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  1. CalebA

    Temporary Top Strands in Prestressed I-Girders

    I believe they serve the same function as temporary/sacrificial strands, except they are left in place so it will negatively effect in-service bottom flange compression. My guess is that the fabricators around here just haven't adopted this practice for one reason or another. I found a good...
  2. CalebA

    Temporary Top Strands in Prestressed I-Girders

    ...I'm back-calculating the pull percentage correctly. Say the default pull percentage for 0.6" 270K LL strands (43.94 kips max allowable force per strand) is 75% and the 3/8" support strands are tensioned to 8 kips. Would the pull percentage for the support strands be 75%*(8 kips/43.94 kips) =...
  3. CalebA

    Temporary Top Strands in Prestressed I-Girders

    Both of the DOT's in this area (same fabricator) call them support strands. I dug up some shop drawings and did not see any details for the pockets you mentioned. I believe these "support strands" are permanent.
  4. CalebA

    Temporary Top Strands in Prestressed I-Girders

    How do they cut them at midspan if they're encased in concrete?
  5. CalebA

    Temporary Top Strands in Prestressed I-Girders

    Well they are called support strands, so I suppose they would remain in the girder? I included a link to the NU Girder standard I'm referring to. Would I then need to include the WWR reinforcing in the top flnage as well as the support strands? Since I'm using LEAP and you can only define one...
  6. CalebA

    Temporary Top Strands in Prestressed I-Girders

    Do you all consider temporary top strands in your design? I found that they effect camber and prestress losses, but would this effect be small enough to ignore? Also if I have a matt of WWR in the top flange, do I need to include this in my design for tension forces or would I leave it out? I am...
  7. CalebA

    Hammerhead Pier STM - Lateral Loads

    I am designing a hammer head pier using a 2D strut and tie model. I am using the linked example as a design guide and noticed they didn't include lateral loads in the STM. Is this just a simplified example? Do I need to transfer the longitudinal and transverse loads into the strut and tie model...
  8. CalebA

    Thermal Point of Origin - Locating Fixed Supports

    How do I determine which equation to use for calculating the stiffness of a hammerhead pier? To get EI, I am treating the hammerhead pier as a wall, using an average value for the width. Then I'm finding that there are two equations for calculating pier stiffness, 3EI/H^3 (pier cap free to...
  9. CalebA

    Thermal Point of Origin - Locating Fixed Supports

    For anyone else who comes across this thread, I found the answer: https://wisconsindot.gov/dtsdmanuals/strct/manuals/bridge/ch27.pdf When deciding which bearings will be fixed and which will be expansion on a bridge, several guidelines are commonly considered: • The bearing layout for a bridge...
  10. CalebA

    Thermal Point of Origin - Locating Fixed Supports

    I am calculating the stiffness of the substructure elements and bearings to determine the thermal point of origin (TPO) on a continuous steel bridge. How do I determine which supports to make fixed supports? Is it just the support closest to the TPO? The supports to the left and right of the...
  11. CalebA

    Program for Designing Multi-Span Steel Beam Bridges (Simple for Dead Load, Continuous for Live Load)

    The problem with defining a short section at the piers is that the beam & deck self-weight would also be modeled as continuous instead of simple.
  12. CalebA

    Program for Designing Multi-Span Steel Beam Bridges (Simple for Dead Load, Continuous for Live Load)

    Do I need to model my girders as simple or continuous?
  13. CalebA

    Program for Designing Multi-Span Steel Beam Bridges (Simple for Dead Load, Continuous for Live Load)

    This is the design of a replacement bridge requested by the DOT since they had success with it during a design build project, so it's a matter of accelerated construction. The spans are relatively short at 23'-40'-23', so the idea is that the negative moment is completely taken by the deck...
  14. CalebA

    Program for Designing Multi-Span Steel Beam Bridges (Simple for Dead Load, Continuous for Live Load)

    Can anyone elaborate a bit on how MIDAS construction staging works to accomplish this?
  15. CalebA

    Program for Designing Multi-Span Steel Beam Bridges (Simple for Dead Load, Continuous for Live Load)

    Unfortunately, I don't think we have the budget to build a tool like this for a one off project, but I think I figured out a solution with LEAP Steel. I'm going to make my model continuous for live load and then I'm going to calculate all of my other loads separately and enter them in the...
  16. CalebA

    Program for Designing Multi-Span Steel Beam Bridges (Simple for Dead Load, Continuous for Live Load)

    I'm looking for a program that will allow me to make the live load continuous, but the dead loads simply supported. So for I have tried LEAP Steel, MDX, & MIDAS. I also have access to LUSAS, but haven't used this program much. If I can't get one of these programs to work I may just end up using...
  17. CalebA

    MDX Bracing Connection Plates Fatigue Overstressing

    I'm designing a curved steel plate girder bridge that is continuous over the piers. I'm using MDX to model the bridge. I designed the flanges with varying widths and varying thicknesses between field splices. I did not specify any transverse stiffeners, but MDX defaults in the connection plates...
  18. CalebA

    When is a concrete pier cap considered integral?

    I'm talking about lateral loads.
  19. CalebA

    When is a concrete pier cap considered integral?

    Can someone explain the difference between the pier cap types listed below and how the loads would be transferred for each? 1. Open pier cap 2. Pier cap w/ 1 or 2 rows of dowel bars going into a concrete diaphragm 3. Pier cap w/ stirrups extending from the pier cap into the concrete diaphragm...
  20. CalebA

    Prying Action - Floorbeam to Girder Double Angle Connection

    ...failing for rotational ductility > I ended up eliminating the eccentricity by removing part of the existing structure. I got T from the following equation that RISA Connection uses, but I'm not sure where it's found in AISC: Me = V*ex + P*ey & Tbolt = (6Me/(b*d^2))*At*keff & T = Tbolt + P/(n*b).

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