Engineering Tools

ACS SASSI NQA

It is a highly specialized user-friendly, finite element computer code on the MS Windows PC platforms for performing efficiently linear or nonlinear 3D dynamic soil-structure interaction (SSI) analyses for complex geometry foundations subjected to spatially varying incoherent motions or multiple support seismic excitations. ACS SASSI that is a modern software coded using advanced features of VC++ and Fortran90+, languages, provides a set of totally new engineering capabilities for SSI analysis in comparison with the original SASSI developed by Professor J. Lysmer and co-workers at University of California at Berkeley.

2022-2024 SELECTED PAPERS ON ACS SASSI APPLICATION TO SEISMIC SSI ANALYSIS:

SMiRT27 CONFERENCE, YOKOHAMA, JAPAN, MARCH 3-8, 2024

Division V Special Session on "Seismic SSI Including Nonlinear RC/SC Structures and Base-Isolated Structures"
SSSI Effects on SMRs: "Seismic SSSI Effects for Deeply Embedded SMR with SC/RC Walls Under Severe Earthquakes in Nonuniform Soils" 
Incoherent SSI: "Nonlinear SSI Analysis Study for RC Building on Soil Site in Tokyo Area in Compliance with JEAC 4601 Recommendations for Structure Modeling"
Base-Isolated SMR: "Study on Seismic SSI Effects for Deeply Embedded Base-Isolated SMR on Different Site Conditions"
Methodololgy Study:  "Applicabiliy of Equivalent Linear Three-Dimensional FEM Analysis for Reinforced Concrete Shear Walls"

Division III Special Session on "Nonlinear Structure Fluid-Soil-Structure Interaction (FSSI) Analysis"
Deeply Embedded Structures::  "Study on Fluid-Structure-Soil Interaction (FSSI) Effects for A Deeply Embedded Nuclear Facility wih A Large-Size Pool Under Severe Earthquake. Part 1: Linear SSI"
Deeply Embedded Structures:  "Study on Fluid-Structure-Soil Interaction (FSSI) Effects for A Deeply Embedded Nuclear Facility wih A Large-Size Pool Under Severe Earthquake. Part 2: Nonlinear SSI"
Large-Size Pools: "Hydroelasticity and Nonlinearity Modelling for Fluid-Soil-Structure Interaction (FSSI) Analysis of Large-Size Water Nuclear Reactor Pools"
Pile-Foundations: "Efficient Seismic FSSI Analysis Methodology of Large-Size Tanks on Piles Including Soil and RC Structure Nonlinear Hysteretic Behavior"

Applications of FVROM-INT Approach for Deeply Embedded SMR SSSI Models
Detailed SMR SSSI Model:"Site-Specific SSSI Analysis for Deeply Embedded SMR Using Flexible Volume Reduced-Order Modeling with Impedance Interpolation (FVROM-INT)"
Coherent and Incoherent SSSI Effects "Seismic SSSI Analysis for Deeply Embedded SMR Structure Founded on Different Nonuniform Soil Site Conditions"


SMiRT26 CONFERENCE, BERLIN/POSTDAM, GERMANY, JULY 10-15, 2022.

SMRs:"Studies on SMR SSI Responses Under Nonvertically Propagating Seismic Waves for Nonunifform Soils With Abrupt Stiffness Variations"
SMRs: "Efficient Linear and Nonlinear Seismic SSI Analysis of Deeply Embedded Structures Using Flexible Volume Reduced-Order Modeling"
Pile Foundations: "Seismic SSI Analysis of RB Complex on Piles Including Effects of Motion Incoherency and Nonlinear Soil Behavior"
Probabilistic SSSI: "Probabilistic SSSI Analysis of Reactor and Auxiliary Building without and with Incoherency Effects"
Base Isolation: Seismic SSI Analysis of A Base-Isolated Storage Structure Founded on Firm Soil'

