Traditional Strip Mall Lateral System 2

[StrEng007]

Most of my design work has been located in high wind zones and I've been able to (for the most part) require well defined lateral systems. I haven't done any strip mall designs except for outparcel/stand alone buildings located within these types of commercial properties.

As a general question for those who specialize in strip mall buildings, where are you drawing your lateral system from regarding longitudinal winds? It seems like the traditional strip mall contains storefront for a majority of the front elevation. I image the ones that have an overhang and columns at 20ft - 30ft centers use some sort of portal frame. Are the rest all being designed as 3-sided diaphragms?

This is general curiosity so I don't have any drawings to share... I'm sure we've all been that person waiting for a take-out order while starting at the underside of an OWSJ building (always easy to recognize others who are also in the building trade).

 

[phamENG]

Most are 3- sided or a series of them, depending on aspect ratios. Sometimes moment frames, but it's hard to get much meaningful stiffness out of the column sizes you get to work with there.

I'm sure we've all been that person waiting for a take-out order while starting at the underside of an OWSJ building

My wife always gives me a hard time when I do that...

 

[Aesur]

My wife always gives me a hard time when I do that...

haha, same here! I think this is a sign of a good engineer versus an average one..

 

[Greenalleycat]

Here in NZ the answer is one of
1) 3 sided 'diaphragm' held up by ceilings/roofs/prayers
2) Concrete moment frames across the openings, usually quite light, often with whole steel I-beams embedded in them for some sort of funky composite vibe
3) Structural non-structural glazing shear walls..............................

 

[StrEng007]

Yes, some people get generally concerned when we're staring off into space. Even worse is when someone asks us to explain what we're looking at.

Most are 3- sided or a series of them, depending on aspect ratios.

Do you know of any texts on this besides the Malone/Rice book on irregular structures?

3) Structural non-structural glazing shear walls

I just cringed.

 

[phamENG]

The SDI Diaphragm Design Manual

 

[StrEng007]

Thank you.

 

[KootK]

Do you know of any texts on this besides the Malone/Rice book on irregular structures?

As of last year, there's a decent, free structuremag article on this topic: Link

Any practicing engineer with the ovaries that it takes to publish a sketch of a differential shear element gets my respect.

In low seismic areas, I feel pretty good with the long, three sided buildings sans portal frame. Small eccentricity aside, they wind up being not wholly disimlar to the power I shape shown below which has much to recommend it. Most of the exercise of doing it "right" for low seismic areas comes down to this in my opinion:

1) Solid design and detailing of the diaphragm.

2) Explicit consideration of the movement that can be expected at the corners of the diaphragm and how that may impact stuff that might be damaged by such movements.

 

[phamENG]

As of last year, there's a decent, free structuremag article on this topic: Link

Not sure how I missed that one - thanks, KootK!

 

[JLNJ]

If the strip mall is too long, then the length-to-width of your diaphragm can be problematic, even if it works as 3-sided in the other direction.

 

[KootK]

If the strip mall is too long, then the length-to-width of your diaphragm can be problematic, even if it works as 3-sided in the other direction.

Right, but that's no different than it would be if the building were four sided, correct?

 

[StrEng007]

Pham and Koot,
For longitudinal wind, if you can resolve all windward and leeward in the "outer" 3-sided diaphragms, do you consider the internal to be dead zones? Also in the case of expansion joists, let's say they're at 1/3 points.

 

[phamENG]

Dead zones? No. If they're there, they're attached, and have strength and stiffness I'll use them.

Expansion joints? Each area needs to have its own LFRS unless you have some sort of clever expand-but-doesn't-slip collector connection that I haven't heard of.