Does notching or cutting out the corner of an angle brace distribute stress better along the flange of a member with shear lag or reduce the stressed edge of the flange's ability to resist deformation?

Previously, user CableStay had illustrated Shear Lag concept in a bolted angle iron member very well.

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My question then asks if it is possible to better distribute the stress of the uniform stress closer to the end of the member by notching or cutting the corner of it.

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  • $\begingroup$ Adding a screenshot of the old question really confused me for a minute! $\endgroup$
    – hazzey
    Dec 17 '18 at 17:18
  • $\begingroup$ Yeah. It's also really weird seeing my comment under CableStay's post (though I 100% stand by what I said :p). On a more serious note, @LLF264, why do you think a notch would improve the stress distribution? An argument could be made that perhaps you could cut such notches to reduce the weight (since that part of the beam isn't really doing much of anything), but I can't see why it'd improve the stress distribution. $\endgroup$
    – Wasabi
    Dec 17 '18 at 18:39

It makes sense to stream line the shape of connection at the end so as to eliminate the part that is not in the path of stress for two reasons:

A - In a situation of dynamic loading such as a truss in a bridge under impact of vibration of passing traffic the part which is not sharing the stress, does not strain with the rest of the structure either, and in the long run this sea-saw effect causes fatigue in the connection.

B - In a large structure with many complex joints removing excessive material leads to easier inspection and maintenance of the structure and lighter weight, think about power towers, bridges, stadium roofs, etc.

  • $\begingroup$ Is the stressed vs. non-stressed area of the flange the same region in tension as it is in compression? $\endgroup$
    – LLF264
    Dec 18 '18 at 18:44
  • $\begingroup$ For normal frequencies encountered in constructions yes. But in rapid high frequency loading and vibrations there is S waves which is outside of the scope of this answer. $\endgroup$
    – kamran
    Dec 18 '18 at 18:56
  • $\begingroup$ kamran.... That is interesting... are you saying that a C shaped channel bolted via the web to another member would not benefit from having the end capped if the cap is beyond the effective area of the uniform stress? or by the nature of it would the reverse be true and not only would a channel shape benefit from that, and likewise, @Wasabi, would placing a cap (45 degree plate in the case of an equal leg angle iron) on the end of the angle iron eliminate the shear lag area or reduce it or have no effect? $\endgroup$
    – LLF264
    Dec 18 '18 at 21:37
  • $\begingroup$ @LLF264, right, adding a cap near the bolts may be a bad idea. unless the designer has other functions for the cap. It encourages brittle behavior due to excessive stiffness near the bolts. The bolts could rip through the web under extreme stress as opposed to stretching it to plastic range. $\endgroup$
    – kamran
    Dec 18 '18 at 22:47
  • $\begingroup$ very interesting... In the case of capping the channel, it would be to aid in bending to some small degree, but also with a different open shape, but that is getting into a different discussion. Thanks so much kamran !! $\endgroup$
    – LLF264
    Dec 19 '18 at 16:35

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