Beam Reinforcement Calculation 5

[Nick6781]

Let's say I need to use a web plate instead of a flange cover plate (I know...) to reinforce a beam. How do I calculate the required weld to ensure the section acts compositely? The shear flow equation gives the shear along a horizontal plane, but in this case, the faying surface is vertical. I can't quite wrap my head around it.

 

[Stress_Eng]

Here's a very simple example of the shear stress.

 

[BAretired]

That is odd BA retired given that A-A2 is the longitudinal shear flow and it clearly shows zero at the top of the plates.

It's really not odd at all, human909. I would expect the shear stress in each side plate to follow a parabolic curve from zero top and bottom of plate to a maximum at mid height. I would expect the total shear for the height of plate to be shared by the I-beam web and the side plates. And I would expect the welds to resist the forces generated.

If you were to say that none of this is necessary, I would agree because the additional side plates add negligible capacity to the I-beam when all is said and done. However the OP wanted to know in his original post, how the welds would behave.

 

[human909]

However the OP wanted to know in his original post, how the welds would behave.

That is shifting the goal posts. Specifically "How do I calculate the required weld to ensure the section acts compositely?". No weld at the edges is required to ensure the section acts compositely. Sufficient connection to transfer vertical shear all that is required which is significantly less than indicated.

 

[Celt83]

That is shifting the goal posts. Specifically "How do I calculate the required weld to ensure the section acts compositely?". No weld at the edges is required to ensure the section acts compositely. Sufficient connection to transfer vertical shear all that is required which is significantly less than indicated.

Ah I think we've been talking past each other I read the ops thread as I am doing these welds how do I figure out the demand in them and I believe how am reading your responses now the approach is don't do these welds at all connect everything at the midline. Which I don't disagree midline connection is much simpler to determine the force requirement.

 

[BAretired]

Sorry human909, but without the welds, the plates are not engaged compositely. But I do agree that the plates do not NEED to be engaged compositely. In fact, the plates do not NEED to be there at all.

Can we move on now?