Two directional bending and tension

[Fernando799]

Hi, i have a question, how to calculate a column when it is affected by two directional bendin and tension.

Ej:

Column 40x40 cm
Pu= -90kN Tension
Mux = 50knm
Muy = 90knm

Thx.

 

[rb1957]

"column" not usually in tension. Superposition is handled in any text or google. Do you understand stress due to bending ? If you do, how do you think the two bending moments stresses will interact ? then adding tension should be easy. this is the student forum, but you have to put in some work. At least google it.

 

[TLHS]

What are you trying to calculate and what material is this? I ask because if you're talking about concrete capacity design, this is actually a pretty complicated answer that doesn't necessarily pop up easily. It's the weird 'thing that you'd think is basic but is actually a giant giant pain' of structural engineering. It's not a superposition problem because of the composite nature of reinforced concrete.

Here's a reasonable example but there are simplified tabulated/charted approaches in the handbooks.

https://structurepoint.org/publication/pdf/Designing-Columns-for-Biaxial-Bending-using-Manual-Design-Procedure.pdf

 

[rb1957]

I guess mentioning "concrete" would help answering. At the same time I appreciate that the OP knows (or not) if the question is about concrete.

 

[GregLocock]

The tension is shown as -ve, does this mean it is compressive? If the material is linear can I take a punt and guess that Mohr's circle raises its annoying and long forgotten head?

 

[Fernando799]

Yes, its about concrete, and the tension is Tu=90kN, its not compresion.

 

[rb1957]

I think Greg was talking about this ... I guess Pu defaults as compression, so -ve compression = tension ?





IDK concrete but I understand concrete is quite durable to compression, and quite intolerant to tension. Maybe you shouldn't superimpose stresses, but maybe use "utilization factors" = applied load / allowable load ??