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  2016 Coming-Soon ACS SASSI with Super-Fast Solver & Advanced SSI Modeling Options
  글쓴이 : 관리자     날짜 : 16-06-08 13:54    
2016 Coming-Soon ACS SASSI with Super-Fast Solver:
The 2016 ACS SASSI software that will have a much faster SSI Solution for large-size SSI models. The 2016 ACS SASSI software running on PC workstations will handle efficiently up to 1.5 million dof SSI model sizes. The new 2016 ACS SASSI software will have a super-fast adaptive solver that will use a hybrid direct-iterative algorithm with advanced solution preconditioning, and will take more advantage of the memory allocation for parallel solution. We estimate a speed-up of several times comparing with the current fast-solver. Optionally, the new version will work without writing restart files (still available if user wants to save them).  Thus, the new super-fast solver will be capable of running in a single SSI analysis run tens to hundreds of simultaneous dynamic load cases! The speed-up will be at least of tens of times for the multiple load case analyses.  This large speed-up will permit extending SASSI methodology to 3D SSI models that include 2D soil layering models eventually with topographic features (via 3D2D models) instead of using the traditional SASSI methodology with 3D SSI models that include 1D soil layering models with horizontal layers (via3D1D models). 

2015 Existing ACS SASSI Advanced SSI Modeling Options:
The current software version in addition to baseline software includes some unique optional SSI modeling capabilities that you need to know about:

i) Option AA for the advanced ACS SASSI-ANSYS integration permits to run SSI analysis using directly sophisticated 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.

ii) Option A for ACS SASSI-ANSYS interfacing includes a fast 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.

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.

iv) Option NON or nonlinear structure SSI analysis uses a fast hybrid time-complex frequency approach based on a local, piece-wise equivalent-linearization
for the nonlinear structure SSI analysis. It is hundreds to several thousands of times faster than the time-domain integration nonlinear SSI approaches using the ANSYS, LSDYNA or ABAQUS 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, or to identify and quantify reduced to moderate structure sliding on the ground.

The combined use of these advanced ACS SASSI SSI modeling options offers highly efficient and robust accurate SSI solutions for the design-basis site-specific SSI analysis and/or the seismic PRA/PSA studies. Using combined Option PRO-Option NON, the structural engineers  will have the required SSI analysis tools to compute much more realistically the structural fragilities being not limited to simplistic, linear SSI analysis-based approaches. Thus, the nonlinear reinforced concrete post-cracking behavior and the potential sliding of structures on ground could be efficiently evaluated in a business practical manner on a PC workstation, and not neglected, or crudely represented as quite often was done in the past due to the lack of appropriate practical nonlinear SSI analysis tools.

Detailed Information on the ACS SASSI Software Capabilities:
To learn more about the ACS SASSI software features and SSI capabilities, please see the latest newsletter on "Engineering Advances for Deterministic, Probabilistic, Linear and Nonlinear Seismic SSI Analysis" at http://www.ghiocel-tech.com/storage/publications/GPTech_Newsletter-No-1-2015.pdf .