We have done several underground garages and had to learn a lot through them. We are in Buffalo and have built in Boston (6 and 3 floor down), Milwaukee (4 floors down), and elsewhere. Here are a few suggestions:
1.) I would not use expansion joint unless you have unbalanced earth laods. If...
See attached. A simple FBD ives the answer. Also, remember why reinforcing is there. The reinforcing and concrete have the same stress until the concrete cracks, then the reinforcing acts alone. (compatibility analysis anyone?) Once the concrete cracks, there would be no shear friction since...
For my two cents, I found Ram Elements pretty good. Tedds is VERY limited. You can write code in tedds, but it is not in any standard programming language. Further, if a peice of informaiton changes in the middle of a calc, it is not re-sent back tot he beginning unless you direct it to. For...
Is your slab tensioned too? Primary stressing perpendicular to beams with T&S stressing parallel to beams? The beam may be trying to shorten but be restrained by the slab so the system is relieving the stresses through cracks.
We use Ram, Risa, and Etabs for most calculations with internal spreadsheets and Tedd's for general purpose calcs. We used Staad int he past but gave up on it when we got Risa. The Ram suite is excellent for steel buildings and only OK for concrete. The way it calculates (from the top down)...
Typically, you want a well graded mix to reduce the amount of cement and to provide larger stones for better strength. I would suggest that is you do allow the #78 stone, that you limit the amount of cement (say to 540 #/CY) so that you do not get excessive cracking, especially in an elevator...
I have a question on the wind load provisions of ASCE 7-05 that I thought I would pass around.
Article 6.5.4.4 – Wind Directionality Factor says that Kd (=0.85 for MWFRS and C&C) , “Shall only be used with the combinations specified in section 2.3 and 2.4”. Those (2) sections are the LRFD and...
I would argue that friction connection does not provide a positive load path as the friction force is dependant on the clamping force that may relax over time. Both IBC and AISC require positive load paths.
AISC publishes a guide for single steel angles. In that it talks about bending of angles abotu axes other than the primary axes (which is what you are describing). Basically, you take the elastic deflection and multiply it by 1.86. This accounts for lateral torsional deflections of the angle...
If you have the money, you could add silica fume to the mix. Very fine pozzaloans tend to make the concrte less permeable. Also, consider using a blended (steel and poly) fiber and no WWR. This tends to make the concrete tougher.
I had the opprotunity to teach a structural engineering class to graduate architects focusing primarily on Concrete design, foundations, and some lateral analysis. Does anyone have a suggestion for a GOOD but SIMPLIFIED textbook. Remember, I will be teaching Architects. The idea is to give...
That interior non bearing wall is a problem unless it is detailed correctly. If that wall takes load, the I-Joists go into reverse bending putting the bottom flange in compression. Those elements are not typically designed to be unbraced, so you could have a serios lateral torsional problem...
if you are in a seismic design category C or worse, the ACI makes it very difficult to use hooked anchors. The preferred method these days is to use straight anchors with heads or nuts. See the ACI 318 code for requirements for anchors in concrete.
Unless you can determine that the deck is developed by its interaction with the concrete and that it has yeilded, you can not expect the deck to work as reinforcement. Even if the deck has deformations, it would be difficult to provde it is composite. Further - I think ACI has limits on the...
I did (2) similar garages. The first, we tied the slab into the foundation wall and spent the next year chasing cracks. The wall will be extremely rigid, even after the shrinkage is out, the slab will tend to move. If it is restrained, you will get cracking.
The second garage we detailed a...
