Specialized Software Tools

ACS SASSI

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.

NEWSLETTER: No.1/2015 entitled "Engineering Advances for Deterministic and Probabilistic, Linear and Nonlinear Seismic SSI Analysis". Please provide comments and feedback at acs.sassi@ghiocel-tech.com

BROCHURES:

2014-2015 ACS SASSI VERSION 3.0:
Brief technical description brochure of the 2014 ACS SASSI Version 3.0 including the Options A, AA (ACS SASSI-ANSYS interfacing), Option FS (parallel fast-solver), and Options Pro (probabilistic SSI), RVT (random vibration SSI) and Non (nonlinear concrete). The ACS SASSI Version 3.0 User Manual without Options Pro, RVT and Non) is available here and the ACS SASSI-ANSYS Integration Manual is available here.
2009-2014 ACS SASSI VERSION 2.3.0:
Brief technical description brochure of the 2009-2013 ACS SASSI Version 2.3.0 including the Option A (ACS SASSI-ANSYS interfacing) and Option FS (multicore fast-solver).

NEW UPDATES ON ADVANCES IN ACS SASSI SSI ANALYSIS CAPABILITIES:

The ACS SASSI software is a software in a continuous fast development. In addition to the computational speed improvements through a full parallelization of the code that makes it hundreds of times faster than the university SASSI code, ACS SASSI includes a totally new set SSI analysis capabilities that extends the linearized SASSI methodology to nonlinear soil and structure and probabilistic SSI problems, including eventually incoherent seismic wave fields and inclined soil layering geometries. The new added SSI capabilities makes ACS SASSI the most complete seismic SSI analysis engineering tool for nuclear structure projects. Please see above newsletter and brochure for technical details.
- - Option AA or Advanced ANSYS, makes possible to run directly ANSYS FE structural models in ACS SASSI with no modelling limitation, including all ANSYS refined shell, beam and solid element types, rigid links, coupled nodes, or constraint equations, and even fluid elements. The structural animations at shows the ACS SASSI-ANSYS fluid-structure interaction capability.
- - Option A or ANSYS includes fast automatic export of the seismic SSI boundary conditions for performing a detailed nonlinear/linear stress SSI analysis using refined ANSYS FE models via the ACS SASSI-ANSYS integration capability.
- - Option PRO is consistent with probabilistic site response and SSI procedures in the ASCE 04-2016 standard (see Chapters 2 and 5) and 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 material stiffness and damping for each group of elements depending on the stress levels in different parts of the structure.
- - Option NON or Nonlinear structure, applicable to the low-rise concrete shearwall buildings and foundation isolation problems. The nonlinear structure analysis capability is based on a highly efficient hybrid frequency-time domain SSI approach. This makes Option NON highly applicable to nonlinear structure applications, including foundation isolation and reduced to moderate sliding effects. Option NON is useful for including the reinforced concrete cracking and post-cracking behavior in the SSI model in accordance to the new ASCE 04-16 and ASCE 43-05 standards, and the updated USNRC SRP requirements for site-specific applications. The nonlinear SSI analysis is fast being only about 2-3 times the runtime of the linear SSI analysis (hundreds to thousands of times faster than a nonlinear time-domain SSI analysis). The ductilities and inelastic absorbtion factors for each shearwall panel are computed based on the nonlinear time domain results after the last iteration. Comparative results between the new hybrid approach and the nonlinear timeintegration approach showed extremely good matching, as shown in the above newsletter.
- - Option 2DSOIL that will be available in the next upgrade, uses a soil deposit model in the 2D space with inclined soil layers, or including topography effects. The nonlinear site response analysis for the 2D soil deposit models uses the iterative equivalent-linear procedure applied in 2D space. The traditional 3D SASSI model with 1D free-field soil impedances and motions (3D1D SASSI model) is replaced by a 3D SASSI model with 2D free-field soil impedances and motions (3D2D SASSI model).

RECENT EVENT PAPERS AND PRESENTATIONS ON THE ACS SASSI APPLICATION:

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.

