should a skew mesh be adopted or the transverse members are set orthogonal to the main members?

For skew deck, the transverse members are set orthogonal to the main members to find out the correct moment and deflections. Skew decks develop twisting moments which is more severe for higher skew angles.

The most economical way of designing reinforcing steel is to place the reinforcement along the direction of principal moment.

For skew angle less than 35^o, it may not be practical to adopt this approach in the skew region. Instead, the transverse members are kept parallel to the support line so that a skewed mesh is adopted. The use of skew mesh suffers from the demerit that it would slightly overestimate the output of moment and deflections.

This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.