SA17: Shear Influence Line

[@k.w.9242]

Best tutorial ever. Well presented. If I were rich I would fund people like you. Thanks for making student's lives easier. God bless!

[@tauseefraza3094]

Very high thinking May Allah make you capable of this

[@a-02sagarjadhav53]

I too 👍10000000000.....K👍

[@abhishekmina3996]

You deserve a gold medal ...... Just cleared my concept in just 15 minutes , which I was facing from last two year

[@thobanigoba2024]

I’m watching this from my structural mechanics class and in 15 minutes I assure you I’ve learned more than 75% of the people listening to the lecturer for the passed 45 minutes. Quality video👌🏽👌🏽👌🏽

[@musica3955]

ahahahahha Savage

[@87455451jose]

Amazing, I've been struggling with this for weeks, and I got it all cleared in 15 min. Cant wait to see SA18 moment influence lines. Cheers!

[@INDIA_PRIDE_I]

This channel is a gem.

[@tabzz03]

I can't thank you enough. I was breaking my head from past three days on drawing ild. I saw numerous videos on yt but thy didn't help. Thank you so much for making us understand in such simple way. God bless 🙏

[@azhysurkew]

idk how to thank u,, this influence line has been a nightmare for me but u make it very simple and easy ,, much respect

[@patrickwoolery6000]

Thank you so much for these videos. My SA professor spent like 5 minutes on influence lines and thought we'd all understand. I don't know why he didn't just play your videos for the class because these teach the material so much better. Again, thank you.

[@DrStructure]

Thank you for the feedback.

[@لاتحزن-ف9ك]

@@DrStructure am from Iraq and very difficult to understand English language

[@musichub6752]

best explanation i have ever experience in my student life . Thanks alot

[@abeal-qudah1619]

Thank you. I was to understand influence lines from you video that 5 years of education could not do for me. Thank you again!

[@AhmetOzdemir-lk1bl]

)))

[@asaddavar43]

This is the best youtube video for influence line of beam so far.... thanks from bd..

[@FaizYah]

God bless you Dr. ! Thank you for such an easy-to-understand explanation!

[@wongsathornphatcharaphisut3020]

This video is better than my in class lecturer. I can understand all of a chapter just in quarter an hour. Thank you so much Dr.

[@ahmadshahi4421]

This was the greatest training videos i ever seen in youtube

[@love-and-faith]

You deserve gold you have to teach other teachers how to teach 😮😮😮😮

[@omohosagie4772]

Demystifying....You are truly a Doctor of Structures!

[@reginavillalobos1301]

OMG years of trying to understand this concept and I just finally did! Thank you so much!

[@DrStructure]

You’re welcome.

[@rahulmalpekar4631]

Thankyou so much @Dr. Structure for providing this wonderful video. It was really concept clearing.

[@ieuhfuffffff]

I'm Vietnamese, I'm not good at in English, but I can understand all of things you explain. At my University, I cant understand it. Thank you very much, you are a master in explain.

[@DrStructure]

Thanks for your comment and feedback.

[@johnkim4026]

Dude i have a final tomorrow and this saved my life. U are amazing

[@ibrahimacar8262]

Whoever found this is out of this world bro, It's epic. You don't need functions to solve anymore.

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What a wonderful video ❤❤❤

[@prakashpandey4907]

You have mind blowing teaching style....

[@Kamikorosu0416]

Unbelievably amazing! Very clear and understandable. Cheers from the Philippines

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I just love you Dr Structure....

[@noorhanalkhatib4341]

I love this channel .. amazing

[@_jojo11]

this is a godsend a few days before structure exams thank you

[@moisestorrespe]

Excelente video!!! It helps me a lot in my master's advanced bridge design class

[@bishalnayak6162]

God bless you to whoever made this video.

[@tuze5474]

OMG you helped me a lot, now I understand how it works! Marvelous video!

