A diaphragm is a structural system that transmits lateral forces to shear walls without exceeding deflection, causing distress to any vertical element. It is properly designed and balanced to balance internal forces within the truss members. A girder truss is a type of truss consisting of two or more simple trusses connected by a central support element known as a girder. The girder runs along the bottom chords of the simple trusses and transfers lateral loads to the foundation.
Metal Plate Connected Wood Trusses are typically designed to bear directly on top of a wall or beam, or to frame into the side of a Girder Truss. If the element ends were to be welded or bolted rather than simply pinned, the end connection could transmit transverse forces and bending moments into the element. This structure would then be a simple truss.
Structural models employed by grid analyses do not directly model the top flange lateral trusses. Analytical methods for determining top lateral truss forces are discussed. The girder CD takes reactions from the beams and transmits loads through its bending to the columns. The girders and columns form the rigid frame system to support. Under gravity loads, the top and bottom chords of the truss provide compression and tension resistance, while the bracing resists shear loads.
A truss is a structural system made entirely of axially loaded members connected at pin joints or nodes. Generally, truss members are assumed to be joined together to transfer only axial forces and not moments and shears from one member to the adjacent. Shear force transfer, also known as shear transfer, is the transfer of lateral force to shear walls and lateral frames.
📹 The Secret to the Truss Strength!
Truss structures are more common than you think. But why do we use them? Beams seem to work fine right, well yes but there is a …
How do trusses transfer loads?
Roof trusses are subject to two axial forces: compression and tension. The loads are mainly applied to the joints, causing compression in the upper part of the truss, including diagonal struts and rafters. Secondary stresses are minor and counteracted by certain elements of truss design. Compression occurs when material particles are pushed together, and in roof trusses, the weight of the roof exerts a downward force on the upper members, causing compression in the top chord. The hardness of the timber in Oak Trusses reduces the effect of compression, enhancing the stability of the structure.
How do trusses distribute weight?
Truss design is a crucial aspect of structural engineering, where loads are distributed through web members to direct forces towards support points at the ends of the truss. This allows the truss to span a larger distance without the need for intermediate supports. Load distribution is influenced by various factors such as load type and positioning, truss geometry, and member connections. Even slight changes can alter the load path, impacting the truss’s ability to bear the load. Engineers often use computational methods to analyze load distribution, ensuring the design is robust and reliable.
Safe load-bearing capacities in truss design are based on understanding the structural behaviors of materials and the forces they will encounter. Wood is a popular material for trusses due to its strength-to-weight ratio and ease of use. Its natural flexibility and resilience make it a reliable material for trusses, provided it is used correctly and sourced from high-quality providers like local suppliers in the Ramona, CA community.
What is the difference between a girder truss and a regular truss?
Common trusses are symmetrical in design, featuring a pitch and heel on both sides and a peak at the center. In contrast, girder trusses are specifically engineered to accommodate additional roof loads.
How does a girder truss work?
Girder trusses are secondary roof supports used in the construction of irregularly shaped buildings. They are designed to carry higher loads than other trusses in the same construction, with additional plates and posts providing added strength against bending and shear. The design is long and straight, with a top chord and bottom chord, and diagonal and vertical webs separating them. The top chord is in compression, while the bottom chord is in tension.
The webs can be in tension or compression depending on their direction. Timber girder trusses are ideal for large structures and are visually appealing when combined with steel joinery. They are built to be extremely robust and stiff, making them ideal for supporting other structural elements in the frame.
What are the advantages of a girder truss?
Girder trusses are more rigid and offer strength compared to girder beams, but they are shallower, providing slightly better clearance height for machinery. Shed project ideas showcase the use of girder beams and trusses, with a gallery of shed project examples to learn more about their applications. Both types of structures are suitable for various applications, including construction and maintenance.
How do trusses distribute tension and compression forces?
The addition of trusses to bridges serves to augment their overall thickness. This is achieved by the distribution of stresses back to the foundations through the loading of individual beams in triangular patterns. This configuration ensures the maintenance of load in both tension and compression.
Are trusses stronger than beams?
