Torsion and bending/torsion buckling may occur for compressed thin-walled open profiles used in engineering and architecture applications. We report experimental results provided by PZT pickups stuck on thin-walled aluminium beams with open modified cruciform cross-section, exhibiting non-zero warping stiffness. The buckling loads and the natural frequencies corresponding to various compressive forces were detected for free and (at least partially) restrained warping of the ends of the specimens. The results are compared with those of a FEM (commercial) and an in-house numerical code that examines the stability of non-trivial equilibrium paths in a dynamic setting. The results seem new and confirm that: (a) PZT pickups can be efficient in extracting modal parameters of thin-walled beams; (b) the numerical simulations are robust and accurate in finding the buckling loads in all analyzed configurations.