[@coolbro1502]

You deserve to be respect sir

[@UnknownUser12]

Thank you for your videos and putting so much effort in them. Regards from Aus

[@manikantagodi3239]

is that that much hard? my reaction when I heard this topic in the class...but after this video is that that much easy?...overturned my reaction...thank you so much..you just nailed the topic...

[@veersundarr7821]

Very nice explanation!

[@gopalkumar-mh7zx]

thanks from India ..for make understanding concept very clealy

[@عمارسامي-ز7ص]

الله يباركلك يا هندسه❤

[@KonjoTube]

u save my life i love u Dr.

[@ahamadromen]

A wonderful work. Thank you for your v.well simple explanation.

[@obaidurrahman4300]

Good lecture. Thank you ❤❤

[@DELICKNSUBUGA]

Your the best ❤

[@madisonstafford6619]

You actually just saved my grade.

[@lifeisbeautiful350]

Thanks so much for this presentation

[@osuwatchdog7154]

thanks for saving my life

[@franciscovasquezramirez5705]

Thank Dr Structure; Congrats from Bolivia

[@ahmetkasmoglu1576]

Great work. İ know a little english but i understand this lesson. Thank you very much.

[@ibrahimyasser4719]

Great thanks and great respect

[@pronoybhat]

What a way to learn Structure.. Great work. Thanks !

[@smboston12]

this is so great, makes it so easy to understand. Thank you

[@saurabhdhadiwal129]

Excellent video

[@rmrafsanzanilabib6881]

You explained IL so well. thank you for making our study easier

[@yadrzgar9980]

A structural analysis professor at my uni who has a PhD & 12 years experience could bot explain this half as good as this video! Thank you 😭😍

[@omarpasha2968]

I believe it! I once took my junior College electrical problems to a university electrical engineering tutor. And, the problem was too complicated for him!

[@rubencasinillojr9852]

Thank you! Great explanation ever.

[@rabbiahmed6760]

u explained in the easiest way.tnx a lot

[@engineersoutlook7]

Excellent tutorial

[@kaylal3875]

The best video out there! Thank you so much!

[@bendeng2768]

Very good explanation.

[@williamsentemtz9652]

Mind blowing!👍👌 5 stars for u

[@saurabhdhadiwal129]

4 yr passed away in college didn't understood the concept but ur video clr my doubt...🙏🙏🙏

[@陳建忠-t6d]

認真的老師.

[@sabbirnadim5269]

best tutorial ever

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very convenient explanation thanks...

[@greatminds8977]

God bless you 🙏

[@VuralinToronto]

Awesome.! Greatings from Turkey , Dear Dr.Structure :)

[@1f7sivakumarponakalla74]

U really nailed it! Thanks a ton!!

[@ikbenvoetbal]

Thank you so much. I would bake you a cake. This really helped me a lot. May God bless you and your family

[@Ilsan1111]

thanks for this lecture! awesomeeee

[@1carlos83]

Thank you for this, the graphics are the best I have seen for anyone lecturing structures. You should do a P.E. course.

[@SHUBHAMKumar-qd1pi]

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[@dayana6532]

This is amazing! Thank you so much for this!

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Thanks 💖💖💖

[@Mm-hw9yb]

Thanks a lot Dr. Structure!

[@kitetama13]

thanks for sharing! God bless you

[@imbimb1403]

Thank you for such a great explanation. It really helped me .

[@catobsessed379]

u r awesome dr.!!!!!!!!!!!!!!!! thank you

[@gnidnoeled786]

Let's say we have a simply supported beam like as shown at 3:45 mark. The beam span is 10 m and the moving load is 50 kN. Is the MAXIMUM shear value at point C (at the midpoint of the beam) be 50 kN x 0.5 = 25 kN (+ and -) and the MAXIMUM moment at the same location be 50 kN x 2.5 = +125 kN-m? Where 2.5 is the ordinate of the moment influence line at point C. Thanks in advance for your reply.

