Application of Sustainable Concrete in the Seismic Evaluation of an Innovative Type of Buckling Restrained Brace

Abstract

The Buckling Restrained Braced Frame (BRBF), consisting of a ductile steel core in concrete or a steel tube encased in concrete, is constructed to avoid brittle failure modes. The application of ductile materials with improved damping properties, such as tire-derived lightweight aggregate concrete, has not been investigated in BRBF systems, but it enhances the overall performance of the system and contributes to sustainability. Hence, this study aims to investigate the influence of such an application on the response modification, overstrength, and ductility factors, as well as the general earthquake performance, of 4-, 8-, and 14-story special reinforced concrete moment resisting frames equipped with BRBF. The current study compares 48 different BRBF models with TDA infill and conventional concrete infill by considering various bracing configurations, such as Chevron (Inverted V and V), Split X, and Single-Leg BRBF, and different span lengths of 6 m and 8 m. The evaluations include nonlinear response history analyses intended to provide insights into the performance of BRBF when exploiting the available experimental stress–strain characteristics of tire-derived lightweight aggregate concrete as an alternative material. Furthermore, the effectiveness of using tire-derived lightweight aggregate concrete as an alternative damping material in BRBF is examined by comparing BRBF with the new damping properties of concrete. Buildings equipped with BRB encased in TDA showed reduced base shear demand (by an average of 7%) when compared to concrete infill, and the prescribed value for the response modification factor for buildings of 50 m or less provides an acceptable estimation of the lower bond factors in approximately 95% of the cases. Furthermore, when a system requires more damping, the application of BRB encased in TDA is recommended.