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Complete Offshore Capability
ASAS provides comprehensive capability for offshore
engineers. ASAS-OFFSHORE has beam a leading system for jacket design
for 30 years encompassing wave-loading, analysis, code checking,
fatigue and coupled soil-pile-structure interaction. The ASAS solver
has also been integrated with FEMGV to provide powerful finite
element analysis facilities including modelling and post processing.
Non-linear capability in ASAS(NL) also covers offshore and general
FE capabilities.
User Results Integrated Database (URSD)
In 2003 ASAS 14 was released. The main feature
of this release was a common database across all modules which allow
post-processors to access all results from ASAS(L) or ASAS(NL) and
other post-processors. The database results are divided into four
categories - Equation, Nodal, Element and Global - and are fully
documented. An ASAS -Toolkit is supplied which enables user to write
their own routines and extract the information for further
processing.
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Direct access of
ASAS results from MS-EXCEL© and Mathcad©.
When ASAS is installed additional functions are
added enabling all the ASAS results to be accessed and retrieved
from MS-EXCEL and Mathcad. Standard report templates can easily be
created and re-used.
This facility provides a number of major
benefits. Firstly it introduces a facility for the user to perform
further post-processing using MS-EXCEL (including Visual Basic) and
Mathcad. Secondly it provides a facility for a user to design
his/her own report templates. Once designed, templates can be
re-used thus saving considerable effort.
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Coupled Wave
Structure Interaction with Regular and Random Waves
This additional feature is available in
ASAS(NL) and includes the capabilities of the comprehensive wave
loading program ASAS-WAVE. The significant difference is that full
hydro-elastic coupling is introduced. This makes ASAS(NL) suitable
for jack-ups, compliant structures, manifold installation and riser
analysis. Features include:
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Wave, current and wind load
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Regular and random waves (JONSWAP,
Pierson-Moskowitz and user defined)
-
Airy, Stokes 5th, Cnoidal, Stream Function and
Shell New Wave plus user defined wave grid
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Tube and beam elements
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Flooded or sealed members
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Drag and inertia force
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Marine Growth
-
Wave loading within the API code of practice
including effects of current wave period, current stretching,
current blockage factor and wave kinematics factor.
-
Reynolds number effects.
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ASAS-VISUALIZER
The ASAS-VISUALIZER was introduced in 2003 as a
replacement for the original graphical programs (PICASO, ASDIS and
BEAMVIEW). It works in conjunction with the ASAS URSD and provides a
highly intuitive and powerful graphical presentation capability. The
GUI format is relatively common across other Century Dynamics
products including AUTODYN and AutoReaGas.
Other features
include:
Display parts of a structure through sets - (directly
from ASAS or user defined by list or via screen).
Display of
parts of a structure through groups, element type or material
type.
Display of beam sections
Unity check values from a code
check
Highest unity check values across a set of load
cases
Beam offsets
Display of point and distributed
loads
Contour plots
Mode shapes
Animations
 
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Capacity and performance
ASAS is often used to analyse very
large structures such as ships and large concrete structures. Right
from the beginning ASAS has been designed to cope with these
demands. Firstly ASAS has multi level substructuring capability.
This means a large structure can be broken into more manageable
components. Advantage can be taken of symmetry and repeatability.
ASAS can also 'stitch' together these components automatically when
the model is assembled. Substructuring also permits model creation
to be split across a number of engineers.
Most Finite
element systems running under MS-Windows 32 bit operating systems
are restricted in the size of models due to the 2.1GB
addressability. Not ASAS. We have introduced a virtual addressing
capability which permits very large single shot (or substructured)
models whereby 64GB files can be addressed in ASAS(L) and 8GB in
ASAS(NL). This capacity increase requires not changes whatsoever to
the data.
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Pressure and Motion Transfer from ANSYS AQWA
As well as calculating pressure
loads for fixed tubular structures via ASAS-WAVE it is also possible
to transfer pressures and motions from an AQWA-LINE
diffraction/radiation model directly to an ASAS model via AQWA-WAVE.
Each combination of wave frequency, heading, height and phase
becomes a quasi static load case. AQWA-WAVE is also capable of
transferring wave loads for structures made up of both diffracting
and tubular elements such as may occur in semi-submersibles or
truss-spars.
Both the AQWA and ASAS models can be created by
FEMGV and both can be different meshes AQWA-WAVE automatically
interpolating the correct pressures at the ASAS nodes. For those
elements which cut the still water surface AQWA-WAVE will make
appropriate corrections to the pressures.
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Stiffened Panel Assessment
Ships and offshore structures often
generate large finite element models. As well as having many load
cases the models usually involve idealisation and are performed in a
linear domain. However as with framed structures the finite element
analysis is only a partial solution. It is necessary to look deeper
at the real structure and determine things like flange and panel
buckling, spectral and deterministic fatigue and strength of
individual characteristics. Both uni-directionally and orthogonally
stiffened panels can be assessed.
PANEL-ENVELOPE is the
interface between the PANEL-CHECK program and ASAS. Capabilities
include:
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Selection of individual load cases
from ASAS to be factored, selected, discarded, reversed or
combined using an extensive set of logic instructions.
-
Converts basics stress results to
stress components (Ns, Np, Nsp, M, S)
-
Forms envelopes of the maximum and
minimum extreme values at selected locations.
- These envelopes can be used for
strength and serviceability checks in:
PANEL-CHECK which can be used
stand-alone or interfaced to ASAS. Capabilities include:
- Ultimate limit state
calculations to determine stability against buckling of various
parts such as stiffener, stiffener outstands and the plate panel.
Rules include DNV 301. (flat and curved), BS5400 and IDWR.
- Serviceability limit state
calculations to determine the level of stress in each part of the
structure and compares against acceptable limits.
- Stiffeners may be tees, angles, bulb
flats or plat plates.
- Deterministic or spectral fatigue
analysis.
Pre-Stressed Reinforced
Concrete Assessment
Analogous to stiffened panel
assessment Century Dynamics also provide ASAS-CONCRETE for the
assessment of pre-stressed reinforced concrete. The combination of
ASAS and ASAS-CONCRETE provides a capability to perform a linear
global analysis (ASAS) followed by a non-linear analysis
(ASAS-CONCRETE) which uses a 'finite layer method' involving the
material properties of concrete, tendons and reinforcements.
Non-linearities are taken into account at a local level where the
checks are to be performed. This approach greatly reduces the
analysis complexity and facilitates the principle of superposition
which means numerous load cases and combinations can be
handled.
CONCRETE-ENVELOPE is the interface between the
CONCRETE-CHECK program and ASAS. Capabilities include:
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Selection of individual load cases
from ASAS to be factored, selected, discarded, reversed or
combined using an extensive set of logic instructions.
- Converts basics stress results to
stress components (Nx, Ny, Nxy, Mx, My, Mxy. Nxz, Nyz)
Forms
envelopes of the maximum and minimum extreme values at selected
locations.
- These envelopes can be used for
strength and serviceability checks in:
CONCRETE-CHECK which can be used
stand-alone or interfaced to ASAS. Capabilities include:
-
Ultimate limit state calculations to
determine stability against buckling of various parts such as
stiffener, stiffener outstands and the plate panel. Rules include
DNV 301. (flat and curved), BS5400 and IDWR.
- Serviceability limit state
calculations to determine the level of stress in each part of the
structure and compares against acceptable limits.
- Stiffeners may be tees, angles, bulb
flats or plat plates.
- Deterministic or spectral fatigue
analysis.
CONCRETE-PLOT is an interface program
between CONCRETE-CHECK and FEMVIEW for presenting results in
graphical form such as utilisation ratios.
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