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  1. jmurph36

    Endwall stiffness of post=frame building

    Hello all, I have recently started working in the post-frame timber construction industry and I have been reviewing ASAE EP484.3. In section 5.3 it states that endwall and shearwall stiffness can be obtained from either full scale building tests, validated structural models, or from tests of...
  2. jmurph36

    mean roof height of elevated steel building

    Hello everyone, I am attaching a snip of a structure that I am designing. This structure is supported by a concrete wall on slab. My question is simple, do I measure the mean roof height (h) from the top of the mat foundation or would it be measured from the top of the wall where the steel...
  3. jmurph36

    Wind uplift on bar grating

    Hello all, My company designs a lot of structures for the mining and aggregate industry. Typically, we use 19W4 bar grating for the floors on the towers we design. I have struggled a lot with vertical effects of wind on these structures. Some in our office have the opinion that we should...
  4. jmurph36

    Seismic Classification of material conveyor

    Hello everyone, In the pictured that I have pasted to this message is a material handling conveyor that I have worked on. This conveyor is approximately 171 feet long and sits on lattice supports called bents that are concentrically braced. I am really struggling with how to classify the truss...
  5. jmurph36

    Figure 27.3-4-7, ASCE 7-16

    I am attempting to understand the wind loading in the new ASCE 7. At the bottom of Figure 27.3-7 on page 262, in the caption, there is a condition in parentheses (0.25 less than or equal to h/L less than or equal to 1). I design screen towers for the aggregate industry a lot which look similar...
  6. jmurph36

    Knife Plate Design

    Yes. I'm now understanding that. Maybe the example in the DG just assumes that the compression/flexure interaction is more critical than tension/flexure.
  7. jmurph36

    Knife Plate Design

    One more question. I've reviewed the AISC DG 24. It seems as though the only time eccentricity is considered is when the brace goes into compression but I don't see the DG checking eccentricity for tension. I also see that the stem of the tee or knife plate is assumed to absorb all the buckling...
  8. jmurph36

    Knife Plate Design

    Ah, that makes sense. That was why I was questioning the analysis initially. We like to have knife plates because we want to eliminate the need for erection crews to field weld connections. I have taken this to my manager and he thinks that it is more economical and in our best interest to just...
  9. jmurph36

    Knife Plate Design

    Then why does RISA not check the gusset for this same moment interaction? If there is moment, then it should transfer to the gusset as well. And the gusset is passing with a 3/8" thickness. Every design example I've seen for this type of situation only considers tension and shear.
  10. jmurph36

    Knife Plate Design

    In the attached file, I am showing a bracing connection that I am attempting to design. The connection is failing according to RISA Connection because the software is considering bending in the knife plate as well as a combined tension/compression and flexure interaction per Chapter H in the...
  11. jmurph36

    AISC Section J10.8 - additional stiffener requirements

    I have been reading through the limit states for transverse stiffeners. I am attempting to formulate a design strategy for stiffening column base plates to avoid using extremely thick plates when the moment gets large. I have come to the conclusion that, because the stiffener is welded to both...
  12. jmurph36

    Moment due to Tension on Anchor bolts

    That's exactly what I'm referring to. Thanks so much for the help. I racked my brain trying to figure that problem out.
  13. jmurph36

    Moment due to Tension on Anchor bolts

    I have been reading through AISC design guide 1 and I came to appendix B to the design example of a base plate with large moment. I have been staring at the equation for the bending moment in the plate per unit width of plate for hours trying to understand how it is derived. I don't understand...
  14. jmurph36

    Wind simulation in Robot Structural Analysis

    I am attempting to learn Robot Structural Analysis. I am trying to understand how the automatic wind simulator works. I see that you can set either the pressure or wind velocity then build a profile with velocity coefficients. I use ASCE 7-10 so I am curious if anyone knows which coefficient I...
  15. jmurph36

    Applying wind area loads to vertical braces

    Well at least I'm not crazy. In that case, does anyone have experience modeling open structures using area loads for wind? What are some tips for getting accurate results?
  16. jmurph36

    Applying wind area loads to vertical braces

    Glad I'm not the only one. I'm inclined to believe though that it may not be necessary to do so since RISA doesn't consider shielding when applying area wind loads onto open structures. The automatic distribution of the load on all faces on the plane will probably still give a reasonably...
  17. jmurph36

    Applying wind area loads to vertical braces

    I am applying an area load to an open lattice structure. But when I run the analysis and look at the transient loads, it doesn't seem to be considering the chevron bracing between columns on the lattice. I am pretty sure that, even though it is only L2x2x1/4 shapes, it still would be exposed and...
  18. jmurph36

    Wind load on trussed tower

    So when you say you split it into 4's, you mean that you take the total calculate design fore, divide it by 4, then apply 1/4 total calculated load to each member both front and back? So a line load of 1/4 of the total force would be what I need to apply?
  19. jmurph36

    Wind load on trussed tower

    Its a truss the supports a conveyor for moving aggregate at a rock quarry.
  20. jmurph36

    Wind load on trussed tower

    I agree. And my understanding is that the force coefficients given in figure 29.5-3 are higher to account for the effect of the leeward side so it is not necessary to apply the wind load to both faces.

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