system over-strength , omega in ETABS-2013 1

[ayelamayem77]

Dear all,

Etabs2013 asks for system over-strength factor when assigning seismic forces using ASCE-7-05,the program mentioned that this value is used solely in design.
Referring to (ASCE 7-05 Section 12.3.3.3) Required strength of columns supporting discontinuous vertical elements the design of these elements should be done under load combinations with the over strength factor
Ex:
(1.2+0.2sds)d +omega*E + L + 0.2S

i tried to make an example of the previous design case required by ASCE-7-05 and check the design by etabs2013 for the columns supporting discontinuous vertical element to know whether or not that these elements designed by the previous load combination but the fact was that the program ignored the over-strength factor in his design.

so my question:

why the program asks for this factor and in which cases it is used in design by etabs2013 ?????????

 

[ayelamayem77]

would any one help we why this idiot program asks for omega factor ?????

 

[ayelamayem77]

No one can give even a general idea !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

[ingdaniel]

That combination is use for some types of structures.

In steel for OCBF is use for checking connections.

It depend of the Structural Lateral Resisting System. (I believe that is only use for steel design)

Regards

 

[ayelamayem77]

thanks ingdaniel for your support.