EXPERIMENTAL STUDY ON PRACTICAL-SCALE UNBONDED BRACES

Abstract

The practical - scale "unbonded braces" were tested and the following conclusions were obtained. 1) Basic model : In the practical - scale test, it was confirmed that the stable hysteresis characteristics was obtained up to an axial displacement of ± 50 mm (axial strain : approximate 1/80). 2) Thin-walled pipe model : Safety from buckling under the present design standard is sufficiently high. 3) Model with different unbonding material thickness : In the elastic region, there is no difference in initial stiffness. It was, however, found that if the thickness of the unbonding material is increased, plasticization proceeds at a higher rate due to delicate undulation of the core steel plate. 4) Model using different grades of steel as the core : There is possibility of producing a brace which can freely control the hysteresis characteristics. 5) Eccentric model : In the "elastic region" corresponding to the behavior of the brace which is set in the frame, a sufficiently high buckling constraining effect can be obtaind, regardless of the magnitude of eccentric moment. Lateral deformation and rotation proceed in the plastic region and maximum strength decreases in the compressive region.