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@The Engineering Hub You have the gift, my friend. This is the best introduction to structural shapes and selection I've ever come across. When I was getting a bachelor's and master's in architecture, many courses failed to properly create an overview of the subject matter, but you get that right in just the first 45 seconds. Most who purport to teach get bogged down in details and trivia, get sidetracked, or don't really understand their audience. Here on the other hand, at 2:00, you include the comparatively complex equation for buckling, but without distracting from what a novice needs to know. Really quite extraordinary. Many thanks!
Have another look at the cross section of rolled channel iron. You will notice how they have more material at the bends inside, rounding the section, and the base is usally thicker than the wings. They are not half an i beam! Also the way they are rolled makes them more dense than other profiles. You'll notice the forge when cutting. They are a beast of their own.
I'm retired mechanical designer. . .We used STAAD structural analysis software in the 1980's . . . Cell Phone towers have wind load and ice build-up weight, so hollow was good.. . . .acid plants have corrosion problems with hollow members, so hollow was bad. . . .channels and angle iron have totally different applications. . .and Equipment supports made of tubular members need extra flanges welded on to attach Electric / Hydraulic lines, so I-Beams are perfect for 1 and 2 story equipment platforms. . . .Every situation is unique.
I think it is a bit strange to rate H- beams higher than square hollow profiles when it comes to workability. For welded constructions the fabrication cost for H-beam based structures are typically 3-4 times compared to square hollow profiles. Due to more complex prefab (cutting and weld prep), more complex welding and NDT and more time consuming surface treatment. Another huge benefit with square hollow profiles is that the other geometry is constant. If you increase wall thickness it builds inwards. Meaning in 3D models there are no changes to overall dimensions and joints if one changes wall thickness. With H-beams everything changes. I would chose square hollow profiles whenever possible.
When it comes to surface treatment open sections are vastly superior. The entire surface is easily treated, while hollow sections often suffer from poor treatment on the inside (if they even try to galanize it properly). Also the enclosed spaces are suspectible for trapping moisutre thus accelerationg corrosion. As for workablility it depends what your goals are. Bolted connection are much easier to make using I beams. As for 3D models with a well built up model in a modern software its incredibly easy to change section sizes. When it comes to smaller welded structures with lsmall loads square tubes can be advantageous indeed. But also depends on a lot on the application and I beams can be better dispite the slightly more welding required.
H beams give unlimited easy attachement capabilites, as someone who has to constantly do rigging and installation of large equipment/ installation of necessary plumbing and other support accessories, beams are just easy.
@@istvanditamas2959 Yeah, the automotive industry switched from C channel to box channel. While the box was somewhat lighter thinner metal and controlled twisting better, it trapped moisture and got poor rust treatment inside. While the I-beam is incredibly strong, it fails much quicker under high heat than wood laminated. The extremely dense laminated beam will only char the outside, while the steel will twist and fail above 2,000F.
Hurricane Katrina gave a great opportunity for the observation of structural steel failures. There were hundreds of tall billboards in and around New Orleans. Unfortunately, I cannot give the weight per foot of the supports but I can say that the external dimensions were similar. Some billboards were mounted on three or four I-beams of constant dimension. Others were mounted similarly on round pipe of diminishing cross sections as the height increased. Peak winds were in excess of 150 mph (240 kph). My observation was that I did not see a single billboard on I-beams that was still standing after the hurricane. All of the I-beams failed by bending, not buckling, over a radius of several feet parallel to the webs of the I-beams. The bends were remarkably gentle, on the order of a 3'-5' radius. Once the I-beams gave way, the billboards themselves were pushed to or nearly to the ground. I did not see any billboards that were on pipe fail. The hollow round shape stood up to the wind very well.
Wind loads on billboard (in reality) create more torsion than bending. Wide flanges still better in bending and circular sections are better in torsion, that is why you see more circular supports still standing for billboard structures.
Have any of you any practical experience installing HSS column over a h-beam column no I seen one comment dude said he was going to use pipe obviously has never made a column out of pipe if you had 10 HSS 12 x 12 by 5/8 on one side and 10 on the other side with a space of 10ft between sides and 8 ft between columns and a top of beam height of 10 ft and you built comparable structures The h-beam Columns would have less lateral movement when you were walking across the structure it's often fun to take Engineers on a deck when they don't have a clue and see the reaction on their face when they stand still and feel someone walk across a structure that has HSS columns and that would be multiple X bracing to combat thing down so the problem with that is on a boat dock when they have the boats at the bottom and the deck on the top they engineer a lower structure made of rock or fuel to get to the sheer out of the building
I'm an immortal highlander who has been blacksmithing since medieval times & doing structural engineering with steel for 135 years, and I learned more from this video than during my entire cursed existence.
Love the use of radar plots, this is an ideal situation for using them. I also can't believe it never occurred to me that the framing+sheathing in home construction created a compound I/T shape for strain calculation purposes!!!
I'm not an engineer or construction dude. When putting up a shed a couple years ago, once all the walls and roof trusses were up it seemed pretty rigid. Once the sheathing was on it _was_ very rigid. That's a lot of "triangles" working for you (triangles formed by fasteners through the sheathing - whether walls or roof). The tension on the roof truss horizontal beams becomes the hero of the project, actually.
Before watching, my answer to the question in the title was, "All of them. Depending on what you are looking for from the shape and material." As an example, it's hard to pump water anywhere using an I-beam.
While not really part of the data visualization, an awesome but rarely used part of computer interface is a three-variable slider, which is visualized as a triangle, with each point in the triangle being a different distribution between the three options. It could be used as a data visualization for some things too, like "time spent working/sleeping/other" with every point on the triangle being a different set of these three numbers with a constant sum.
I would have tought this was common knowledge ... build a basic box ... if you start with the sides it is great top to bottom but may not stay square as it wobbles ... add a bottom and poof it goes rigid ... I learned that back when I was about 8 years old building a birdhouse for cubs ... it was a royal pain getting all the sides to stay square ... then the dad showed me the easy way ... start at the bottom and work around ... each addition adds strength ... to the last ... no more fiddling with square
Developing an intuitive sense of the effect of displacement of material from the neutral axis is a valuable design skill that can be only partially replaced by CAD and simulation software but a team's design effectiveness is significantly enhanced if both the software tools and the intuition are effectively utilised within the team.
@@ESALTEREGO No, it's a padding problem. Most 15 minute videos are 1 minute of actual useful information and 14 minutes of "Like and subscribe to my channel", "see our patreon here ...", "join us on discord...", "today's sponsor is: ...", jokes, side-tracks, history of, explaining basic concepts that should really just be a reference to another video.
@@soylentgreenb add is a thing too! I know I’m on a good vid if I don’t start scrolling… I’m typing this with playback speed at 1.5, less than one minute in… now I gotta back up
Another good thing the hollow sections have is that you can make composite columns with them. Helps in the workability when you pour the concrete in. Also, it has more resistance than a normal hollow section due to the interaction of the hollow section and the concrete column, meaning it can result in having even longer span of elements than with a steel section alone.
