Double T section in Steel

[luiscelorrio]

Hi, I would like to computer and simulate a steel frame that consist in doule T sections. I will consider the width and height of column secctions and beam section as parameters or design variables in an optimization problem. I am modelling these beams and columns as nonlinearBeamColumn elements and sections using a fiber type section with 3 patch comands (upper flange, botton flange and web). Is this correct?.
How could i compute the gradients with respect to these parameter (b = width and h = height)?
Thanks in advance.