The SMiRT23 Conference, for NPP Structures, 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"

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

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)"

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

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

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

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"

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

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

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

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

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

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

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:
Animation(49MB): Comparison between SSSI Effects for Coherent and Incoherent Motions
Animation(38MB): Embedded Nuclear Reactor Building Acceleration Response
Animation(186MB): Nuclear Standard Plant Seismic Response Animation
Animation(8.1MB): Large-Size Structure Acceleration Under Coherent Input - Below Basemat View
Animation(7.5MB): Large-Size Structure Acceleration Under Incoherent Input with Wave Passage
Animation(1.5MB): Seismic Pressure Fluctuation for Y-Input on An Embedded Foundation
Animation(25MB): Deeply Embedded Structure Acceleration Deformed Shape Under Coherent Input
Animation(27MB): Deeply Embedded Structure Acceleration Deformed Shape Under Incoherent Input
Animation(4.1MB): Deeply Embedded Structure SYY Stress in Walls Under Coherent Input
Animation(3.6MB): Deeply Embedded Structure SYY Stress in Walls Under Incoherent Input
Animation(11MB): EPRI AP1000 Stick Coherent Displacement on Rock Site wrt to Free-Field Input
Animation(11MB): EPRI AP1000 Stick Incoherent Displacement on Rock Site wrt to Free-Field Input
Animation(4.4MB): Embedded EPRI AP1000 Stick Acceleration for A Soft Soil Under Coherent Input
Animation(4.7MB): Embedded EPRI AP1000 Stick Acceleration for A Soft Soil Under Incoherent Input
Animation(5.2MB): EPRI AP1000 Stick and Annex Bldg. Coherent Displacements wrt FF Input
Animation(6.1MB): EPRI AP1000 Stick and Annex Bldg. Incoherent Displacements wrt FF Input

ProCORFA

It is a highly specialized, Windows XP, user-friendly computer code for performing probabilistic life, and reliability prediction for aircraft and vehicle structures subjected to progressive stochastic corrosion-fatigue damage including the effects of maintenance activities. In addition to stochastic modeling and risk prediction capabilities, ProCORFA includes a stochastic cost modeling module. ProCORFA has a fully integrated software interface with the USAF AFGROW code for fatigue crack propagation computation. ProCORFA package also includes an interface with ANSYS code that is programmed in ANSYS ADPL language. ProCORFA is being developed in collaboration with STI Technologies and Cornell University. ProCORFA is programmed in Visual Basic and Fortran90.

Description

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GEOMIS

It is a highly specialized computer code for performing extremely fast and accurate mistuning analysis of bladed disk assemblies of gas turbine engines or power turbines. GEOMIS has the unique capability of considering the blade geometry mistuning effects due inherent manufacturing deviations on turbine blade-disk system vibration. GEOMIS performs geometry mistuning analysis using an efficient reduced-order modeling (ROM) based on “iterative eigensubpace projection” (IES) and “stochastic perturbation matrix” (SPM) approach.

GEOMIS is intimately interfaced with the ANSYS code that is used for bladed-disk system finite element modeling. Both the IES and SPM ROMs were developed by GP Technologies under its own internal resources. No publication is available for IES, and only a single publication is available for SPM (but only for mistuning analysis directly in the complex frequency domain, not in the modal domain - click on "related paper" link to see the paper on SPM). Both IES and SPM are very accurate for both frequency and geometry bladed-disk mistuning predictions. Both IES and SPM do not need any preliminary sector frequency calculations that provide a significant relief to the structure analyst.

Also, both IES and SPM do not require any preliminary work for identification and separation of system modes in isolated mode families which many times is an almost an impossible task for the analyst, especially for frequency ranges in which mistuned mode frequencies of different mode families interfere in a unknow, random pattern. Under "Animated Demo" selection a prototype MATLAB software version is shown. The full capability version of the GEOMIS code is programmed in VC++ and Fortran90.

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BladeHCF

It is a highly integrated, graphical computational environment for preforming probabilistic forced response and failure risk assessment for turbine engine bladed-disk assemblies that are subjected to high-cycle fatigue (HCF). The HCF damage occurs due to the structural vibration of these assemblies due to steady and unsteady gas pressure fluctuations on rotating blades. BladeHCF is a user-friendly, object-oriented, prototype software developed under the MATLAB/SIMULINK environment that can be easily adapted to various advanced turbine design, analysis and risk prediction applications.

The BladeHCF structure is modular and incorporates a number of graphical computational modules. BladeHCF uses ANSYS finite element code for steady and unsteady structural stress analysis. Aero-forcing is defined deterministically or probabilistically using simple engineering calculations based on aeromechanical tests. Brief animated demos for different graphical computational modules can be seen by clicking on Blade Geometry Variation module, Preliminary Deterministic System Force Response module, Probabilistic System Forced Response module, and Blade HCF Risk Prediction module.

