| FEDRA - Frequently Asked
Questions |
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|
I am tryng to put a balcony on the wall. Just put at left
and front side. I cant put a balcony
right or at back side |
|
Each object has an orientation, left and right. The
small blue mark is the left side. When we look from left to right
there is a front and back. Front is outside. In your case in wall
properties add 180 degrees to the wall angle, so the wall will turn
around.
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|
| 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. |
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How can I preview
the report?
From the right green window. By clicking at the corresponding
report chapters. |
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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? Try to 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 more 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 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? From the menu [Parameters/Materials/Masonry],
after you click at Edit you are at the basic form with the properties of a masonry unit. 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. |
|
| What is the
project folder? It is a folder container of the subfolders of a
group of designs. You can specify the project folder with the menu [File/Mail folder for
Projects]. 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. |
|
| How can I modify
the appearance of the report? With the menu Report/Report
setup. You can 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. |
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| Can I get the
report of FEDRA into word or other text editor? Yes, export to PDF (Adobe) or RTF(word) format. |
|
| 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 can give long walls. It
is advisable althought 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. |
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| 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 recognizes 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. |