My opinion: Circular hollow (but not too thin wall) for torsion and for carrying fluids (literally a pipe) Circular solid for dynamic crankshafts (like transmission and engine shafts) Square hollow for smallish columns H-beam for large columns (possibly embedded into a concrete pillar) I-beam for any type of uniaxial bending about x-axis (such as a beam supporting only weight of gravity) I-beam for columns, if braced in the y-axis Angles for connecting other beams together Rectangular solid for any type of wood (this is also the only type available for wood generally) Channels for embedding needs T-sections are more or less outclassed by I-beams for most applications (also calculating the moment of inertia for T-sections is a huge pain in the ass)
I've worked with U Channel beams, and for their weight, they got quite good bending strength. Certeinly, a good option for longe free span structures without much torsion loads... Anyway. Nice video man.
@makermartin10 - How about U-Channels attached to Tubular Cores? Or Square Tubes fitted with Round Types, internally? Adhesive Bonding, Welding (via Rosette Welds from the Square Tube in Circular Openings, not too big), or Bolting Through, to transfer and Share Loads!
@9:13 those are not structural pipes but Fire Protection. the "victaulic" grooved couplings that you call "collars" are only meant to join the pipe to convey fluid not add reinforcement to the building
I am constructing a small home on 1500 squarefeet plot. Traditionally, constructions in my area is done by raising 12 RCC pillars (columns) on the plot before pouring concrete to form a flat roof. From this roof and above, residential quarters begin where each floor raised above the column is considered independent residential units. I, on the other hand, prefer a mezzanine construction on my 1500 squarefeet area. Purely for personal use. So my priorities are lightweight and economical materials versus the traditional RCC columns that need steel bars concrete mix. Would I be wrong if I prefer H or I beams instead of traditional RCC column for framing the structure to lessen the concrete use? Would it be economical and would I be able to achieve better structural strength than RCC columns?
Thank you for this interesting and informative video. Three other properties occur to me: Crushing (eg elephant sits on a tube) Crippling - relates to length/stiffness in and end-load situation (eg elephant sits on a platform atop a long tube) Impact strength (eg car veers off the road and hits a structural member, or any day in a war situation)
To answer why these are not included; crushing is better known as the compressive strength and, ignoring buckling, it is directly related to the area of the section; crippling is better known as global buckling which is addressed in the video; and impact will relate to local buckling and material properties, assuming we are only using steel, then it is also addressed in the video. Have a look into global and local buckling then I’m sure you’ll have a better understanding how those concepts are related
I am an Engineer.I covered,Strength of Materials,Mechanical Systems,Engineering Design and Mechanical Technology. Beam Shapes and Hollow Section Profiles as stated in the video,depend on many factors. Nowadays there are many newer materials in existence ,compared to when I started my Higher Education and Training in Engineering. Composites and Nano-Materials are a few.
It’s amazing how some people can take something so natural and common sensical as balance and strength of an object and complicate the Hell out of it with unnecessarily complex or obscure words, diagrams and formulae, for what should come as intuitive awareness or knowledge to others. I guess not everyone is cut out for engineering.
Channels and angles also deflect rotationally under bending, especially when cantilevered. They make poor beams when the load is placed perpendicular to the flanges. As one commenter notes below they walk off access to the direction of the load. Triangular shapes are actually better in bending than square shapes of equal area and, when extruded, extra material can be placed at the corners to maximize section modulus. Unintuitively, symmetry is good. Connectivity is of course horrible. I would be interested to see your analysis of solid and hollow triangular sections.
Very good point about rotational deflection under bending. In fact, we happen to be developing our next video on this very topic! Noted on your comment about triangular sections. We'll look into this more and see if we come up with anything. Cheers!
I am building a full-length (19.5 ft) pipe rack for a pickup truck. The longitudinal pipe (back bumper to front bumper) needs to be strong enough to be able to haul heavy cargo. I have posed the question to friends about what size square tubing should be used and I have received several confusing explanations about this design. Keep in mind that I have to keep it as lightweight as possible. The first method is to use a single 2x1 thin-walled square tube to run the length of the rack. The second method is to use "two" 1x1 thin-walled square tubes either welded together or bolted together in order to make a final 2x1 length. I was told that the more angles that you have on a span the stronger the span will be. The other thought is that a consistent uniform design (2x1) will be stronger. Which would you prefer and why? Thanks.
Cool video, I like your rating method! The only thing is that the transverse stiffener shown at 5:03 does not improve torsional resistance, it improves local web buckling. Torsional stiffeners would need to run down the axis of the beam closing the section for the entire length of the beam loaded with the torque. Great video otherwise!
6:27 - - *THIN PLATES BUCKLING UNDER STRESS* 6:58 - - *Rectangular + square sections can be OPTIMIZED by creating hollow sections (or tubes)* 13:00 - - How would a *hexagonal* hollow cell/member rate on this score-system?
Excellent video, this explains the pros/cons of structural shapes much better than conventional resources and curriculum. The school of RUclips is putting colleges in their place, they better embrace it and adapt or they'll become outdated.
Instead of surrounding rebars with concrete, how about filling hollow pipes with concrete. Or fill with resin for smaller structures like furniture. This would reduce the chance of buckling since the internal fillers are solid and resist compression.
Since the comparisons were based on equal cross sectional area (in other words for a given material the same weight per length) the analysis tended to obscure the strength per weight. If building something like a race car chassis where weight matters a lot, it's impossible to beat round tube. But cutting it to make joints does require special equipment and skills. You can buy jigs that use just a hand drill and hole saw, but getting the measurements and angles right takes thinking and attention. Square tube is a second place. The weight is higher for the same strength but welding joints is as easy as it gets. A handheld band saw will allow you to make just about any joint between two square tubes that you can imagine. I was surprised that he rated workability so low for square tube. But he was looking at bolted connections more than welded. It's just that among DIYers the people needed to choose different steel shapes are probably mostly people that can weld
Nice video! I liked the side-by-side rankings of the different shapes. Another great video would be if you delved more into the bracing, connection, or other practices that improve on the relative weaknesses on each type of section.
I often see elliptical tubing used for things like motorcycle and aviation framing/support elements... in talking about wood framing, sheathing, with adhesives, seems to offer a big advantage in making a kind of 'tubular', or even, monocoque, structure, with much added stability. Thanks for an interesting presentation, and interesting graphical/numerical scoring method(s).
I had forgotten about elliptical tubing. It seems to combine the properties of circular pipe with the properties of hollow rectangular tubes. I first saw them being used for reducing weight on bicycle frames while increasing bend resistance in the commonly loaded direction.
It can be noted that the Double-T Precast concrete beams mentioned at @11:41 which are commonly used in parking garages and bridge decks are structurally somewhat different than simple metal t-shapes as the required included reinforcement is nearly always pre and/or post-tensioned steel rods and/or cables. this significantly increases the bending resistance of the complete part.
