ASCE 7 WInds Loads on a Very Small Building

[CARunderscore]

Good morning,

I have a what is essentially a small hut design that I am trying to apply ASCE wind loads to. Architecturally, the thing is just four walls with a flat roof and an overhang all around. The windows and doors are proportionally large enough that the roof is primarily supported by short beam-columns rather than shear walls. Basically every structural element is also part of the building envelope. The gross outside surface area of the entire structure might not even add up to 700 square feet (it's very close). I am at home and don't have my copy of ASCE 7 in front of me, but I'm not even sure it meets the standard definition of a building, now that I think about it.

Based on the size and relatively small amount of redundancy within the structure, I'm wondering if there is anything that can even be meaningfully classified as the MWFRS. Every component receives wind load directly or from a window, door, or the roofing materials, after which the load has a short, straightforward path to the foundation.

My boss says that individual components should be checked for Components & Cladding pressures, but that the overall structure should be checked for MWFRS pressures. Intuitively, that doesn't make sense to me in this case. If I have a single wall to be checked for a component pressure, and that wall represents the entire upwind face of the building, isn't it non-conservative to not follow that whole load into the foundation? Before being told otherwise, I was inclined to just conservatively apply C&C pressures on all surfaces simultaneously such that the MWFRS pressures were included in and exceeded by the C&C pressures, and then see if the resulting forces were onerously high or not.

I used the Simplified Envelope Procedures (once again, don't have the book in front of me... sorry if I'm calling it the wrong thing) to generate the MWRFS pressures, and the corresponding simplified procedure to generate C&C pressures, if that makes a difference.

Thoughts?

 

[Ron247]

Only the lower half of the wind load on the stud has a "short path" to the foundation. The upper half takes a much longer trip and will get more frequent flyer miles. The upper half will travel up to a diaphragm roof, then over to some vertical bracing system. Since you state you have virtually no shear walls, you are left with some type of frame to resist the lateral forces. The size of the structure will not negate how structures react to applied forces.

 

[gte447f]

I think you are overthinking this. Whatever system keeps the building as a whole from sliding sideways or tipping over (the MWFRS) can be designed using MWFRS wind pressures, regardless of the size of the building, and regardless of what type of system it is (e.g. shear walls, frames, cantilevered columns, etc.). Some of the components of the MWFRS may also have to be designed for C+C wind pressures separately, like a wall stud that is part of a shear wall.

 

[CARunderscore]

Okay, thanks, guys. I will take your advice into account in the future when applying my pressures.

This is/was a very low-priority project that only gets worked on sporadically, so it may take some time for me to come back to it.