ETABS

[krenardila]

hello
can y help me how to model a pile in etabs or palankola

[deviationz]

ETABS User Manual

Code:

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[dvng]

P Delta Analysis

I am currently checking PEB Steel Building which was design by Etabs using ASD 89. The user specify Pdelta analysis and Use effectice length 1.0xL since @nd order analysis is performed. However, in Etabs ther is two options for Pdelta analyis, one is usimg mass based the other using load combinations. The user here, chooses Mass based and sets the factor for mass as 1.0. Is this correct? as i understand inthe ASD 89 you are require to set load factors to 1.6 if 2nd order is used and later apply the same division factor of 1.6 for the stress check. Under ASD, can you set the effective length to 1.0L? I know you can for LRFD. Anyone care to enlightened me??

[RANA WASEEM]

hello every body!
i have etabs model and its meshed already slab and walls and there are some areas with wrong local axes...giving me stupid moment values....now the problem is i want to match the wrong areas local axes to the right ones...the problem is my model is too complex and its already meshed....this is not possible to check every 1m x 1m mesh and rotate it...isnt there any way to reset local axes...

[deviationz]

Yes.
Do the following. Select the shell element with the right local axis. Select Assign->Copy Assigns.

Then select all the shell elements that you want to assign this axis system and do Assign-->Paste Assigns-->Shell/Area Local Axis.

Done.

Now you can thank me.

[imran]

How do I find the critical load combination for moment in

Beam
Column and
slab in etabs

[mig21]

How do I find the critical load combination for moment in

Beam
Column and
slab in etabs

hi

for beams and slabs create a new load combination and use "envelope " option as combination type ans use as load all the desired loads combination for which you want to know the critical moments. this will produce a bending moment diagram that is an envelope of all the load combinations you defined.

For columns there is no such thing as critical load/forces/stresses ,, since columns are subject to axial+bending moment forces you have to create iteration diagrams. you cannot use, for example, the maximum axial load with the maximum moment because they, eventually, do not occur in the same load combination. create an iteration diagram a see if the combined loads from your analysis fail or not. see/search the forum for excel spreadsheets that can do this for you. hope i can helped.
PS.. ETABS, also creates/draws the iteration diagram for columns but i prefer to use excel sheets

regards

[imran]

mig21

I did as you told me

please check the screenshots and tell me whether it is correct. I have included comments with the images please check them

[robertsas]

Dear Imran,

Are you a new user in ETABS ?
After seeing your pictures attach and your reply comment above, I think you not familiar with ETABS.
DCON1, DCON2,... they are the default load combination on ETABS for concrete analysis.
You can make your own..like COMB 1 = 1.4 DL, COMB 2 = 1.2 DL + 1.6 LL, etc..

You should make the right model in ETABS include the Load Combination, and then you run your model.

After that you can click or select elements (Beam, Column) that wat you want to control, click FILE - Print Tables - Analysis Output - Check "FRAME FORCES" only - Click "SELECT LOADS" button - Choose all Combination - Check "PRINT TO FILE" and "ENVELOPES ONLY" - make your own name for the txt file - Click OK.

Click FILE - Display Input/Output - double click the txt. Now you can see the MAXIMUM and MINIMUM value that happened on beam or column that you had selected.

FYI : ETABS cannot show all Critical forces (Moment, Shear, etc) in one table/windows on grapichal view together. But in other software like SPACEGASS, can do it.


regards,
robertsasmita

[sonidero]

Dear Imran:

Apart from the comments made by robert, I see your images that you are using envelopes (?) The envelopes are useful to give you an idea how to find the solicitation more critical in a design manual. But if you do a design based on design codes included in ETABS or other software, it is not necessary, even more, and is beyond logic, for the same program evaluates all combinations and look at each element combination is the most critical and need not be the same throughout the structure.

Instead of using combinaciontes type "ENVE", use the type "ADD" to consider different load factors according to the rules in use