| FEDRA - Frequently Asked
Questions |
|
| When do I save a file? |
| The program saves automatically the data into
various files. For each project you define a name. With the File/(New/Open) project
command, it makes a folder with this name and keeps inside all the necessary files. |
|
How can I preview the report?
From the right green window. By clicking at the corresponding report chapters. |
|
What are the basic steps to make a design?
Open a project, click at the yellow left window at Drawing plans
and give the drawing, click the topology for topology evaluation of the building. (there
the various closed areas must be recognised if the structure elements are inputted right.
Click at the Solution and compute everything. The design is done automatically based on
the topology recognition of the building already done. The loads are evaluated and carried
to the corresponding elements. The walls are automatically divided into finite elements
and after the solution all the necessary checks according to Eurocode 6 are performed.
Check always the report chapter under the title Masonry design. If the walls are not
adequate red lines will appear, with notices for the design errors. In the same way check
the titles Slab design, Beam design and column design, for the concrete element design. |
|
How are roof loads computed and
transferred on the walls?
The roof loads are computed from the enclosed roof area,
multiplied by a factor c=Roof Load Coefficient, (this can be changed by clicking at the
yellow pad the line Structure loads/Roof). The total roof load is distributed to the
carrying walls in proportion to their length. |
|
How are the floor loads computed
and transferred to the walls?
The loads from the concrete
floors are computed doing an analysis (slabs according to Marcus theory, beams as a grid).
The loads from wooded floors are computed and transferred to the walls as the roof loads
above. |
|
How do I start a drawing?
The best way to start a drawing is by creating an outline. Then
by clicking at the middle points of the outline the external walls are placed
automatically with the outside face on the outline side. Before this you may select the
outline and stretch it to the grid or the mesh. This is described step by step in the user
manual, chapter Drawings. |
|
What to do if the topology
evaluation is not right?
Increase the value of d min and click Compute. Repeat this until the topology is
right or go back to the drawing and change the length or the position of the walls. It is
good for the walls when they are crossing to overlap. Maybe you have placed objects on top
of each other. E.g. A wall is placed on top of another wall in the same floor. (this may
happen when you do copy paste a floor and you paste in the same floor). Also, do not place
beams on top of walls in the same direction. The beams must be free to deform. They can
span between two walls. |
|
How do I change the symbol for
the reinforcing bars?
The symbol for the reinforcing bars is usually Ö, but because some window
installation may not see Greek mathematical symbols, in the program by default we use the
symbol #. With the menu Parameters-Reinforcing bar diameter symbol, you can specify
another symbol. |
|
In the solution of roofs with
Eurocode 5, I do not get right the mathematical Greek symbols.
Go to the menu Options/Language set/English without support of Greek mathematical
symbols, and another modulus will be installed, where the Greek mathematical symbols are
written explicitly, e.g. Beta, gamma. |
|
How are the seismic loads
computed?
The
seismic loads are computed as horizontal static loads at the level of each floor. The
vertical distribution of the seismic force is a reverse triangle. The total seismic force
is (seismic coefficient)x(total vertical load). The seismic coefficient is defining the
horizontal seismic acceleration, and can be changed from the first line of the yellow pad,
or the menu Parameters/Initial values/Earthquake. The total seismic load is distributed to
the walls taking into account the eccentricity of the seismic force. (offset of floor mass
center from building elastic axis). The computed eccentricity is increased by a factor
specified in the menu Parameters/Initial values/Earthquake/Increase of seismic
eccentricity. (by default this factor is=1). |
|
How can I make different walls
from the ones existing in the program?
With the menu
Parameters/materials/Masonry, after you click at Edit you are at the basic form with the
properties of a masonry unit. You unlock, and then specify the name of the wall (e.g.
Brick wall 35 cm), choose the masonry units, the mortar and specify the wall thickness in
meters (eg. 0.35) then the rest is done automatically. |
|
Some
windows do not appear right.
The size, colour and font of windows are locked. You can change
this by going to Options/Environment/Windows. Uncheck the locking of position colour or
font, and then open the windows you want to change and change their size. By right
clicking at the window a menu shows and you may also change the font or the colour of a
dialog. |
|
What is the project folder?
It is a folder container of the subfolders of
a group of designs. You may specify the project folder with the menu Options/project
folder. All design (project) creates a folder inside the project folder, with the name of
the project and a pointer file with the name of the project and the ending rpr. |
|
Why two different design for
timber roofs?
The most advance and complete is the design with Eurocode 5
(EC5) where a detailed design is performed according to Eurocode 5, with all the load
combinations and designing of joint. The timber roof design with allowable stresses is an
old modulus, which may be used for small timber roofs, and performs a design with the old
timber code. |
|
How can I modify the appearance
of the report?
With the menu Options/Printout report. You may specify the logo
at the bottom of the page, the appearance, or not, of the date, etc. and the character set. (for the character set
choose non-proportional font as Courier or Courier New in order to have the report tables
aligned properly. It should be mentioned that although you can change the font type you
cannot change the font size. It is standard in the program. |
|
Can I get the report of Fedra
into word or other text editor?
No, it is not possible. If
you have installed the acrobat Distiller you may select it as a printer, and printing the
report into it you have the report as PDF file. |
|
How can I change the number of
finite elements a wall is divided?
From the menu Parameters/Eccentricity-finite
elements, you may specify the number of vertical subdivisions cross the floor height
(default 8). The subdivisions along the wall length are set automatically so the
proportions of finite element side are about 1:2.It is advisable to solve a structure first with the
default number, 8 vertical subdivisions, and then with more refined mesh for example 16
vertical subdivisions and compare the results.
Usually from our experience the default 8
subdivisions give accurate enough results for the most common buildings of masonry
structures. |
|
How long can a wall be?
We consider the wall long when the ratio
length/height is over 3. You may give long walls. It is advisable thought to keep a
relative uniform wall length. Do not use e.g. walls with length 3m and 12m in the same
floor. The long walls will have larger stiffness and they will take the most of the
seismic force. It is probable more reasonable a long wall to be made of two or three
smaller walls next to each other. |
|
What to do when I get the
message,” Problem in floor grillage solutions”?
The floor beam system is solved as space grid. If there is not
enough support, then this grid is not in equilibrium. This usually happens when there are
free beams or beams continuing with walls in the same direction. To avoid the problem
simply extend this beam until it meets a perpendicular wall so its rotation is blocked. |
|
Can I place beams on top of the
walls along the walls?
No, the
beams considered in the program must be free to deform. Do dot use beams lying on top and
along a wall. The beams lying on top and along the walls must not exist in the design. Eg. of floor beams. In
the drawing you may draw two beams from one wall to the opposite. The program
automatically recognises and numbers the two spans of each beam. |
|
Can I place columns inside the
walls?
No, the columns in the program must be free
columns. Columns inside the walls are not considered, these are strengthening of the wall
system. In order for the columns to take loads they must have beams on top. The loads are
transferred to the columns only from beams. |
