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1. RECENT APPLICATIONS
1.1 Bridge analysis
The remarkable design practice
using PENTAGON-3D has been done in the turnkey base bridge design
during April 1998. The aim of using the program is to check the
settlement and the stress distribution of the substructure and
the super-structure of the 6 to 7 span motorway bridge.
The site has the geological
condition of limestone with several joint sets and faults. The
reinforced concrete pier height is about 30 to 40 meters and the
super-structure consists of steel box girder. Using PENTAGON-3D,
the ground settlement and the stability were checked. For the
pier, several load cases were applied and combined to get the
worst loading condition. From the stress along the cross beam,
the amount of reinforcement was estimated.
Finally, all the members of
superstructure were modeled and the structural analysis was
accomplished successfully. To do this, many practical functions
were implemented such as various kind of loads located on the
element surface and nodes. Now, the design modules are under
development.
1.2 Large shaft construction
near subway station
Flexibility of mesh generation
enables the PENTAGON-3D user to model the complicated
intersection between the 40m-diameter shaft and the 23m wide
tunnel.
However, all the reality of
construction could not be modeled due to limit of time and
effort. A good simplification of mesh was applied by using 3D
load distribution concept where the total excavation load was
stored, divided and applied to the next stages. Suppose the LDF
concept in 2D analysis. The result was quite tolerable for
practice.
2. New Products
2.1 Tunnel Master (Korean
language version)
Tunnel Master is the design
tool to obtain 20 to 30 shop drawing sheets within just a few
hours including the material bill. One of recent user, Pyong-Hwa
Engineering was fascinated by this product and are ready to apply
the program in practice.
Tunnel Master is developed to
design the Motorway tunnel quickly. Tunnel Master may be very
effective at the planning and design stages when the design
condition should be changed so frequently.
3. PENTAGON-3D
3.1 PENTMESH
(Pre-processor)
Layer and sub-layer
PENTMESH has been developed for
the perfect GUI environment. To do so, the Layer and Sub-layer
concepts were newly defined and implemented. The layer is the 3D
data extended from the sub-layer and additional data. The layer
is connected with the construction and load stages. The sub-layer
is the group of the selected nodes and elements in 2D. The click
of sub-layer name reduces the effort to define the 3D data.
New files
In developing the full GUI, the
STG (stage) file is added besides the MSH file. The STG file
contains all the database for the analysis. The input data for
analysis is generated with one touch of menu from these MSH and
STG files.
Loads within the shell and
frame element
In the bridge analysis, the
load can exist at any location within the structural element such
as shell and frame elements.
3.2 PENPOST (Post-processor)
The mirror display
The mirror function is added in
PENPOST to view the double size model. The nested mirroring is
not available.
Color palette
For the better view, new color
palette is added where you define new color band and save in the
color file to be opened later.
3.3 FRONTDBX (Main
processor)
Load combination feature
with load factor
PENTAGON-3D has considered the
staged construction by far, but now, it is available to calculate
each load case and combine several cases with load factors.
Hyperbolic model with
unloading and reloading logic
The hyperbolic model
(Duncan-Chang mode) is developed with the unloading and reloading
features. For unloading, the program checks the first and second
stress invariants to check the volumetric and deviatoric stress
unloading. The program remembers the maximum stress invariants
and recognizes where the reloading stops
4. PENTAGON-2D
Now, you can meet more
beautiful PENTAGON-2D like PENTAGON-3D. The color
table is updated in PEN2POST module. In the new color table, the
color band can be edited and saved to user specified file (*.clr). You can simply open the color file.
5. ACTIVITIES NOW !
Going overseas
Now, most of the documents of
PENTAGON-2D and PENTAGON-3D are translated into English version,
and we are extensively searching and contacting the potential
foreign agencies. We estimate PENTAGON series programs are very
competitive also in oversea market as well as the domestic one.
The consistent program structure guarantees the stable feature of
analysis for the staged construction with the complicated
geological and loading condition.
Welcome to our educational
course
Over 200 engineers and students
have visited our training courses since our training course
opened in Oct. 1996. We always thanks your aggressive interests
in our FEM world and its development.
We are concentrated on quickly
reducing your trouble for special project.
6. Tips and Tricks
Why Initial stage does not
permit even very small plastic region ?
Most users have experienced the
error message after the initial stage. In the initial stage,
PENTAGON requires that the insitu stress be free perfectly from
plastic state because the plastic state is the potentially
unstable state before the man-made construction. If there is even
very small plastic region in the model, PENTAGON will stop.
In short, the initial stage is
the starting point of loading analysis. The situation after
loading will be usually worse than the initial stage.
However, the recent version after 13 August
1998 will continue the elasto-plastic analysis if the elastic
stress violate the yield condition. In some cases, user want to
make the plastic state in the initial stage due to complicated
geological conditions. This means that the program modifies the
stress condition to fit the yield condition. Normally, it is
strongly recommended for you to run the model elastically first,
and then, to establish new model not to violate the yield
condition.
How the load distribution
factor is applied ?
This is closely related with
the load concept of PENTAGON. Most load types are externally
defined such as the point load, the surface load, the body load,
the prestress, and the prescribed displacement. However, some
loads are estimated internally such as the load due to excavation
(element removal), the seepage forces, and the self-weight change
due to groundwater level fluctuation.
All the loads are compared with
the stresses in the elements, and the residual or unbalanced
forces are estimated.
After removal of elements in
construction stage, the residual force is generated on the
exposed surface by element removal. Please note that the
construction stage changes only the structure and the load stage
estimates the load and calculates the FE equations. Now, there is
another stage to estimate the residual forces named Save
residual stage.
The excavation load is
estimated and stored here, in the save residual stage. The LDF is
distributed in the following load stages. For example, to input
40%-> 30% -> 30% LDF sequence, you input the LDF values, (-0.6)
-> 0.3 -> 0.3. The negative value means the
reaction and positive values mean that the initial excavation
load looks vanishing after the reaction is applied because all
the external loads including the reaction forces reach at the
equilibrium with internal stresses. So, in next stage, the
positive LDF is used. All the input loads are added, in other
words, accumulated.
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