Abstract
SummaryBuckling‐restrained braces (BRBs) have proven to be very effective in improving the seismic performance of existing and new structures. They provide strength, stiffness and add energy dissipation to the structure. However, being BRBs characterized by a low post‐elastic stiffness, their use may lead to residual deformations hindering the building's reparability and to excessive cumulative ductility demand possibly compromising the residual capacity of BRBs. To overcome these drawbacks, BRB frames (BRBFs) can be coupled with moment‐resisting frames (MRFs) to form dual systems. If properly designed, MRFs acting as back‐up frames allow the control of the residual drifts and the optimization of the performance of the BRBs. The contribution of this study is to provide insights into the performance and residual capacity of BRBFs‐MRFs dual systems and to shed light on the influence of the main BRB's design parameters. To this end, a nondimensional formulation of the equation of motion is introduced for a single degree of freedom system, and an extensive parametric study is performed for a set of natural ground motion records with different characteristics and scaled to various intensity levels. This allows the investigation of a wide range of configurations, considering different levels of the relative strength and ductility demand of BRBFs and MRFs, and obtains useful information for their design. Finally, two case study frames, modeled as two‐dimensional nonlinear multi‐degree of freedom systems, are analyzed, and the results were compared to those obtained from the nondimensional formulation to show the capabilities and the limitations of the adopted methodology and of the SDOF approximation.
Highlights
Buckling‐restrained braced frames (BRBFs) are earthquake resisting systems employing elasto‐plastic passive energy dissipation devices, i.e., buckling‐restrained braces (BRBs),[1,2] to resist the horizontal seismic forces and to dissipate the seismic energy
This paper presents an extensive parametric study investigating the seismic performance and residual capacity of dual systems consisting of buckling‐restrained braced frames (BRBFs) coupled with moment‐resisting frames (MRFs)
This permits the evaluation of how the system properties, including different levels of the relative strength and ductility demand of the BRBF and MRF, affect the median demand and the dispersion of the normalized displacements, accelerations, residual displacements, and cumulative BRB ductility demand
Summary
Funding information UK‐India Education and Research Initiative; (UKIERI) joint research program, Grant/Award Number: 2017‐UGC‐10070. The contribution of this study is to provide insights into the performance and residual capacity of BRBFs‐MRFs dual systems and to shed light on the influence of the main BRB's design parameters To this end, a nondimensional formulation of the equation of motion is introduced for a single degree of freedom system, and an extensive parametric study is performed for a set of natural ground motion records with different characteristics and scaled to various intensity levels. A nondimensional formulation of the equation of motion is introduced for a single degree of freedom system, and an extensive parametric study is performed for a set of natural ground motion records with different characteristics and scaled to various intensity levels This allows the investigation of a wide range of configurations, considering different levels of the relative strength and ductility demand of BRBFs and MRFs, and obtains useful information for their design.
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