SPECIAL SESSION ON "NONLINEAR SEISMIC SSI ANALYSIS BASED ON BEST ENGINEERING PRACTICES IN US AND JAPAN"
Chairs: Dan M. Ghiocel, GP Technologies, USA, and Yasuo Nitta, SHIMIZU Co., Japan
ABSTRACT: Due to the high seismic site conditions, the nonlinear seismic SSI analysis is required in Japan for the design basis analyses on the NPP structures In many other countries including US, the nonlinear seismic SSI analysis is not required for the design basis analyses by current regulations, except for some special design detailed aspects related to foundation soil interface modeling that need additional research studies. This special session introduces a practical engineering approach for nuclear industry for performing nonlinear seismic SSI analysis of buildings The introduced SSI approach implementation follows the Japanese nonlinear structure modeling and seismic analysis practice for reinforced concrete buildings, and it further extends it to detailed 3 DFEM SSI models. It has a robust engineering foundation, i n compliance with Japan standards (JEAC 4601 2015 JEAC 4618 2009 AIJ RC 2018 and US standards (ACI 318 19 ACI 349 14 ASCE 4 16 ASCE 43 19 for RC and SC wall modeling. The
introduced approach is based on a hybrid SSI approach that uses an iterative scheme which couples the equivalent linear complex frequency SASSI analysis with the nonlinear time domain RC/SC structure analysis. The iterative approach is fast converging in few SSI restart iterations, being attractive to industry due to its accuracy, convenience and affordability, plus its close compliance with standard and regulatory requirements. This special session presents a set of two papers that introduces key modeling and implementation aspects of SSI approach, and another set of three papers that presents few independent verification and validation studies performed by Japan industry, universities and nuclear agency.
PAPERS:
"An Efficient Seismic Nonlinear SSI Approach Based on Best Practices in US and Japan. Part 1:Modeling"
"An Efficient Seismic Nonlinear SSI Approach Based on Best Practices in US and Japan. Part 2:Application"
"Comparative Study using Stick and 3DFEM Nonlinear SSI Models Per JEAC 4601-2015 Recommendations"
"Applicability of Equivalent Linear 3DFEM Analysis of Reactor Buildings to the Seismic Response of a Soil–Structure Interaction System"
"Seismic SSI Analysis of Reactor Building Complex including Foundation Uplift based on JEAC 4601-2015 Recommendations"

2021 NEWS:

2-DAYS ACS SASSI NQA V4.3 WORKSHOP PRESENTATIONS, TOKYO JAPAN, DECEMBER 2-3, 2021 (Slides)
Below are the links to the presentation slides of  the online ACS SASSI NQA workshop entitled "ACS SASSI NQA V4.3 Advances on Seismic SSI Analysis of NPP Structures Using Best Engineering Practices in US and Japan",
Day 1: "Brief Overview of ACS SASSI NQA V4.3 New SSI Capabilities" & "Nonlinear Seismic SSI Analysis Based on Best Practices in US and Japan"
Day 2: "Option UPLIFT Nonlinear Uplift SSI Analysis Per JEAC 4601 Standard" & "Advances for Efficient SSI Modeling of Deeply Embedded SMR"

5-DAYS ACS SASSI V4.3 INTRODUCTORY TRAINING NOTES, UPDATED IN OCTOBER 2021 (Slides)
Below are the links to the presentation notes of the recent 5-days introductory ACS SASSI NQA training entitled" Overview of ACS SASSI NQA V4.3 Application to Seismic SSI Analysis of Safety-Related NPP Buildings" in five parts. Option RVT-SIM not included in the 5-days training.
Part 1 -"Understanding Seismic SSI Effects"
Part 2-"ACS SASSI Methodology"
Part 3-"ACS SASSI NQA V4.3 Software Description and Use"
Part 4-"Description of ACS SASSI Advanced Options A-AA and NON"
Part 5-"Description of ACS SASSI Advanced Options PRO and UPLIFT"

ACS SASSI V4  BRIEF DESCRIPTION OF TECHNICAL CAPABILITIES:
The ACS SASSI V4 is a state-of-the-art engineering analysis tool for performing the seismic analysis of complex, surface, embedded, deeply embedded or buried structures. ACS SASS offers a good engineering balance between numerical sophistication and engineering practice with the intention to provide an affordable safe design for the hazardous facility structures. ACS SASSI includes a totally unique set  of SSI analysis capabilities not existent in other specialized SSI codes, that extended the original linearized SASSI Flexible Volume methodology to nonlinear soil and nonlinear structures, and also probabilistic SRA and SSI, also including incoherent seismic waves using advanced stochastic simulation algorithms. The many added specialized capabilities made ACS SASSI the most complete engineering analysis tool for the seismic SSI analysis of safety-related structures of hazardous facilities. The recent versions included automatic section-cut capabilities and back-bone curve generation for RC walls, and a powerful ACS SASSI-ANSYS integration capability that permits to use the ANSYS modeling capabilities, such as dynamic super-elements or fluid elements necessary for a refined  seismic fluid-SSI analysis. It also includes special 3D HVD base-isolators (acting in horizontal and vertical directions) which outperform the traditional 2D-space LRB (only in horizontal directions), especially in vertical direction, and for incoherent seismic motions that could affect severely the efficiency of base-isolation systems.

