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  1. agostage

    ACI 318-08 D.3.3.5 - Connecting Fuse Element Design

    Continuing on the closed thread (thread167-289587) topic of ACI318-08 D.3.3.5 - can anyone provide more guidance, details or links-to-examples of how to design the fuse element? More specifically, what overstrength factor to use and how to apply it in LRFD design? Is there an additional safety...
  2. agostage

    Partially Threaded Bolt

    I've used the formulas for stress areas and lengths of engagement of screw threads in the Machinery's Handbook
  3. agostage

    Classification by Table B4.1 + Chapter H

    I believe I see, you are trying to justify using compact section design in your moment capacity equations given that the section elements may not go into compression. The way the code is setup one has to select the section of design based solely on the element section properties without...
  4. agostage

    Classification by Table B4.1 + Chapter H

    You need to check both case 1 and case 9 and follow the appropriate section in Chapter F. If your member goes into compression then you need to check case 3 and case 10 as well and apply to Chapter E. The rest of your understanding seems to be sound.
  5. agostage

    sap2000 anxious check

    I took a quick look at your file and the model itself seems sound. But it's difficult to tell without knowing the background of the project. I see you're not running a modal analysis. I would suggest always running a modal analysis because it serves as a great troubleshooting tool. Check...
  6. agostage

    bearing capacity of pinned(frictionless) joints in AISC?

    Johnny is correct for the pin connected elements. For the pin itself check section F11 for yielding of bars. Note that the equation uses Z not S and allows for permanent deformation. If your application necessitates elastic behavior you'll need to use S instead.
  7. agostage

    Modeling plane stress/cable

    I'm a little foggy about your application yet, but I can say that in order to capture catenary action you will need several segments of the strap element, i.e. several nodes along its length and a geometric nonlinear analysis. Depending on how much catenary deflection you're expecting, you may...
  8. agostage

    Modeling a box section using Shell Elements

    What about your mesh? I would suggest at least two rows of elements per side to place a node at mid height each side.
  9. agostage

    Modeling a box section using Shell Elements

    A few things come to my mind. One, how long was your span? If you had a 4'x4' box with a short span, shear deformations could be controlling rather than moment deformations, which would not be accounted for in your equation. I would use a span/depth ratio of at least 10. How fine was your mesh...
  10. agostage

    help me with end lenght offset plz!

    I see what you mean. Off the top of my head I can think of two possibilities. Either your capacity is changing as you split the members, or it's attracting more load. If your capacity is changing it's likely that SAP is not assigning your length factors correctly to the segments. The default...
  11. agostage

    help me with end lenght offset plz!

    For your first problem the answer is yes, you can use the end length offset in SAP. What it does is exports forces only to the face of the connecting section and puts a rigid link in as the offset. I'm not sure what you're asking in your second question. If your section has different cross...
  12. agostage

    Beam Support

    To clarify a bit more... In 2D for simplicity, one node can capture 2 translations and 1 rotation. What you're trying to capture is 2 translations and 2 rotations with one node since your column and beam can rotate to different values. This isn't mathematically possible for a single node.
  13. agostage

    Beam Support

    If I understand correctly... This is a common issue in direct stiffness method analysis. What you're trying to do is not possible with a single joint(node). Drawing the column and beams to a single node is creating an equation where there is some stiffness relation between the members, when in...
  14. agostage

    sap2000 (problem at the edge of a beam)

    I do not believe that SAP has that ability. The easiest way to capture the small moment induced from that cable is to attach a infinitely rigid link equal to the depth of your beam to the end of the beam, then attach the cable to it.
  15. agostage

    Membrane Tension only behaviour

    In order to model a tension only membrane you need to use a nonlinear analysis with p-Delta plus large displacements analysis and provide several nodes in plane. Doing so allows the the membrane to buckle under compression loads, and with a negligible bending resistance defined, the element will...
  16. agostage

    Using "Force Controlled" Frame Hinges

    I haven't used the hinge function in SAP much but it seems to me that if your hinge has failed your column would then be unstable and no moment or shear would be valid. SAP is probably spitting out the last diagrams that were solvable. What I would do is make a frame with a single hinge that has...
  17. agostage

    AISC 13th Ed-W beam to HSS column moment conn.

    Yes I believe you're on the right track, that is what I'd use anyway. Since you're putting additional stress on the HSS side wall, you need to know how much stress is already there. U gives you that ratio of how much capacity is already being used. If you're U is over one, you should check your...
  18. agostage

    Connection plate eccentricity

    whoops, I did punch that in wrong. statics does it.
  19. agostage

    Connection plate eccentricity

    Based on statics alone your fixed end moment increased 57% I'm not sure why you'd be getting 75% unless you're running a geometric nonlinear analysis and are accumulating P-Delta effects.
  20. agostage

    HSS or box shape allowable bending in sap

    Correct, as I said, the section designer in Sap will reduce allowable stress based on buckling modes, i.e. web and flange buckling of non-compact or slender sections. This would not occur with HSS.

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