Creating ETABS Default.edb file

When you start ETABS and click on New Model…, it asks
to choose edb file, either default or custom. In this tutorial you will be able
to create a default.edb file. The advantage for this option is, you can immediately start working on building the model
instead of first defining the material and section properties. The choose.edb
option is for selecting an ETABS file which is not default but you want to use
parameters of the model used in other project.
So, in this tutorial you are going to make a default edb
file containing all the information, units and options in which you want to
work and don’t want to waste your time every time you start a new model.
We will work in SI units in this
tutorial.
1-Start ETABS
3-Select kN-m from lower right
corner units drop box.
4-Start a new
model and when asked for edb file, Choose No, because at this time you are
creating your first edb default file.
5-Select “Grid Only”
option and press ok.
No we will work menu by menu. So first
one is file menu.
FILE menu
i-Print Setup
Select your default printer and paper size.
DEFINE menu
Select your units to be N-mm
i-Material Properties
Select add new materials and define different concrete
strengths you use commonly. For example
Conc. 21: 21N/mm² compressive strength and 420N/mm²
steel strength with 4700√f’c as modulus of Elasticity.
Conc. 25, Conc. 30, Conc. 35, Conc. 40
etc.
ii-Frame Sections
Select the first section in the list then scroll to the
bottom and while holding the Ctrl button select the last section in the list,
then click on delete button. All frame sections except the last one will not be
deleted. You can add new sections and once you have defined your section, you
will be able to delete also this last undesired section.
Add all the sections, you want to
be in your project, for example rectangular, circular etc. Define as many
sections as you can. Sometimes, you want to optimize your sections and want to
increase say a beam’s depth by 50mm and check if it is passing or not. So
first define the smallest section and then define all other sections with depth
increment of 50mm (or 3 inches) keeping the width same. Once you have reached
the limit for the depth of the members, say 1000mm then start defining the
sections with width increment. This step is most time consuming, but as you do
it, I bet it will be much time saving for your next models. If a beam say
250×300 is failing, you will not need to define another section say 250×400,
rather you will just select it from the pre-defined sections and change the
section to see if its passing or not and so on. You MUST concentrate hard on
this step and on cover values and material of sections, because once you define
the sections, it will be hard to catch the error in
cover or depth or width values. For an example you can have your sections like
this:-
B-250x300           B-300×300           C-300×300
B-250x350           B-300×350           C-400X400
B-250x400           B-300×400           C-500X500
Note:
Cover to rebar center is distance b/w edge of beam to
centroid of reinforcement. I recommend you to use two layers of the main bars
you use commonly for top and bottom reinforcement and #3 bars or (T10) bars for
stirrups and 40mm cover. Remember when you use two layers, the distance b/w
bars (vertically) should be larger of 25mm(1”)
or main bar dia. For example for moderate height and size of
buildings.
You can 2 layers T-16 main T-10 stirrups so cover = depth –
40cover – 10stirrups – 16 (1layer of T016)-(25/2mm) for half of
dist b/w bars. = depth – 80.
iii-Wall/Slab/Deck Sections
Define all your slab sections here. For example 2way150 (two
way slab 150thick) 1way125(one way slab 125 thick)
etc. Please select material for each section carefully. Membrane and bending
thickness is same mostly. But if you have pre-cast slab with 75mm topping, your
bending thickness will be 75mm and your membrane thickness will total thickness
(slab+topping). If you have flat slab, select shell option, otherwise membrane
option. For one way slab use special one way slab
distribution option.
SHELL: Transfers load to horizontal boundary elements (beams
in two way slab with beams).
MEMBRANE: Transfers load to boundary nodes (columns in flat
slab).
Slab load is distributed by 45 degree tributary area method.
iv-Static Load Cases
Define all your static load cases. To be simple, define
Dead, Live, EQ and wind loads.
Put dead load multiplier 1 in one of any dead load case. No
need to put separate Self wt load case. Usually dead load cases are DL, WALLS, Finishes. For simplicity and for small projects, you can use
only 1 case as DL (including all finishes, walls, self wt) etc and one LL.
For earthquake loads, you must define four cases
EQX1- X direction + Y Eccent.
EQX2- X direction – Y Eccent.
EQY1-Y direction + X Eccent.
EQY2-Y direction – X Eccent.
Eccentricity ratio should be 0.05(5%). These four directions
are necessary for irregular buildings. If you have perfectly regular and
symmetric building, you can use only one X and one Y direction.
v-Special Seismic Load Data
Select do not use special seismic load data and press ok.
vi-Mass Source
Select “From loads” option because we will not
generally put additional masses inside our model and self weight is also being
calculated with DL (self wt. multiplier is 1). So everything will calculated based on your given loads. Use 100%DL(all dead load not just self wt.) + 25%LL (see UBC-97
code). For light buildings you can use 100%DL + 15%LL.
ANALYZE menu
i-Set analysis options
Unselect dynamic and P-Delta option, if you do not want to
use these options. (UBC Equivalent Static Process, used in moderate size
buildings.) If you run your model with dynamic option selected, you will not be
able to see static seismic calculations in summary file, even if you remove
dynamic option and run the model again. This is a bug in ETABS. So if you are
sure that you will use STATIC process, remember to check dynamic option is unselected
before running your model.
OPTIONS menu
i-Preferences>Concrete Frame Design
Select your code. For ACI, ACI-02 is best. Select seismic
design category. If you want to convert UBC Seismic zone to seismic category,
refer to ACI table R1.1.9.1 in Chapter 1. Do not change pattern load factor.
Utilization factor limit is the additional ETABS factor of safety. It’s
not recommended to change this factor also.
ii-Preferences>Reinforcement Bar Sizes
Change to your needs and delete unnecessary bar data.
iii-Preferences>Live Load Reduction
Select your parameters. Usually no live load reduction is
selected.
And that’s it. You are done. You have successfully
configured everything you needed for your next models. Now it’s the time
to save it in proper location.
Click Save As… in file menu and select the
installation folder of ETABS, if there is already default.edb file, overwrite it, otherwise save as “Default.edb”.
Now every time you start a new model and when asked to
choose edb, just select the Default.edb button and you will find all the
settings there.

6 Comments

  1. 1909.3.2.3 Shear and torsion (See also Section 1909.3.4 for shear walls and frames in Seismic Zones 3 and 4) . . . . . . . . . . . 0.85
    1909.3.4 In Seismic Zones 3 and 4, strength-reduction factors  shall be as given above except for the following:
    1909.3.4.1 The shear strength-reduction factor shall be 0.6 for the design of walls, topping slabs used as diaphragms over precast concrete members and structural framing members, with the exception of joints, if their nominal shear strength is less than the shear corresponding to development of their nominal flexural strength. The nominal flexural strength shall be determined corresponding to the most critical factored axial loads including earthquake effects. The shear strength reduction factor for joints shall be 0.85.

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