Panels appeared only to be able to inhibit or partially reduce the slip of beam-column connections, improving their load pickup compared with those shown by specimen F1, in turn causing the connections to fail at lower displacement demands. Figure 19 provides an example
of such behavior, where the local response of the same beam-column joints, examined for specimen F1, is shown, in terms of interstory force versus relative horizontal displacement curves. The shape of the hysteresis loops was significantly different, particularly for nodes 2 and 5b, and,
and more than halved relative horizontal displacements were measured for slightly lower interstory forces. As a result, even if overall global response of the frame and local response of the joints appears more stable, the interaction between the cladding panels and the structure must be accounted for in the design process of these early structures, still common in Italian and European scenarios, as cause of anticipated collapse, rather than as a latent source for stiffening and strengthening.