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Nonlinear
static analysis
XFINAS
provides a series of solution
strategies for nonlinear analysis.
Both force and displacement
loading can be applied in static
analysis. An automatic selection
of constraint equation and arc-length
control are available for highly
nonlinear problems. The solution
procedure uses either full or
modified Newton-Raphson method.
Mode
superposition method for linear
dynamic analysis
These
orthogonal vectors were used
to reduce the size of the problem.
The need for the exact solution
of this large eigenvalue problem
was eliminated. The superposition
of Ritz vectors yielded more
accurate results, with fewer
vectors, than that of the exact
eigenvectors. The proportionally
and non-proportionally damped
dynamic system can be solved
using the mode superposition
method. For the analysis of
non-proportionally damped system,
the option of the manufactured
damper with linear viscous damping
is available in XFINAS. The
computational speed of the subspace
iteration method is improved
significantly by using new starting
vectors.
Nonlinear
dynamic analysis
The
step-by-step numerical time-integration
schemes are implemented into
XFINAS. For the nonlinear time-history
analysis, explicit method by
the central difference method,
implicit methods by Wilson-theta
method, unconditionally stable
Newmark family of algorithm
and Hilber-Hughes-Taylor (HHT)
are implemented for solving
the equation of motion by numerical
integration methods.
Eigenvalue
solver
The
efficient eigen-solver is implemented
using (1) Lanczos vector algorithm
(2) subspace iteration method
and (3) inverse iteration method
to calculate few most important
eigenvalues and eigenvectors.
In order to calculate complex
eigenvalue, the one sided Lanczos
algorithm is implemented considering
proportional and non-proportional
damping.
Seismic
Analysis method
1.
Linear, direct time integration
methods (Central Difference
Method, Wilson-Theta Method,
Newmark
Linear
Acceleration Method and HHT
Method)
2. Linear, Vector
superposition methods (Eigenvector
base, LD Ritz vector)
3.
Linear, Response spectra method.
Two modal combination method
are used, the CQC method for
cases
of close frequencies, or coupling
of modes and SRSS method for
general, simple, and
separate
frequencies structures
4.
Multi-components seismic excitation
5.
Generation of recorded data
into structure¡¯s principal
coordinates
6. Data interpolation
for short period structures
and large recording time step
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