Problem:

Applying Wood and Armer equations gives worse results.

Solution:

The twisting moment Mxy is apportioned to the moments in the steel direction by the Wood and Armer equations; the M*x and M*y moments produced being an optimum that is required. If more steel is provided in one direction than is required then Wood and Armer will not directly allow for this. The equation in BA 44/96 clause 5.4.2 doesn't help. The Cement and Concrete Association gave a solution in 1971 which uses the Wood and Armer theory to utilise any spare capacity of steel in one direction to assist in resisting twisting and bending in the skew direction. I have written Proforma WoodArmer (see Excel Proformas) to evaluate the strength of skew reinforcement to resist the triad moments Mx, My, Mxy.