Concrete Beam Biaxial bending 3

[LOKSTR]

I have a rectangular concrete beam SS at ends. I need to design the reinforcement for point loads acting in both x-x and y-y axis at the same time. The beam is supported in both axis at the ends.

My question is what is the right procedure for biaxial bending in concrete? Is it same as in case of steel beam where we check (Mfx/Mrx) + (Mfy/Mry)<=1 or I need not check this condition ?

Thanks

 

[WillisV]

Interaction needs to be considered.

Think of it as a column (it just happens to have 0 axial load) and use one of the many approximate methods available for biaxial concrete column bending (e.g. reciprocal load) or use a program that can generate a 3-D interaction surface (or generate one yourself if you have nothing better to do all day).

 

[dik]

You will have a neutral axis for both the reinforcing as well as the moment...

Dik

 

[miecz]

According to PCA Notes on ACI 318-02, the Reciprocol Load Method should only be used when flexure does not govern the design. Looks like PCA favors the Load Contour Method for this.