Question about Conctact for Implicitc Analysis
Luis Tuarez
James M. Kennedy
Dear Luis
Some seismic (SSI) notes and presentations.
-------------------------------------
*BOUNDARY_PRESCRIBED_MOTION.
These two options are for fixed-base structures. If you want to model soil-structure
interaction, please see the following page:
A note I found given by Ushnish Basu:
If you want to apply the ground motions directly at the base of the bridge, you can
use *BOUNDARY_PRESCRIBED_MOTION to apply the accelerations directly,
which will give you total motions in the structure.
[Fixed base model: Input motion applied directly at the base of the building (No SSI)]
Alternatively, you can use *LOAD_BODY to apply D'Alembert forces on the structure,
if you have spatially uniform motions at the base. This will give you structure motions
relative to the ground motion. If you have spatially-varying motions, you should use
http://ftp.lstc.com/anonymous/outgoing/ubasu/SSI-in-DYNA/
-------------------------------------
Did you look at this example?
http://www.lstc.com/applications/soil_structure/esi/examples
https://www.lstc.com/applications/soil_structure/esi/implementation
An example of a purely dynamic analysis of this system - without any gravity load
- is given in the input deck ssi-dynamic.k. Transient analysis of the system following
an initial static analysis is demonstrated by a pair of input decks: ssi-static.k and
ssi-transient.k, to be run one after the other. The ground motions used in the analysis
are given in elcentro-x.ath, elcentro-y.ath, and elcentro-z.ath.
Another example:
http://www.lstc.com/applications/soil_structure/dams/example
Dam analysis example | Livermore Software Technology Corp. (lstc.com)
-------------------------------------
Seismic Input in LS-DYNA
Effective seismic input has been implemented in LS-DYNA, with INTERFACE_SSI
cards used to identify the soil-structure interface, and LOAD_SEISMIC_SSI used to
specify the ground motion on such an interface. Typically, only ground acceleration
histories are required to specify the ground motion, but if ground velocity and disp-
lacement curves are also available from signal processing of the accelerograms, then the
ground motion may be specified using DEFINE_GROUND_MOTION.
http://www.lstc.com/applications/soil_structure/esi/implementation
-------------------------------------
*LOAD_SEISMIC_SSI_OPTION1_{OPTION2}
Available options for OPTION1 include:
NODE
SET
POINT
OPTION2 allows an optional ID to be given:
ID
Purpose: Apply earthquake load due to free-field earthquake ground motion at
certain locations — defined by either nodes or coordinates — on a soil-structure
interface, for use in earthquake soil-structure interaction analysis. The specified
motions are used to compute a set of effective forces in the soil elements adjacent
to the soil-structure interface, according to the effective seismic input–domain
reduction method [Bielak and Christiano (1984)].
-------------------------------------
A presentation which you might find of interest:
Zhenxia, S., and Haiping, D., “The Analysis of Seismic Response for Base-isolated
Structure by LS-DYNA”.
https://www.iitk.ac.in/nicee/wcee/article/14_14-0204.PDF
-------------------------------------
This dissertation assessed industry-standard equivalent linear and nonlinear site-response
and soil-structure interaction (SSI) analysis programs, and provides practical guidelines
on their usage. The assessment included benchmarking the time-domain programs against
frequency-domain programs for analyses involving almost linear soil response, and a
comparison of the predictions of these programs for analyses involving highly nonlinear
soil and foundation response. The assessment also identified the various pitfalls that can
be expected when using these programs and suggested workarounds:
Bolisetti, C., "Site Response, Soil-Structure Interaction and Structure-Soil-Structure
Interaction for Performance Assessment of Buildings and Nuclear Structures", Ph.D.
Thesis, Department of Civil, Structural and Environmental Engineering, University of
Buffalo, State University of New York, Buffalo, New York, October, 2014.
https://ubir.buffalo.edu/xmlui/handle/10477/51327
The studies presented herein share the common goal of a better understanding of the
phenomena of site response, soil-structure interaction (SSI) and structure-soil-structure
interaction (SSSI), and advancing the numerical tools that simulate these phenomena.
Bolisetti, C., and Whittaker, A.S., “Site Response, Soil-Structure Interaction and
Structure-Soil-Structure Interaction for Performance Assessment of Buildings and
Nuclear Structures”, MCEER-15-002, University of Buffalo, State University of
New York, Buffalo, New York, June, 2015.
https://www.buffalo.edu/content/dam/www/mceer/Reports/15-0002.pdf
-------------------------------------
Sincerely,
James M.. Kennedy
KBS2 Inc.
