How to do a steel beam calculation - Part 4 - Checking deflection
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- Опубликовано: 11 сен 2024
- Learn how to do STEEL BEAM CALCULATIONS in this four part tutorial by a Chartered Civil Engineer!
▶▶Get the reference tables I use in this video here: geni.us/steelt...
In this video you will learn how to check the deflection in your chosen beam. I provide you with a shortcut calculation that's easy to use.
Check out the playlist here: • Structural steel beam ...
Great approach and summary of the tools and how to use, simple and correct. Thank you also for the books recommendation, it's always good to get advice from an experienced engineer. Keep up the good work Robin!
You're very welcome!
Brilliant series Robin. Very useful for confirming one's instincts on a domestic renovation project without the cost and delay of bringing in an expert. My estimates are complicated but the fact I seem to have some 100mm IPE's in my French project and those don't figure in the UK tables but it's very reassuring to get figures in the right order of magnitude.
You r the best. Thank you for teaching us.
It's my pleasure!
Thank you for the video
Very interesting series of videos. Explained realy well.
Thanks - hope you find these useful.
An excellent refresher for my own engineering degree I sat 15 years back. Thanks Robin for these really good videos, which are nicely done (better than my lecturers who seemed more interested in their next cigarette breaks!). Really looking forward to any new ones from you.
Thanks Tom!
You explained it more simple,.thanks alot!
Hi Robin, you have really simplified the concepts, thanking you Sir. Good work.
Nice series of videos Robin - thank you.
Thank you very much describing in such a simple way . It helps us alot..
It's my pleasure!
Thanks for another great video. Would you be able to explain in a video how building foundations are calculated? Preferably something like a reinforced strip. Or why you might use a raft in place of a strip.
That's complicated but I'll give it some thought!
Great tutorial very informative, thank you.
Thanks - glad you found it helpful!
Wow thank you so much for this series, It has really helped me understand designing a domestic steel beam. Can you do a tutorial on calculating Padstones?
Thanks for the idea!
Great video, keep up the good content
Thanks!
@@RobindeJongh how can u design a moment connection by hand
Great videos. Could you do a deflection calc for a ridge beam please as I believe it to be different to a standard beam. Thanks
A ridge beam would be more or less the same - just take into account the pitch of the roof.
Hi Robin. Many thanks for the very useful series of videos on beam design. Have you covered padstone design in any of your other videos?
damn! so much stuff i don't know :)) Thanks :)
Hi Robin, thanks for the video. Could you also cover how to calc retaining walls and how to calc punching shear.
Hi Olga. Thanks for the suggestions!
Hi Robin, this is a fantastic video- the best I have seen. I have managed to follow this with ease! I am curious how I would now calculate the new take down load and if I have to consider if foundations are suitable for the new load?
Hi Kyle. Thanks for your kind words. You get the beam support reactions from video 2: ruclips.net/video/lVFb_iOhAtA/видео.html and then would need to do a masonry check and padstone check, which is best carried out by an experienced structural engineer. They should also be able to advise on your foundations.
Robin. Good content. One thing though. What if the wall you were removing was an external cavity wall. I assume you need two beams then or a padstone to bridge? What does needing two beams do to the calculation??
Hi John. Two beams are usually designed seperately, ignoring any effect they have on each other.
Hello Robin, thank you for your Videos. I’ve noticed that with Universal beams you use ‘Buckling resistance moment’ but equal leg angle do you use Flexural buckling resistance F or is it not comparable. I’m trying to see if angle can be used.
Really nice video. Can you show how to do a loft conversion beam calculation set?
In a typical mid terrace house a loft requires usually around 4/5 beams and sometimes a post when there is a chimney.
Thanks
Hi. My steel beam beginner course is still open to pre-release members who can influence the content of the course. Sounds like this may be a good topic to cover there: structural.thinkific.com/courses/steel-beam-calculations
💥Get the table with the values for this calculation here: geni.us/steeltables
What does the 2.24 relate to....????
Thanks for the video Robin. Some very useful stuff here, most of which I haven't fully understood yet. I need some advice on how to calculate steel sizes for cranked beams, such as from a ridge to an outside wall where the beam needs to support a hipped roof and also where a low ridge beam joins a higher one so has to be kicked up at an angle in order to do so. Can you help?
