Although many investigators have set out to find a method of determining the buckling and failing stresses for unstiffened shear webs with flanged or unflanged lightening holes, it seems that so far no really satisfactory method has been found.

A number of empirical and semi-empirical expressions have appeared over the years which agree closely with the limited series of tests on which they are based, but which the writer has found not to agree with the general mass of experimental data which is now available on this subject.

Following a recent examination of the available data another attempt has been made to derive some expressions or formulae that would help the designer to estimate buckling and failing stresses of such panels, and as a first step a semi-empirical formula has been derived that appears to fit the test results reasonably well for the initial buckling case. It applies to panels with edges fixed.