Oldestguy, ACI 318 and ACI 350, Sections 6.4.2 call for the concrete at Construction joints to be wetted immediately before concrete is placed. I wonder how often this actually happens.
Thanks to both of you for your comments. I agree that if I use a keyway I should move the waterstop up out of the keyway. I would need to check the required clearances though. Better yet to just omit the keyway and roughen to 1/4" as suggested. What is your experience regarding the ACI...
I have designed a wet well for a pump station (water only) with 18" thick walls on a 24" thick base slab. I have shown a 3 1/2" wide by 1 1/2" deep keyway in the top of the base slab at the center of the wall with a bentonite water stop in the keyway. Both ACI 318 and 350, Sections 6.4.2 call...
Thanks for all your comments. I found that in the commentary portion of ACI 2005, section 7.10.5.4, it states that "continuouly wound bars or wires can be used as ties .....". I read this to mean that even though it looks like a "spiral", it isn't, and the 3" maximum spacing doesn't apply.
I have designed a large residence in California which is supported by 16 inch diameter drilled piers (caissons). I have specified #3 ties with a spacing of 6" o/c for the full length of the piers. The contractor is proposing to use a continuous spiral instead of individual ties. The code (UBC...
I have always felt that the 10 psf dead load for roofs is low. Some of the higher end composition roofs can run 400 pounds per square (4 psf). When you add plywood (1.5 psf), insulation (0.5 psf), 5/8" gyp board (2.8 psf), mech & elect (0.5 psf), misc. (1.5 psf), trusses/girder trusses or 2x12...
Is there a code requirement that requires an asphalt shingle roof to be designed for 2 layers (original plus one overlay). I work in California which still uses the 1997 UBC.
Thanks
Are you considering the load to be transferred only by bearing on the end of the pile or does bond between the concrete pile cap and the pile contribute to the load transfer? Are the #6 bars there to counteract the bursting (lateral) forces from the high bearing stresses? Do the #6 bars need...
I am designing a concrete pile cap/beam for a center bent of a 2 span bridge. The piles are HP 12x74. The concrete pile cap/beam is 28" wide and 30" high. The piles are to be embedded 12" into the bottom. Do I need to check the concrete bearing stress at the top of the piles? If so, do I...
I am building structural engineer taking a graduate level steel bridge girder design class. We are using a very old shareware program (DOS based) to perform the analysis of the girders and then transferring the information into an EXCEL spreadsheet to plot the moment and shear envelopes. Is...
Exception #1 of the stated UBC section allows wood framing to carry up to a 4" thick, non-structural, masonry or concrete floor or roof surfacing. I often design garages on downslope lots with a 3 1/2" concrete slab supported by wood framing.
If you are attaching one wood plate by itself, you can use powder actuated fasteners by Hilti or similar. The information I received was they could be driven into a 1/2" thick steel flange. I wouldn't use them where a plastic hinge was expected in the beam (seismic).
The exception to UBC 1807.2 allows for "other approved methods" if "equivalent restraint can be provided." If the soils near the surface are stiff/strong enough to provide lateral restraint (based on lateral passive resistance) for the top of the pier, this is often used as...
I am interested in obtaining a copy of research done by Ploessel and Slosson (1974) regarding the level of seismic response actually felt by a structure as compared to the peak ground acceleration. Does anyone know where I can obtain a copy?
I am working with someone who is interpreting this...
It is my understanding that the code does not require ledgers to be pressure treated unless they are in contact with "foundation concrete". I think it is a good idea however for roof ledger to be P.T., particularly if the possibility exists for moisture to wick through the wall. This...
This brings up a question I have. I design a lot of light frame structures in Caliornia (seismic zone 4) with drilled pier foundation due to expansive soils and/or hillside locations. I often give contractors the option of using spirals for cast in place pier reinforcing instead of square...
There is a two-page article in the September 1989 issue of Civil Engineering magazine on Flitch Beam Design. The article is by J. D. Wiesenfeld, who was (is?) a professor at the New York Institute of Technology's School of Architecture.
In running bond the vertical joints between the units are staggered (normal condition). In stack bond the vertical joints between the units line up. A wall laid up in running bond will be stronger because the units interlock better.