I have always wondered about triangular shapes like trusses. Triangles are geometrically rigid by definition. I can see them buckling unless you put in a compensating truss. Your thoughts?
Log cabins with almost round solid circles (flat at top and bottom if I don't recall wrong) would have been lovely to see here even if it's not a modern approach. Curved wood was also used back in the day for certain roles, think of the wood where a branch leaves the tree or in the roots etc. I'm no expert on that kind of things, but I'd love to learn more.
You correctly inform us that we need to select our section acording to the application. Therefore there can not be a clear winner. You say the torsion in an I beam depends on its 'J'. If you mean 'J' as it is usually understod, IE Ix+Iy then you are wrong. It depends on its 'K' which is much less. I recomment Roarks formulae for stress and strain for a better understanding. 'U' or 'C' sections have a further disadvantage to the doubly symetric 'I' in that they have a shear centre outside of the section which can easily lead to combined bending and torsion when loaded with simple shear. From a practical point of view, closed sections are difficult to treat against corrosion and equally difficult to inspect, unless of course you can get inside it eg the leg of an oil rig.
Hi again Emma, by J we mean the ''torsional constant J'' and not the polar moment of inertia or the summation of the moment of inertia about the x and y axes. Check out Chapter 3.10 in Mechanics of Materials by Gere, the twisting of noncircular prismatic shafts and the torsional constant are explained there. The factor K in ''Roark's formulae for stress and strain'' is the same factor that Gere calls J and is the torsional constant. In regards to the shear center, we agree that this is an important point that is worth mentioning. Maybe we can do another video only on the shear center of sections in a future video. Thanks for the good discussion as always.
If someone were to build a structure with square tubing but the main external framework were to be arched in long bows. How would this effect the over all structure when it is properly supported from within? Example a nearly flat dome with a 6 foot rise but a span of 88 ft span. With some supports that are truss type but others are double square tubing with a single web between them for added torsion strength to prevent downward collapse potential.
Anyone that knows what "area moment" and "section modulus" are already knows the answers to these questions. Those that don't are not being helped by throwing in words that are not familiar.
how strong is 3x5 steel angle 1/4inch thick? can I use 2 of them to sandwich 6x10 in order to increase the span? I can't use steel plates wider than 5 inches because I don't have access from both sides of the beam. Thank you
Very well done. I'd be interest in a follow up video where multiple shapes are combined. adding an angle to a flat surface creating a triangle, and combining triangles to make a honeycomb.
Helpful video, thanks. I would say that workability depends a lot on the tools available for a given material and shape. Having the appropriate tools can make the workability much easier. And not having them can make anything difficult. All that is to say I would not have given workability as much weight as it is given. Or, in practice, weight it in light of the available resources.
Yeah, workability is a bit of a strange category to me. I also don't see how I-beams are more workable than hollow rectangular tubes. If you have to trim out an I-beam, it gets pretty awkward for where to attach your stuff. But trimming out a hollow rectangular tube wouldn't be that hard IMO.
What type of materials can be used to manufacture the structure with high corrosion resistance and strength also considering the costs of the materials
Excellent overview. Like the rating system. I weld pipe. Don't like the unsafe person cutting steel at 10:33. No glove, no cutting wheel guard is a bad idea.
Fair video, i would have liked in the conclusion to highlight framing outside of wooden construction with the correct fastening and alignment many flaws in each element can be reduced
There are many structural shapes because different loads required difference design considerations. No one is BEST for all things, but each has it's place. There are no winners or losers.
Paintability (e.g. corrosion protection/inspection) is a big disadvantage to closed, hollow sections. Could be baked into the Workability metric, but could be a game-changer alone.
On the other hand, the structure could be designed so that the inside is sealed up so it doesn’t matter. This is most likely the case anyways when the ends need to be welded up.
I have a question that I have not been able to find a clear answer for. Can you help? For two examples of the same material, length, and outer measurement (not material area), which is stronger in bending resistance: an i-beam, or a solid square/rectangle? This is if the greatest height and width of the i-beam are the same as the greatest height and width of the solid square or rectangle beam. Does an i-beam gain any strength properties that the solid beam of equal size does not have? I understand that weight, cost, workability and such will be disadvantaged on the solid part. Help!
If I understand your question right, you're asking if an I-beam is stronger than a solid rectangle of the same size, right? The solid rectangle will always be stronger simply because there is so much more material. Example: 4" tall x 2" wide I-beam made out of 1/2" steel will always be weaker than a solid 4" tall x 2" wide steel rectangle. The advantage of the I-beam is that it is a much more efficient use of material. With the material of a solid 4"x2" rectangle, you could make something like an 10"x5" I-beam, which would be much stronger.
In that analysis you are neglecting the self weight of the structural member. The wide flange beam is stronger due to supporting less self weight. Take examples of both and extend them to 6,000 ft. horizontally and create a fixed end on one side and no connection on the other. Apply the self weight plus a 100 pound dead load at 4,000 ft. away from the fixed connection. What is the deflection of each at the unsupported end?
Have any of you any practical experience installing HSS column over a h-beam column no I seen one comment dude said he was going to use pipe obviously has never made a column out of pipe if you had 10 HSS 12 x 12 by 5/8 on one side and 10 on the other side with a space of 10ft between sides and 8 ft between columns and a top of beam height of 10 ft and you built comparable structures The h-beam Columns would have less lateral movement when you were walking across the structure it's often fun to take Engineers on a deck when they don't have a clue and see the reaction on their face when they stand still and feel someone walk across a structure that has HSS columns and that would be multiple X bracing to combat thing down so the problem with that is on a boat dock when they have the boats at the bottom and the deck on the top they engineer a lower structure made of rock or fuel to get to the sheer out of the building
when bending angle over a long span, it's interesting because it will dive or climb in the axis that you aren't bending and will have to compensate for
I would say it is a very well informed purely scholarly approach with some notable gaps in real world knowledge and experience. For example the double T bridge sections he described. Those are generally post tensioned with cables for the strength of the structure rather than relying on rebar that is only contained in each individual section and doesn’t transfer load. He also ignored how the shapes he discussed are used as part of a larger system and the loading in each member is influenced by other members. And the shapes he deems less worthy are great at transferring smaller loads between more larger examples of ideal shapes.
Good overview!!! An error at 5:02: Those stiffeners will help nothing against torsion!!! On should add them on the sides over the length of the I-beam (to give it a tube shape).
the idea of using L sections to create a T Z or H section by simply riveting or bolting them together has been the cause of several disasters as they do not have the same strength as a proper H T or Z section ether extruded or full pen welded and should be noted by designers
Next you're going to try and tell us that hanging slabs of concrete such as hotel walkways from compound threaded rod assemblies or traffic tunnel ceilings from rods questionably glued into overhead concrete could result in fatalities... The nerve if this person!
Still trying to find the answer: In my area, if you have a two story (wood framed) house, you need at least 2x6 -24inch on center studs. Can you use 4x4 -24inch on center instead? Does that have comparable strength for framing?