Hi Bruce. Sure, that can be done. I may have a space for some consulting - fill in the form here forms.gle/2KaBVfsZoK6t3khPA
Once again fantastic well explained video.....how does the deflection number convert to mm. Designing a beam above a bifold so want it to a minimum
Good question! This quick method uses span/360, so for example if you want 5mm deflection on a 5m beam, that would be span/1000, so you could adjust the 2.24 value by 1000/360 to get the smaller deflection. In this case, 6.22
Very good, if I have a 24' trusses and an opening of 22' under a 4/12 pitched roof what size I-beam am I likely to need to free span that opening? I am using 2x4 wall studs to build a room addition. I would like to sit an I beam on the walls to rest the trusses on. Thanks
Happy to help: forms.gle/fSMzoXMJPrpzVctv6
Does it apply for rectangular hollow sect calculation?
Yes, works for steel hollow section also.
Hi Robin, I am removing load bearing walls in an apartment building of 5 floors (all are stacked vertically), do I need to add the distributed load of all the floors above? therefore would i start by calculating the bending moment to find the beam at the fifth floor, then do the same at the fourth floor by adding the distributive load of the 5th floor as well ?
Hi Esther. Usually you would add the load of each floor and each wall storey, then apply the whole load to the beam to work out the bending moment. Be careful here - always get your calculations checked by an experienced structural engineer. It's the masonry strength that's often the critical thing.
Thanks for this, really interesting videos and very informative. Do I need to get a SE now to do these same calcs for me to remove a wall and install the beam I have now calculated? Thanks very much.
Hi Sam. You would need to involve an SE at some stage to either check what you have done or to do their own calculations. There are lots of other things to consider such as padstones, wall stability.
@@RobindeJongh ok, thanks very much, I'll contact one then.
Dear Robin, thanks for your very informative videoes. The only point that I couldn't follow was how did you calculate 2.24 for Ix? is it a constant?
thank you
Hi Nasser. It's a constant, worked out by substituting L/360 and values of youngs modulus into the deflection calculation.
@@RobindeJongh Thanks very much Robin
I have another question if you wouldn't mind addrssing pleas, What happens if two beams are used in patallel right next to each other instead of using one single beam? does the load capacity double up or does it get multiplied by a certain factor?
many thanks
Second moment area required (I) = (5/384) x (WL^4/Es x deflection)
Es = Youngs modulus = 205x10^3 N/mm^2
Deflection = L/360
If the deflection is 12mm then enter the deflection as 12x10^4 this way your answer will be in cm^4.
Enter the value for L in millimeters.
Finally Robin's method works as well and obviously it's easier; for curious minds the calculations above should help.
Hi Robin - Can i ask, why do you prefer to use BS literature and not the Eurocodes versions? Is there a time frame of UK phase out of Residential design to BS codes?
Just wondering if this gets picked up by building control and what their response would be? Thanks.
Oh, and one final comment, you mentioned the book, chudleys, for specification. Do you know any good websites that off a specification template for residential as a starting point?
Thanks - and great videos!!!
Hi Mark. Good question! I prefer BS because it is prescriptive and pragmatic, and has stood the test of time, whereas Eurocodes are bloated, easy to make mistakes with, and hard for the beginner to decipher. BS are still widely accepted in the UK and I can't see that changing, especially now that the UK is outside the EU.
@@RobindeJongh having been surrounded by engineers for the last 15 years, they echo your thoughts. BS 5950 all the way!!!
I honestly didn't know people were still designing to BS and that it was still accepted. I know you more or less get the same answers. Obviously partial safety factors a different, but I guess you get the same result given the utilisation factors/capacity within steel design.
Really interesting. I have Chanakya Arya's Element design book, updated with eurocodes, but have always ignore the front portion as it was being phased out (or so I was told). I may just get it in writing from BC just so I have something. Appreciate the info!
So let’s say I have a beam that’s too weak for my 40 foot opening, what can I do to reinforce it? I plan to knee brace it back to the posts, then do some bar joisting off of the braces below it. Obviously I don’t wanna overload beam with reinforcement as that would be counter productive….
Hi - a 12m opening is a serious structure and I would definitely have a structural engineer look at it. There aren't many beams that can even span that far, so you would usually go with a truss.
@@RobindeJongh ya I plan to involve one here pretty quick. Don’t want it falling in on my resto project.
So if I add the bracing to the beam will that work or is there a quick and easy formula / constant for “too much weight” overhead?
Great video.... in South Africa our second moment of area is in mm^2 , so what must I do in order to get my Ixreq to be in mm^2 ?
