How Trusses Work! (Structures 5-1)

We can combine tension and compression elements to form trusses that span further than the pieces from which they're made. Exciting stuff! We start with a cantilever and then build to a full structural span. I show you some bridge examples and also how to optimize a truss for material efficiency. Enjoy!

I'm Paul Kassabian. I'm a structural engineer and a Principal at SGH in Boston, MA. I taught graduate students at MIT for nine years and currently teach on/off at Harvard's Graduate School of Design (GSD). These are videos based on my years of teaching structures to students.

[timclark]

this is what's great about YouTube, by accident you learn about something you've been observing but not really understand for years 👍

[howitstartsmm]

First time viewer.
Genius is the ability to teach a complicated subject clearly, simply and comprehend able to an average person.

Thank you for your time and knowledge.

[daved]

That was brilliant. I really liked how you developed this, logically, from a single tension and a single compression structure to a structure with multiple members. Thank you.

[rodrigovelasco]

Great explanation Paul. I am an architect, and these kind of clear explanations gelp not to exclude us from understanding structural behavior.

[robtristram]

What I learnt after a whole career in structural engineering is that most of the time no one really cares about getting even an efficient structure (unless it is the primary structure of something huge), let alone a theoretical optimum. The exception is design-and-build contractors where their profit margin depends on minimising materials, but of course they won't do that at the expense of complication, which costs "more than materials".

[Flurib]

Thank you so much for taking the time to make this video. I had a basic understanding of the loads involved in a truss, but some times had a hard time determining how the load was transferred through the structure. And it turns out because I was looking at it backwards. I would look at a bridge and try to figure out the load distribution by the weight of a truck sitting on it, not as the support structure resisting that load. I’m not sure if I explained that well, but your explanations helped a lot. What finally made it click, where I had that lightbulb eureka moment, was your graphics of the hands supporting the structure. I am very grateful for that,
and again I appreciate you making these videos for everybody

[martingagnon]

One thing that pop in my head is when you build a truss on the ground and you use a crane to put it in place you have to consider that forces (tension and compression) will be the opposite way temporarily while moving it! Good video sir!

[jeremiahbarlow]

I have designed trusses at a wood truss manufacturing plant, but never understood this. The software just did if for me. Thank You for sharing.

[dalegray]

As part of my job, I have to record historic bridges, both automotive and railroad. I love watching your video showing how variations on the Warren and Pratt truss bridges work.

[nicolasramirez]

Paul this is such a concise and beautiful presentation! Your style works so well, like a great piece of music. Well done!

[gaetanomontante]

Liked and subscribed. I am an engineer and having come across your channel by chance I found it to be be beautiful in the simplicity with which you explain things that in our days professors bored us to death with explanations of vectors and forces that in the end left us as ignorant as we were before. Thank you Paul and please continue the illuminating work. Hopefully some young blood will stick with your presentations and learn much from them, especially in the area of being opened to the enthusiasm of learning beautiful concepts.

[BackToReality]

I'm less than two minutes in, but can already tell that I've just struck YouTube gold! New sub!

[kishfoo]

Thank you sir. Anyone with a PHD can explain physics to other well educated people. It takes a master to explain it well to us simpletons.

[ShahroozAryan-ezcc]

As a structural bridge engineer, I often watch your clips and thoroughly enjoy them. You demonstrate great creativity and innovation in your work. Particularly impressive was the clip featuring an arch structure built on a small scale model, where you deformed its shape by applying load with your finger. Additionally, the clip discussing trusses was captivating, especially when you introduced the optimized truss, with one part functioning as an arch and carrying compression loads, while the other part acted as a cable and carried tension loads. Overall, your work is truly amazing. Thank you for creating such incredibly beautiful clips.

[CMRHM]

wow, you demonstrate the truss concept in step by step, this is very easy to understand and truly a clever method. Thanks!

[TRON]

Vid came up with the algorithm while I've been studying for my Architect exams and brushing up on my structures. Just excellent explanations! VERY helpful.

[kushanimehta]

Just discovered this while taking a structures class, this is very helpful and easy to understand. Thankyou!

[jimmimak]

I like how you teach visually, as it can be difficult going straight to maths without an intuitive understanding.

[kasirk]

The tutorial showed up when I needed it the most. God Bless you Sir.

[stevenkamp]

well explained, I think the magic in understanding it all, is breaking it down into small thinking process blocks