It should be noted that GEOMIS code (please see above) that provides unique computational capabilities using reduced-order modeling for performing efficient and accurate geometry-based mistuning analyses of bladed-disk assemblies is included as a part of BladeHCF, namely within the Probabilistic System Forced Response module. Blade HCF risks are predicted using the probabilistic Goodman diagram failure criteria. Stochastic modeling uncertainty effects on probabilistic blade stresses due to small sample size effects, i.e. limited number of measured blades/rotors are included and used to define HCF risk variation bounds. BladeHCF also includes algorithms for aggregation of various information sources coming from computational blade stress/strain predictions, available test data, i.e. strain-gage and/or rig test data, and expert opinions.

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BLASTEX

It is a set of five highly specialized, Windows XP interactive, easy-to-use computer programs for a rapid evaluation of typical explosion blast effects on buildings, vehicles and surrounding people. The five computer codes are designed to be used by non-experts in blast physics and non-engineers. An earlier version of BLASTEX codes was distributed at a number of police departments, government agencies and national labs. The distribution of the BLASTEX package is limited to the US government agencies or institutions and national labs.

Description

ProMACOR

It is a highly specialized, Windows XP interactive, user-friendly computer code for performing probabilistic life, and reliability prediction for gas turbine engine blades subjected to low-cycle fatigue (LCF) and high-cycle fatigue (HCF) damage including the uncertainties associated with periodic maintenance inspections. For computing LCF-HCF interaction effects, ProMACOR uses advanced nonlinear damage models. Effects of random foreign object impacts on blade can also be included using stochastic simulation. ProMACOR is being developed together with STI Technologies. ProMACOR is not available as an integrated commercial package for sale. We are interested to work with gas turbine engine manufacturers to develop in-house customized versions for them.

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StoFIS

It is a collection of software modules and libraries that can be integrated for performing in-flight risk-based fault diagnostics and prognostics in aircraft jet engines. To capture the complex functional stochastic relationships between different engine performance parameters or statistical features of vibration measurements, StoFIS combines advanced stochastic modeling with artificial intelligence tools for engine health risk management. StoFIS is an adaptive stochastic-fuzzy network-based inference and prediction system. Although, the software is based on complex stochastic approximation and prediction techniques, its output is simple, easy to interpret and highly practical. The user views probabilistic predictions interms of simple reliability metrics that can be easily interpreted for maintenance decisions. StoFIS has been developed together with STI Technologies. StoFIS is not available for sale as an integrated commercial package. We are interested to work with aircraft and helicopter engine manufacturers to develop refined in-house customized versions for them.

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StoOPT

It is a collection of powerful computational toolboxes for complex stochastic-optimization problems involving large number of uncertain variables and/or high nonlinear noisy responses. The StoOPT package uses advanced dynamic simulation based on multilevel Markov Chain Monte Carlo algorithms with gradient hints coming from moving particle inertia. Based on extensive testing of convergence robustness for finding the global extrema, the StoOPT algorithms outperform all other reputed stochastic-optimization algorithms. To take full advantage of these robust algorithms in our reliability-based design optimization analyses, we use these algorithms in conjunction with advanced response surface modeling techniques based on stochastic field models integrated in our StoRES software. StoOPT is not available for sale as an integrated commercial software package. We are interested to work with our industry customers to developed in-house customized implementations for them.

StoRES

It is a collection of computational toolboxes for approximating complex system response surfaces involving a large number of uncertain variables and/or high nonlinear noisy responses. The StoRES package uses advanced stochastic field models for response surface modeling including one-level, two-level and three-level hierarchical stochastic approximation models, MCMC simulation-based approximation models, statistical and fuzzy clustering-based interpolation models, (non-Gaussian) translation field models and spatial stochastic-interpolation models including Gaussian krigging and radial-basis functions. The StoRES approximation models applied in conjunction with the StoOPT simulation-based stochastic-optimization models provide a unique set of toolboxes for rapidly solving reliability-design optimization problems. Based on numerical investigations done in-house and in collaboration with University of Iowa, we noticed that our StoOPT-StoRES suite of algorithms can reduce the number of computational mechanics analyses (function evaluations), such as finite element analyses or computational fluid dynamics analyses, needed for performing a reliability-based design optimization by 4 to 8 times. StoOPT is not available for sale as an integrated commercial software package. We are interested to work with our industry customers to developed in-house customized implementations for them.

StoUNC

It is a collection of computational toolboxes based on new theoretical concepts that were developed in-house for incorporating epistemic uncertainties in probabilistic structural mechanics analyses. The new concepts are being built on the imprecise probability theory that addresses practical, real situations when available statistical data is limited or very limited. StoUNC is not available for sale as an integrated commercial software package. We are interested to work with our industry customers to developed in-house customized implementations for them.