The Secret to the Truss Strength!

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On your truss/beam testing table, drill a large hole in the table w/ a 6in holesaw, this would you allow you to load the test beams axially. I suspect the truss may have tested over 25% compared to the beam if the load was purely axial. The higher center of gravity and torsion induced by the rope twisted it significantly and in my opinion it failed prematurely. Great video, regards.

Well done. The most interesting part for me was the explanation of why it's so important to get all of the members connecting to the gusset to line up on the same point.

I have been a pressed metal pated wood truss designer (and also engineered wood) for around 30 years now. This was a good video. I was worried your staple connections were too weak as the connections are where the engineering really matters, but they seemed to hold up well. In pressed metal plated wood trusses, when a truss is overloaded it always fails at a joint not in a member. A well overloaded joint actually causes the pressed metal plates to slowly roll out of the wood.

During the course of my career I have recorded nearly a thousand bridges. Many of these were actual pin-connected bridges that did not use gussets. These were usually older railroad bridges from the late 19th and early 20th century. Some have been repurposed as local access bridges, but they are still around. That said, even through I have been immersed in bridge tech information, I learned quite a few new things from your video, always something new to learn. Thank you.

The first example I can think of, of a suspension bridge with a railway on it is the "Seto Ohashi Bridge" in Japan. It's actually a series of bridges, jumping between small islands to link the Japanese main island of Honshu with the large southern island of Shikoku over a total distance of 13km. There are six individual bridges: a truss bridge, two cable stayed bridges, and three suspension bridges, the longest with a 1100m centre span. All bridges are double decked with a highway on the upper deck and railway tracks on the lower deck. Currently it has two narrow gauge tracks, but the bridges were designed to carry four tracks to allow for an eventual Shinkansen line.

As a maker and not an engineer you helped me a lot with this description. Thanks

Loved it - especially the work that went into the simulated catastrophe! The pin / convergence point explanation gave me exactly what I need for a roofing solution at home. Many thanks for the clarity you provided.

Very well explained, cleared a lot of concepts. Really good job!

Thanks that was a very nice video, additionally the stiffness of the gusset plate, and bolts tightening condition allows for deformation during loading and that adds up into the explanation of pinned connection.

7:55 bro did can carry me 😂

Exciting to make connections between my uni classes and these videos!

Excellent video my dude

That was very insightful, would definitely be great to see more model experiments like this in the future :)

Would love to hear more about how this applies to trusses loaded axially as in the case of lattice boom cranes!

7:33 apart from the support for your truss failing before the truss, the way you've loaded the truss with lines running near horizontal out to the table edges guarantees that you won't have a proper vertical load on your truss, and the way you wrapped the line around the bottom chord where it is unsupported also guarantees that the bottom chord is loaded in both bending and shear.

Doing engineering at Napier in the 70s we were given a sheet of balsa, a tube of glue and a craft knife (Aaargh! student risk assessment kills this idea in 2023!) and challenged to build a bridge across a gap between two benches in the lab. A truss just managed to outperform my box girder. It was a really great exercise. I have used the intuition about the distribution of structurally significant material that developed from that exercise many times since then!

Wow thanks for another great video. Enjoyed the experiment--would be cool to see more of those!

Make the truss bridge in a way that the load is hanging from a pin joint and not from the middle of a truss (place the joints in a way that one joint is placed exactly in the middle). Thus you can avoid breaking the truss by a bending effect.

Lisbon, Portugal, 25 April Suspended Bridge, was after-built adapted to accommodate a railway underneath. It work fine, and heavily, the train is of suburban type.