[@DrStructure]

It is important to remember that the shear influence line does not give us any information about the location of max shear in the beam. Rather, it lets us determine the maximum shear at a specific point due to a moving load. The maximum shear in a simply supported beam does not occur at the midpoint of the beam; it takes place close to either support. However, for the simply supported beam you’ve referenced, assuming we want to determine the max shear at the midspan (and not the max shear in the beam), your analysis is correct.

[@gnidnoeled786]

@@DrStructure Your detailed explanation is awesome. It gives me a better understanding of influence line. I really do appreciate it. Salute to you. 👍👏

[@gnidnoeled786]

@@DrStructure With reference to your explanation, the maximum shear is at the support and that's 50 kN x 1 = 50 kN and the maximum moment is at midspan 50 kN x 2.5 = 125 kN-m.

[@DrStructure]

Correct!

[@charrysalce4580]

Very well presented and explained. Thank you so much!

[@DrStructure]

Thank you for the feedback.

[@FRSHBL]

Very creative .. Thanks alot

[@eminashindahouse]

Dear Dr. Why at 3:04 , would you describe the shear at C decreases linearly when the load moving from A to C? Isn’t it increases linearly? My understanding is that the negative sign only indicates the right hand side of shear with respect to the load at current time.

[@DrStructure]

If the value of shear is increasing in the positive direction, we say shear is increasing. On the other hand, if the value of shear is moving in the opposite direction, we say it is decreasing. That is, if shear goes from 0 to, say, -100, we say shear is decreasing, since -100 is smaller than 0.

[@eminashindahouse]

Dr. Structure understood. Many thanks 🙏🏻🙏🏻

[@DrStructure]

You're welcome.

[@nisreensalameh1887]

Keep up the good work. Can you do some video series on concrete and steel design? Thank u so much, people like you makes world a much better place

[@oscarrinn]

I love Dr. Structure!! My structural sicknezz is kured

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you are best

[@meargbrihanu8139]

thank you so much its very help full , please add some videos on design

[@sheilabelcabrera4043]

thanks Dr. Structure! you're good at explaining.. i understand the video:) i just hope i could answer our exam..

[@허준범-e4h1o]

OMG Thank you i love this video

[@meetvaghasiya3681]

tnk u so much..... upload more n more video.... 😎

[@GracefoolReacts]

Thanks a lot maam!!!

[@mutv5642]

Helping ❤️

[@Julian-xe3gw]

Just one word: thanks!!

[@junielvillas8820]

for 4:10, is it possible to be drawn the other way around, like upward force at the left roller and downward at right?

[@DrStructure]

By definition, shear in a beam segment is considered positive when the force is acting downward at the right end of the segment, and upward at the left end of the segment. That is what you see @4:10, positive shear in both segments. If we define positive shear the other way around, then yes, we would have to switch the direction of the arrows.

[@rahul1268]

great video,but there is minor error for direction of shear u mentioned section left upward and section right downward is considered as positive ,so what u applied is negative shaer @4:18 sec check it

[@DrStructure]

Thanks for the comment. Although sign conventions are rather arbitrary, in structural engineering it is a common practice to consider a shear force that tends to rotate the beam segment in the clockwise direction as positive. Accordingly, the pair of shear forces applied to the roller @4:14 indeed are considered positive. This beam sign convention is different than the sign convention we generally use for the plane stress element. For such an element four shear forces are drawn along the four sides of the element: right, left, top and bottom. Shear is considered positive if the right and left shear forces (acting in opposite directions) tend to cause a counter-clockwise rotation while the top and bottom pair tends to cause a clockwise rotation. Your description matches this sign convention.

[@rahul1268]

So it's just a matter of sign convention nothing else

[@rahul1268]

Thanx for rply u r video r really to the point and interactive plz upload more videos on structure analysis on topic like slope deflection ,mdm ,matrix method egarly waiting

[@DrStructure]

akash poddar Although beam sign convention could be picked arbitrarily, it is very important to be able to relate the positive and negative force/moment to the state of stress in the member. Let's take the case of bending moment. By convention bending moment in beams is assumed positive when it tends to bend the beam concave up. So a positive moment in the beam means its bottom fiber is in tension and its top fiber is in compression. When designing such a beam (say as a reinforced concrete beam), we should place the reinforcement bars at the bottom (tension zone) of the member as concrete cannot handle too much tension force by itself. Generally no reinforcement is needed at the (top) compression zone. Now if we have used the opposite sign convention for bending moment, and make the statement that bending moment in the beam is negative without clearly identifying the tension and compression zones, the reinforcement bars could end up at the wrong zone causing member failure.

