ASCE does not give the L/600, but it's spreading like wildfire. It started with Brick Institute Tek note 28-B. The L/600 requirement now appears in UFC 3-301-01, Structural Engineering, which is required for all military projects. It is often specifically written into the Statements of Work for...
It's not pushback from an architect or contractor; it's me. I'm just trying to be responsible with the owner's money. I have full confidence of success using an Importance Factor of 1.0. Every building I've designed using I=1.0 in my 28 years of practice that has gone through hurricanes has...
I am not suggesting using L/240 for brick deflection. I am satisfied with the L/0.7(600)=L/420. But I'm not sure that even L/240 would result in "mortar joints cracking all over the place". We're designing for a once in 10 years event. Because stud strength is satisfied, the studs will remain...
If you have a builidng that requires an Importance Factor of 1.15 for wind (per ASCE-7), can this factor be waived in non-life safety situations? For example, it is neccesary to design metal stud backup of brick veneer for a deflection criteria of L/600? I don't believe this is addressed in...
Thanks for all your input. I do use the 0.7 factor for wind deflections, which effectively reduces L/600 to L/420. And I do think that is too stringent, but the Brick Institute is clear about their recommendation and I don't know any way out of it. But that's another subject for discussion. I...
If you have a builidng that requires an Importance Factor of 1.15 for wind (per ASCE-7), can this factor be waived in non-life safety situations? For example, it is neccesary to design metal stud backup of brick veneer for a deflection criteria of L/600? I don't believe this is addressed in...
I'm trying to figure out what would cause the spandrel to pop out so far. I suspect that the spandrel was flexed horizontally and loaded like a spring. If you lightly hold a business card between your thumb and ringfinger and bend it in then release it, you can make it fly a good ways. A...
In all that recent research on vapor barriers, I ran into a detail that showed a vent for radon gas. See page 5 of the pdf in the link below.
http://www.buildingscience.com/documents/digests/bsd-103-understanding-basements
kslee1000,
That sounds like a good practical way to go. Specify a coarse granular fill that will serve both functions; a capillary break and a subbase.
The well graded ACI subbase could be underneath that IF needed for high performance slabs.
I've got some General Notes to edit now!
As to kslee1000's question about why and how a "capillary break" becomes an important factor on top of such typical concerns over strength of sub-base, and wet floor?. I don't think it is AS important as strength of sub-base, but it is related to wet floor. Here's a link to an article that...
I was about to hit Submit and accidentally hit some key that made my post disappear. I had typed several paragraphs. Maybe it got submitted and thus I'll be repeating myself. It went something like this...
JAE, we're are in total agreement that to be a capillary break it needs to be uniformly...
I believe that kslee1000 is agreeing with me that this granular layer should not be called a capillary break. My point is that it is OFTEN mislabelled as one. Compacted well graded granular material does not provide a capillary break. Only a poorly graded material will provide a capillary break...
Thanks for your replies.
I agree with the belt-and-suspenders approach. However, "a well graded compacted gravel fill" is going to be more of a wick than a capillary break (see fattdads's calcs and experiments showing that water climbed to the top of his 15" cylinder and his calcs showed it...
I've been practicing for 26 years and never thought about this question recently posed to me by a contractor. Why do we need a "granular capillary break" if there is a vapor barrier? I can see the need if there is groundwater present; the capillary break will provide a conduit for ground water...
Write the word "structural" under your signature. There is an outside chance that it is not clear what is structural and what is not, but I don't worry about it and its never come back to bite me. The Florida law states that when there are multiple engineers on the same drawing or spec., to...
Dave:
I am insisting on Exposure C because the higher roof IS greater than 30 ft. The architect wants to average the high and low roofs to say that the "mean" roof height is less than 30 ft. That would be a wrong interpretation of "mean roof height". I believe that UcfSE has given me the...
UcfSe thanks for pointing out that different surfaces can have different Exposures. I have never considered that.
DaveViking: Exposure B conditions exist for 1500 ft. between the the body of water and my structure, so if less than 30 ft. tall, Exposure B should be okay.
This is a church family...
David: The building is not a box, so I'd say it is not regular. It's somewhat irregular in plan and it's not regular in elevation since the middle pops up. I believe engineering judgement is involved. A wind tunnel test would be too expensive.
The exception basically says that if I'm 1500 ft...