When you position material furthest from the centre, and then make a cellular character within the outer wall, with cross ties to reduce buckling risk, congratulations, you have invented a stem of grass, or bamboo.
I am stricken by the extent of variety in shapes chosen by the state highway agencies in various American states for the identical task: posts for small highway signage. Right off the top of my head, I can think of various states that use perforated hat channel, perforated square hollow, circular hollow, and square solid (wood). Surely each has advantages and disadvantages, but one would think that more consensus would have developed as to which is the best value over the long term.
What about tension and compression? And the planes of tension/compression. T shape, round, square, and angle are used alot in truss systems. Analysts and design was fun, i became to see the formulas in the 3d spaces.
I was going to make a very similar comment. Angles are used in tension on the bottom cord of many flat roof trusses. And welded connections can not be ignored when discussing workability of structural steel. As another commenter pointed out, many times the decision comes down to cold hard cash. What is the cheapest way to meet the requirements without exceeding them. Many times designers create impossible conditions that can’t be fabricated in the real world. So I am not sure how much I trust them to care about what the constructors go through.
I'm curious how a hollow circular beam internally connected with a Y-shaped beam would perform. The 120 degrees in a Y-shaped beam would normally make it difficult to work with if by itself, but would fit perfectly in a circle, supporting it against bending by being resistant in the same way I-beams are, and likewise the circle would support it against torsion which it'd otherwise be weak against. Of course having such a complex structure would reduce workability a lot, but if that wasn't a factor, would this come close to the optimal shape for strength proportional to area?
Several years ago at work, we needed to install some bollards. My suggestion was to slip a square, I, or triangle tube into a circular tube or a circular tube into a square tube to increase bend resistance. What are your thoughts on combining shapes looking just at the factor of bend strength?
Bollards are designed to stop smart people and slow down idiots. If bollards were made stronger the risk of injury would increase. Cars have crumple zones for a reason. Oh and a single thin wall pile filled with concrete is cheaper than the fancy strong design.
Sorry, extremely valuable and sensitive equipment that MUST work at all times. After getting called out a few times at 2AM when it was raining sideways to repair the damage caused by some dimwitted moron that couldn't control his vehicle - I really don't care HOW damaged the vehicle OR injured the dimwitted retard gets.
I am using a channel post to attach a satellite to. It has all of the strengths i need except one vital one I didn't account for or anticipate. The torsion, if the wind blows slightly, the dish will sway nonstop because the post is twisting. What can I do to reinforce and prevent the dish sway on the u channel post which i believe is the source of the weakness?
Nice. Any idea where I would find out the unsupported span of an I beam ? I want to build a 3 story concrete house using I-beams to support floor joists.
You got a like how some of this engineered wood products mimic the cross-section of an I-beam. You have two two by fours with a groove cut in them with a jointer of plywood. The end up being lighter than a typical Lumber member but you have a bit more convenience on putting holes through for plumbing and electrical for example
Hello Dr Renard, The 80/20 brand products are very interesting. One way to look at such products is to reduce them to the simple shapes which their sections generally contain. For example, their smaller T-Slotted profiles (25mm) start to include more enclosed area which makes them better at resisting torsional forces and starts to make them more comparable to rectangular tubes. All of the 80/20 sections have advantages of channels in terms of workability due the the exposed slots on each side for positive connectivity, which is what makes them particularly unique. Cheers and thanks for the comment! Link for reference: 8020.net/framing-options/t-slotted-profiles.html
@@TheEngineeringHub thanks for the reply. It is a very complex design and so I made some suggestions of what I could extrapolate based off the video. I am actually glad you could actually give feedback on this as not particularly my field of expertise and I have really been looking into 80/20 (and off brand extruded t-slot aluminium but used more for recognition). Thanks for expanding my knowledge base and giving me insight into how something not covered could be used, even just based off of structural examples you've already made. So pretty much I beam with more workability. Though the mention of torsion, I remember some of the bigger ones have kinda hollow center too so is partially a tube build as well. Would explain why it is a pretty useable structural material that's useable in hobby and professional development. Yet again, thanks for the actual feedback on my question.
So ... would an I beam be stronger as a fence corner than a pipe? Lets narrow it down and say they are both steel, with dimensions giving them an equal weight of steel. Yes might seem to be the obvious answer, but the reason I ask is because I beams are typically used to span horizontal distances, not to be set vertically as a post.
I read somewhere that the strongest was one that is rarely seen, as it would be very vexing to manufacture. The structure is a round post made up of wedges. From the top it would look like a pie cut into equal slices. Could this be true?
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@The Engineering Hub You have the gift, my friend. This is the best introduction to structural shapes and selection I've ever come across. When I was getting a bachelor's and master's in architecture, many courses failed to properly create an overview of the subject matter, but you get that right in just the first 45 seconds. Most who purport to teach get bogged down in details and trivia, get sidetracked, or don't really understand their audience. Here on the other hand, at 2:00, you include the comparatively complex equation for buckling, but without distracting from what a novice needs to know. Really quite extraordinary. Many thanks!
Have another look at the cross section of rolled channel iron. You will notice how they have more material at the bends inside, rounding the section, and the base is usally thicker than the wings. They are not half an i beam! Also the way they are rolled makes them more dense than other profiles. You'll notice the forge when cutting. They are a beast of their own.
@@SynomDroni thanks Synom! I see what you mean about that 🙏🏼
What about shapes like ➕ & 🔼🔺both hollow and solid
I'm retired mechanical designer. . .We used STAAD structural analysis software in the 1980's . . . Cell Phone towers have wind load and ice build-up weight, so hollow was good.. . . .acid plants have corrosion problems with hollow members, so hollow was bad. . . .channels and angle iron have totally different applications. . .and Equipment supports made of tubular members need extra flanges welded on to attach Electric / Hydraulic lines, so I-Beams are perfect for 1 and 2 story equipment platforms. . . .Every situation is unique.
I think it is a bit strange to rate H- beams higher than square hollow profiles when it comes to workability. For welded constructions the fabrication cost for H-beam based structures are typically 3-4 times compared to square hollow profiles. Due to more complex prefab (cutting and weld prep), more complex welding and NDT and more time consuming surface treatment. Another huge benefit with square hollow profiles is that the other geometry is constant. If you increase wall thickness it builds inwards. Meaning in 3D models there are no changes to overall dimensions and joints if one changes wall thickness. With H-beams everything changes. I would chose square hollow profiles whenever possible.
When it comes to surface treatment open sections are vastly superior. The entire surface is easily treated, while hollow sections often suffer from poor treatment on the inside (if they even try to galanize it properly). Also the enclosed spaces are suspectible for trapping moisutre thus accelerationg corrosion.
As for workablility it depends what your goals are. Bolted connection are much easier to make using I beams. As for 3D models with a well built up model in a modern software its incredibly easy to change section sizes.
When it comes to smaller welded structures with lsmall loads square tubes can be advantageous indeed. But also depends on a lot on the application and I beams can be better dispite the slightly more welding required.
