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  1. fuchsjr

    Depth of Foundation for Bearing Capacity Analysis

    You might find the following site of interest. Does not address equivalent depth. http://www.union.edu/PUBLIC/CERDEPT/FACULTY/GHALY/FOUNDATION/
  2. fuchsjr

    viberating concrete in hot weather?

    It is my understanding that properly vibrated/consolidated concrete has the vibrator inserted at each location for a few seconds at the most. The operator then pulls it out and inserts it adjacent to the prior insertion to get some minimal overlap in the zones (circles) of consolidation. If...
  3. fuchsjr

    New driveway cracking like a potato chip

    Excellent earlier responses! May also want to find out where the rebar was placed in the slab. Sounds like the slab was not wet cured or protected from the drying elements.
  4. fuchsjr

    Support of wwf in slab on grade

    I find it easier to put in wide spaced #4 rebar on bricks and then put the WWF on top of it. I use the rebar grid on bricks to hold up the WWF at the proper elevation. Bends a little bit when walking, but it bends back up when you step off.
  5. fuchsjr

    Rolled Steel Beams and HPS 70W Steel

    You could also just vary the spacing at each abutment. Have one abutment at a tighter spacing than the opposite end. Splay the girders.
  6. fuchsjr

    The Sound of Concrete?

    LPPE, The operative words are "bearing connection as designed." Sometimes slip critical connectors are installed because it is easier and faster. BUT, the number of connectors typically required for a truly slip critical connection are more than for a bearing connection. Thus, the slip...
  7. fuchsjr

    10 ft Continuous Weld Beam to Cover Plate

    Welding can definitely distort the steel after it cools. If you are putting a cover plate on, I normally require both sides of the cover plate to flange weld to be welded at the same time with the maximum difference in longitudinal location not to be more than 2'. Otherwise, the cover plate...
  8. fuchsjr

    The Sound of Concrete?

    If it was steel framing, it could be that slip-critical connections were made by the erector and the connections are slipping into a bearing configuration. Sometimes when a connection "goes", it sounds like a small gunshot. This is ussually not a problem, just a little unnerving until you find...
  9. fuchsjr

    Strength gain by concrete in cold weather

    gb238, You may find the following of interest: http://www.nrmca.org/aboutconcrete/cips/CIP%2010p.pdf http://www.cement.org/tech/faq_rebound_hammers.asp
  10. fuchsjr

    Strength gain by concrete in cold weather

    BigH, The latest copy of ACI 228.1 that I have is 1995 with a total of 41 pages. The copy I had originally referred to was 20 plus. The 1995 version has the calculation in chapter 6, table 6.2; rather than the 3.5 and table 3.3 that I referred to in an earlier post. If you want, let me...
  11. fuchsjr

    Strength gain by concrete in cold weather

    Lastly, sometimes it does not matter to the homeowner that the concrete foundation is structurally adequate. In their mind, they paid for a 3000 psi of 3500 psi mix. That is what is shown on the drawings. Why should they settle for an average strength of 2000 psi? They paid for the higher...
  12. fuchsjr

    Strength gain by concrete in cold weather

    BiGH The difference in this case is not a design or the testing of cylinders, it is the evaluation of concrete in place. ACI 228.1 is entitled as "In-Place Methods for Determination of Strength of Concrete." Some cylinder sitting in a curing box is not representative of a core taken from a...
  13. fuchsjr

    Strength gain by concrete in cold weather

    gp238 You may want to do the rebound hammer at the core locations prior to taking the cores. That way, when the cores are tested, you can get some sort of correlation between the rebound value and the actual strength for the cores. Next, since you are in New York, you need to check the NYS...
  14. fuchsjr

    multi-ply wood constructed columns

    Lots of questions: 1. What type of pressure treated wood was used? Is it the new stuff? If yes, you almost have to use stainless steel for fasteners. 2. What is the maximum vertical load on any column? 3. What is the maximum horizontal load on any column due to: wind on the cabin, water force...
  15. fuchsjr

    How to form exterior cip concrete stair with radius

    I have used Azek material in the past to form stairs like that, that were wider than 8'. Makes a nice smooth finish with easy release from the concrete.
  16. fuchsjr

    Use 64 Year Old Concrete Bridge Pier for New Bridge

    You could use a concrete rebound hammer. Core those areas. Then test for compressive strength. Determine a correlation between the rebound and the compressive strength. Then go back and use the rebound hammer on the rest of the structure to test strengths. If that is not good, you could use...
  17. fuchsjr

    Phased Bridge Construction

    DRC1, You have been fortunate in your past experiences. We have tried the low speed routine; didn't work, still ended up with a weaker deck at those locations. As for the dowels, you must have a real stiff superstructure, otherwise, the dowels in the already cast deck will "move" upwards in...
  18. fuchsjr

    Column Steel Base Plate Design

    If you weld the plates together, you should check the shear stress to insure that the weld is adequate to insure composite action for the two plates. Just a simple matter to check the shear forces along the length of the plate and then calcuate the VQ/It value.
  19. fuchsjr

    Phased Bridge Construction

    Crossframe has it correct. Most states use closure pours to isolate the stages. The diaphragms are then bolted solid in the closure pour bay to try to limit the differential vibrations/deflection due to one stage having live load. Another option is to close the bridge over a weekend using...
  20. fuchsjr

    Bridge over Environmentally Sensitive Area

    Depends on how much funding you have available, and your construction schedule. You could do a "launched" type structure using precast elements, with a cased drilled shaft substructure; depends on soil conditions.

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