m_xy results not maintaining sign at max tension/max compression for plotting

[Agent6-6-6]

Hi @robbievanleeuwen

In concrete_section.calculate_ultimate_section_actions() when the m_xy results are calculated, you're effectively calculating an absolute value, so when you plot based on the m_xy moments for a given theta you get some weird results where the values bounce back off the vertical axes when you have an unsymmetrical M/N curve:-

Not quite sure how to address this, need some way of adjusting the sign appropriately based on what plan quadrant your result is in relative the neutral axis or load angle (load angle being as discussed in #31) you've analysed?

Potentially it's as easy as just checking if both m_x or m_y change sign from some prior or following value in the positive side of the curve (depending on what way it is stepping through the axial loads) that you know is past the origin. Then for the plot the m_xy resultant it's deemed negative as its crossed the origin? That would signal the results straddle an orthogonal vertical plane through the origin?.......... I'm sure it' trickier than this though given not yet working in terms of load angle for the M/N curves!

[robbievanleeuwen]

Thanks for brining this one up @Agent6-6-6. Yes at the moment m_xy is a 'sum of squares' resultant so will always be positive. I think this will need to be investigated more when I propertly sort out the load angle business.