Civil Engineering/E-tabs


hello sir,
I'm a civil engineer student, and kindly i ask you for some explanations,
when i used to design in robot i used to assign a diaphragm behavior instead of the slab,
But why in Etabs although I've assigned a slab i also have to assign a diaphragm ?? please answer me as soon as possible with best thanks and  regards.

Dear Ali

Rigid diphragm is an ideal model. The slab modelling is a realistic model. You should select between these 2 models. You are not obligated to assign diaphragm when you have a slab. BUT you must get sure about the slab model to use it instead of an ideal diaphragm. If you are not sure and in the case of any doubt , you may need to use diaphragm constraints to model the slab action. Please feel free to ask me further in the case of any doubt.


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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.

Sinam Consulting Engineers Co.

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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