Truss design for roofs offers better performance in terms of resistance and stiffness compared to an I beam, especially for long spans and heavy loads. This advantage is more significant if the truss’s height is not limited by structural efficiency criteria. However, truss fabrication is generally more time-consuming than an I beam, despite modern fabrication equipment being efficient. The balance between minimum weight and cost depends on factors like fabrication factory equipment, local manufacturing costs, and steel unit costs.
Trusses are generally an economical solution for spans over 20 meters. An advantage of truss design is that ducts and pipes for building services can be installed through the truss web, allowing service integration.
How are forces transferred in a truss design?
A truss bridge is a load-bearing structure that uses vertical, horizontal, and diagonal members to support weight from above and direct it to the foundation below. The horizontal members, also known as chords, help reinforce the bridge by transferring compression and tension forces. The trusses provide the structure with the strength needed to handle the load, often with less raw materials and weight than a beam bridge.
On the other hand, a beam bridge is a simple structural form with an abutment or pier at each end. It contains a set of horizontal beams, typically I-beams, connected to abutments at each end of the structure. During load transfer, forces from the walking deck are transferred down the beams and to the abutments supported by the ground. Both truss and beam pedestrian bridges are excellent options for trails, parks, and community spaces.
Do trusses eliminate load bearing walls?
Floor joists that frame into an exterior wall need to be supported by a bearing wall or beam at the opposite end. The joist span depends on the wood species/grade, applied load, and joist depth/spacing. A wall within this range is more likely to be bearing than a wall a few feet away. Roof trusses can span longer distances than joists, so a gable roof may not require an interior bearing wall for support.
When removing a bearing wall in a residential home, a beam or lintel is required to replace the wall and carry the load to each side of the opening. A beam can be dropped and have floor joists sit on top of it, or the beam can be in the same plane as the joists, having the joists frame into the side of the beam. This ensures that the interior walls may not support the weight of the roof structure and snow.
How do trusses connect to walls?
Toenails can be employed for the repair of damaged components, while connectors that have been specifically designed for this purpose are readily available.
What is the load transfer mechanism of a roof truss?
A portal frame structure transfers roof loads to the foundation using secondary beams and primary beams. The purlins are bolted to columns via a welded end plate, transferring the load to the foundations. The columns can be rigid or braced in a steel portal frame to resist gravity and lateral loads. The load path is a crucial component of building design, ensuring safe and efficient transfer of structure weight from the roof to the foundation. Proper load path mechanisms can resist gravity, lateral loads, and environmental factors, ensuring the safety and longevity of the structure.
📹 Understanding and Analysing Trusses
In this video we’ll take a detailed look at trusses. Trusses are structures made of up slender members, connected at joints which …
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 article, regards.
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 article, always something new to learn. Thank you.
I have been a pressed metal pated wood truss designer (and also engineered wood) for around 30 years now. This was a good article. 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.
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.
I love the models and since you clearly state the drawbacks and simplifications, I am super fine with crude models (although YOUR woodworking skills still esceed mine BY FAR, obviously 🙂). And remember, whe can’t all be ‘Practical Engineering’ on the first tries 😉 Thanks for putting all the effort and work in these articles, much appreciated and future engineer generations will thank you 🥳
Since you have connected loading string twice to your bridge you created shear and twist. The shear failure is evident, 2 ropes cut you bridge. Put some metal clip first on the bridge then connect rope to the clip to get a better failure modes. To eliminate sideway force use pulleys at the edge of a table and make sure that the structure is centered
The truss is amazing in its visual simplicity and elegance, which hides its technical complexity. Many years ago I built a small truss bridge from Lego Technic. It spanned about 5 feet, and had almost zero deflection.. So I put a question to myself: how far COULD it span.. What is the physical limitations of Lego in a truss system.. Long story short, I am the designer and builder of the world’s second longest and fully self-supporting Golden Gate Bridge.. It is a suspension bridge, of course, but the deck sections are trusses, the mid span of the bridge is an impressive 8 metres (26 feet) with a total length of over 13 metres (46 feet).. as long as a semi trailer truck. It’s a 1:160 scale replica and has been exhibited and a number of Lego expos here in Australia over the years.. It stuns all who see it, children and adults alike. I’d love to be able to take it to California and set it up on the hill in Marin County overlooking the real bridge..
