Determine Critical Load of a Beam

[Gray.host]

Hi All,

Hope you can help me with the below. Your support is a much needed one. Thank you in advance.

How to identify the critical load at which the material reaches its assumed yield point of 30 MPa for a simply supported RC beam?

This load represents the maximum load the beam can sustain before experiencing plastic deformation.

 

[drawoh]

Gray.host,

Working out stresses in beams is very basic mechanics of materials. If you cannot do this, your engineering strategy must be to approach a qualified engineer and ask him or her to work it out.

--
JHG

 

[Gray.host]

Hi drawoh,

I hope you are not talking about Stress = P/A; This is basic equation that every school student is aware.

I am talking about the critical load as in like Euler's buckling formula for column. What is the formula to assess the critical load on a beam member which will experience failure through elastic instability ?

 

[271828]

Gray.host, the following two questions are about different failure modes, so you're going to have to be much clearer or maybe add a sketch..

"How to identify the critical load at which the material reaches its assumed yield point of 30 MPa for a simply supported RC beam?" I assume RC = reinforced concrete. This question seems to ask what bending moment could be applied without causing yielding, but yielding of what? The concrete or the rebar?

"I am talking about the critical load as in like Euler's buckling formula for column. What is the formula to assess the critical load on a beam member which will experience failure through elastic instability ?" Are you talking about lateral-torsional buckling of the beam?

 

[phamENG]

for a simply supported RC beam

Euler's buckling formula for column

critical load on a beam member

Anyone else feel like they're watching a tennis match?

Gray.host - all kidding aside, what are you looking for? Lateral torsional buckling of a beam? Because P/A and Euler's are not for flexurally dominated beams, they are for axially loaded members. Elastic instability of a beam sounds like lateral torsional buckling, but I've never seen that applied to concrete. I imagine bridge structures have to deal with it, but most reinforced concrete beams in buildings are torsionally stable and that isn't much of a concern.

 

[drawoh]

Gray.host,

I interpreted your question as being about cantilever beams, not columns. All of this still is pretty basic engineering.

--
JHG