H beams give unlimited easy attachement capabilites, as someone who has to constantly do rigging and installation of large equipment/ installation of necessary plumbing and other support accessories, beams are just easy.
yeah I dunno why he said what he said about the limitations of H beams before then giving it a nearly perfect rating..
@@istvanditamas2959 Yeah, the automotive industry switched from C channel to box channel. While the box was somewhat lighter thinner metal and controlled twisting better, it trapped moisture and got poor rust treatment inside. While the I-beam is incredibly strong, it fails much quicker under high heat than wood laminated. The extremely dense laminated beam will only char the outside, while the steel will twist and fail above 2,000F.
This video seems misleading especially the title. Every single beam has its purpose and use case, why "rate" them in this way?
Hurricane Katrina gave a great opportunity for the observation of structural steel failures. There were hundreds of tall billboards in and around New Orleans. Unfortunately, I cannot give the weight per foot of the supports but I can say that the external dimensions were similar. Some billboards were mounted on three or four I-beams of constant dimension. Others were mounted similarly on round pipe of diminishing cross sections as the height increased. Peak winds were in excess of 150 mph (240 kph).
My observation was that I did not see a single billboard on I-beams that was still standing after the hurricane. All of the I-beams failed by bending, not buckling, over a radius of several feet parallel to the webs of the I-beams. The bends were remarkably gentle, on the order of a 3'-5' radius. Once the I-beams gave way, the billboards themselves were pushed to or nearly to the ground. I did not see any billboards that were on pipe fail. The hollow round shape stood up to the wind very well.
Wind loads on billboard (in reality) create more torsion than bending. Wide flanges still better in bending and circular sections are better in torsion, that is why you see more circular supports still standing for billboard structures.
Wind loads (in reality) are fluctuating thus it creates more torsion than bending loads.
Have any of you any practical experience installing HSS column over a h-beam column no I seen one comment dude said he was going to use pipe obviously has never made a column out of pipe if you had 10 HSS 12 x 12 by 5/8 on one side and 10 on the other side with a space of 10ft between sides and 8 ft between columns and a top of beam height of 10 ft and you built comparable structures The h-beam Columns would have less lateral movement when you were walking across the structure it's often fun to take Engineers on a deck when they don't have a clue and see the reaction on their face when they stand still and feel someone walk across a structure that has HSS columns and that would be multiple X bracing to combat thing down so the problem with that is on a boat dock when they have the boats at the bottom and the deck on the top they engineer a lower structure made of rock or fuel to get to the sheer out of the building
I'm an immortal highlander who has been blacksmithing since medieval times & doing structural engineering with steel for 135 years, and I learned more from this video than during my entire cursed existence.
There can be only one.
Still on the “old math” huh?
Love the use of radar plots, this is an ideal situation for using them.
I also can't believe it never occurred to me that the framing+sheathing in home construction created a compound I/T shape for strain calculation purposes!!!
Thanks for the feedback Adam!
I'm not an engineer or construction dude. When putting up a shed a couple years ago, once all the walls and roof trusses were up it seemed pretty rigid. Once the sheathing was on it _was_ very rigid. That's a lot of "triangles" working for you (triangles formed by fasteners through the sheathing - whether walls or roof). The tension on the roof truss horizontal beams becomes the hero of the project, actually.
Before watching, my answer to the question in the title was, "All of them. Depending on what you are looking for from the shape and material."
As an example, it's hard to pump water anywhere using an I-beam.
While not really part of the data visualization, an awesome but rarely used part of computer interface is a three-variable slider, which is visualized as a triangle, with each point in the triangle being a different distribution between the three options.
It could be used as a data visualization for some things too, like "time spent working/sleeping/other" with every point on the triangle being a different set of these three numbers with a constant sum.
I would have tought this was common knowledge ... build a basic box ... if you start with the sides it is great top to bottom but may not stay square as it wobbles ... add a bottom and poof it goes rigid ... I learned that back when I was about 8 years old building a birdhouse for cubs ... it was a royal pain getting all the sides to stay square ... then the dad showed me the easy way ... start at the bottom and work around ... each addition adds strength ... to the last ... no more fiddling with square
Developing an intuitive sense of the effect of displacement of material from the neutral axis is a valuable design skill that can be only partially replaced by CAD and simulation software but a team's design effectiveness is significantly enhanced if both the software tools and the intuition are effectively utilised within the team.
Wow, a 15-minute video that actually kept my attention!
Sorry but looks like an "You" problem
@@ESALTEREGO No, it's a padding problem. Most 15 minute videos are 1 minute of actual useful information and 14 minutes of "Like and subscribe to my channel", "see our patreon here ...", "join us on discord...", "today's sponsor is: ...", jokes, side-tracks, history of, explaining basic concepts that should really just be a reference to another video.
@@soylentgreenb add is a thing too!
I know I’m on a good vid if I don’t start scrolling… I’m typing this with playback speed at 1.5, less than one minute in… now I gotta back up
15 minutes is all you got? Lol
I’m a software engineer who makes web apps. Why the hell am I binge watching these videos?
Another good thing the hollow sections have is that you can make composite columns with them. Helps in the workability when you pour the concrete in. Also, it has more resistance than a normal hollow section due to the interaction of the hollow section and the concrete column, meaning it can result in having even longer span of elements than with a steel section alone.
A follow up with real scenarios and what (+ why) a certain option was best would be great!
Came thinking I’d get a meme list, stayed for a bunch of engineering jargon and math I don’t understand.
9/10 stars, good video.
My opinion:
Circular hollow (but not too thin wall) for torsion and for carrying fluids (literally a pipe)
Circular solid for dynamic crankshafts (like transmission and engine shafts)
Square hollow for smallish columns
H-beam for large columns (possibly embedded into a concrete pillar)
I-beam for any type of uniaxial bending about x-axis (such as a beam supporting only weight of gravity)
I-beam for columns, if braced in the y-axis
Angles for connecting other beams together
Rectangular solid for any type of wood (this is also the only type available for wood generally)
Channels for embedding needs
T-sections are more or less outclassed by I-beams for most applications (also calculating the moment of inertia for T-sections is a huge pain in the ass)
I've worked with U Channel beams, and for their weight, they got quite good bending strength. Certeinly, a good option for longe free span structures without much torsion loads... Anyway. Nice video man.
Thanks for sharing!
@makermartin10 - How about U-Channels attached to Tubular Cores? Or Square Tubes fitted with Round Types, internally?
Adhesive Bonding, Welding (via Rosette Welds from the Square Tube in Circular Openings, not too big), or Bolting Through, to transfer and Share Loads!
such an outstanding analysis!
@9:13 those are not structural pipes but Fire Protection. the "victaulic" grooved couplings that you call "collars" are only meant to join the pipe to convey fluid not add reinforcement to the building
I am constructing a small home on 1500 squarefeet plot. Traditionally, constructions in my area is done by raising 12 RCC pillars (columns) on the plot before pouring concrete to form a flat roof. From this roof and above, residential quarters begin where each floor raised above the column is considered independent residential units. I, on the other hand, prefer a mezzanine construction on my 1500 squarefeet area. Purely for personal use. So my priorities are lightweight and economical materials versus the traditional RCC columns that need steel bars concrete mix. Would I be wrong if I prefer H or I beams instead of traditional RCC column for framing the structure to lessen the concrete use? Would it be economical and would I be able to achieve better structural strength than RCC columns?
