How to handle shear in a 3-wall Commercial Building? 1

[EngineerofSteel]

I have just never learned how to handle this:

I have an existing building, 36x30.5, with 10' walls. The existing frontage wall of this commercial building will be remodeled to be all windows. There are only 2 small full-height sections of wall flanking the entrance door.

Basically, there is no front wall. The remaining 3 walls have a lot of wall. Each has only one puncture: a window or a door.

Existing walls are 7/8" stucco.

The roof is normal weight concrete tile: 24 psf, with 2' overhang on all 4 side. The total dead load is 44 psf.
Cs =.102

I attempted to handle this using torsion...using the 2006 IBC Structural/Seismic Design Manual.

I end up with a center of mass slightly adjusted toward the full wall, away from the glass frontage wall. But, the center of rigidity is in the plane of the lone wall. So, the resultant total force is huge, and not manageable.

Suggestions? Corrections?

 

[EngineerofSteel]

Looking at IBC 2006 SEction 2305.2.5 "Rigid Diaphragms", the l = 30.5, and w= 36 in this building. (See Fig. 2305.2.5(1) at bottom of page 438.

The problem is, for an open front structure, the maximum l is 25 feet.

Is it possible to modify this building into an open front building?

 

[msquared48]

Put a steel moment frame, or two, or three... at the window wall side of the structure.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask