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Civil Engineering/Etabs element type


QUESTION: sir can you pls. explain what is the difference of Sway special, intermediate, ordinary and non-sway for etabs? for frames like column and beams the default is sway special.
for my beams im using the Non-sway type. what is the effect of this actual in structure? I observed that more rebars output design.
thank you.

ANSWER: Dear Seco

Which code of practice are you working with? The sway option will activate the sway moment in related formula for design under combined axial and moment. Non sway will result to more economical result but you have to be sure about the fact. The sway option may be neglected in columns for braced frames or frames with very small deflection.


---------- FOLLOW-UP ----------

QUESTION: The design code im using is aci 318-05 sir.

Dear seco

Please take a look at this address:

Sway or non sway frames can be distinguished according to the Sway factor which can be calculated after one run of the software. Relation 10-6 of the above document. If the Q factor is less than 0.05 then you have a non sway frame. No matter if you consider beams in sway or non sway frames.

But ordinary , special or intermediate frames are related to the ductility level of the structure under seismic effects. It is the duty other engineer to select one of the ductility levels but I guess you in Saudi Arabia don't have to consider more the ordinary structures because you don't have earthquake in Saudi Arabia.

Don't hesitate to ask when needed.


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Babak Esmailzadeh Hakimi


I can answer questions in Structural Engineering, Earthquake Engineering, Project Management and Project Control topics!


I am experienced in the area of earthquake engineering in electrical power industry, i.e. Lifeline Earthquake Engineering. My focus has been on structural seismic design of power installations. Recently I have got involved in project management in the category of constructional engineering.

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Bs degree in Civil Engineering from Ferdowsi University ,1988, Mashhad Iran, Ms degree in Earthquake Engineering, Sharif University of Technology, 1993, Tehran, Iran

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