Thank you for this interesting and informative video. Three other properties occur to me:
Crushing (eg elephant sits on a tube)
Crippling - relates to length/stiffness in and end-load situation (eg elephant sits on a platform atop a long tube)
Impact strength (eg car veers off the road and hits a structural member, or any day in a war situation)
To answer why these are not included; crushing is better known as the compressive strength and, ignoring buckling, it is directly related to the area of the section; crippling is better known as global buckling which is addressed in the video; and impact will relate to local buckling and material properties, assuming we are only using steel, then it is also addressed in the video. Have a look into global and local buckling then I’m sure you’ll have a better understanding how those concepts are related
@@WillDiggy1 Thank you, Sir,
I am an Engineer.I covered,Strength of Materials,Mechanical Systems,Engineering Design and Mechanical Technology.
Beam Shapes and Hollow Section Profiles as stated in the
video,depend on many factors.
Nowadays there are many newer materials in existence ,compared
to when I started my Higher Education and Training in Engineering.
Composites and Nano-Materials are a few.
It’s amazing how some people can take something so natural and common sensical as balance and strength of an object and complicate the Hell out of it with unnecessarily complex or obscure words, diagrams and formulae, for what should come as intuitive awareness or knowledge to others. I guess not everyone is cut out for engineering.
Hahaha cut out
I wish I had this in school. Quick and efficient concepts make long calculations way easier.
Channels and angles also deflect rotationally under bending, especially when cantilevered. They make poor beams when the load is placed perpendicular to the flanges. As one commenter notes below they walk off access to the direction of the load. Triangular shapes are actually better in bending than square shapes of equal area and, when extruded, extra material can be placed at the corners to maximize section modulus. Unintuitively, symmetry is good. Connectivity is of course horrible. I would be interested to see your analysis of solid and hollow triangular sections.
Very good point about rotational deflection under bending. In fact, we happen to be developing our next video on this very topic!
Noted on your comment about triangular sections. We'll look into this more and see if we come up with anything.
Cheers!
Neat rating scheme and animations! Keep up the great videos
Thanks!
what about a square with a cross in it?
kinda like an horizontal i and a vertical i merged together.
How does a triangular tube compare? Or a solid one? Are they viable? Or even used for that matter?
I am building a full-length (19.5 ft) pipe rack for a pickup truck. The longitudinal pipe (back bumper to front bumper) needs to be strong enough to be able to haul heavy cargo. I have posed the question to friends about what size square tubing should be used and I have received several confusing explanations about this design. Keep in mind that I have to keep it as lightweight as possible. The first method is to use a single 2x1 thin-walled square tube to run the length of the rack. The second method is to use "two" 1x1 thin-walled square tubes either welded together or bolted together in order to make a final 2x1 length. I was told that the more angles that you have on a span the stronger the span will be. The other thought is that a consistent uniform design (2x1) will be stronger. Which would you prefer and why? Thanks.
Stumbled across your video, you earned my subscription!
Thank you, and welcome aboard!
Cool video, I like your rating method! The only thing is that the transverse stiffener shown at 5:03 does not improve torsional resistance, it improves local web buckling. Torsional stiffeners would need to run down the axis of the beam closing the section for the entire length of the beam loaded with the torque. Great video otherwise!
6:27 - - *THIN PLATES BUCKLING UNDER STRESS*
6:58 - - *Rectangular + square sections can be OPTIMIZED by creating hollow sections (or tubes)*
13:00 - - How would a *hexagonal* hollow cell/member rate on this score-system?
I'm sure there's better media for today's engineering students but i would have loved this video back in the day when i was in school.
Hah, yes it would have been nice for us to know this back in school too.
Excellent video, this explains the pros/cons of structural shapes much better than conventional resources and curriculum. The school of RUclips is putting colleges in their place, they better embrace it and adapt or they'll become outdated.
Instead of surrounding rebars with concrete, how about filling hollow pipes with concrete. Or fill with resin for smaller structures like furniture. This would reduce the chance of buckling since the internal fillers are solid and resist compression.
those are called composite sections. They are in the AISC manual.
I'm doing that for a crane I'm building this weekend
Since the comparisons were based on equal cross sectional area (in other words for a given material the same weight per length) the analysis tended to obscure the strength per weight. If building something like a race car chassis where weight matters a lot, it's impossible to beat round tube. But cutting it to make joints does require special equipment and skills. You can buy jigs that use just a hand drill and hole saw, but getting the measurements and angles right takes thinking and attention. Square tube is a second place. The weight is higher for the same strength but welding joints is as easy as it gets. A handheld band saw will allow you to make just about any joint between two square tubes that you can imagine. I was surprised that he rated workability so low for square tube. But he was looking at bolted connections more than welded. It's just that among DIYers the people needed to choose different steel shapes are probably mostly people that can weld
It completely depends on what you're wanting it to do.
Nice video! I liked the side-by-side rankings of the different shapes. Another great video would be if you delved more into the bracing, connection, or other practices that improve on the relative weaknesses on each type of section.
I often see elliptical tubing used for things like motorcycle and aviation framing/support elements... in talking about wood framing, sheathing, with adhesives, seems to offer a big advantage in making a kind of 'tubular', or even, monocoque, structure, with much added stability.
Thanks for an interesting presentation, and interesting graphical/numerical scoring method(s).
I had forgotten about elliptical tubing. It seems to combine the properties of circular pipe with the properties of hollow rectangular tubes.
I first saw them being used for reducing weight on bicycle frames while increasing bend resistance in the commonly loaded direction.
It can be noted that the Double-T Precast concrete beams mentioned at @11:41 which are commonly used in parking garages and bridge decks are structurally somewhat different than simple metal t-shapes as the required included reinforcement is nearly always pre and/or post-tensioned steel rods and/or cables. this significantly increases the bending resistance of the complete part.
I have always wondered about triangular shapes like trusses. Triangles are geometrically rigid by definition. I can see them buckling unless you put in a compensating truss. Your thoughts?
Trusst in triangle
Also what about a t beam virtually a reverse triangle (3 points of contact)
I am building a hanging bar and was going to use angles for them, after watching this I will be using hollow rectangular pipes.
Thanks !!!
This is very interesting !
One of my favorite courses was "Strength of Materials".
We got into some of this but not with the depth that you included.
Great presentation! Thanks for taking the time to explain it.
one thing, which i wanted to see was price comparison - probably the most important of all, seriously.
You help us do it right the first time. Thank you.
The voice is so soothing, I would play it for children to fall asleep. But the content is very interesting.
Thank you for this great informational video. Keep up the good work. 👍
Cheers, will do!
Sir, how can I prevent cracks in non-loading partition walls due to deflected steel structural beams' interaction?