October 17,2022
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James M. Kennedy
Dear Luis,
Perhaps these presentations might be of interest:
This dissertation assessed industry-standard equivalent linear and nonlinear site-response and soil-structure interaction (SSI) analysis programs, and provides practical guidelines on their usage. The assessment included benchmarking the time-domain programs against frequency-domain programs for analyses involving almost linear soil response, and a comparison of the predictions of these programs for analyses involving highly nonlinear soil and foundation response. The assessment also identified the various pitfalls that can be expected when using these programs and suggested workarounds:
Bolisetti, C., "Site Response, Soil-Structure Interaction and Structure-Soil-Structure Interaction for Performance Assessment of Buildings and Nuclear Structures", Ph.D. Thesis, Department of Civil, Structural and Environmental Engineering, University of Buffalo, State University of New York, Buffalo, New York, October, 2014.
https://ubir.buffalo.edu/xmlui/handle/10477/51327
The studies presented herein share the common goal of a better understanding of the phenomena of site response, soil-structure interaction (SSI) and structure-soil-structure interaction (SSSI), and advancing the numerical tools that simulate these phenomena.
Bolisetti, C., and Whittaker, A.S., “Site Response, Soil-Structure Interaction and Structure-Soil-Structure Interaction for Performance Assessment of Buildings and Nuclear Structures”, MCEER-15-002, University of Buffalo, State University of New York, Buffalo, New York, June, 2015.
https://www.buffalo.edu/content/dam/www/mceer/Reports/15-0002.pdf
Sincerely,
James M. Kennedy
KBS2 Inc.
October 18, 2022
From: ls-d...@googlegroups.com [mailto:ls-d...@googlegroups.com] On Behalf Of Luis Tuarez
Sent: Monday, October 17, 2022 2:03 AM
To: LS-DYNA2 <ls-d...@googlegroups.com>
Subject: [LS-DYNA2] Question about Conctact for Implicitc Analysis
Hi,
--
James M. Kennedy
Dear Luis,
Perhaps these presentations may be of interest:
The “effective stress” material model used in this presentation is the non-linear hysteretic soil model (*MAT_079) that Arup originally developed about 20 years ago. A number of enhancements have been made in the intervening period. This model provides great flexibility for users to specify, in a tabular or parametric manner, the stress-strain curves, pressure-sensitivity of strength and modulus, rate sensitivity of strength and shear-induced compaction or dilatancy:
Willford, M., Sturt, R., Huang, Y., Almufti, I., and Duan, X., "Recent Advances in Non-Linear Soil Structure Interaction Analysis Using LS-DYNA", Workshop on Soil-Structure Interaction (SSI) Knowledge and Effect on the Seismic Assessment of NPPs Structures and Components, Ottawa, Canada, October, 2010.
http://www.xiaonianduan.com/media/LS-DYNA_for_SSI.pdf
A study was performed to investigate how the choice of material models and their parameters used to represent nonlinear soil behavior affects the response of a structure undergoing large displacements within the soil. *MAT_005, *MAT_010, *MAT_025 and *MAT_079 (data included) were the material models used:
Kulak, R.F., and Schwer, L.E., "Effect of Soil Material Models on SPH Simulations for Soil-Structure Interaction", 12th International LS-DYNA Users Conference, Dearborn, Michigan, June, 2012.
http://www.dynalook.com/international-conf-2012/fsi-ale23-d.pdf
The MAT_HYSTERETIC model (*MAT_079, and referred to as the “Arup model”) using the Masing rules was employed in this study. The Arup model requires the backbone curve to be defined using a maximum of 10 discrete stress-strain points. Preliminary analyses using this material model revealed an unrealistically large contribution of higher frequencies to the acceleration response, especially in cases involving large strains. To address this numerical problem, an alternative approach was adopted that involved superimposing 12 solid elements that act in parallel, instead of one element with 10 discrete points in the backbone curve. The superimposition results in stress-strain curve with 120 points in the backbone curve (refer to Bolisetti [2015] for details):
Bolisetti, C., Whittaker, A.S., Almufti, I., Mason, H.B., and Wilford, M., "Numerical Methods in Site Response Analysis for Nuclear Applications", 22nd International Conference on Structural Mechanics in Reactor Technology (SMiRT-22), San Francisco, California, August, 2013.
https://repository.lib.ncsu.edu/bitstream/handle/1840.20/32845/Pap_184_ver_5.pdf
This dissertation assessed industry-standard equivalent linear and nonlinear site-response and soil-structure interaction (SSI) analysis programs, and provides practical guidelines on their usage. The assessment included benchmarking the time-domain programs against frequency-domain programs for analyses involving almost linear soil response, and a comparison of the predictions of these programs for analyses involving highly nonlinear soil and foundation response. The assessment also identified the various pitfalls that can be expected when using these programs and suggested workarounds:
Bolisetti, C., "Site Response, Soil-Structure Interaction and Structure-Soil-Structure Interaction for Performance Assessment of Buildings and Nuclear Structures", Ph.D. Thesis, Department of Civil, Structural and Environmental Engineering, University of Buffalo, State University of New York, Buffalo, New York, October, 2014.
https://ubir.buffalo.edu/xmlui/handle/10477/51327
The studies presented herein share the common goal of a better understanding of the phenomena of site response, soil-structure interaction (SSI) and structure-soil-structure interaction (SSSI), and advancing the numerical tools that simulate these phenomena.
