# Beams | Bending Moment and Shear Force Diagram

Beams are structural members which are

most commonly used in buildings in a beam transverse load is acted, which

in fact comes from the slabs to the column or walls for analysis beam can be separated out

from beam column system length of a beam is much higher than its lateral

dimensions axial strain developed in a beam is very

small compared to shear strain or strain induced due to bending So for design purposes beams, analysis of shear force and bending moment induced

are of atmost importance The interesting thing is that you can

draw a sheer force and bending moment distribution along any beam by understanding what exactly is sheer

force and bending moment first shear force. Shear force is the

resistance created in beam crosssection in order to balance transverse external

load acting on beam Consider this beam. It does not matter

from where you take a section when you add forces acting on it it, it

should be in equilibrium shear force is induced exactly for this

purpose to bring the section to equilibrium in

vertical direction It acts parallel to cross section Usual sign convention is as follows: So just by applying force balance in vertical direction on the free body

diagram, we can determine value of shear force at a particular cross-section now we can apply same concept

in different cross-section and find how shear force varies along the length of

the beam But balance of transverse forces alone does

not guarantee equilibrium of a section there is another possibility a beam rotation, if

moment acting on it is not balanced If this is the case a bending moment

will be induced in cross-sectional beam to arrest this rotation It will be induced as normal forces

acting on fiber cross-section as shown Resultant forces were be zero, but it will produce a moment to

counterbalance the external moment sign convention a bending moment is as

follows: so we can calculate moment induced at any cross-section by balancing the

external moment acting on the free body diagram with these concepts developed we can

easily calculate distribution and shear force and bending moment along the length of

the beam we will see some examples For this cantilever carryng three loads

we can start analysis from the free end so between the A&B if you take a section

the only external force acting on it is F1 so a sheer force should induce in

section to balance this force so value of here force between A and B is

F1 but force balance alone does not guarantee equilibrium of the section there is an external moment on the

section so a bending moment will be induced in Section in order to

balance the external moment since value of external moment is F1 into X bending moment will vary in the nearly Between B&C effect of F2 also comes So sheer force becomes F1 plus F2 in bending moment effect f2 also gets added similar analysis is done between section

C and D also so SFD in BMD have this problem would

look like this Now consider this problem a simply supported beam with uniformly distributed load first step here would be determination

of reaction forces since the problem is symmetrical

reaction forces will be equal and will be have have total load acting

on beam Lets start analysis from point A if you take in between points A&B it should be in

equilibrium so shear force will have equal magnitude of

reaction force so bending moment also gives a linear

variation but after point B effect a point load

and distributed load comes effect have distributed load is

something interesting take a section in BC in this section along with two point

loads there is a distributed load also this distributed load can be assumed as

a point load passing through centroid of distributed load value of this is U into X minus L by

three and it is at a distance (X-L/3)/2 from section line so shear force will have one more term

which comes from distributed load from the equation it’s clear that shear

force varies linearly you can easily predict how bad a moment varies along length from the

same force diagrams since this equation is quadratic it will

have a parabolic shape same procedure is repeated in remaining

section since this problem is symmetrical

bending moment and shear force are having a symmetrical distribution hope you got a good intern analysis beams thank you

It was an awesome learning experience…:)

Thanks man

plz do upload more videos…. 🙂

Is shear force and bending moment diagram is unique for a given beam? If yes, why does different text books use different sign convention and diagrams?

thankyou thankyou thankyou thankyou

good …can u explain y we need the sfd and bmd diagram?? which force causes failure of the beam

I had always had trouble with understand what bending moment really meant. Your diagram showed the BM as something arising from the internal forces along the length of the beam; this is honestly the first time in years that I have really understood it. I've read so many lengthy explanations in books and on the internet but not one gave a succinct and visually apt explanation as yours. Thanks a million and keep up the good work!

very clear, thank you so much !

very good ……….

3:57

~~> section "C-D" you write moment equation [F1.x + F2.(x-L1) + F3(x-L2)] but I mean it is wrong. Because instead F3(x-L2) should be F3.[x~~(L1-L2)].Why does the narrator use broken English. Its sounds like a Native American autobot.

Bending moment of the beams

thannks

thanks

Please Upload mire vedios on Civil Engineering .Thanx alot fr this 🙂

why the bending moment in case of cantilever is negative?

Why this autobot voice???

which software is used for this illustration?

Why Bending moment is maximum at a point where shear force is zero in the above diagram?

It would really help your videos to have a real person talking..

I was fascinated by how you explained car transmissions, so I subscribed and looked at your page. I was so glad you also cover structural analysis because I'm a graduating Civil Engineering student and it would be good to hear about what I'm studying and maybe I can learn more because of how you explained them!

Bullshit computer voice. Unwatchable.

can we have a video on moment of inertia, area moment of inertia?

what an explanation

good…keep it up…

i am really starting to love your channel !! Please keep up the great work !

Please translate to arbic language

omg now i finally understand what exactly shear force is, thank you very much 🙂

In my uni, the bending moment signs in the tensile side just opposite with your bending moment diagram.

quite good

Please make a video about carborater

Thank you very much. I finally understood how bending moments are developed in sections!

Please can you Tell me ,,, which software is use to make this animation

so thanks dear engineer!it was so Important information for all engineer student so so thanks!

Perfect

this channel is not learn engineering.. this is learn mechanical engineering 😅

3:47 correct the x length

I have dougt in my life .. how is form bending movement and shear force….

Prepare one such complete video for industrial shed if possible

outstanding sir

written text background should be transparent. plz keep in mind.

Amezing

It's help a lot… thank you…

at 3:53 bending moment due to F3 should F3 X (x-(L1+L2))

Thank you gentleman

good one

lenght is wrong when calculating bending moment