Self-centering energy dissipative bracing system for the seismic resistance of structures: Development and validation

Buildings designed according to modem seismic codes are expected to develop a controlled ductile inelastic response during major earthquakes, implying extensive structural damage after a design level earthquake, along with possibly substantial residual deformations. To address this drawback of traditional yielding systems, a new bracing system that can undergo large axial deformations without structural damage while providing stable energy dissipation capacity and a restoring force has recently been developed. The proposed bracing member exhibits a repeatable flag-shaped hysteretic response with full recentering capabilities, therefore eliminating residual deformations. The mechanics of this new system are first explained, the equations governing its design and response are outlined, and one embodiment of the system, which combines a friction dissipative mechanism and Aramid tensioning elements, is further studied. Results from component tests, full-scale (reduced length) quasi-static axial tests, and quasi-static and dynamic seismic tests on a full-scale frame system are presented. Experimental results confirm the expected self-centering behavior of the self-centering energy dissipative (SCED) bracing system within the target design drift. Results also confirm the validity of the design and behavior equations that were developed. It is concluded that the proposed SCED concept can represent a viable alternative to current braced frame systems because of its attractive self-centering property and because the simplicity of the system allows it to be scaled to any desired strength level.