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  • Users: jbuening
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  1. jbuening

    Concrete Slab/Drive interface detail at overhead doors

    I was just curious how everyone handles the concrete detailing at an overhead door where the interior concrete slab meets the driveway. We are designing the foundation and slab for a prefabricated variable depth column building that will be used as a heavy highway maintenance facility (snow...
  2. jbuening

    Mechanical Bar Splicers and Drilled Shaft Spiral Cage Clearance

    This may be a contractor issue, but figured I'd get some insight from other designers on here. We did some plans for a bridge that used 6' diameter drilled shafts with #14 vertical bars. The contractor ordered the bars straight with the ends threaded where the mechanical splice occurs just...
  3. jbuening

    Basic truss chord splice question

    A bit of office discussion around here and surprisingly the opinions are split down the middle, so curious what you all think. If you were to analyze a Pratt truss in a program like RISA and determine the max tensile force (lets say 100k) in a lower chord midspan at a node, for a connection...
  4. jbuening

    Wind Pressure on Trussed Towers - Distribution Type?

    We are designing agriculture support towers with a square footprint in RISA. We have calculated our wind pressure (67psf for this 6'x6' footprint) from the formulas in ASCE 7-10 and utilized the Trussed Tower Force Coefficient from Fig 29.5-3. I am a little confused on if the wind pressure is to...
  5. jbuening

    Unbraced Length of Tower "X" braces with bolt at intersection

    What is everyone's take on unbraced lengths when modeling towers that utilize single angles forming an "X" for bracing between columns? The intersection point will have a through bolt, so my thought is the bolt will reduce the effective length for buckling vertically but the buckling will still...
  6. jbuening

    Openings in new slabs with slabs supported by walls

    Unless I'm misinterpreting things, all I can find in the ACI code is openings in new slabs without beams. Essentially it is a continuous slab that is only supported by columns in each corner. What is typically done when you have a slab supported by walls on all four sides? I'm struggling with...
  7. jbuening

    Unbraced Lengths

    I'm modeling a steel frame structure (pipe bridge) and this is both a question related to RISA as well as structural engineering. Attached is a screenshot of my model. In RISA there is four different unbraced lengths you can input for the member info, Lb yy, Lb zz, Lcomp top, and Lcomp bot. I...
  8. jbuening

    Coped beam ends and increasing block shear strength of existing members?

    I have a project that involves an existing structure that the client wants to add more loads to (industrial application). It is essentially a steel support structure with 6 columns (2 per side) a continuous beam atop the three columns, and coped beams connecting the two continuous beams (at each...
  9. jbuening

    RTU on Existing Bar Joists - Load Combination Question

    We have a client that wants to add a generator to a roof of an industrial building that has metal decking and 32LH07 bar joists feeding to an interior 40G 6N 12k girder joist. The generator is a 2600lb unit of 42"x94" base (92psf). My question for those that may do these more often than us...
  10. jbuening

    Ineffective Flows with channels skewed to roadway emabnkments

    I couldn't find much about this other than the usual 1:1 Upstream and 2:1 Downstream ratios (which most seem to show examples with 0 skew), so hopefully someone can help me. When you have a channel that is skewed to the roadway embankment, is the 1:1/2:1 perpendicular to the embankment or the...
  11. jbuening

    Braking force at Piers with Elastomeric or HLMR Expansion Bearings?

    I'm just curious if other bridge designers on here consider elastomeric/HLMR bearings and fixed bearings to take their respective contributing span length for braking force equally, or if all braking force of the bridge is transmitted at the fixed bearing down into the pier? For example, a 4...
  12. jbuening

    Heavy Machinery loads on Slab on Grade design

    Does anyone have any insight or tips on a slab on grade design for heavy mining trucks? For example, a mining truck manufacturer needs a parking lot designed for their finished heavy machinery and one of their trucks has a single wheel load of 62k but is spread in 13.2 ft^2 contact patch (large...
  13. jbuening

    Bridge LRFD Web Splice question

    Can anyone tell me if the the maximum flexural stress, fcf, used in AASHTO Eq 6.13.6.1.4c-1 uses the girder section modulus using the net area or the gross area? In LFD I was taught to calculate the section modulus using the net area (subtracting bolt holes only for controlling flange) when...
  14. jbuening

    TL5 Barrier-Moment Slab Design

    I have been asked to design a moment slab (6' shoulder width) that has an attached TL-5 rated concrete barrier/parapet. There doesn't seem to be much information out there for the design of these things. The overturning and sliding checked out fine due to the length of the system, but I'm not...

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