Is My Professor Wrong? Shear Stress Distribution

A picture may be worth a thousand words...but that one certainly isn't worth anything, it is just about incomprehensible.
Del

Are you kidding, what is not to understand here? Imagine you cut a beam in half and look inside the beam at the cross-section. It is just a picture of the shear distribution over a complicated cross section.

The stresses are drawn like that in all the engineering books I've read, so I really can't see what it is you can't understand.....

Here's a quick lesson that you won't learn in class, Junior:

When you come to someone with a question, you don't berate them if they don't know the answer either or if you don't like their answer. Unless your original intention was to come off looking like a spoiled child.

Try to also apply that in the areas of your life beyond Engineering.

You're welcome.

Guest,

Del is telling the truth and is not berating you. I couldn't tell from that 2D drawing what it was either.

You must have very thin skin to fly off the handle like that on one of the most respected members of this forum.

You won't even register and you feel that you have a "voice" here. With an attitude like that, my advice is "take a f***ing hike. Beat it, dumb*ss!

Ok, sorry for being rude if that is what you think I was.

I googled shear stress distribution over a cross section and these pictures came up:

The picture I drew was supposed to illustrate the shear distribution like these do.

I do appologize to del if he thought I was rude, I had a bad day.

However Mikero, you seem like a very troubled person. I don't see why you have to tell me I don't have a voice in here just because I am a guest. And using words like dumb*ss and fuc*ing etc. just makes me sick to my stomach, mature persons don't use language like that.

The latest three are very clear. I still don't understand your original example. Maybe it would help if we understood the shape of the cross section.

For a rectangular cross section under vertical shear, the shear stress varies parabolically from 0 at the top and bottom to a maximum of 1.5V/bd at the mid-height.

Ok, I see now that I have been stupid sorry, my picture is maybe not clear at all. The cross section is what is drawn in black.

Here is a picture of just the cross section. The things I drew with color in my origianl picture is the shear distribution.

http://img222.imageshack.us/i/crossf.png/

Again, sorry if I hurt someone.

I have reproduced your cross section here. It looks like a cross section of a rectangular bar, but the vertical line down the middle seems redundant. What does it mean?

If your sketch indicates three vertical webs and two horizontal flanges, then the shear is taken primarily by the webs. Shear stress in the flanges would be minor and would not be considered in design.

Having said that, I don't think I agree with either your professor or your text book regarding the slope of the shear force diagram in the flanges.

This is the way I believe the shear stresses vary in a box girder. The web shear is typical for all three webs, assuming they are all the same thickness.

Shear stress in the bottom flange is similar to the top flange except that the signs are opposite.

You berated Del, apologised, took a bite into mike and now have shown your faulty drawings were your own work, I have been on this site for a long time with no voice, in my silence I see many questions answered and help given to tons of appreciative people. I am nothing and no one yet no matter who you are (3rd year) you should always thank those who try to help you.