## longitudinal shear in composite sections

## longitudinal shear in composite sections

(OP)

Say I have a steel angle section and I weld a rather heavy piece of steel plate to the flange and I want the section to behave as a composite section. I have to size the weld connecting the two pieces to be able to transfer the longitudinal shear stress. However I note that there is also a transverse shear stress which is equal to the longitudial shear.

Should I size the weld based on th combination of these stresses or simply consider the longitudinal stress. Textbooks I have seem to imply the latter is sufficient.

Should I size the weld based on th combination of these stresses or simply consider the longitudinal stress. Textbooks I have seem to imply the latter is sufficient.

## RE: longitudinal shear in composite sections

## RE: longitudinal shear in composite sections

## RE: longitudinal shear in composite sections

theshear stress, whatever you call it, longitudinal or transverse (as you correctly noted, they are the same).Both components of shear stress are present, under all circumstances, not only in the case you mention (except that of course in 3D problems you have 3+3 components). The ground for considering combination of direct and shear stresses is the Mohr's circle and a failure criterion, such as von Mises or Tresca.

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## RE: longitudinal shear in composite sections

Secondly,

AISC LRFD Specification, 1999, Appendix J2.4, tells us, in words, "Fillet welds are approximately 50% stronger in the transverse direction than in the longitudinal direction" (because notice there's a 50% increase in Eq. A-J2-1 when theta = 90 deg).Therefore, for your stated scenario, you compute and check the weld shear stress only in the longitudinal direction (applied to the weld effective throat width). This includes (and envelops) the vertical (transverse) shear stress in your weld.

And, by the way, regarding combining the weld longitudinal

normalstress, AISC LRFD, 1999, Sect. J2.4, Table J2.5, footnote (e), says, paraphrasing, "For built-up member flange-to-web welds,ignorethe tensile or compressive stress in the weld longitudinal direction."## RE: longitudinal shear in composite sections