I need a help with modeling of a beam. For example, the length of my beam is 3 meters.

At the first meter of beam i want to put Transverse reinforcement with bars 6 mm and spacing 20 cm, at the second meter of beam i want to put Transverse reinforcement with bars 6 mm and spacing 30 cm, at the first meter of beam i want to put Transverse reinforcement with bars 6 mm and spacing 20 cm. How is it possible?
Before i read about integration sections of element and didn't understood a lot. In Building modeller we put reinforcement in start/middle/end of the element. How can i put the reinforcement by parts of beam (1st, 2nd, 3rd meters)?
Thank you!