Civil Engineering/why1.4 A .B?


dear Mr Esmailzadeh
seismic cods says which we should for time history analysis to compare average of response spectrum with standard 0.2T to 1.4T . my question is why 1.4T ?

Dear Behzad

I am not in the current of development of the procedure but I can ask you what you suggests? You must compare the spectra around the period of the structure. But the calculation of T is not very exact and also the higher mode periods may be effective too. Then codes suggest you to do this comparison not at a specific period but in a range of period from 0.2 T ( for higher modes effect) to 1.4T ( for the errors of calculation being taken into account). 1.4 is a multiplier which give you an idea of the extreme credible amount of the first period of the structure. I hope this would be satisfying.


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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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