Application of lateral load on irregular buildings in Pushover analysis

02-Getting started with the modelling
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rajdeepsaharia
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Joined: 11 Mar 2021, 11:23

Application of lateral load on irregular buildings in Pushover analysis

Post by rajdeepsaharia »

According to ATC4O volume 1 for torsional considerations the static lateral forces should be applied at the Centre of Mass of each floor. But the centre of mass does not necessarily fall at a beam column joint always. If we insert a node for the centre of mass at any intermediate point on the floor, it is not considered as a structural node by the software and if we make it a non-structural node the lateral loads can not be applied. So, how can we apply the lateral loads at centre of mass at each floor?
huffte
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Location: Cookeville, Tennessee, USA
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Re: Application of lateral load on irregular buildings in Pushover analysis

Post by huffte »

You could create a structural node at the desired center of mass location. Rigid links or diaphragm constraints could then be used to connect the center of mass node to the remainder of the floor.
Tim Huff
rajdeepsaharia
Posts: 8
Joined: 11 Mar 2021, 11:23

Re: Application of lateral load on irregular buildings in Pushover analysis

Post by rajdeepsaharia »

I have tried creating the structural node at the centre of mass and connected the node with diaphragm. After that I applied the load at that node. But on running the analysis was showing warning, displaying " The output steps are not enough to bilinearize the capacity curve, and the target displacements will not be calculated." The eigen value analysis was also not completed. What should we do to avoid this error ?
huffte
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Joined: 22 Jul 2011, 10:19
Location: Cookeville, Tennessee, USA
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Re: Application of lateral load on irregular buildings in Pushover analysis

Post by huffte »

It would seem that there is some problem with your modeling if the eigenvalue analysis did not complete. Are masses generated from element masses or applied loads or both? Will a simple static analysis run? Will the pushover run with manually specified target displacement instead of internally calculated target displacement (that is the way I usually run pushover)? What response control are you using?

There are simply too many variables to know exactly what the problem is from a brief description. I encourage you to start simple and gradually work your way into the more complex features of the particular structure you are trying to model. Structural modeling is quite a challenge. So don't be discouraged. Even most very experienced users have to go through a lot of preliminary issues such as the ones you are having, before getting things accurate.
Tim Huff
rajdeepsaharia
Posts: 8
Joined: 11 Mar 2021, 11:23

Re: Application of lateral load on irregular buildings in Pushover analysis

Post by rajdeepsaharia »

Thank you so much sir, it was of great help.
huffte
Posts: 904
Joined: 22 Jul 2011, 10:19
Location: Cookeville, Tennessee, USA
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Re: Application of lateral load on irregular buildings in Pushover analysis

Post by huffte »

Glad to hear it.
Tim Huff
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