Seismosoft | Earthquake Engineering Solutions

Hi seismosoft team.
I have 2 questions about static pushover analysis:
1. In the seismostruct wizard, we have 2 loading type: Uniform and Triangular distribution. How can we use a loading type with the first mode distribution?
2. How can I estimate the target displacement of my model using in the loading phases?Is there any program to do this?
best regards.
Gonzalo.

Hi Gonzalo,

In order to apply a load distribution proportional to the first mode shape, you should initially perform an eigenvalue analysis, and consequently define your loads proportional to the 1st mode deformed shape.
You don't need to estimate a priori the target displacement. This is just an indicative value to define the displacement at each step and the displacement for which you pushover should stop.
You might be confusing with performance point... If so, i don't know any software that allow you to estimate it. In any case, i believe in the near future SeismoStruct will be able to do so.

Cheers,
Romain

Hi dear Romain,
Thanks for your reply.

Thus, how can I compute the value of my model's target displacement? Using which formula?
Also, How can I determine the value of P0 that multiplies in the normalized 1st mode shape? (Using in the applied loading)

Best Regards.
Gonzalo.

Hi Gonzalo,

in your case, the values that you have to define in the "Applied loading" module refer to the lateral load pattern proportional to the first mode shape. You can compute them by knowing the normalized mode shape (from the displacements obtained performing an eigenvalue analysis) and the story mass.
The target displacement that you have to set in the program is simply the point at which the analysis is to be terminated (as stated in the Help System).

Kind regards,
Federica

Hi there,

May I know the difference between using uniform vs triangular distribution in a pushover analysis? My building has a regular configuration ( box-shaped with uniform spacing ) so i guess higher modes will not govern.

kaysisig,
This is about the basics of pushover analysis and out of the scope of the current forum, which is about the use of Seismosoft's programs.
Different lateral forces disitrbutions are employed in order to be one the safe side, typically two disitrbutions are proposed by the Standards.
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