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Civil Engineering/calculation of Torsional Irregularity Factors Ax

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QUESTION: Good day sir

I am designing a building B+G+14F, Dynamic analysis is being done for the structure,

I need to override the eccentricities for Spectrum Analysis (torsional irregularity)

while calculating the Ax coefficients according to UBC 1997
Ax factor is calculated by equation
Ax = [Dmax / (1.2 Dave)]2

In the above equation displacement values need to considered
from static case "EQXP-EQXN","EQYP-EQYN" or
from SPECTRUM CASES SPECX, SPECY

kindly clarify the dought

Thanks & Regards
Azhar

ANSWER: Dear Azkar khan
There is no evidency about this matter but as a matter of fact there is no real difference between the results. But it is obvious that to move to more sophisticated methods need to control results from more general methods then you should tyry with static method.

Regards
beh

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

QUESTION: Good day sir

1.
I have done one trial for comparison of the results for a building
i found there is a good difference between the results
from static case EQXP,EQYP &
from SPECTRUM CASES SPECX, SPECY

Please find the attach images for your kind perusal

kindly suggest which values need to considered?

2.
secondly as suggested
"to move to more sophisticated methods need to control results from more general methods then you should try with static method".
so to which methods i need to move/use ?

Thanks & Regards
Azhar Khan

Answer
Dear Azhar

The results of static and modal are different but their effect on eccentrencity shall not be because of the same eccentrencity of stiffness and mass centers which are the same for both method.

You should use static method to calculate the random eccentric moments.

Regards
beh

Civil Engineering

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Babak Esmailzadeh Hakimi

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

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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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