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Highly Unsymmetrical Structure

Highly Unsymmetrical Structure

(OP)
Hi Everyone,

This is my first time to design an unsymmetrical structure in both directions and i am confused whether or not my established framing is done correctly. The building is a 9-storey industrial precast structure (prestressed precast beams, precast columns, hollow core slab etc, design to Eurocode specs and imposed loads are quite considerable ranging from 20kpa to 1st storey and 10kpa to 2-9 storey. I have all the load combinations required in accordance with the specified code - dead, super dead, live, wind, seismic, response, prestress. Now my questons are:

1) Is my framing done correctly? considering that all column spacing and quantity are fixed based on architectural specs?
2) My columns are overstressed in shear due to seismic along x (EQX), is it because of structural irregularity?


Thanks in advance and please see attached framing plans. Any advice will be appreciated much.

neukcm

RE: Highly Unsymmetrical Structure

What are your lateral systems here? Shear walls? If you're using moment frames, which seems unlikely but not impossible in precast, then your columns may be drawing heavy shear on the floors where you're down to two columns deep in the x direction. Obviously, you've got all kinds of seismic irregularities to contend with.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

RE: Highly Unsymmetrical Structure

(OP)
Well i'm using moment frames and corewall as part of the lateral system. There are two columns omitted in the architectural drawings (one on top and one near the corewall) so i have no choice but to connect my beams in the corewall and in one staircase wall (so become part of MRF). The building period in modal case along X is less than 2.0secs that made me believe that my framing is quite enough. I am currently working with torsional checks (hopefully results will be around permissible). I just looking for ways how to mitigate this excessive shear due to seismic, maybe by tie beams? adding lateral beams? i'm totally confused as my columns become bigger ( 1.5 to 2.0m width).

Thanks

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