The current ACS SASSI NQA Version 4 software includes in addition to the main software three additional advanced SSI analysis options including Option A-AA (ACS SASSI integration with ANSYS), Option PRO (probabilistic site response and SSI per ASCE 4-16 Sections 2 and 5), Option NON (nonlinear concrete shearwall buildings per ASCE 4-16 Section 3) and Option RVT-SIM (SSI analysis based on the random vibration theory combined with stochastic simulation), which are described below:.

i) Option A-AA. The Option A for ACS SASSI-ANSYS interfacing includes an automatic export of the seismic SSI boundary conditions for performing a detailed nonlinear or linear ANSYS stress SSI analysis using either quasi-static or dynamic refined FE models, or computing soil pressure on baseslabs and embedded walls including soil separation effects. The Option AA for the advanced ACS SASSI-ANSYS integration permits to run SSI analysis using directly ANSYS FEA models. The Option AA ANSYS models could include advanced ANSYS FE types, pipes, shells including shear flexibility, coupled nodes, constraint equations, MPC elements, and even fluid elements (FLUID80) and super-elements (MATRIX50). Option AA uses directly the ANSYS FE model dynamic matrices with no need for model conversion to ACS SASSI. More recently, the Option AA includes two SSI analysis options: 1) The Option AA that uses the ACS SASSI solver for the SSI solution, and 2) The Option AA-REDUCE or AA-R that uses the ANSYS solver for the SSI solution in complex frequency. The Option AA-R capability was introduced starting with the 4.1 version. The Option AA-R largely extends the Option AA capability of using directly ANSYS structure FE models for seismic SSI analysis. The Option AA-R ANSYS models are applicable only to the ANSYS Harmonic SSI analysis in complex frequency. To make Option AA-R more practical a reduced-size soil impedance matrix and a reduced-size seismic load vector are used, based on the condensation of the excavated soil impedance full matrix done in the ANALYS module. The frequency-dependent condensed excavated soil matrix and the reduced load vector produced by ACS SASSI is exported to ANSYS as a super-element (MATRIX50 element) that is attached to the ANSYS structure FE model. Option AA-R is a particular useful tool for performing ANSYS Fluid-SSI analysis (including FLUID30 elements) using SASSI methodology.

ii) Option PRO for probabilistic site response analysis (PSRA) and SSI analysis (PSSIA) using efficient LHS simulations. Option PRO is consistent with probabilistic site response and SSI procedures in the coming-soon ASCE 04-2016 standard (in Sections 2 and 5) and the USNRC guidance for computing the FIRS for new licensing applications. The Option PRO probabilistic modelling includes: i) Response spectra shape model for the seismic motion input, ii) Soil shear wave velocity Vs and hysteretic damping D profiles, defined for each soil layer for low shear strain values, iii) Soil shear modulus G and hysteretic damping D, as random functions of the soil shear strain values for each soil layer, and iv) Equivalent linear values for the effective structural stiffness and damping for each group of elements depending on the stress levels in different parts of the structure.

iii) Option NON or nonlinear structure SSI analysis uses a fast hybrid time-complex frequency approach based on a iterative equivalent-linearization for each nonlinear RC wall structure SSI analysis as functions of the local deformation of the wall panels. It is hundreds of times faster and much more robust than the time-domain integration nonlinear SSI approaches available in other FEA codes. Option NON is applicable to the reinforced concrete structures by simulating the concrete cracking and post-cracking behavior in low-rise shearwalls for design-level or beyond-design-level seismic inputs, or to model the hysteretic behavior of the seismic base-isolators, as LRB or FP isolators. The new upgrade of Option NON to be released in November 2020  includes a significant new development with several new software modules, to include both shear and bending effects in place walls based on the latest engineering practices in US and Japan (ACI-318, ASCE 4/43 standards in US, and JEAC 4601 and AIJ RC standards in Japan).

