Simultaneous Overturning & Sliding???

[jgeng]

I have an elevated small light frame timber construction structure approximately 12'x12' supported by 6 timber posts. With low dead weight there is considerable overturning and uplift due to wind. Is it typical to check sliding base considering only the direct vertical compenent of the wind uplift taking away from the available dead weight in the appropriate L.C.? and consider overturning as a seperate failure case? or do you you need to look at both simultaneously with the increased uplift in the windward footers due to the overturning moment.

 

[Ron]

Generally OT moment will control (and is the code mandate in your area), but check them both. For a small footprint structure, your sliding could be significant. Just keep in mind that your wind design is a gust, not sustained. Makes sliding a bit less likely, since you'll experience an uplift imbalance initially that will likely cause "plowing" rather than sliding.