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# Civil Engineering/story shear problem

Question

story shear
QUESTION: hello sir,
i am designing a 31 floors building using etabs 2013 software but i have a problem with the story shear which is given in the image below. Can u tell me what should be the reason?
Does the stiffness modifiers of retaining wall in the basement be different from the shear wall?
the period given by the first mode is large equal to 6,2 sec"
Thank u!

Are you using static analysis?

beh

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

QUESTION: hello,
i am using both dynamic and static analysis, but the period is due to modal analysis it's the period of first mode.
Thank u

I mean the shear distribution is due to static analysis or not? If so I guess you have made a mistake in applying of static load in the basement and you have to revise the direction of the loads. Please check and give a me a feed back.

Regards
BEH

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

story stiffness
QUESTION: hello,
This shear distribution is the same due to static load and dynamic load but i don't think it's a load problem because the loads are the same in all the building, also its the same distribution for all lateral load. The story stiffness have the same distribution check the image below plz. what can i do with this problem?
Thank u

Dear Batoul

It is not a stiffness distribution problem. The shear must be decreasing along the height of the building according to a trapezoidal increasing floor seismic load. If there is a conflict then your loading ( I concentrate on static loading for the while) must be rechecked.

Regards
Beh

Civil Engineering

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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