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Civil Engineering/SEISMIC JOINT(Modelling, Property)


QUESTION: Hello Sir,

I am a Master's candidate of Structural Engineering. My dissertation/thesis topic is "seismic pounding between adjacent asymmetric building structures".

I am working on ETABS/SAP, can u please suggest me what type of material (property) should i use to fill the gap between adjacent buildings as seismic joint and how to model this.


ANSWER: Dear Shakib

No need to model the soft material in joint.  You may need to use nonlinear links to model the impact effect. For sure you must use the time history analysis to get the links active. Try one nonlinear link with gap in each adjacent joint of each story.


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QUESTION: Thank you for your co-operation,

Sir is it must to use time history analysis to get the links active

Cant we do without time history analysis
i was doing by response spectrum

in that i am using nonlinear link with gap for modelling in ETABS for the impact effect,

while defining the property for link with gap. In ETABS there is a option for gap for non-linear properties, in that there are two options

1) Stiffness - How to give stiffness value sir? any provisions-reference
2) Open - i am putting the value for this one equal to separation distance required for adjacent building as per IS 1893-2002.

is this correct sir how i am doing?

Dear Shakeeb

A link between 2 adjacent structure must have the following properties:

1- Not being active while no impact occurs ( you are right as to set the opening as equal to the gap size)
2- When active having  very large stiffness. ( no provision exists , just choose a very large stiffness compared to actual axial  stiffness of the columns say 100 times)

As I said you don't have to model the filling material because it is rather dummy and just to cover the appearance of the joint.


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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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