iv) Option RVT-SIM. The RVT-SIM approach combines the Random Vibration Theory (RVT) in complex frequency domain with the stochastic simulation (SIM) in time domain for efficiently computing the maximum SSI responses. The RVT-SIM approach input is the ground response spectra (GRS). No input time histories are required in this approach. The RVT-SIM approach uses the input GRS to compute the ground power spectral density (GPSD), and then, used the stochastic simulation to compute the maximum SSI responses based on the computed response power spectral density (RPSD).

v) Option UPLIFT is based on the Japan JEAC 4601-2015 standard recommendations. It uses two nonlinear uplift approaches based on the foundation uplift severity: 1) A simplified nonlinear uplift approach based on a nonlinear static uplift analysis, applicable if the base surface contact ratio is in the 65%-75% range, and 2) A refined nonlinear uplift approach based on a nonlinear time-domain dynamic uplift analysis, applicable if the surface contact ratio is in the 50%-65% range. For contact ratios above 75%, the linear SSI analysis results are considered reasonable accurate. The JEAC 4601 foundation uplift approaches were implemented in the ACS SASSI software by combining the equivalent-linearization of the overall SSI analysis in complex frequency with the nonlinear base uplift analysis occurring at the foundation-soil interface per the JEAC 4601-2015 standard.

ACS SASSI V3 2015 NEWSLETTER entitled "Engineering Advances for Deterministic and Probabilistic, Linear and Nonlinear Seismic SSI Analysis". The newletter describes some key implementations of the ACS SASSI software over last decade. Newer developments are described in more recent papers and presentation shown below.

A SELECTION OF PAPERS AND PRESENTATIONS ON ACS SASSI APPLICATIONS FOR 1998-2020 PERIOD

2020: DOE-NRC Natural Phenomena Hazards Meeting, US NRC Headquarters, Rockville, MD, October 20-22, 2020 (slide presentations)
"Nonlinear Seismic SSI for Reinforced Concrete Buildings in Accordance with Engineering Practices in US and Japan"
"Seismic SSI Analysis of RB Complex on Pile Foundation Including Soil Nonlinear Hysteretic Behavior"
"A Comparative Seismic SSI Study for A Nuclear Island Sitting on Different Base-Isolation Systems"

2020: Architecture Institute of Japan (AIJ) Conference, September 2020 (draft papers):
"3D SSI Analysis of Nuclear Islands Including Foundation Uplift Effects Based on JEAC 4601-2015 Recommendations"

2019: The SMiRT25 Conference, Division III, Charlotte, NC, USA, August 4-9 (papers and slide presentations):
"Sensitivity Studies for Nuclear Island Founded on Piles Including Effects of Seismic Motion Spatial Variation and Local Nonlinear Behavior" and slides are here.
"Probabilistic Seismic SSI Analysis Sensitivity Studies for Base-Isolated Nuclear Structures Subjected to Coherent and Incoherent Motions" and slides are here.
"Extending SASSI Methodology to Seismic SSI Analysis of NPP Buildings on Soil Deposits with Inclined Layering" and slides are here.

2019:  3-Days ACS SASSI V4 Training Notes for the US NRC (Part 1, Part 2 and Part 3), US NRC Headquarters, Rockville, MD, June 25-27, 2019.
Part 1: "ACS SASSI Modeling, Theory and Implementation" (slightly modified and reduced)
Part 2: "Advanced Options A-AA (Integration with ANSYS), PRO (Probabilistic SRA and SSI) and NON (Nonlinear concrete structures or base-isolated structures)" (slightly modified and reduced)
Part 3: "User Guide for ACS SASSI V4 Software & Demos" (slightly modified, without demos and example problems)