The Smithfield Street Bridge is 140 years old. The Bridge is in Pittsburgh. The interesting aspect of the Bridge is the small piece of steel as part of the tresses. Also if you look at the parts of steel with “Carnegie Steel”. Another interesting fact is that it a suspension Bridge without cables It has an oval shaped suspension. The Smithfield Street Bridge replaced a Bridge built by Roebling. Roebling’s Bridge was tore down.
Great demo; we can also so see that the bottom cord failed in tension… this demo is well balanced (picture/formula) linear tension-compression vs bending forces against deflection is a great introduction. There is great thinking and a lot of preparation for this very short fun Eng. lesson. 👍 thank you!
It really had potential until the experiment part. it would appear that you did not take it seriously. placing the place of interaction at one small point, pulling at an angle instead of straight down, shoddy construction. this article has potential for greatness, but please do a remake including one or two better models. I suggest using a system of spreading the weight over the span until it collapses.
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!
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.
Great article. The humble bicycle frame is also a perfect truss structure. The difficulty comes when other forces intervene such as the bending force on the head tube when you apply the front brake. Carbon frame engineers have learned a lot in recent years about laying the carbon mat is such a way that maximum stiffness is achieved with minimum weight and they have also learned how to vary the carbon layup so as to allow controlled flex to prevent an over-stiff ride.
When building with lumber, to support across a horizontal span. It’s much better to put the 2×4’s on their side. The wood is much better at supporting downward 👇🏻 pressure when it’s in that position rather than flat because it has much more ability to bend due to downward 👇🏻 pressure across horizontal spans.
Another way to look at how a truss works is that it disperses the load across a wider two dimensional plane whereas a beam is basically one dimensional so the load becomes more focused and less force is needed to compromise it. The longer the beam the more one dimensional it becomes. You can achieve the same strength as a truss with a solid plane attached to a boxed frame but trusses accomplish this with less material and save weight.
One very important aspect of trusses which the common person is not aware off is weight reduction. There comes a point where the size of a solid beam required for a particular span makes it heavier than the load they have to support. Since trusses are more complex than solid beams, for short spans solid beams are preferred.
15% may have been 20-40%had the simulated abutment not yealded first putting the twisting moment into the truss causing it to fail. Thanks for the memories. 8th grade in a class called Exploring Technology, we each built and tested a bridge to failure. 10′ of 1/2″×1/8″ pine, a 12×4″ card stock as decking, and ample wood glue. 1st place got 150lbs I got 110lbs for 2nd place. Lowest was 10lbs for essentially a beam deck bridge,( minimal effort, no super or sub structure) my failure was down to delamination of the wood grain where the super structure notched into the main horizontal member on top of the abutment . Had we been allowed more stick out, on top of the abutment, the delam would have been prevented. My bridge had a minimal failure 1 cracked member. 1st place was a catastrophic failure where it shattered into 100’s of pices my trophy was my bridge, his was a pile of toothpicks.
You opened the article with the collapsed Tretten bridge. In the investigation they talked a lot about bolts possibly failing, the wood breaking etc. But I said from day one : that is NOT even a truss bridge!! All the diagonal truss beams in that bridge was LEANING THE SAME WAY. now Im not an engineer, but surely that will PROPAGATE the stress to more parts of the bridge, an not, as it should distribute the load
Dumb question: At 0:37, it is stated that the top of the beam is under compression. However, it is clearly ELONGATED relative to its unloaded state – It is an arc rather than a straight line. Elongation implies stretching. My question is: ‘Why then isn’t it under TENSION (albeit less tension than the bottom part which is even more elongated) ?
AP Physics class in high school back in 1974 we had a contest to build a bridge with a fixed amount of material to span, I think a 50cm gap between two tables and then load it to failure. Beam bridges did poorly. Truss bridges did better. The one that “won” was 4 elongated pillars going from points on the tables up to a center point with a few cross braces to take care of torsional load as the thing twisted as weights were suspended from it. Unfortunately it wasn’t a fair contest as we found out that the guy who won had cheated (kind of.) The requirement was to build the thing out of a given number of sucker sticks and “white glue.” He had used “white” epoxy glue and not the standard “white glue” wood glue.
