Column Beam Capping plate connection

[Redtelis]

Guys,

If we have a continuous beam with pins at intermediate supports and uniformly distributed load applied, that means that it develops over the intermediate supports moments.

So, if the steel beam is supporting by steel columns (intermediate supports)and we want to show it as a continuous beam, we can show that the beam passes over the column and it is connected with a capping plate connection. Does this capping plate connection needs to be designed as a moment connection, right?

 

[r13]

The design concept is identical to the column baseplate. Distribute the support reactions to the cap plate, and check shear and bending moment on the overhanging plate.

 

[Redtelis]

does this mean that the moment will be transfered to the column though? thus the column is to be designed for this moment?

 

[human909]

Please fix up you sentence structure, it makes it very hard to read.

continuous beam with pins at intermediate supports

....

Does this capping plate connection needs to be designed as a moment connection, right?

Wrong. If you designed the capping plates as moment connections then it wouldn't be a pinned support would it? Design the cap plate connection so that it is relatively flexible, not too different to designing a pinned based plate.

We actually discussed this recently. Some moment transfer to the column is inevitable unless the loads are perfectly balanced. This is probably most easily modelled as a cap plate eccentricity equally to half the width of the cap plate. Overall the effect on the beam/column depends on their relative stiffnesses and the expected rotation of the beam.

 

[JoshPlumSE]

I look at this as being more similar to a beam to column end plate connection in reverse (with the column and beam being switched). You can do end plate connections that only transmit shear and end plate connections that are meant to transmit moment too.

 

[dold]

The time honored "when is a pin a pin" discussion ensues...

I'm not sure if we ever reached a conclusion in this thread: [URL unfurl="true"]https://www.eng-tips.com/viewthread.cfm?qid=469027[/url]

 

[human909]

I look at this as being more similar to a beam to column end plate connection in reverse (with the column and beam being switched). You can do end plate connections that only transmit shear and end plate connections that are meant to transmit moment too.

It is a fair bit of difference as the predominant force in the end plate is 90 degrees different. Also if you think you can design an end plate that can 'only transmit shear' then I have a bridge to sell you.

The time honored "when is a pin a pin" discussion ensues...

I'm not sure if we ever reached a conclusion in this thread

There was another one more recently. The sort of conclusion in that case was using the cap plate eccentricity is a reasonable approximate to a semi rigid cap plate connection. Another approach is to model the connection as completely pinned AND completely rigid an ensure that both are satisfactory.

The more complicated answer is that you have two different members of varying stiffness's and a connection of a stiffness that is hard to quantify without a more thorough examination.

 

[dik]

I'd treat it as pinned and design the beam plastically...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[human909]

I'd treat it as pinned and design the beam plastically...

This is reasonable and conservative for beam design. However treating the connection can be potentially unconservative for column design.