Marcos con Riostras de Pandeo Restringido: Comportamiento y Factores de Modificación de la Respuesta Sísmica


Buckling-Restrained Braces are structural members that are able to yield not only in tension but also in compression. The key to obtain this desirable behavior is to avoid the occurrence of buckling when the element is subjected to compression forces. The result is a member that shows a stable hysteretic behavior and an excellent low-cycle fatigue life compared to a conventional brace. This work encourages the use of Steel Braced Frames with Buckling-Restrained Braces in the design of new building structures and the retrofit of existing structures in Chile. In order to achieve this, a complete state-of-the-art review is presented, which is complemented with a comparative cost analysis in order to demonstrate the advantages of the use of BRBs instead of conventional braces. Subsequently, five different buildings using Buckling-Restrained Braced Frames with the same tipology and different number of stories (between 4 to 24) are analyzed and designed using the Chilean Standard NCh433.Of96: Earthquake Resistant Design of Buildings, along with the corresponding requirements of AISC 2005 Seismic Provisions. Afterwards, the structural capacity and demand for each building is determined by inelastic analysis, using earthquake records selected according to their importance and destructive characteristics observed over the last 30 years. Finally, the seismic response modification coefficients are obtained and compared to the proposed coefficients for steel moment frames in the Chilean seismic code. From this comparison, seismic response coefficients are suggested to be incorporated on the corresponding chilean standard.