I agree that a central principle of a truss is that all intersecting beams must intersect at a common point in order to prevent inducing a moment. However, even if this condition is met, when the beams are attached using gusset plates and lots of pins, simple geometry implies that there MUST BE some angular deflection of the beams in order for the aggregate deflection/bending of the bridge to occur. As a consequence, the pins furthest from the intersection point will experience the greatest shear loads. There have been bridge failures caused by failure of pinned/gusseted joints.
4:43 – I built a model of the Florida concrete truss pedestrian bridge that fell down, replacing the tension elements with chains to demonstrate which elements are tension (chains) or compression (sticks). I think there is no way to add a photo of it here? One factor, given a uniform linear load on the truss (vehicle traffic but mostly just the weight of the bridge itself), is that the vertical elements on the ends must support nearly the entire weight, while those halfway to the middle support only the weight of the middle half, so the end elements must be stronger and heavier. This is not true of the horizontal elements, where (in the article drawing) the middle tension element supports the full tension of the end horizontal elements, PLUS part of the tension of the vertical tension elements, PLUS part of the compression of the middle two vertical elements, so it is the middle horizontal elements that must be stronger than those on the ends! A beam could be designed for similar factors, where the thickness/strength of the flanges and web are varied along the beam length for maximum strength to weight ratio.
I think if you are testing bridge strength, and your moment of weight is coming from an angle, it might make sense to have the bridge sit at the same angle? I guess it depends on if the sideways force is desirable. Otherwise, maybe balancing between two chairs might be better, if you don’t have two equal height tables. This was fun to watch either way.
I do really want to know about what we need to know to calculate curved reinforced concrete shells. Like, a rectangular pilar and rectangular beam is already a bit hard to give dimentions and to chose the steel. A lot of rules and things like that. What we nee to know to advance to curved or nor linear shapes?
I found this article very informative, I have passion in engineering but never took up the subject. I live near an interesting bridge and would enjoy your take on the skills used in its construction. It is the Ironbridge in Shropshire UK, it is said to be the first bridge in the world to used iron as it main material. Before this bridge most were built using stone or timber. If you are interested there are many site that show it constitution methods. Have great Christmas or should I say holidays sorry don’t what the PC term is. kind regards.
the oakland to san francisco. was built to handle freight and passenger rail cars pulled by stem locos. this was done on the lower deck, and the sf part is and still is a suspension. sad the steel oakland side was taken down and replaced with a weaker concert structure. no trains have been on this bridge in a very long time.
The results of experiment is not occurate because some of the load are transferred to both sides of the table through ropes. It’s better to put holes on the center of the table so that the rope is free. Another thing is, it should be two parallel trusses and the apply the load on top of the trusses so that it will equally distributed the load to each member of the truss.
made one for the ” Gifted Program” in Grade school, limited materials, A package of 3/16″ 18″ long square profile Wooden Sticks, a Bottle of Wood Glue. The object was to hold Weight of over 10 pounds My Hybrid Trussle Span Bridge using Woven Structure ” similar to Japanese bridge’s” accomplished 80 Pounds of Stress using NO Glue. The key was that Every Stick was beyond it’s Normal rest tensile State of Resistance..and Woven into alternative max Potential of Energy. A Bow at Rest vrs a Bow Potential Kinetic Transfer of Molecular angular attenuation.
The Patullo Bridge in Vancouver BC has a commuter train – ‘The Sky Train’ – running on it. In 1990, when it opened, it was the world’s longest transit span and the world’s only cable-stayed bridge designed solely for carrying rapid transit. It held its distinction until 2019 when it was surpassed by the Egongyan Rail Transit Bridge in Chongqing, China.
TEH You asked about sending new bridges. or interesting bridges. I say several combination steal Arch with suspension of a truss. So i thought about the arch then the Arch in St. Luis MO. Why well its shape is from taking a fine chain and hanging it upside down letting the chain form the reverse arch with same ratios of width to height. Is that still the strongest in cases of smaller Arches. Obvious you would not want the higdth of the St. Louis Arch.
