I've dealt with this on a couple of jobs. Why is cracking such a huge issue? I know you want to control it but its not avoidable(for the most part). Design the slab to carry the point load. Treat it as a simple span between supporting steel members. You definitely don't want to cut joints in...
Thanks sundale
Thats the process I normally go through. So I'm familar with the tags and SJI and so forth. This building had a remodel about 4 years ago a another parapet was added to the building adjacent to where I'm adding a parapet. All the joists and spans are the same. And no additional...
I have situation where I am adding 4' of new parapet to an existing building (only about a length of 20'). This will cause some drifting. I seem to be confused everytime I do something with an existing structure. At this time it is not known the size of the roof bar joists. I do have spans and...
I have a situation where I can only get about half the nut turned on four 3/4" dia. F1554 Fu=58 ksi anchor rods. I don't have any uplift on the base plate but I still don't feel comfortable leaving them only half threaded. What can be done? Can they be plug welded? Thanks for the help.
Why is that most structural engineers specify in their notes that concrete poured walls shalled not be poured more than 40'-0" (or close to that) in one single pour. Is this a curing issue? Does this need to be true in control joints are placed every 20'-0"? Thanks
Go to this website:http://www.nap.edu/catalog/9801.html
Its says you can read it for free. Actually once you get into it you can print a version of it. Good luck
I've personally designed my fair share of buildings that size that I didn't provide expansions joints. There are some factors as that may affect this though. I have a report that I got off the internet that helps decide whether you might need an expansion joint. Check out "Expansion Joints in...
Lutfi-I did calc the floor vibrations and pretty much come up with what you did. Basically at the acceptable range. Usually if this were an office building I would have increased the stiffness. But this is a retail building with a few offices. So I was a little more lenient on the design...
Lutfi- I have 28K7 joists spanning 38'-0" with a 3 inch slab with a 1.0 deck. I think by going to a 9/16" deck will help matters a little bit. I personally don't think the vibration is bad at all. The owner's rep. was a truss designer and thinks he knows everything about vibration and...
WillisV-thanks, I finally got that through my thick skull. I think my best bet at this time is to go to a 9/16" deck vs. 1" deck. I'm also going to add an additional joist at each column line to help mitigate the vibration through the floor as you pointed out.
Thanks for the help everyone.
WillisV-I guess I'm still not seeing your point. So your saying severe cracking has virtually no noticeable effects on vibration characteristics? So basically your saying if you pieces together concrete chunks (like a puzzle) that thats going to act the same as a slab that's properly...
WillisV, I did use the reduced moment of inertia per section 3.6. I would tend to agree with jike that cracking or control joints would have an effect on the system. I look at it like this; If the joist and deck are assumed to act compositely (if thats a real word) then the concrete deck would...
