Low‐prestressing, self‐centering energy dissipative brace

Abstract

AbstractSelf‐centering energy dissipative (SCED) braces are designed to limit the maximum story drifts in buildings during earthquakes and to nearly eliminate residual drifts. SCED braces that have been developed in the past face three major challenges: they require high levels of prestressing force, they have limited elongation capacity, and their energy dissipative systems have inadequate reliability or excessive complexity. This paper proposes a new SCED brace that addresses these three challenges with the use of a mild‐steel dissipative element that never experiences compression, so it will not buckle. The feasibility of the new system was demonstrated with a set of experiments in a configuration that uses a series combination of post‐tensioned steel tendon and Belleville springs for re‐centering. The paper develops equations that govern the brace's performance, identifies key parameters and develops a numerical modeling method. The design of an example building shows that the new brace only requires approximately 6% of the prestressing force required for existing SCED braces to achieve similar hysteretic relationships. Numerical analysis confirms that a braced frame equipped with the new brace would control the maximum response to about the same extent as would for existing SCED braces and buckling‐restrained braces, while effectively eliminating residual drift under severe earthquakes. Meanwhile, the new system generates 18–26% smaller axial forces than existing SCED braces and appears to have a large elongation capacity. Based on these findings, it is concluded that the proposed brace successfully addresses the major challenges of previous SCED braces.