Thank you for the article which gave me an idea about truss bridges. Please correct me, if I mention that the important supports are the piers (vertical columns) between the truss. Should they not take the major load of the movement of traffic moving? They should be able to prevent the bending of the truss.
There looked to be less material in your beam bridge than your truss. As weight is a good indication of the quantity of material used, were they equal weights? They were nowhere near the same depth. Yes friction in your strings interfered. Why not bridge between two tables? Then no friction in the ropes. In your assesment of a truss you consider the deck separately. Like it or not the deck is part of the bridge. In a plate girder bridge the deck can/is part of the structure and thus removes the inefficientcy of requiring two structures. It is a fact that a plate girder of the same depth as a truss is much stiffer than the truss. Assumming the truss is not rigid (infinite stiffness!) then the horrizontal members, as a whole, adopt a curvature. Thus there is bending. Just as there is in the flange of a plate girder bridge. Unfortunately the bending is redistributed towards the joints. In the uk there were only three (so I read) examples of railway suspension bridges ever built, the most notable being that on the GWR at Chepstow which was demolished and replaced by a plate girder bridge in the 1960s because of the weight limit and the 10mph speed limit. Disregarding masonry bridges, I’m struggling to think of a non plate girder bridge on the railways here though there are some (Stevenson’s box girder Brittania and Conway bridges obvious exceptions). There are many reasons to chose a truss or a plate girder. Quantity of material, number of rivets (or feet of weld), ease of manufacture and errection.
Thank you. You illustrated it, you implied it, but you did not say it. The secret to the integrity of a truss, scaffold or any such structure involves no math or calculation. More often than not, it is the cause of failure of scaffolds That is, the members must form True Triangles. Not right triangles necessarily, or any particular type. Just 3 “pointed” triangles.
I’m a first year engineering student, and I just finished a course where this exact topic was covered, only it wasn’t covered nearly as well. I could do the math before I watched this, but this article gave me an actual intuitive understanding of the subject. If I could have changed anything, it would’ve been to find this article before my final exam.
@TheEfficientEngineer, you providing such HQ content not just graphically but conceptually that too with so lesser views and subs…really MOTIVATES ME TO WORK HARD without worrying about others appreciating .I know my comment won’t affact you in slightest but still couldn’t stop myself. #RESPECT FROM INDIA
Thank you for this article. You just explained to me in 20 minutes what my professor has not been able to in 2 months. It’s so simple. I didn’t realize it. I will sleep better tonight actually understanding the hw I just suffered through this evening. Wow, and to think, I hated my statics class. It’s actually quite fascinating. I am so perusal all of your articles for next semester. Dynamics and strength of materials just became a lot less dreadful!! You’re awesome. If I could, I would ‘like’ this article 1,000 times.
you are brilliant mate .Tomorrow is my sem sem exam, dont know how i was able to find this website but surely it helped me a lot.The way my professors teach is quite boring I wish my professors explained the concepts the way you did. All i have to say is post more articles related to mechanical engineering for my future semesters.
I am a graduate of Civil Engg in 1979 and my professors were still primitive on the way of teaching. The calculators have been invented introduced late during my studies. My professors did not explained to us in detail about the design of trusses. It was up to us to dig out . Your website is very much helpful in understanding the structural analysis of truss. This is a huge help for Engg students and also those who graduated in a less college or university of less standard in teaching . Your website is amazing.
We need more websites and articles like this. Thank you very much for taking the time and making such articles. I wish I had such resources when I was in college. I want more of such articles from your side but understand that it takes time to do research, do all graphics work and put together a article, and rushing will only lead to a decrease in quality. I want your articles to reach out to all the students.
It is very sad that there are so many articles in YouTube which are gaining wasteful views. But seriously this website and its articles must be have views and subscribers in millions. Really very valuable for all engineers. Thank you sir from bottom of my heart your articles always clear my concepts. Respect your hardwork and efforts. Love from engineer. 🖤
Your website is exceptional. I wish I could go back in time to when I got my BSME and have these articles as introductions to all my classes. The quality, clarity, accuracy, and delivery are legitimately better than what you would often get in university courses back when I attended. Thank you for all you do. You’ve probably helped more students understand these concepts than you could imagine.
