains at its small-strain value. This observation indicates that high-frequency components of motion are consistent with small-strain damping, rather than the strain-compatible damping used in site response analysis. It is demonstrated that equivalent-linear site response analyses for large strains can be modified to generate surface motions with more realistic high-frequency content by scaling the predicted surface motion to fit the small-strain [Formula: see text] or by employing frequency-dependent soil properties that account for the frequency dependence of the induced strains.

Simplified Model for Small-Strain Nonlinearity and Strength in 1D Seismic Site Response Analysis

2016 ◽  
Vol 142 (9) ◽  
pp. 04016042 ◽  
Author(s):  
David R. Groholski ◽  
Youssef M. A. Hashash ◽  
Byungmin Kim ◽  
Michael Musgrove ◽  
Joseph Harmon ◽  
...  
Keyword(s):  
Site Response ◽  
Small Strain ◽  
Simplified Model ◽  
Site Response Analysis ◽  
Response Analysis ◽  
Seismic Site Response

scholarly journals One Dimensional Site Response Analysis of Liquefaction Potential along Coastal Area of Bengkulu City, Indonesia

2018 ◽  
Vol 20 (2) ◽  
pp. 57
Author(s):  
Lindung Zalbuin Mase
Keyword(s):  
Coastal Area ◽  
Pore Water Pressure ◽  
Site Response ◽  
Water Pressure ◽  
Site Response Analysis ◽  
Response Analysis ◽  
Liquefaction Potential ◽  
Excess Pore Water Pressure ◽  
One Dimensional ◽  
Excess Pore

This paper presents one dimensional non-linear site response analysis of liquefaction potential caused by the 2000 and the 2007 earthquakes in coastal area of Bengkulu City, Bengkulu, Indonesia. Site investigations, including Standard Penetration Test (SPT) and shear wave velocity (VS) measurement, were conducted in three locations along the coastal area of Bengkulu City. Further, the site investigation data were used in simulation of one-dimensional non-linear site response analysis by applying the synthetic ground motions at bedrock. The results show that liquefaction could happen at 0 to 1.5 m deep. This was indicated by the excess pore water pressure ratio (ru) which exceeded one. At depth between 1.5 m and 20 m, the excess pore water pressure almost reached the initial effective stress decreasing the effective confinement pressure close to zero. The results also indicated that liquefaction is possible to occur in this depth range if a stronger earthquake occurs.

Rate-dependent soil behavior in seismic site response analysis

2008 ◽  
Vol 45 (4) ◽  
pp. 454-469 ◽  
Author(s):  
Duhee Park ◽  
Youssef M.A. Hashash
Keyword(s):  
Shear Modulus ◽  
Site Response ◽  
Rate Dependence ◽  
Site Response Analysis ◽  
Response Analysis ◽  
Soil Behavior ◽  
One Dimensional ◽  
Rate Dependent ◽  
Seismic Site Effects ◽  
Laboratory Test Results

One-dimensional site response analysis is widely used in estimating local seismic site effects. The soil behavior in the analysis is often assumed to be independent of the rate of seismic loading. Laboratory test results, on the other hand, indicate that cyclic cohesive soil behavior is influenced by the rate of loading. Three models of rate-dependent dynamic soil behavior were derived based on available laboratory data. The models were implemented and evaluated in a modified one-dimensional equivalent linear site response analysis approach. Results show that rate-dependent shear modulus and damping can have a pronounced influence on propagated weak ground motion but a secondary influence on propagated strong motion. Rate dependence of the damping ratio has a greater impact on the computed response than rate dependence of the shear modulus. This paper highlights the relevance of the compatibility between frequencies at which dynamic soil properties are measured and their use in site response analysis.

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