[@accessuploads7834]

you are our master

[@siguerhakim4723]

thanks, great teacher

[@eironce9032]

Life SAVER! 😍😍

[@FlowerFati907]

On the example with shear @ E, rollers B & C on either side, (@7:54 )with a hinge at D. What if B & D were switched to: hinge at B and roller at D instead? The shear with a hinge next to it on the left, roller to the right, and roller to the left of the hinge? I did not see an example with a hinge and then a roller next to the IL of question, only saw rollers side by side or roller / hinge combo. Does it act like the example with two rollers where the bar cannot move and the IL goes to the hinge and stays there? Thank you! Hope that makes sense.

[@DrStructure]

Thanks for the question. Yes, in such a case the left segment of the beam from A to B (the new location of the real hinge) remains flat. E moves downward to the left of the fictitious roller at E, causing BE to rotate clockwise. And, E moves upward to the right of the fictitious roller making EC to turn clockwise as well.

[@FlowerFati907]

Makes sense!!! I appreciate it!

[@AyaanKhan-ei3gk]

I don't understand how can the pin move vertically up and down ? As you mentioned at 9:15

[@DrStructure]

At 9:15 we place a pair of vertical rollers, not a pin, in the beam. By definition a roller can roll/move. Since they are placed in the vertical directions, the rollers can move/roll up and down. Since we have two of them, they can move independently in opposite directions.

[@AyaanKhan-ei3gk]

@@DrStructure no that's not what I asked , I am asking that there is an internal hinge between two rollers right ? I am asking how can that internal hinge point move up ? Doesn't the pin restrict vertcal motion ?

[@DrStructure]

If you are referring to the real hinge, yes, it can move up/down. A hinge is unlike a pin or a roller. You can view the hinge as a single bolt that connects two beam segments. It allows one segment to rotate relative to the other segment. You can create and experiment with a hinge connection using two balsa wood sticks and a push pin.

[@AyaanKhan-ei3gk]

@@DrStructure hi , thank you so much for your reply , so what I have understood is that a hinge and pin are two separate entities , and point which is hinged on a beam can actually move up and down that's why we have the point moving up , but if we had a pin there then it would have remained at its position and would not have travelled up , right ? Because the pin connection and roller connection resists the vertical movement ,

[@DrStructure]

Correct. The pin and the roller are mechanisms that connect the beam to the support. Neither the pin or the roller can separate itself vertically from the support. The hinge however is not attached to a support, so it’s vertical displacement is not restrained.

[@imanfarahbakhsh4052]

Brilliant ... thanks a lot

[@hectormunoz4812]

@ 9:17 I am confused as to why the beam EC does not move up as one, but is held down at point C. It is not a pin, so it cannot be held down, can some one explain?

[@DrStructure]

The actual beam does not move up or down at C, the fictitious beam does that. We are inserting an imaginary hinge at C thereby creating a fictitious beam. We then subject that hinge to a shear force causing point C to move up/down in the fictitious beam. Why are we introducing the imaginary hinge and creating a fictitious beam? Because the resulting displaced shape of the fictitious beam corresponds to the shear influence line in the real beam.

[@callofpotatoe]

Holy Crap, amazing explanations, thankyou!!

[@xtr3m385]

Shouldn't the maximum shear force at C, VC, be 6 kN? at D on the other hand, VD = 6*1.5 = 9 kN?

[@DrStructure]

Not sure how you arrived at this conclusion, please elaborate.

[@Gespenstish]

Thanks a lot, this is very helpful.