Bolisetti, C., and Whittaker, A.S., “Site Response, Soil-Structure Interaction and Structure-Soil-Structure Interaction for Performance Assessment of Buildings and Nuclear Structures”, MCEER-15-002, University of Buffalo, State University of New York, Buffalo, New York, June, 2015.
https://www.buffalo.edu/content/dam/www/mceer/Reports/15-0002.pdf
Sincerely,
James M. Kennedy
KBS2 Inc.
October 18, 2022
From: ls-d...@googlegroups.com [mailto:ls-d...@googlegroups.com] On Behalf Of Luis Tuarez
Sent: Monday, October 17, 2022 2:03 AM
To: LS-DYNA2 <ls-d...@googlegroups.com>
Subject: [LS-DYNA2] Question about Conctact for Implicitc Analysis
Hi,
--
James M. Kennedy
Dear Luis,
Several other presentations:
ASCE-4 2015 Appendix B provides general criteria to consider while performing NLSSI analysis, but lacks a methodology for performing the analysis. This paper provides a description of the NLSSI methodology developed for application at nuclear facilities, including NPPs. This methodology is described as series of steps to be followed to produce reasonable results. These steps require some numerical capabilities, such as nonlinear soil constitutive models, which are also described in the paper.
Coleman, J.L., Bolisetti, C, and Whittaker, A,S., “Time-Domain Soil-Structure Interaction Analysis for Nuclear Facilities”, Nuclear Engineering and Design, Vol. 298, pp. 264-270, 2015.
Justin_L_Coleman_Soil_structure_2016.pdf
https://www.osti.gov/servlets/purl/1372687 (added)
Soil-structure interaction (SSI) analysis is generally a required step in the calculation of seismic demands in nuclear structures, and is currently performed using linear methods in the frequency domain. Such methods should result in accurate predictions of response for low-intensity shaking, but their adequacy for extreme shaking that results in highly nonlinear soil, structure or foundation response is unproven. Nonlinear (time-domain) SSI analysis can be employed for these cases, but is rarely performed due to a lack of experience on the part of analysts, engineers and regulators. A nonlinear, time-domain SSI analysis procedure using a commercial finite-element code is described in the paper. It is benchmarked against the frequency-domain code, SASSI, for linear SSI analysis and low intensity earthquake shaking. Nonlinear analysis using the time-domain finite-element code, LS-DYNA, is described and results are compared with those from equivalent-linear analysis in SASSI for high intensity shaking. The equivalent-linear and nonlinear responses are significantly different. For intense shaking, the nonlinear effects, including gapping, sliding and uplift, are greatest in the immediate vicinity of the soil-structure boundary, and these cannot be captured using equivalent-linear techniques.
Bolisetti, C, and Whittaker, A,S., and Coleman, J.L., “Linear and Nonlinear Soil-Structure Interaction Analysis of Buildings and Safety-Related Nuclear Structures”, Soil Dynamics and Earthquake Engineering, Vol. 107, pp. 218-233, April, 2018.
https://www.researchgate.net/publication/322775359_Linear_and_nonlinear_soil-structure_interaction_analysis_of_buildings_and_safety-related_nuclear_structureshttps://www.sciencedirect.com/science/article/abs/pii/S0267726118300289?via%3Dihub
The objective of this study was to evaluate the performance of four commonly used LS-DYNA concrete models, *MAT_072R3 (KCC), *MAT_084 (Winfrith), *MAT_159 (CSCM), and *MAT_272 (RHT), for seismic applications. The first phase of analysis used individual elements to demonstrate the effects of element size, element formulation, hourglass formulation, and strain application rate on each material model’s performance. Additional single-element analyses were conducted to investigate each model’s capability to accurately capture different components of seismic loading, such as shear, cyclic compression, and cyclic load reversal. This single-element study yielded a collection of strengths and weaknesses associated with each material model. The second phase of analysis investigated how the strengths and weaknesses identified in the single-element analyses applied to multi-element simulations:
Coleman, D.K., "Evaluation of Concrete Modeling in LS-DYNA for Seismic Application", Master’s Thesis, Department of Civil, Architectural and Environmental Engineering, University of Texas at Austin, Austin, Texas, December, 2016.
https://repositories.lib.utexas.edu/bitstream/handle/2152/47239/COLEMAN-THESIS-2016.pdf
Sincerely,
James M. Kennedy
KBS2 Inc.
October 19, 2022
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