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  1. snowmachine88

    Technical Inquiries

    I just found out in a previous post there is a location to ask Technical inquiries for the AISC steel design manual. Are there similar locations for technical inquires for AASHTO and ACI codes?
  2. snowmachine88

    Pile Bent Design

    Forgot to insert after loading ithttp://files.engineering.com/getfile.aspx?folder=46020d3c-a458-4756-beef-6eb48a1bc4d4&file=Pile_Loads.JPG
  3. snowmachine88

    Pile Bent Design

    Just as a clarification I have attached the loads from the analysis tab. Are these the loads you are referring to when you say I need to get the pile loads from the analysis?
  4. snowmachine88

    Pile Bent Design

    I have seen the option of design the "piles integral with cap". The DOT here has provided tables that list the effective horizontal loads that different size piles can withstand assuming there are embedded in sand with a friction angle of about 30-32 degrees. This allows the use of RC Pier's...
  5. snowmachine88

    Pile Bent Design

    I've done this both ways. When I worked for the DOT we considered all lateral forces (wind, temperature, braking, stream, ice, etc.) as being applied to the piles with fixed heads in the direction perpendicular to the beams (or slab spans) and with a free head in the direction of the spans...
  6. snowmachine88

    Thermal Restraint Forces

    Hookie, I have no doubt the whole project is rife with poor details since I am a bridge designer by trade. The reason the wall is cast as a solid piece then the columns on top is due to the fact that the wall is actually a weir so I didn't want to introduce any joints below the top of the...
  7. snowmachine88

    Checks Required at Concrete Column Transfer Slabs (Walking Columns)

    Let me preface my response by saying I typically over check failure modes. I definitely believe the 1-way shear model should be checked. Then the question becomes how long of a line of the slab should be used for the check? I would use the distance between your 2-way shear lines that you drew...
  8. snowmachine88

    Thermal Restraint Forces

    Here's a drawing showing how the bottoms of the columns frame in. The columns in the middle of the slab are even shorter because beams frame into them in one direction.http://files.engineering.com/getfile.aspx?folder=80c8d2e0-7bde-4c0f-8ecc-1747451aa24a&file=Column_Bottoms.pdf
  9. snowmachine88

    Thermal Restraint Forces

    I like your reasoning. My original numbers were mearly for force calculations according to AASHTO. They allow you to use the gross section and then reduce the forces from temperature (shrinkage also) by half because of stress relief from cracking. Therefore, if I use the 1.2 load factor for...
  10. snowmachine88

    Thermal Restraint Forces

    Hookie66, Does it matter that the short columns are supported on a wall of the same thickness? The wall will be stiffer than the columns, but less so than a typical footing. It may allow for some additional movement. Would additional steel in the slab help reduce the shrinkage enough to...
  11. snowmachine88

    Thermal Restraint Forces

    What is a delay strip? Based on your comment I assume it will make the slab crack before the columns? I assume this also means no hooks into the slab? Just continue straight bars to w/in 2" of the top of the slab? Is spacing key here, or can I use 13M (#4) bars @ 6-8" for the same area of...
  12. snowmachine88

    Thermal Restraint Forces

    Kootk, I would think the structure underneath will see less thermal strain. There could be water on the lower structure so the temperatures will likely be different, as well as shading from the above structure. I agree shrinkage may be an issue also. Will the slab crack and relieve these...
  13. snowmachine88

    Thermal Restraint Forces

    I have not used capacity design before. Should my calculated shear (2*M*Overstrength)/3' use my moment from my gravity loads then? Also, should my over strength factor be 1.33, I think I saw that at one point. Then is my shear capacity only dependent on my rebar, since I am assuming the...
  14. snowmachine88

    Thermal Restraint Forces

    KootK, The axial load on the columns is very small, on the order of 5 kips. If I use the same assumptions to calculate shear I get 54K and 46k in orthogonal directions, whereas a 12" square column can only support up to 60k with maximum steel. The columns are not part of the lateral system...
  15. snowmachine88

    Thermal Restraint Forces

    I have a slab supported on very short concrete members. The members are 3.5' from bottom of slab to top of the wall they are supported by and are 12" square. The slab is supported by a wall on one face. The slab is 56' x 33'. If I assume the slab expands due to a 45 degree temperature change...
  16. snowmachine88

    Nylon Shims between bolted plates

    I am modifying a typical detail for a decorative railing design. All of the locations where plates are bolted together have nylon shims between the plates. What is the purpose of the nylon shims? Is it to prevent moment transfer between plates so that the railing and connection can be...
  17. snowmachine88

    Maximum Post Spacing for Decorative Railing

    The 6" pipe is just decorative. I believe the architect called the bottom bar a kick bar. I looked at the loading on the bar in the other direction such that Zx = 2.5*1.25^2/4=0.98 and it still works. I guess I was looking or more of a rule of thumb for maximum post spacings. I can up size...
  18. snowmachine88

    Channel expansion joints

    I am designing a concrete channel bottom. Can I simply use silicone joint sealant for the expansion joints or should I use a compressed joint sealer that can be used on pool bottoms?
  19. snowmachine88

    Maximum Post Spacing for Decorative Railing

    I have a decorative rail along a stair case bolted to concrete posts at the top and bottom. The length along the rail between posts is up to 14.7 feet. I am using a 1.25" x 2.5" kick bar to meet AASHTO loading requirements for pedestrian rails. This seems like a heavy bar to use, but the top...
  20. snowmachine88

    Concrete Slab on Grade Stair

    The purpose of the walls on the sides going down to frost depth is to retain the soil under the stairs. Since a standard 7/11 stair is steeper than 2:1 I need the walls so that the grade next to the stairs can be flatter. My feeling was the key at the bottom is only to prevent sliding so I...

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