Civil Engineering/Periods in etabs


QUESTION: From your answer to one f the query post, you ave mentioned that periods of between 4-5s is ok. Anything more tha 5 will have to look deeper. How about a value less than 4, say 2-3s?


Please give me details of the question and my response. Give me more detail from your own problem please.


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

QUESTION: I was looking for an answer to intepret the result of my etabs  model. The output of the period in mode 1 and 2 is around 2.8s and 2.2s and mode 3 is 1.8s. My question is is this model stiff enough? I understand that period is inverse of frequency. If that is the case, the frequency will be very very low (the comfortable frequency I am looking for us 5hz and more).

Dear SN

To interpret the period or rigidity of the structure you have 2 ways : 1- control the first and second ( X and Y ) mode period with tips given by seismic codes.

2- control the lateral sway and drift of the each story under lateral loading using the provisions of your local code.


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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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