huangyhg

tji end reaction
i am trying to determine the design assumptions which limit the end reactions on a tji joist.
the confusion for me lies when comparing intermediate allowable reactions and end reactions.
tia

i think the difference is that at the ends, you have a terminated web end that can buckle more easily than within the span.

jae,
would you happen to know the design check for this?
out of curiousity, i just ran a continuous joist with point load near the end (using tj-beam). as end bearing the joist failed in end reaction. i then assumed 2x4 support wall and cantilevered the joist 2" over and the joist worked fine.
this little experiment in this case is going to save $8,000 on my project.
i don't know the formulaic check - attached is a georgia pacific data sheet what includes end bearings along with notes about bearing lengths, end/intermediate reactions, and what to do about them.

thanks jae,
the notes for end reaction made much more sense to me. the note saying for 4" bearing or greater set the end reaction to max. shear.
i have another reason for this post. i am sure others have encountered what i have regarding floor systems being redesigned by lumber suppliers. in a nutshell i have had numerous times where our design would be scrutinized and redesigned by the supplier. this last time was a set of shop drawings with tji doubled in lieu of singles. the response from the supplier was our design was flawed and their program told them doubles were required. i requested the calcs and reviewed.
1) end bearing input was 3" with a rimboard (1.88" effective). joists bear on 2x8 plate.
2) higher loads then required.
using their loads and the cantilever approach i mentioned the joists work within their software. using the intended loads the joists work either way.
i feel this is a problem in our industry regarding the suppliers of trusses, joists, etc. designing buildings using software they do not understand and with limited engineering knowledge.

i raised a similair question in the past with lp. the answer was very involved, so i concluded it was easier to just follow the guidelines and limitations listed in their catalog.
there is a lot of information here on bearing design and stiffeners.

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