ABSTRACT
This paper presents the results of an experimental campaign on the dynamic behavior of a single story, one bay-by-one bay, reinforced concrete space frame equipped with three different arrangements of steel bracings incorporating hysteretic dissipating devices made of a special compound of high damping rubber (HDRDs). The dampers were implemented atop the bracing systems and connected to the girders of the frame in such a manner that the relative displacement between the floor and the braces would be completely turned into pure shear or shear-torque deformation in the HDRDs: that was made possible by properly designing the bracing systems which, moreover, added the frame different amounts of lateral stiffness. The authors decided to investigate the dynamic behavior of the damped braced space frame in service conditions by subjecting the system to both free vibration tests and forced sine sweep excitations in order to obtain results which would be simple and clear to understand. Forced sinusoidal loading tests have been performed in a wide range of frequencies and displacement amplitudes, in order to simulate the frequency content of an earthquake shaking. The results in terms of dynamic parameters and structural response are outlined; it is possible to identify both the damping and the stiffness increment given to the structure by the dissipating bracing systems. The devices re-centering capacity has been as well observed after different displacement amplitudes.
