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  1. mecheng24

    Fatigue stress category for weld shear flow

    Suppose you have a built up I beam, with fillet welds connecting the flanges to the web. This matches AISC Description 3.1 for stress category B (16ksi), or I suppose 3.4 if the welds are intermittent for category E (4.5ksi) But if the welds are transferring the shear between the flanges and...
  2. mecheng24

    Minimum number of cycles to consider fatigue

    @drawoh I am thinking along the lines of some threaded part, where the stress concentration can be almost 4X. It guess it just doesn't make sense to me to say if you are designing something for 10,000 cycles you don't need to consider fatigue but for 20,000 cycles you do. When the fatigue curve...
  3. mecheng24

    Minimum number of cycles to consider fatigue

    AISC states that for steel structures, fatigue does not need to be considered for less than 20,000 cycles. This never made sense to me, if you look at a S-N diagram, the fatigue strength begins to decrease before this. Is the thinking that if you have your safety factors against static, the...
  4. mecheng24

    Simply supported vs fixed bolted connections

    @cal91 @Earth314159 Even though it is fatigue, I am not talking about small loads in my case. Say you have a connection like the bottom scenario, the bolts still need to be sized to resist the full moment. If they are not then it will still be considered a pinned connection correct (well...
  5. mecheng24

    Simply supported vs fixed bolted connections

    Mechanical engineer here...having some trouble wrapping my head around things. Say for example you have a beam botted between columns with an end plate bolted connection. My understanding is that these connections are typically designed as simply supporting, taking only shear load. I guess the...
  6. mecheng24

    Which AISC fatigue weld stress category would this be?

    Hi, I am trying to determine what fatigue weld stress category would be used for the picture. I was thinking perhaps C'' from description 5.6? but that wouldn't be quite right since it is not a plate and the fillets are not parallel. Category C from description 8.1 would be my other thought...
  7. mecheng24

    Which AISC fatigue weld stress category would this be?

    Hi, I am trying to determine what fatigue weld stress category would be used for the picture. I was thinking perhaps C'' from description 5.6? but that wouldn't be quite right since it is not a plate and the fillets are not parallel. Category C from description 8.1 would be my other thought...
  8. mecheng24

    Where can I purchase 17-4PH in the H1150 condition?

    Hi, Does anyone have a source for this? I am located in western Canada and everybody seems to only supply it in condition A. Thanks in advance
  9. mecheng24

    Zinc plated lifting eyes

    Hi, I need to purchase some DIN 580 lifting eyes. I was wondering if there is any danger in using zinc plated ones. I know that zinc plating is bad for threaded fasteners in fatigue if they are over a certain hardness. Does anyone know if this would apply to these lifting eyes? Thanks, J
  10. mecheng24

    Any method for determining material? (round bar)

    What about temper, is there a way to determine from hardness or do you need a separate test?
  11. mecheng24

    Any method for determining material? (round bar)

    metengr, Ok so from what I understand, this will give me chemical composition. What about grade? Strength of the material is also important, would I need to send a sample out for testing to determine this?
  12. mecheng24

    Any method for determining material? (round bar)

    Hi, I have a feeling I am out of luck but I have about 30 lengths of unidentified round bar stock. I was wondering if anyone could point be in the right direction for a process or even test to narrow down or determine what material we have. Regards, Justin
  13. mecheng24

    Induction hardening depth (core machineability)

    Hi, I have a 3" diameter shaft (4140 per astm a434 gr.bd) which I have spec'd on the drawing to be induction hardened to RC55-58 to a depth of 0.03" I still want the core to be machinable as I need to machine a bore in it of 2" diameter. I am worried about the core @.5" depth being to hard to...
  14. mecheng24

    Contact mechanics of close fitting tolerances

    Hi, can anyone point me in the right direction for a source on contact mechanics between say a lug in a hole with a tight tolerance (d/D ~1 or very close to 1). The equations in the two texts I have (Shigley / Roark) give a contact area of 180deg. Are these equations valid for such situations...
  15. mecheng24

    Moment resistant slip critical connection

    @canwesteng >The "slip capacity" is not per bolt; your slip capacity increases with more bolts as the clamping force between the plies increases. You should be able to analyze it either way. Section J3.8 calculates the slip resistance per bolt. More bolts = less shear force per bolt. @azcats...
  16. mecheng24

    Moment resistant slip critical connection

    sketch attachedhttp://files.engineering.com/getfile.aspx?folder=7f3506af-8d76-44f5-ae8b-6b6530b84880&file=sketch.png
  17. mecheng24

    Moment resistant slip critical connection

    Please see sketch attached. I suppose this would apply to an end-plate connection as well however. So intuitively, I would usually perform all checks on one of the front two bolts. However that blurb is telling me that unless the slip capacity is reached for every bolt then the connection is...
  18. mecheng24

    Moment resistant slip critical connection

    Hi, wondering if anyone can help clarify the proper way to analyze this type of connection. Say you have a bolted connection resisting moment which is putting a tension force on the bolts. Bolts further away from the connection centroid see a higher tensile force than those closer to the...
  19. mecheng24

    Moment resistant slip critical connection

    Hi, wondering if anyone can help clarify the proper way to analyze this type of connection. Say you have a bolted connection resisting moment which is putting a tension force on the bolts. Bolts further away from the connection centroid see a higher tensile force than those closer to the...
  20. mecheng24

    Question about unloading of slip critical bolted connection due to tension

    Hi all, In AISC 13, J3.9 Combined tension and shear in slip critical connections there is a factor to derate slip resistance due to tension on the joint. In eqn J3-5. the term Ta for tension force. In a preloaded joint, is this the total external applied tension force. or is it the tension...

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