Not sure why I had to take Statics as an EE major, but I ended up enjoying the class. The professor was one of the most helpful teachers I ever had. He took the time after class to help people understand, which for some reason ticked of the chair of the Civil Engineering department. He was let go literally because too many people passed his class. Great article!
Please correct me if I’m wrong here… According to your complete definition at the beginning, a roof truss isn’t actually a truss, its a frame. A simple roof truss carries side loads (snow or a bunch of kids with slingshots) directly on two of its members which means it isn’t a truss… No? And… Thanks for all the awesome articles!
Not an engineer at all, unless you count building shit using lego and wood sticks, but this has me fascinated. I was able to understand the concepts even though I don’t understand how they apply to a real world situation (like, I get how a truss joint has 10kN but how would that translate into building it) but I dig that sorta knowledge, the theory of how stuff works and why. Now…I just need to find a reason to build a truss.
What I would have given in my youth for that Trigonometry Recap! That is about a week (maybe a semester) of pounding my head illustrated/displayed for a few seconds (that I could watch/understand instantly). Back in the day it was a noisy chalkboard, dumpy old teacher, triangles and forced imagination/concentration (with the blond babe wearing a tight sweater sitting in front of me for a lovely much needed distraction).
I think its a good attempt for young practioners to understand theoretical concept, But some explanation is wrong about Pratt truss at 15:57 sec of this article which as follows Vertical members are in compression as per narrator but loading applied would generate tension in Vertical member. So change the load path to make yu explanation correct.
Sir, I think I’ve found a miscalculation here, at exactly 8:12 you made the two horizontal force acting at point B as postive, but it should be represented as negative to left horizontal force and postive to the right horizontal force, so they both would cancel out each other and the sum of horizontal forces at point B is equal to zero, correct me if iam wrong thank you sir
Very nice article! Keep up the great work! I am curious, what are you using to produce these high quality animations? I tried to explain tension and compression in members of a truss by creating a scaled model of a truss in my recent article (youtube.com/watch?v=C3iPgAosAl8) but its quality and clarity is nowhere near that of your articles.
It’s a amazing article, i would like to thank your website for making this possible… I studied mechanical engineering in Spanish, them i learn english and this entire chanel allows me go over the career and learn the English vocabulary at the same time. Many topics are better explained than my teachers did which is amazing..
AT 6:18 “take the moment at C” gives you an equation that Mc = Fa(d) + -Fe(d) = 0, but doesn’t actually resolve anything. You should actually take the moment at the Pinned support (A), to find the reaction force at the roller joint (E). Thus Ma = -20(1d) + Fe (2d)= 0, then Fe = 20 x 1d / 2d = 10kN. Then do sum of the forces in Y to resolve Reaction Fa.
Love the vid, I’m just having one slight issue. It is said that trusses only can carry joint loads but that is rarely the case in reality right? I mean for example one of the roof trusses pictured in the article will have a linear snowload acting on the “outer” members. If one would want to calculate the forces acting in each member would one multiply the linear load with the number of meters between each joint to combine it into a point load? In reality the members will not only have tension or compression forces but rather a moment and shear forces aswell. Is it corret to assume that these forces doesn’t exist?
Hey man where were you back in 2014 when I started my bachelor of engineering degree?😅 Literally just discovered your website today. I swear I could have had more free time on my hands for the pub while I was still studying if you were making articles back then haha. Your articles are awesome to watch, keeps me in touch with the basics as a mechanical engineer now almost 8 years later since I graduated. Always great to revisit the basics and freshen up on forgotten concepts. Thanks a bunch man.
Heidi, K-Wheel Icee Respect with All Wheel Drive from Brooklyn Ahab Floors… jus’ work the VA, honey, and you’ll find my bum beard, there… but, we met, in New York, over rabbit sauce, with the Rebbe on the landing, back in 1978… in Jenny duplex, or near it… I was 4 with your brass-looking buckle pension, you had a brown check book, we all knew an ‘anthony’, a ‘tony, or a ‘monaco cherry’… I was already ‘Brown University Math Club’ and invented the ‘Polo Math Car Hatchback’@1979.tur.n.pik
note 4: angles (stability) of basic triangular truss only depends on the length of each member. other shapes may not. so, how do we prevent elastic deformation (past yield strength of ductile material) or rupture (*somewhere past tensile strength of brittle material) (and thus “improve” stability)? probably with internal force analysis.