Very good video stress wise. My only real disagreement is with the workability values. Good Job!
Log cabins with almost round solid circles (flat at top and bottom if I don't recall wrong) would have been lovely to see here even if it's not a modern approach.
Curved wood was also used back in the day for certain roles, think of the wood where a branch leaves the tree or in the roots etc.
I'm no expert on that kind of things, but I'd love to learn more.
You correctly inform us that we need to select our section acording to the application. Therefore there can not be a clear winner.
You say the torsion in an I beam depends on its 'J'. If you mean 'J' as it is usually understod, IE Ix+Iy then you are wrong. It depends on its 'K' which is much less. I recomment Roarks formulae for stress and strain for a better understanding.
'U' or 'C' sections have a further disadvantage to the doubly symetric 'I' in that they have a shear centre outside of the section which can easily lead to combined bending and torsion when loaded with simple shear.
From a practical point of view, closed sections are difficult to treat against corrosion and equally difficult to inspect, unless of course you can get inside it eg the leg of an oil rig.
Hi again Emma, by J we mean the ''torsional constant J'' and not the polar moment of inertia or the summation of the moment of inertia about the x and y axes. Check out Chapter 3.10 in Mechanics of Materials by Gere, the twisting of noncircular prismatic shafts and the torsional constant are explained there. The factor K in ''Roark's formulae for stress and strain'' is the same factor that Gere calls J and is the torsional constant. In regards to the shear center, we agree that this is an important point that is worth mentioning. Maybe we can do another video only on the shear center of sections in a future video. Thanks for the good discussion as always.
@@TheEngineeringHub I am reassured. Being aware of different definitions is important, particularly when presenting forbeginners.
Glad to help.
If someone were to build a structure with square tubing but the main external framework were to be arched in long bows. How would this effect the over all structure when it is properly supported from within? Example a nearly flat dome with a 6 foot rise but a span of 88 ft span. With some supports that are truss type but others are double square tubing with a single web between them for added torsion strength to prevent downward collapse potential.
Great video! Do you have a video for which shape (or material, including wood) works best for certain spans? Thanks for your channel.
Anyone that knows what "area moment" and "section modulus" are already knows the answers to these questions. Those that don't are not being helped by throwing in words that are not familiar.
how strong is 3x5 steel angle 1/4inch thick? can I use 2 of them to sandwich 6x10 in order to increase the span? I can't use steel plates wider than 5 inches because I don't have access from both sides of the beam.
Thank you
Nice job. Clear explanations and almost no math!
Very well done. I'd be interest in a follow up video where multiple shapes are combined. adding an angle to a flat surface creating a triangle, and combining triangles to make a honeycomb.
you have to recalculate the moment of inertia to determine flexural limits.
Helpful video, thanks. I would say that workability depends a lot on the tools available for a given material and shape. Having the appropriate tools can make the workability much easier. And not having them can make anything difficult. All that is to say I would not have given workability as much weight as it is given. Or, in practice, weight it in light of the available resources.
Yeah, workability is a bit of a strange category to me.
I also don't see how I-beams are more workable than hollow rectangular tubes. If you have to trim out an I-beam, it gets pretty awkward for where to attach your stuff. But trimming out a hollow rectangular tube wouldn't be that hard IMO.
What type of materials can be used to manufacture the structure with high corrosion resistance and strength also considering the costs of the materials
Excellent presentation. That plots are really helpful and easy to understand the differences between steel sections.
Glad you enjoyed it!
Where was all this when I was in school, great job
Excellent overview. Like the rating system. I weld pipe. Don't like the unsafe person cutting steel at 10:33. No glove, no cutting wheel guard is a bad idea.
Fair video, i would have liked in the conclusion to highlight framing outside of wooden construction with the correct fastening and alignment many flaws in each element can be reduced
There are many structural shapes because different loads required difference design considerations. No one is BEST for all things, but each has it's place. There are no winners or losers.
Oftentimes, these shapes can be used in conjunction with one another to strengthen areas in which one shape is weak. Thank you for sharing this video.
Excellent video- teaches you how to think about structural shapes, not what to think.
If you're clocking a burglar over the head with a steel member, I've found just about any of these geometries to suffice.
Paintability (e.g. corrosion protection/inspection) is a big disadvantage to closed, hollow sections. Could be baked into the Workability metric, but could be a game-changer alone.
On the other hand, the structure could be designed so that the inside is sealed up so it doesn’t matter. This is most likely the case anyways when the ends need to be welded up.
I have never studied this before, this been in my mind for long time
Thank you for makign this video, really helpful for some engineering students who ae going to take the final exam in less than 2 weeks
Thanks for the video! Have been interested in this topic but didn’t know where to start.
Glad it was helpful!
2:00 "I.E. Stiffness" I see what you did there
hahhaha finally someone picked up on that !! It's been a year
I have a question that I have not been able to find a clear answer for. Can you help? For two examples of the same material, length, and outer measurement (not material area), which is stronger in bending resistance: an i-beam, or a solid square/rectangle? This is if the greatest height and width of the i-beam are the same as the greatest height and width of the solid square or rectangle beam. Does an i-beam gain any strength properties that the solid beam of equal size does not have? I understand that weight, cost, workability and such will be disadvantaged on the solid part. Help!
If I understand your question right, you're asking if an I-beam is stronger than a solid rectangle of the same size, right? The solid rectangle will always be stronger simply because there is so much more material.
Example: 4" tall x 2" wide I-beam made out of 1/2" steel will always be weaker than a solid 4" tall x 2" wide steel rectangle. The advantage of the I-beam is that it is a much more efficient use of material. With the material of a solid 4"x2" rectangle, you could make something like an 10"x5" I-beam, which would be much stronger.
In that analysis you are neglecting the self weight of the structural member. The wide flange beam is stronger due to supporting less self weight. Take examples of both and extend them to 6,000 ft. horizontally and create a fixed end on one side and no connection on the other. Apply the self weight plus a 100 pound dead load at 4,000 ft. away from the fixed connection. What is the deflection of each at the unsupported end?
Answer: It depends on the application.
well explained, understandable
Have any of you any practical experience installing HSS column over a h-beam column no I seen one comment dude said he was going to use pipe obviously has never made a column out of pipe if you had 10 HSS 12 x 12 by 5/8 on one side and 10 on the other side with a space of 10ft between sides and 8 ft between columns and a top of beam height of 10 ft and you built comparable structures The h-beam Columns would have less lateral movement when you were walking across the structure it's often fun to take Engineers on a deck when they don't have a clue and see the reaction on their face when they stand still and feel someone walk across a structure that has HSS columns and that would be multiple X bracing to combat thing down so the problem with that is on a boat dock when they have the boats at the bottom and the deck on the top they engineer a lower structure made of rock or fuel to get to the sheer out of the building
Very clear information explained. Thanks
when bending angle over a long span, it's interesting because it will dive or climb in the axis that you aren't bending and will have to compensate for
Yes, you are correct there. In fact, we happen to be developing our next video on this very topic!
as a Civil Engineer i would say your analysis was good.