2018: Invited Technical Seminar Presentations for the US NRC (Session 1, Session 2 and Session 3), US NRC Headquarters, Rockville, MD, November 15, 2018.
Session 1: "An Overview of Seismic SSI Analysis for Nuclear Structures Based on Various Case SSI Studies" - 9:00am-10:00am
Session 2: "Studies on Seismic SSI Effects for Deeply Embedded Nuclear Reactors, as SMRs" - 10:15am-12:00am (proprietary, not available)
Session 3: "ACS SASSI Capabilities and Options Including Demo Sample Problems" - 1:00pm-3:00pm

2018: DOE-NRC Joint Natural Phenomena Hazards Meeting, US NRC Headquarters, Rockville, MD, October 23-24, 2018 (slide presentations)
ASCE 4-16 Standard-Based Probabilistic Seismic SSI Analysis. Part 1 Application for Design Basis Earthquake (DBE)
ASCE 4-16 Standard-Based Probabilistic Seismic SSI Analysis. Part 1 Application for Beyond Design Basis Earthquake (BDBE)
Limitation of RVT SASSI Approach for Application to Seismic SSI Analysis of Nuclear Structures
Probabilistic Simulation Procedure for Developing Site-Specific Plane-Wave Coherence Functions

2018: 2nd International Nuclear Power Plants: Structures, Risk & Decommissioning, NUPP2018, London, UK, June 11-12, 2018 (papers)
Seismic SSI Effects for Deeply Embedded Nuclear Islands Surrounded by Soft Backfill Soil
Evaluation of Reinforced Concrete Cracking and Post-Cracking Behavior for Nuclear Buildings Under Design and Beyond Design Earthquake Levels
ASCE 4-16 Standard-Based Probabilistic Seismic SSI Analysis for Design-Basis and Fragility Analysis

2017: The SMiRT24 Conference, Special Session SS6 on "ASCE 4-16 BASED PROBABILISTIC/NONLINEAR SOIL-STRUCTURE INTERACTION, Seoul, Korea August 2017 (papers):
"New ASCE 4 Standard-Based Probabilistic Soil-Structure Interaction (SSI) Analysis for Seismic Design-Basis Analysis and Fragility Calculations"
"Automatic Computation of the Strain-Dependent Concrete Cracking Pattern for Nuclear Structures for Site Specific Applications"
"Fast Nonlinear Seismic SSI Analysis of Low-Rise Concrete Shearwall Buildings for Design-level (DBE) and Beyond Design-Level (BDBE)"
"Understanding Seismic Motion Incoherency Effects on SSI and SSSI Responses of Nuclear Structures"
"Accurate Linear and Nonlinear Seismic SSI Analysis Based on ANSYS FE Modeling by Extending SASSI Methodology"
"Seismic SSI Effects on Design of Curved Sliders for Base-Isolation and Recentering Capability of Rectagular Shearwall Structures"

2016: 10th Nuclear Plants Current Issues Symposium: Assuring Safety against Natural Hazards through Innovation & Cost Control, Charlotte, North Carolina, December 11-14, 2016 (slide presentation).
 "New ASCE 4-Based Probabilistic Nonlinear SSI Analysis for Improving Seismic Fragility Computations"

2016: 2-Day U.S. Department of Energy Natural Phenomena Hazards Meeting, Germantown, MD, USA, October 18-19, 2016, Session on "Soil-Structure Interaction" (slide presentations)
"Fast Nonlinear Seismic SSI Analysis for Low-Rise Concrete Shearwall Buildings for Design-Basis and Beyond Design Application"
"Critical Modeling and Implementation Aspects for Seismic Incoherent SSI Analysis of Nuclear Structures with Surface and Embedded Foundations for Rock and Soil Sites"
"Probabilistic SSI Analysis Per ASCE 4-16 Standard; A Significant Improvement for Seismic Design Basis Analysis and Fragility Calculations"

2016: The 3rd Annual ACS SASSI Workshop in Tokyo, Japan, May 12-13, 2016 (slide presentation). Herein is the 1st day wokshop presentation on  "ACS SASSI Application to Seismic SoilStructure Interaction (SSI) Analysis of Highway Bridge Structure"

2015: Technical presentation on "Sensitivity Studies for Evaluating SSI Effects for Seismically Base-Isolated NPP Structures." for the ASCE Dynamic Analysis Nuclear Structure (DANS) working group during the ASCE 43 standard meeting in San Diego, November 6, 2015, PART 1:Deterministic SSI Analysis and PART 2:Probabilistic SSI Analysis The seismic SSI analysis for the base-isolated RB complex was performed using the advanced ACS SASSI Options NON and PRO. Please see animation for coherent and incoherent inputs for the base-isolated RB complex.

