Improved Approach for Modeling Nonlinear Site Response of Highly Strained Soils: Case Study of the Service Hall Array in Japan

Motamed, Ramin; Stanton, Kevin; Almufti, Ibrahim; Ellison, Kirk; Willford, Michael

doi:10.1193/121714eqs212m

Cited by 18 publications

(16 citation statements)

References 15 publications

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“…However, a bi-directional shaking model can more realistically reproduce the physical process in which seismic energy propagates to the ground surface and could potentially dissipate in all directions. The importance of bidirectional shaking in site response has been reported by many researchers such as Stewart et al (2008), Bolisetti et al (2014), and Motamed et al (2015Motamed et al ( , 2016. In this study, the recorded acceleration data at the deepest downhole sensors of each array were input in both horizontal directions (bidirectional shaking) simultaneously to better represent the complex multidirectional ground shakings.…”

Section: -D Sra Methodologymentioning

confidence: 93%

“…Site characterization data for the SHA and KK5 were obtained from TEPCO (2007). Similar to the approach from Motamed et al (2016), an updated shear wave velocity profile was adopted for the SHA in this study to incorporate P-S suspension logging data, as described in Yee et al (2013).…”

Section: Selected Arraysmentioning

confidence: 99%

“…For the SHA and KK5, seven (including two strong ground motions) and four (including two strong ground motions) sets of recordings were analyzed, respectively. The raw data obtained from TEPCO was filtered in the same manner as described by Motamed et al (2016). In total, 41 ground motions ranging in amplitude from PGA at the surface of 0.004g to 0.98g were utilized in this study and summarized in Table A1 in online Appendix A.…”

Section: Ground Motion Datamentioning

confidence: 99%

“…LS-DYNA is an advanced finite element (FE) program with versatile capabilities for modeling the dynamic response of soils. Furthermore, LS-DYNA has been used to approximate nonlinear 1-D SRA by other researchers (e.g., Bolisetti et al 2014, Motamed et al 2016) and has been shown in these investigations to produce results that can be considered reasonably accurate for practical applications.…”

Section: Introductionmentioning

confidence: 99%

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

Motamed

Dickenson³

2018

Earthquake Spectra

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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.

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Section: -D Sra Methodologymentioning

confidence: 93%

Section: Selected Arraysmentioning

confidence: 99%

Section: Ground Motion Datamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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

Motamed

Dickenson³

2018

Earthquake Spectra

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“…The results from the analyses are in general accord with the records obtained after the earthquake and highlight the utility and versatility of the modified models. Tables Table 1: Assumed soil types and unit weights used in analysis (Motamed et al 2016) .......... 15 Table 2: KKNPP soil-specific calibration parameters for the Duku et al (2008) model. ........ 17 Table 3: Correction Factor, C2D, for Two-Dimensional Shaking (Lasley and Green 2012).…”

Section: General Audience Abstractmentioning

confidence: 99%

Expanded Byrne model for evaluating seismic compression

Jiang

Green

Taylor³

2020

Earthquake Spectra

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Seismic compression is the accrual of contractive volumetric strain in unsaturated or partially saturated sandy soils during earthquake shaking and has caused significant distress to overlying and nearby structures. The phenomenon can be well characterized by load-dependent, interaction macro-level fatigue theories. Toward this end, the Byrne cyclic shear-volumetric strain coupling model is expanded and calibrated for evaluating seismic compression for several soil types. In addition, the model was transformed to allow it to be implemented in a “simplified” manner, in addition to the original “non-simplified” formulation. Both implementation approaches are used to analyze a site in Japan impacted by the 2007, Mw6.6 Niigata-ken Chuetsu-oki earthquake. The results from the analyses are in general accord with the post-earthquake field observations and highlight the sensitivity of predicted magnitude of the seismic compression to the input variables used and modeling assumptions (e.g. relative density of the soil, magnitude of the volumetric threshold strain, orientation of the ground motions, settlement of soils below the ground water table, and accounting for multidirectional shaking). Although additional studies are needed to further validate the findings presented herein, estimation of relative density and threshold shear strain of the soil and ground motion orientation individually have moderate-to-significant influence on the computed magnitude of seismic compression, but they have a significant influence when taken in combination. Also, the seismic compression models can seemingly be used to predict the settlement in fully saturated sand when the excess pore water pressures are limited. Finally, accounting for multidirectional shaking has a significant influence on the computed magnitude of seismic compression.

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Impacts of Transition Piece Designs on the Resilience of Large Offshore Wind Turbines Subject to Combined Earthquake, Wind and Wave Loads and Soil‐Structure Interaction

Fairley,

Fatahi,

Hokmabadi

2024

Earthq Engng Struct Dyn

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The urgent global drive to mitigate greenhouse gas emissions has significantly boosted renewable energy production, notably expanding offshore wind energy across the globe. With the technological evolution enabling higher‐capacity turbines on larger foundations, these installations are increasingly situated in earthquake‐prone areas, underscoring the critical need to ensure their seismic resilience as they become a pivotal component of the global energy infrastructure. This study scrutinises the dynamic behaviour of a 15 MW offshore wind turbine (OWT) under concurrent earthquake, wind and wave loads, focusing on the performance of the ultra‐high‐strength cementitious grout that bonds the monopile to the transition piece. Employing LS DYNA for numerical simulations, we explored the seismic responses of four OWT designs with diverse transition piece cone angles, incorporating nonlinear soil springs to model soil‐structure interactions (SSIs) and conducting a site response analysis (SRA) to account for local site effects on ground motion amplification. Our findings reveal that transition pieces with larger cone angles exhibit substantially enhanced stress distribution and resistance to grout damage, evidenced by decreased ovalisation in the coned sections of the transition piece and monopile, and improved bending flexibility. The observed disparities in damage across different cone angles highlight shortcomings in current design guidelines pertaining to the prediction of grout stresses in conical transition piece designs, with the current code‐specified calculations predicting higher stresses for transition piece designs with larger cone angles. This study also highlights the code's limitations when accounting for grout damage induced by stress concentrations in the grouted connections under seismic dynamic loading conditions. The results of the study demonstrate the need for refinement of these guidelines to improve the seismic robustness of OWTs, thereby contributing to the resilience of renewable energy infrastructure against earthquake‐induced disruptions.

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Improved Approach for Modeling Nonlinear Site Response of Highly Strained Soils: Case Study of the Service Hall Array in Japan

Cited by 18 publications

References 15 publications

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

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

Expanded Byrne model for evaluating seismic compression

Impacts of Transition Piece Designs on the Resilience of Large Offshore Wind Turbines Subject to Combined Earthquake, Wind and Wave Loads and Soil‐Structure Interaction

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