Wood and Armer

[haceng]

I am perplexed by the way the classic Wood and Armer equations are applied. Assuming the Z axis is pointing upwards and a typical case where positive values of Mx and My create tension in the top surface (i.e. the element is hogging) and Mxy is added to My on one edge and deducted from My on the other and Myx (which presumably = Mxy) acts similarly on Mx. So, the maximum positive value of Mx becomes Mx + Mxy. This gives rise to tension on the TOP surface which determines the reinforcement in the TOP surface. However, every example I have seen shows the Mx + Mxy as the value for calculating bottom reinforcement. Surely this is a dangerous approach anyway because if Z is pointing downwards (after all we are talking about local axes here) everything is reversed. It would be much safer to say +ve Z face and -ve Z face.