Bending + Tension Combination

[Abuh001]

What is a good way to calculate Bending + Tension Interaction. I know one could use the standard interaction formula of

Bending Force/Bending Resistance + Tension Force/Tension Resistance < 1.0

But this does seem a tad bit conservative

 

[IDS]

Use the same method you would use to calculate bending + compression interaction:

Find the neutral axis depth that generates a reaction equal to the applied force.
Calculate stresses over the depth of the section.
Take moments.

Doug Jenkins
Interactive Design Services

http://newtonexcelbach.wordpress.com/

 

[dik]

T/A +/- M/S will give you the outer fibre stresses...

Dik

 

[Ron]

Not sure where you are located, but in the US, the interaction equation you gave is code mandated....conservative or not, that's the way it is!

 

[dik]

in some jurisdictions, the ratios are squared... rather than a straight line, the envelope is curved.

Dik

 

[Hokie93]

If you are using IBC and the AISC Specification for Structural Steel Buildings (AISC 360-10, for example), the interaction of axial tension and flexure should be evaluated using Eq. (H1-1a) or Eq. (H1-1b), neither of which are as conservative as the equation you quote. The quoted equation is permitted by AISC in Specification Section H2. Note that if your member is doubly symmetric and subject to strong-axis bending, the flexural strength may be increased by the factor given in Specification Section H1.2. Note also that AISC permits a "more detailed analysis" of flexure and axial tension, in lieu of Eq. (H1-1a) and Eq. (H1-1b).