To get from cm^4 to mm^4, just multiply by 10^4
Hi Robin, Thanks for the video. Where did the 2.24 come from Robin?
Just found the answer below!
So this calculation for the second moment of area will determine the minimum size of the steel required, disregarding the universal beam calculator on skyciv?
Hi Alan. Skyciv (free version) doesn't do a deflection check, only the moment and shear force diagrams. So you need to do this check to see if the beam you've selected in video 3 is within the allowable deflection.
Right so the deflection check could potentially indicate that any particular beam selected could be unsuitable? So long as the deflection reading is below the second moment of the selected beam then it will be suitable?
@@swimminglikeabrick The formula will give you the required I value. Check this against the value for the beam. The beam value needs to be equal or greater.
Hello Rob, 2.24 x W x L3
Which L? Is this the length of the beam or the length to be supported by the beam?
It's the length of the beam.
@@RobindeJongh thank you..
Hi Robin - thanks again for another fantastic, valuable video. Regarding the 2.24 value, am unsure how this is derived?
Good question! If you take span/360 and substitute it into the deflection formula, and take into account unit conversion, this is the shortcut formula you end up with.
I was just about to ask the same. So is this a constant you use regardless of span?
@@stevegittins6470 Yes, the 2.24 is a constant. What I have done is taken the values for E and span/360 and turned them into a constant to make the formula much easier to use.
@@RobindeJongh Is it span/360 or span/400? My handbook says 400 But other sources including you go with 360 😅
Hi Robin - can I ask why you're recommending the out of print version of the Structural Engineer's pocketbook over the Eurocodes version?
Good question! Here in the UK the standards institution has adopted Eurocodes but the majority of structural engineers have stuck with British Standards for a multitude of reasons. Unfortunately book publishers superceded BS versions of their books with EC versions, even though they are not like for like. BS are easier for a beginner to get their heads around, which is why I recommend sticking with BS on this channel, though it makes little difference to what I'm teaching whichever code you wish to go with.
@@RobindeJongh Thanks for your response - I'm a very junior Structural Engineer here in the UK (after a career change) and just want to say I'm really enjoying your channel and informative vids. Please keep up the good work!.
@@richiejanukowicz Thanks Richie - much appreciated!
He'll sir i need this book
Sir please I want to steel beam full load calculation mathod picture or vedio
I wish to calculate 1 RSJ only to open up a load bearing wall max width 3 mtrs would your new book allow me to carry this out
Hi Alan. Yes, the steel beam course would allow you to do this. See the course at geni.us/beamcalculations
Is the 2.24 * w * L^2 formula only applicable to a simply supported beam with a UDL?
Hi Neil. That's correct. There are other formulas for other cases.
Brilliant thank you Robin. I don’t suppose there’s a chance of a video of some other cases? For example, if there was say a simply supported beam with 2 point loads. I suppose you could calculate the equivalent UDL that would give the max moment so the 2.24 formula can be used.. but if there are other simple formulas then that would be useful (if you don’t mind obviously)
@@neilwilliams9494 It would be good to have you on the pre-release group for the course I'm creating at the moment: gum.co/kNpxfO In the group you will be able to let me know what topics you want in the course, and then have lifetime access to the finished course.
Hi Robin, Great video and so well informed. It would be good if you tutored some real life examples of standard construction, flat roofs, concrete lintels, Catnics, structural timbers.
Thank you for everything! The blue book section explained a lot, which was bugging me ....keep up the good work!
Thanks for your feedback, Mark. Glad you found the tutorial useful!
Most definitely helped, this is also great CPD, I’m practicing now and really enjoying it. Just a few more schooled examples would be great.
Suck a breath of fresh air to have these videos.
What’s the 1.2xspan for, when selecting beam size in blue book. Why 1.2? Cheers
It’s a factor for restraint at the supports, 1.2L + 2D.
@@markwoollacott8402 Hi Mark. The 1.2 is a factor for effective length based on the degree of restraint at the supports. See pages 33-34 here: www.steelconstruction.info/images/0/0e/Sci_p360.pdf
That pen writing sound killing me.
so I sat through 4 parts of a video just to be told I need to buy a book?
Look at the online Blue book he used in Pt3 for the deflection, the tables he shows in the Structural Engineers book are there too. The SE book is worth having too though and The Architects Pocket book, among others...
Hi Scott. No, the videos gave you the process to design the beams without any books using pen, paper, and free websites. Can't get more generous than that. Get the books if you are serious about structural engineering.