How Beams Work! (Part 2): Structures 6-2

Here we are! We can bring together the previous videos on cables and trusses to understand how beams carry loads in bending. They look so simple these one-way spanning beams but there’s a lot going on! Don’t worry, we’ll go through it step by step and I’ll show you diagrams from the previous videos too. 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.

[@MrScubacat]

84 years old machine design engineer. Love this program. Your skill at presenting the physics of structures is outstanding

[@PaulKassabian]

Thanks!

[@greggsenne1268]

I learned more in the fifteen minutes I spent watching this than a semester of statics!

[@tommy-ij9nd]

Ok, I’ve been a veterinarian for 35 years and now I want to become a structural engineer after watching your well explained video. You would have been one of my favorite professors! Thanks for taking the time to do these videos

[@zachweyrauch2988]

This video helped me repair my old house today. Im trying to modernize and strengthen a severely slumped old home in Nova Scotia, and i cant tell you how helpful this has been in helping me understand alot of my problems.

[@beyourself8654]

Thank you so much! It hepled me a lot to understand why the proffesor always talked about the cable analogy! Keep doing these videos! You are great! 🤗

[@PaulKassabian]

Thanks, will do!

[@taboosaboo]

Your bringing Me to the next Levelse of Structure! This makes me realize, a split tube, with laces, can be adjusted flexably. Between this and tensigrid style trussing, better perfromances can be achieved efficiently. Thank You, For the knowledge and overstanding (superseedment of understanding) of the structural subject, and sharing the inspiration.

[@Conservator.]

Thank you so much for making these videos. My background is in computer science and information management but I’ve always been fascinated by mechanical (or is it called civil?) engineering and the way you are explaining structures make them seem like common sense. That is, until you have to design and optimise something but let’s not spoil the illusion. 😁 Thanks again, I just wanted to say that I’m thoroughly enjoying watching your videos. 🙏

[@PaulKassabian]

Glad you like them!

[@xingchenghuang5324]

Really appreciate the comprehensive introduction on structure systems, fantastic insights to link different structure elements and highlight their inherent similarities, it would be great if we can learn how to design a structure and have tutorials like a case study for bridge or architecture structure with simplified structure analysis!

[@smileyhunter8480]

Om

[@iamyou6555]

So essentially the load path comes from column to slab UDL into beams then to the connected girders perpendicular to beams as point loads then to below columns So roof -> column -> slab/floor -> beam -> girder -> next below column and repeat minus the roof

[@dedisetiadi7642]

Thankyou mr paul, from winayamukti university indonesia.

[@josephshaff5194]

Thanks. Couldn't read those for the longest time as a Drafter. Headed back for a Physics Deg.

[@A_struggle2563]

Sir, In an ideal truss the members shall be not continuous , i.e. they shall be broken at joints. But in practice for steel trusses , top and and bottom chords are sometimes continuous over 2/3 joints and spliced at 12 m, will it remain an ideal truss. Does the Chords not behave like beams in such a case. Kindly explain.

[@abdullahtamawi6021]

Mr.Paul Kassabian thank you for the great videos I have a question if you may tell us about the bending moment in cantilever beams why it behaves differently

[@johnmarkpateno4264]

thank you so much sir.

[@mgreasan2921]

Your explanation very simple and very understandable thank you so much

[@PaulKassabian]

Glad it was helpful!

[@gerrybeylerian5290]

Hey! If you're still doing this series, I'd be very interested in seeing your take on shear reinforcement in beams as well!

[@miscuitsmarmelade]

Same as well!

[@liboy9844]

Grab by the ends...is it also called ‘restrained’ or fixed? Nice tutorial. Thanks.

[@sportybry7676]

Really enjoying watching your video series. I'm curious on the effect that notching the ends of the beam where it is supported would have on it's load bearing capacity? For instance - picture a triple laminated 2x6 beam (made from standard dimensional pine/spruce lumber), supported at each end by metal brackets it sits on freely. Now, an additional 2 plys are laminated (1 on each side) making a beam that is now 5 plys "wide", HOWEVER the new plys measure 2x8 instead of 2x6 like the rest of the beam. As the tops must be even with the original triple laminated 2x6 beam, the very end of each 2x8 needs to be "notched" so they can rest on the same bracket supporting the 2x6s. This means that, outside of the notches at the ends, the "new" added laminations hang down 2" further than the original 2x6 beam. How will these extra laminations enhance the beam structurally? Will they behave as 2 added 2x8 laminations? As 2 added 2x6 laminations? Or something else entirely? I have a suspiscion on what the effect would be, but don't want to jinx the answer! (lol) Assume they are fastened from each side to the original 2x6 beam using high grade construction adhesive and structural screws that penetrate the new ply and all 3 old plys. Part B would be whether "filling in" the empty "channel" between the 2x8's at the bottom of the tri-lam 2x6 beam would improve the load carrying capacity (although I have no idea how you'd properly fasten it in there!). My guess is that the improvement would be minimal if not insignificant.

[@oswald2358]

👍👍👍

[@History9-33]

Very clear teaching n good lecturer... Tq

[@PaulKassabian]

You are welcome

[@arnulfodefeo7747]

Wish to know also what's the purpose of the car's underchassi,and the spring plate in it, and why mostly the back tire of a car or a truck is attach to that area,.want to know also the different type of works of a beam with that?..tnx sir! More power..

[@AlanThomas1]

is the bending moment the derivative of the beam curvature?

[@PaulKassabian]

Thanks for your question. Bending moment is directly related to change of curvature. Look online for the M=EIK equation where K=change of curvature.

[@inderjitsingh5928]

Sir, I wNt to construct si ngle story house of 500 sft on single beam. What should be the size of beam, its depth on ground and maximum weight can we put on it.

[@americanmale2011]

One continuous grade beam throughout the perimeter. Hire a local engineer and apply for permits to have it inspected.

[@EdwinColubioChannelENJOY]

full pack already engr.hope mine too thank you.

[@musicshow4241]

Cool

[@alfredosei4315]

Please I want to be a Structural Engineer.....show me the steps for Reinforced concrete design

[@periodictable118]

just glue the 2 beams on top of each tbh

[@SUYADI1]

Top

[@jamesmerkel9442]

25: your rubber beam if it when it sags just turn the cable motion into lift cable move ment motion lifting up on the ends to counter so not really using beam rubber as support really. u just need multi pulley make small sagging force hve grand pulley pulling apart lifting force into the built design. GOD free help. If beam twisted by design so even though will sag not pulley that much back up. If u twist 1 beam right ^ & 2nd beam left twist then make weld one structural member backed up by pulleys lifting pulling on end, & if pulley back up piece connection fails it makes it to long after fail for beam to come off or fall thru bc of extra length connection, just 30sec working the problem godly approach. No thought given, tossing it rubber beam out there.

[@keypoint1293]

So you do beams without talking about shear strength and also fail to explain why a single deep beam bends less than two half depth beams.

[@davidaugustofc2574]

I can see why, but maybe it's my fault I came here already knowing a few things