You can also use cable elements and for tensile forces following the cable use some equivalent temperature descent. It seems natural that to impart prestress one uses the tendon element suited to it. It is easy to make the lenticular example by drawing tendon pieces following equally the segments of the bottom chord. The tendon runs straight single piece the whole bottom chord, and applies a 20000 kgf of concentrical prestress.
25x.25m rendered weightless through changes in properties. This model is a concrete Warren truss that has prestress modeled as a Tendon Load (no cable element is used).