2015: The SMiRT23 Conference, Manchester UK, August 2015 (papers):
"SASSI Flexible Volume Substructuring Methods for Deeply Embedded Structures; Selection of Excavated Soil Interaction Nodes and Element Meshing"
"Fast Nonlinear Seismic SSI Analysis Using A Hybrid Time-Complex Frequency Approach for Low-Rise Nuclear Concrete Shearwall Buildings"
"Probabilistic-Deterministic SSI Studies for Surface and Embedded Nuclear Structures on Soil and Rock Sites"
"Seismic Motion Incoherency Effects on Soil-Structure Interaction (SSI) and Structure-Soil-Structure Interaction (SSSI) of Nuclear Structures for Different Soil Site Conditions"
"Random Vibration Theory (RVT) Based SASSI Analysis for Nuclear Structures Founded on Soil and Rock Sites"

2015: The 2nd Annual ACS SASSI Workshop in Tokyo, Japan, April 14, 2015, on "Engineering Advances Implemented in ACS SASSI Version 3.0 for Seismic SSI Analysis of Nuclear Structures"(slide presentations). The SSI wokshop presentation slides can be downloaded here by clicking on Part 1 and Part 2

2014: 2-Day U.S. Department of Energy Natural Phenomena Hazards Meeting, Germantown, MD, USA, October 21-22, 2014, Session on "Soil-Structure Interaction" (slide presentations)
"Effects of Seismic Motion Incoherency on SSI and SSSI Responses of Nuclear Structures for Different Soil Site Conditions"
"Comparative Probabilistic-Deterministic and RVT-based SASSI Analyses of Nuclear Structures for Soil and Rock Sites"
"SASSI Methodology-Based Sensitivity Studies for Deeply Embedded Structures Such As Small Modular Reactors (SMRs)"

2014: The 1st Annual ACS SASSI Workshop in Tokyo, Japan, March 24-25, 2014, on "Recent Advances Implemented in ACS SASSI Software for Linear and Nonlinear Seismic Soil-Structure Interaction (SSI) Analysis"(slide presentations). The wokshop presentation slides can be downloaded here by clicking on Part 1 and Part 2

2014: ACS SASSI Workshop in Shanghai, China, April 3, 2014, on "Recent Advances in Seismic Soil-Structure Interaction (SSI) Analysis of Special Structures Using ACS SASSI"(slide presentations). The wokshop presentation slides can be downloaded here by clicking here

2014: The 2nd European Conference on Earthquake Engineering and Seismology, for Civil Engineering Structures, August 2014 (papers):
"Nonlinear Seismic Soil-Structure Interaction (SSI) Analysis Using An Efficient Complex Frequency Approach"
"Seismic Structure-Soil-Structure Interaction (SSSI) Effects for Dense Urban Areas" collaboration with "Dan Ghiocel International Research Center", Bucharest, Romania
"Incoherent Soil-Structure Interaction (SSI) Effects for A 242M Long Concrete Founded on Deep Piles" collaboration with "Dan Ghiocel International Research Center", Bucharest, Romania

2013: The SMiRT22 Conference, for NPP Structures, August 2013 (papers):
"Validation of Modified Subtraction Method for Seismic SSI Analysis of Large-Size Embedded Nuclear Islands" and associated slides
"Comparative Probabilistic-Deterministic Investigations for Evaluation of Seismic Soil-Structure Response" and associated slides
"Efficient Probabilistic Seismic Soil-Structure Interaction(SSI) Analysis for Nuclear Structures Using A Reduced-Order Modeling in Probabilistic Space" and associated slides
"Comparative Studies on Seismic Incoherent SSI Analysis Methodologies" and associated slides
"Structure-Soil-Structure Interaction Effects for Two Heavy NPP Buildings With Large-Size Embedded Foundations"
"Generic Input for Standard Seismic Design of Nuclear Power Plants"
"Fast Nonlinear Seismic Soil-Structure Interaction (SSI) Analysis of Nuclear Shearwall Concrete Structures Subjected to Review Level Earthquake"
"Simplified Modeling of Effects of Concrete Cracking on Out-of-Plane Vibrations of Floors"

