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  1. penpal97

    response modification factor for concrete connection

    If I am understanding you properly... For dowel bars that come up from the footing and into the column, design the dowel bars for bending w/ R=1.0. Then for the smaller main column bars that lap w/ the dowels, design main column bars for bending w/ R=5.0. The lap will be governed by the...
  2. penpal97

    response modification factor for concrete connection

    Thank you for your thoughts. I generally agree with you. The sentiment of the code seems to be that connections should be capacity protected. Shear friction capacity definitely falls under that criteria. The problem comes w/ the longitudinal rebar for the connection under moment. If I design...
  3. penpal97

    response modification factor for concrete connection

    I am designing a bridge pier with columns and a cap at the top. The system works as a moment frame during an EQ. I perform an elastic seismic analysis based on the response spectrum to get axial, moment, and shear. Time to design the rebar... The column rebar will be governed by the moment at...
  4. penpal97

    Skewed Bridges

    Thank you for talking this through with me. The system you have described seems similar to a 2span beam w/ an interior spring support. The "beam" running from obtuse angle to obtuse angle would be the spring support. So if a truck were at the beginning of the bridge, the bearing at the end of...
  5. penpal97

    Skewed Bridges

    paddingtongreen, I do not follow the analogy for a grillage beam setup. Simplifying the setup, place several girders N<>S and one floorbeam in the top layer going E<>W. If the floorbeam is infinitely stiff, then all N<>S girders deflect the same, all girders in positive bending, no uplift. If...
  6. penpal97

    Skewed Bridges

    Thank you for your responses. I have some further questsions and would like to continue the discussion to try to get to a relatively definitive answer. Everyone I have talked to only has "thoughts". graybeach - please let know me if I am interpreting this incorrectly: truck on fascia girder 1...
  7. penpal97

    Skewed Bridges

    Thank you. Why?
  8. penpal97

    Skewed Bridges

    I have seen a few things to worry about w/ highly skewed bridges (over 30 degrees). One is increased shear on some of the girders, and I can understand that since the load path can be kind of odd given the geometry of the loading relative to the abutment. The other is uplift at the bearings...
  9. penpal97

    Simple beam but large displacements

    You guys are brilliant. Thank you. For my final calculation, I will have to account for the shear deflection. Thanks again.
  10. penpal97

    Simple beam but large displacements

    I have a simply supported W27x281, 10ft long, 100kip/ft. Basic beam equations give a displacement of 0.065in. I model the beam in STAAD (single element), and get 0.065in. However, once I model the beam as ten 1ft long elements, I get a deflection of 0.109in. Anyone else have this sort of...
  11. penpal97

    Development length of stainless steel rebar

    There is guidance for development lengths of black bars and epoxy coated bars, but what about galvanized and solid stainless steel? Anyone have any thoughts? Is the stainless surface just as slick as the epoxy? or even more smooth?
  12. penpal97

    Simply supported beam/plate

    I have modeled a simply supported beam 10' long, 5kip point/line load at midspan. Midspan moment = 12.5k-ft. For a 1ft thick concrete slab (and assuming no cracking), there should be ~500psi compression on top, ~500psi tension on the bottom. I run the model and good results for principal...
  13. penpal97

    Simply supported beam/plate

    Thanks.
  14. penpal97

    Simply supported beam/plate

    Thank you for all your responses thus far. crisb: If you look at the top of each index (upper left) of each page, you can see the title of the stresses that are displayed. They are the max/min of the top/bottom; not shear, von mis, etc.
  15. penpal97

    Simply supported beam/plate

    I'm using STAAD plate elements. The stress outputs are the local principal stresses.
  16. penpal97

    Simply supported beam/plate

    Thanks for the reply. It is intentionally skewed so that I cannot use global stresses. My final model will not be oriented along the major axes.
  17. penpal97

    Simply supported beam/plate

    I have modeled a simply supported beam 10' long, 5kip point/line load at midspan. Midspan moment = 12.5k-ft. For a 1ft thick concrete slab (and assuming no cracking), there should be ~500psi compression on top, ~500psi tension on the bottom. I run the model and good results for principal...
  18. penpal97

    Overstrength factor and concrete

    I've read several of the topics on the overstrength factor, but they mostly refer to steel (brittle bolted connections vs ductile connections). How about if I am designing a concrete moment frame for gravity and seismic forces? Overall I divide my seismic forces by R. Given those forces, I...
  19. penpal97

    Intermediate Stiffener Welds

    thank you. does that mean that this is equation is from a paper, not found in the AISC specifications?
  20. penpal97

    Intermediate Stiffener Welds

    I am reading "Structural Steel Design: LRFD 3rd Ed" by A. Williams. For design of Plate Girders, Ch 8.4 says intermediate stiffeners (when required, with or without tension field action) must be connected to webs to resist shear given by f_vs = 1.67h(Fy/340)^1.5 Could someone help tell me...

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