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Recent content by MJC6125

  1. MJC6125

    ACI 318-19, Section 9.9.3.1 - Deep Beam Distributed Reinforcement Question

    When you are determining the distributed reinforcement in a deep concrete beam per ACI 318-19 Section 9.9.3.1, are you supposed to have 0.0025*bw*s of reinforcement area on each face or total between both faces? I have a concrete textbook, Reinforced Concrete: Mechanics and Design by James K...
  2. MJC6125

    Max Fly Ash Specification Limit

    Do you folks include a maximum allowable fly ash limit in your standard concrete specifications? I know Table 26.4.2.2(b) of ACI 318-19 has a limit of 25% for Exposure Class F3 concrete uses. I wasn't sure if anyone puts any other stricter limits than that? A few things I have come across is...
  3. MJC6125

    Precast Parking Garage Topping Slab Special Admixtures / Sealers

    I'm working on a precast parking garage with a cast-in-place topping slab applied over the precast double tees. I found the PCI Parking Structure Manual which has some good information on durability considerations including a geographical zone map and table shown below. For reference, this...
  4. MJC6125

    Adjusting top of deck elevations on a pre-topped twin tee

    Unfortunately, this is an existing pre-topped double tee building that does not meet 2% ADA requirements, and they are now trying to go back and get it to meet the limits. So we are looking at repair options at this stage. No chance to install them as field topped anymore. Thanks for that...
  5. MJC6125

    Adjusting top of deck elevations on a pre-topped twin tee

    Good to know, thank you for the response. Do you have any thoughts on my question #3? Is it safe to assume the new topping can re-bond with the original concrete deck and act compositely for the final compression flange loading condition? Not sure if you guys have to do assumptions like that...
  6. MJC6125

    Adjusting top of deck elevations on a pre-topped twin tee

    I have a project where a client wants to adjust the grading/slopes inside one area of a precast parking garage to meet ADA accessibility slope limits. To achieve this they are proposing raising the deck surface by anywhere from 0" - 4". I still need to check if this extra weight of concrete on...
  7. MJC6125

    Steel Connection Slotted Holes Longer than AISC Long-Slot

    I expect the column will have lateral loads that will need to be resisted by this connection. Have you considered this? Yes, the connection is supposed to resist the lateral loads that the column would see. The connection can be installed initially with the bolt near the upper end if live load...
  8. MJC6125

    Steel Connection Slotted Holes Longer than AISC Long-Slot

    Thank you for the responses. That's good to hear it should have the same strength as a standard long slotted hole. I'll look into the AISC Section 3.11b check when I'm back by my handy dandy steel manual.
  9. MJC6125

    Steel Connection Slotted Holes Longer than AISC Long-Slot

    See detail below for a general question I have. In the detail I am trying to brace the top of a new HSS column to the underside of an existing slab on metal deck. I don't want the slab or structure above to apply load to this new column. I am assuming that the floor above and the floor below...
  10. MJC6125

    Wood Beam Stability Factor for Multi-Ply Beam

    If a multi-ply wood beam is unbraced for lateral torsional buckling, how do y'all calculate the beam stability factor for this beam, like a (4) 1 3/4" x 16" LVL? Do you consider the entire built-up 'composite' beam, thus when you calculate Rb=sqrt((le*d/b^2)) per equation 3.3-5 of the NDS...
  11. MJC6125

    Shear Design for Wood Beam with Biaxial Bending

    I don't have any exact stress ranges at the moment. This question came from a fellow engineer who was wondering if they should check combined shear, and I didn't have a good response as to why they should or should not. We looked at the design programs we have access to including Enercalc...
  12. MJC6125

    Shear Design for Wood Beam with Biaxial Bending

    If you refer to the diagram below, I'm showing example surfaces where I think the shear stress parallel to grain is developing on the member under both loading cases. Does the fact that one happens on xy planes and one on xz planes help anything or are those parallel to grain shear stresses...
  13. MJC6125

    Shear Design for Wood Beam with Biaxial Bending

    I was wondering if shear stress parallel to grain vs perpendicular to grain had anything to do with it. When you load a beam on both the strong and weak axis, are the shear stresses parallel to grain additive in terms of mechanics and materials? Or is it only the shear perpendicular to grain on...
  14. MJC6125

    Shear Design for Wood Beam with Biaxial Bending

    Yes, I was thinking a rectangular section like a 2x8. Thank you for doing that. Please report back with what they say.
  15. MJC6125

    Shear Design for Wood Beam with Biaxial Bending

    If you are designing a wood beam with bending in two directions (strong axis and weak axis), how come you only need to check the shear stresses in each axis independently? Is there no sort of resultant or combined shear stress that develops on the beam cross section face? Seems like this...

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