2011: ACS SASSI Related Papers Presented at the SMiRT21 and ASEM11 Conferences, for NPP Structures, Fall 2011 (papers)
Seismic Incoherent Soil-Structure Analysis of A Reactor Building Complex on A Rock Site
Seismic Soil-Structure Interaction (SSI) Effects for Large-Size Surface and Embedded Nuclear Facility Structures

2010: OECD NEA/IAEA SSI Workshop, Ottawa, October 6-8, 2010 (papers):
Seismic SSI Response of Reactor Building Structures
Seismic Motion Incoherency Effects for Nuclear Complex Structures On Different Soil Site Conditions
Seismic Motion Incoherency Effects for CANDU Reactor Building Structure
EPRI AP1000 NI Model Studies on Seismic Structure-Soil-Structure Interaction (SSSI) Effects

2009: ACS SASSI Related Papers Presented at ICOSSAR09, SMIRT20 and ASME PVP2009 Conferences, in July-August 2009 (papers):
ICOSSAR09 Paper on Seismic Motion Incoherency Effects for Nuclear Island Complexes
SMIRT20 Paper on AP1000 Nuclear Island Complex
SMIRT20 Paper on EPRI AP1000 NI Stick Model
PVP2009 Paper on Typical PWR Reactor Building

2007: ACS SASSI Related Papers Presented at SMiRT19 Conference, August 2007 (papers):
"Seismic Ground Motion Incoherency Effects on Soil-Structure Interaction Response of NPP Building Structures"

TECHNICAL NOTES on Seismic SSI Analysis and Modeling for Nuclear Island Applications:

FAST NONLINEAR SEISMIC SOIL-STRUCTURE INTERACTION (SSI) ANALYSIS IN COMPLEX FREQUENCY DOMAIN, Technical Note GPT-001-10-01-2013, October 1, 2013 and associated slides
THE SASSI FLEXIBLE VOLUME SUBSTRUCTURING METHODOLOGIES, Technical Note GPT-001-430-2012, April 30, 2012. Please see animations of the excavated soil motion for an embedded RB complex foundation using DM , SM and MSM methods.
SOME INSIGHTS ON FREQUENCY VS. TIME-DOMAIN APPROACHES FOR SEISMIC SSI ANALYSIS OF NPP STRUCTURES, Technical Note GPT-001-201-2012, February 1, 2012

1998-2002: Selected Papers on ACS SASSI Application for Probabilistic Seismic SSI and Seismic Fragility Analysis for Nuclear Structures:
Uncertainties of Seismic Soil-Structure Interaction Analysis: Significance, Modeling and Examples, US-Japan SSI Workshop, USGS, 1998
Stochastic Finite-Element Analysis of Seismic Soil–Structure Interaction, Journal of Engineerings Mechanics, ASCE, 2002

2004-2005: Selected Papers on ACS SASSI Application for Seismic Analysis of Large Span Concrete Bridges on Piles in New York City and Washington D.C., USA, and Japan:
Seismic Geotechnical Investigations of Bridges in New York City, 2004
Seismic Soil-Foundation Interaction Analyses of the New Woodrow Wilson Bridge, 2005
Load Bearing Mechanism of Piled Raft Foundation during Earthquakes, 2004

2011: HAND-NOTES FROM ACS SASSI TRAINING in January 2011: 3-Day ACS SASSI Training at the North Marriott Convention Center, Bethesda, MD, in the Washington D.C. area (across US NRC building), January 25-27, 2011, on "ACS SASSI Application to Linear and Nonlinear Seismic SSI Analysis of Nuclear Structures Subjected to Coherent and Incoherent Inputs". Please contact Dr. Dan M. Ghiocel, Instructor, at dan.ghiocel@ghiocel-tech.com if you have any question on the SSI training. The hand-notes could be downloaded here by clicking on Part 1-Day 1 and Part 2-Day 2-3 The list of the 21 atendees of the 3-day SSI training is available here. A brief professional profile of the Instructor is provided here.

STRUCTURE DEFORMED SHAPE AND STRESS CONTOUR ANIMATIONS:

• Comparison between SSSI Effects for Coherent and Incoherent Motions