section modulus for non-homogenous steel section

huangyhg

section modulus for non-homogenous steel section
does anyone know how to get the section modulus of a built up wide flange with a plate welded to the bottom (different yield stress)? is it need to make any modification from normal calculation procedure?
thanks in advance~
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in elastic bending you don't need to do anything different. if the section starts to yield then use the same approach as the equivalent section of a steel reinforced concrete section.
cheers
greg locock
if the elastic (young's) moduli of the two materials are the same (of course true, as they are both carbon steels), then the elastic section modulus is unaffected.
if you need the plastic modulus then you must account for the different yield stresses. the procedure, greglocockfff">, is not exactly the one for reinforced concrete, as in that case the difference in young's moduli are accounted for.
as the plastic modulus is normally calculated by determining the plastic neutral axis that divides the section into two halves of equal areae, the same procedure is adopted, but the area of one of the two materials should be weighted by the ratio of yield stresses.   
prex