I have a question: If you get a negative result for the force on a member, doesn’t that mean you got the direction wrong and need to flip it? For example, on member AB you got a negative result. You drew that member in tension, when in reality it is actually in compression since you got a negative result. Or am i missing something?
When I was 17 in high school I wanted to take the author of my trig book behind the gym building and pinch his head off. But no, “…someday you’ll have a use for trig” I was told. Quite so! In retirement I’ve used trig to make little decorative doo dads out of wooden popsicle sticks. I also make “for sale” signs that look a little like gallows for midgets but still using trig principles.
00:00 Trusses are rigid structures made up of straight members used for creating strong and efficient structures. 02:28 Trusses are planar structures that can be analyzed as two-dimensional structures. 04:43 Calculating reaction forces and unknown forces in a truss 06:57 Calculating forces and identifying zero force members in trusses. 09:28 Identifying zero force members in trusses 11:35 Method of Sections is used to find internal forces in specific members of a truss 13:38 We can calculate internal forces in a truss using equilibrium equations 15:38 Different types of trusses have varying levels of cost effectiveness and efficiency.
i honestly wish i had found this article when i had to solve truss forces in a high school engineering class. My teacher didn’t give any explanations (in fact, he was confused by the problems). I spent many hours after school trying to figure out how to calculate the forces. I was also doing theater at the time, so i didn’t have much free time.
While chords of a Truss are analyzed and assumed as meeting and terminating at panel points, in reality chords are fabricated continuous thru a panel joints and splices may be located somewhere between panel points to take advantage of available commercial lengths simplify erection and not crowd the panels with joint connectors. Due to this continuity I take it that design must take advantage of the available axial stress from chords of adjoining panels to minimize joint connectors. Am I correct?
I really like your animations, however, imho your spoken language could be improved to better match translation into mathematics. When I have finished a paper on a methodology for applied mathematics, I’ll try to connect to you. I hope you don’t get that wrong, but as an applied mathematician I see my self as a tool maker, trying to “hide” most complexity in well selected theorems, for which the engineer/scientist does not need understand the proof, but can use it as a simple law of reality. Maybe you are interested in an cooperation …
Would the top and bottom chords being one solid member end to end make a difference? In the Fink roof truss diagram the pin joint shows chords as being segmented rather than one solid member. I built trusses years ago in the early 80’s along with running the component saw cutting the webbing and chords.
I shoulda been a mechanical engineer. This stuff may be mundane to some but the application of physics here is absolutely fascinating. The only thing not really covered here is how to take into account the truss’s self-load, which is kind of important when building bridges or towers but then that is a much more complicated topic. It also seems to me that wrt the zero load members, if they are there to prevent buckling, then they are there to counter a bending moment and thus not zero load. Just zero wrt to the ideal truss composed of members of infinite strength.
The wrong engineering facet! One assumes due to triangulation that trusses are the best answer for bridges, I beg to differ! I was once given a challenge to construct a bridge out of paper, sellotape and string. One chap did an engineering bridge based upon the truss methodology, whilst I used a totally different concept. I can only add that my concept trounced the engineered bridge!
excellent post my pleasure if u can make more om live load dead load impact load on bridge, also plz explain how harmonic oscillation create problem in structure, example passing mach on bridge march has to lift their foot move small step not by force as usual doing march past on bridge, one more thing plz explain failure of Tacoma bridge, how impact load made equilibrium on all member of bridge, many thanks for your post, i am armature person,
For me and I do not mind showing everyone that I am dumb. I cannot rationalize the initial load numbers in kN so the explanation is of little use to me and is of no value. If the equations proved an ability for the structure to support a car for example and the calculations showed where the weaknesses were and how the structure was to fail then we would be on to something, but as it is for me…… so?