In a truss, the load should be applied only at the joints. So whether you load it from the top or bottom the load should be applied at the joint. The members are not designed to take bending loads. Also the joints need to be pin jointed otherwise bending moment is produced in the members leading to unexpected failure.
@chrisvids1820
2 ай бұрын
This is the most correct answer! What we see here is actually defined as a frame, not a true truss.
@Machailey1
Жыл бұрын
Definitely weight from the top with the truss bottom on the support walls. Try it that way and you'll see.
@WissamSeif
Жыл бұрын
I'm definitely going to haha. I still don't understand it, the FBD should be the same either way. Couple structural engineers have told me the same thing. Perhaps some real world effects that I'm not considering.
@Diogo-dt1uf
4 ай бұрын
No way man.. in a truss the force can be put in any of the nodes...
@NurbolAlpysbayev
4 ай бұрын
Weak glue but most importantly your staples should be aligned exactly as the 45° sticks do, and the three intersecting axes in a nice should intersect at one point ideally, or as close to that as possible.
@probasco1867
Ай бұрын
Your truss failed on the joints, with stronger joinits would carry much more load.
@BBFletcher4202
2 ай бұрын
What do they mean by weight from the top ?
@mauriceholman2984
Жыл бұрын
That information is correct trusses are designed to be loaded on top not underneath your truss resembles a floor truss which is found primarily in homes and they absolutely have to be loaded from the top. That is how they get their strength.
@WissamSeif
Жыл бұрын
Sure. I just can't explain it with a free body diagram. If you switch the load from the bottom to the top, the forces in the members don't change. They just get flipped, as in the ones in tension are now in compression and vise versa
@mauriceholman2984
Жыл бұрын
@@WissamSeif yes, that is correct, but trusses are typically supported on the ends with some kind of mechanical fasteners. Therefore, the ends cannot move. Therefore, you actually keep the members in tension and compression. Just food for thought. Still a really cool video.
@chrisvids1820
2 ай бұрын
Not true! Many truss bridges have their deck loads applied to the bottom chords. The problem is that his hanger is creating a lot of shear force because they are offset from the joints. However, I agree that it would be easy to hang the load directly above a joint.
@chrisvids1820
2 ай бұрын
What you have is defined as a frame. A true truss is defined as only having pin connections and forces applied at the joints. The fact that you have continuous full top and bottom chords makes the joints no longer pin connections. The math is no longer only tension and compression. Moments snd sheer need to be applied. Also, your connection of the weight needs to be directly on the joint. Thay contraption looks like its applying ALOT of shear force. So. If you did flip the truss over and apply load directly above the joint, say with a string, then the frame/truss would absolutely be stronger. It's because the joint is easier to load properly. Not necessarily because the top is loaded
@ScalesOfaRam
Жыл бұрын
The whole of the weight is restricted to those couple of inches on that single slat, not the entire truss. The single slat held 28lbs vs. the beams 87lbs. That truss, if proper gussets are used, should hold roughly 122 lbs based on the web design.
@WissamSeif
Жыл бұрын
Hey dude. 1) How did you come to that calculation, did you assume a thickness and yield strength? 2) If I draw an FBD, and hang all the load right at the center node, then each member takes load. Some more than others, but all the 45deg diagnoals should see the same load. My load kind of straddled the node, but the other members should still take load...I would think, lol
@ScalesOfaRam
Жыл бұрын
@WissamSeif I had a couple years manufacturing trusses. Personally, I think your biggest mistake was using staples and glue as gussets - and your 45° aren't in full contact with the truss - making them useless and your truss only 1/4 as strong as your beam. Math supports that theory. Also, if the wood is spalted, it could be an integrity issue. I slowed down the video and assessed it frame by frame. The gussets on the left side held, but the four on the right started to shift before the bottom board even flexed. When the bottom broke, the weight was then shifted to the top slat, causing it to snap almost immediately after. I would imagine our FBD model doesn't account for those irregularities or the fact that a staple isnt designed to hold weight. Better angles, actual gussets, and I'm sure you'll get it hold about 110-130lbs.
@ScalesOfaRam
Жыл бұрын
@WissamSeif the grain direction is also a factor. If it's straight, angled, cross, etc.. each would possess a unique critical point.
@hafizuddinmohdlowhim8426
Жыл бұрын
Please show your calculation and compare with this experiment. We will see if you are right or not.
@electraveininc.296
Жыл бұрын
Last semester I took a statics course and I absolutely loved that class! Its unbelievable that we have come up with ways to describe how a beam will act vs a truss with same loads on each. I definitely think if you find a good way to link each member to one another that the truss will out do the beam use the good ole parallel axis theorem to make the members of the truss as small as possible to withstand the same amount of load as the beam to show how different the 2 are.
@BogusQuacky
Жыл бұрын
Good luck with your studies. Statics was the first "real" engineering course I took. It was tough, but I powered through it. Im a meche though so it was not my favorite class.
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