An illiterate coward claiming to be an engineer?
I would say it is a very well informed purely scholarly approach with some notable gaps in real world knowledge and experience. For example the double T bridge sections he described. Those are generally post tensioned with cables for the strength of the structure rather than relying on rebar that is only contained in each individual section and doesn’t transfer load. He also ignored how the shapes he discussed are used as part of a larger system and the loading in each member is influenced by other members. And the shapes he deems less worthy are great at transferring smaller loads between more larger examples of ideal shapes.
Reinforcing steel bars must not bee to close to the surface, because with the heat they expand and crack the concrete and rust.
Metal I beam or wooden frame for supporting 3 to 4 shipping containers?
Good overview!!! An error at 5:02: Those stiffeners will help nothing against torsion!!! On should add them on the sides over the length of the I-beam (to give it a tube shape).
and yet a huge amount of frames (equipment bases and adjunct support n mounting) and small structures are fabricated with angle iron in the US
the idea of using L sections to create a T Z or H section by simply riveting or bolting them together has been the cause of several disasters as they do not have the same strength as a proper H T or Z section ether extruded or full pen welded and should be noted by designers
Next you're going to try and tell us that hanging slabs of concrete such as hotel walkways from compound threaded rod assemblies or traffic tunnel ceilings from rods questionably glued into overhead concrete could result in fatalities...
The nerve if this person!
@@MonkeyJedi99 luckily we live in a world where such a thing would never happen
Still trying to find the answer:
In my area, if you have a two story (wood framed) house, you need at least 2x6 -24inch on center studs. Can you use 4x4 -24inch on center instead? Does that have comparable strength for framing?
Wish I had videos like this when I was training to be an engineer 45 years ago.
So is a T peice like and inverted triangle (3 points of contact ?)
circular,angle,t beam and rectangular which can support max load in bending.. plzz ans sir
Thanks for this video. I found out why something that I knew was true by intuition is that way.
Great one.
When you position material furthest from the centre, and then make a cellular character within the outer wall, with cross ties to reduce buckling risk, congratulations, you have invented a stem of grass, or bamboo.
9:41 Well I think the circular hollow section will perform better in bending as well than the solid one because of higher area moment.
I am stricken by the extent of variety in shapes chosen by the state highway agencies in various American states for the identical task: posts for small highway signage. Right off the top of my head, I can think of various states that use perforated hat channel, perforated square hollow, circular hollow, and square solid (wood). Surely each has advantages and disadvantages, but one would think that more consensus would have developed as to which is the best value over the long term.
What about tension and compression? And the planes of tension/compression. T shape, round, square, and angle are used alot in truss systems. Analysts and design was fun, i became to see the formulas in the 3d spaces.
I was going to make a very similar comment. Angles are used in tension on the bottom cord of many flat roof trusses. And welded connections can not be ignored when discussing workability of structural steel.
As another commenter pointed out, many times the decision comes down to cold hard cash. What is the cheapest way to meet the requirements without exceeding them. Many times designers create impossible conditions that can’t be fabricated in the real world. So I am not sure how much I trust them to care about what the constructors go through.
I'm curious how a hollow circular beam internally connected with a Y-shaped beam would perform. The 120 degrees in a Y-shaped beam would normally make it difficult to work with if by itself, but would fit perfectly in a circle, supporting it against bending by being resistant in the same way I-beams are, and likewise the circle would support it against torsion which it'd otherwise be weak against. Of course having such a complex structure would reduce workability a lot, but if that wasn't a factor, would this come close to the optimal shape for strength proportional to area?
Several years ago at work, we needed to install some bollards. My suggestion was to slip a square, I, or triangle tube into a circular tube or a circular tube into a square tube to increase bend resistance. What are your thoughts on combining shapes looking just at the factor of bend strength?
Concrete poured into a circular tube
Bollards are designed to stop smart people and slow down idiots. If bollards were made stronger the risk of injury would increase. Cars have crumple zones for a reason.
Oh and a single thin wall pile filled with concrete is cheaper than the fancy strong design.
@@beerious8392 That was what we replaced. The pipe (6" diameter) bends causing the concrete to fracture then the pipe bends too easily.
Sorry, extremely valuable and sensitive equipment that MUST work at all times. After getting called out a few times at 2AM when it was raining sideways to repair the damage caused by some dimwitted moron that couldn't control his vehicle - I really don't care HOW damaged the vehicle OR injured the dimwitted retard gets.
I am using a channel post to attach a satellite to. It has all of the strengths i need except one vital one I didn't account for or anticipate. The torsion, if the wind blows slightly, the dish will sway nonstop because the post is twisting. What can I do to reinforce and prevent the dish sway on the u channel post which i believe is the source of the weakness?
Not an engineer so only advice I have is bolt another u channel to the first and make it then become an H beam.
Nice. Any idea where I would find out the unsupported span of an I beam ? I want to build a 3 story concrete house using I-beams to support floor joists.
You got a like how some of this engineered wood products mimic the cross-section of an I-beam. You have two two by fours with a groove cut in them with a jointer of plywood. The end up being lighter than a typical Lumber member but you have a bit more convenience on putting holes through for plumbing and electrical for example
Dunno if applies to motorctcle frames too or not?
would 80/20 extruded aluminium be consididered closer to channel or i-beam? just curious how to look at 80/20
Hello Dr Renard,
The 80/20 brand products are very interesting. One way to look at such products is to reduce them to the simple shapes which their sections generally contain. For example, their smaller T-Slotted profiles (25mm) start to include more enclosed area which makes them better at resisting torsional forces and starts to make them more comparable to rectangular tubes. All of the 80/20 sections have advantages of channels in terms of workability due the the exposed slots on each side for positive connectivity, which is what makes them particularly unique.
Cheers and thanks for the comment!
Link for reference:
8020.net/framing-options/t-slotted-profiles.html
@@TheEngineeringHub thanks for the reply. It is a very complex design and so I made some suggestions of what I could extrapolate based off the video. I am actually glad you could actually give feedback on this as not particularly my field of expertise and I have really been looking into 80/20 (and off brand extruded t-slot aluminium but used more for recognition). Thanks for expanding my knowledge base and giving me insight into how something not covered could be used, even just based off of structural examples you've already made. So pretty much I beam with more workability. Though the mention of torsion, I remember some of the bigger ones have kinda hollow center too so is partially a tube build as well. Would explain why it is a pretty useable structural material that's useable in hobby and professional development. Yet again, thanks for the actual feedback on my question.
So ... would an I beam be stronger as a fence corner than a pipe? Lets narrow it down and say they are both steel, with dimensions giving them an equal weight of steel. Yes might seem to be the obvious answer, but the reason I ask is because I beams are typically used to span horizontal distances, not to be set vertically as a post.
I read somewhere that the strongest was one that is rarely seen, as it would be very vexing to manufacture. The structure is a round post made up of wedges. From the top it would look like a pie cut into equal slices. Could this be true?