distribution of winf load in mega braced building with shear core

[ap3120]

I have the following building where the flexural deflection is taken by the corner mega columns and mega cross bracing on the facades, and the shear is taken by braced frame at the core.

To get the flexure deflection, I take the whole wind load divided by two cause I have two mega bracing systems (one on each face), and I take the whole wind load divided by three to get the shear deflection (cause three braced frame in the core).

But then, I feel like I consider two times the wind loading and I was wondering if it shouldn't be redistributed between the core working in shear, and the mega brace+corner columns working in flexure?

 

[Agent666]

I think your overarching assumption that the mega brace takes all the flexure and core all the shear is not accurate. Usually you'd build a 3d model of the entire structure to determine the relative proportion of load each system sees. How much each system sees of the global base shear is entirely dependant on the stiffness of each system relative to the other.

Also, my understanding (at a high level) of mega brace systems is that the mega brace is generally meant to be the primary (stiffest) loadpath, the core is a secondary system to transfer floor loads between the mega brace nodes and to provide stability to the columns between floors and restraint to the mega braces. As such the major component of flexure and shear will be carried by, or is intended to be carried by the mega braces.

If you want to understand in a basic sense the deflection of both systems and their interaction, create an analytical model of the frames in series linked together by rigid elements representing your floor diaphragms and see how they deflect under the full loading.

https://engineervsheep.com

 

[ap3120]

Hi Agent666,

Sorry for the late reply. Yes I think you're right, it is over-conservative to consider that the core and the braced façade work as two different system individually, and the building should be analysed as a 3D model.

Thank you.