Abstract
Background: The seismic retrofitting of frame structures using hysteretic dampers is a very effective strategy to mitigate earthquake-induced risks. However, its application in current practice is rather limited since simple and efficient design methods are still lacking, and the more accurate time-history analysis is time-consuming and computationally demanding. Aims: This paper develops and applies a seismic retrofit design method to a complex real case study: An eight-story reinforced concrete residential building equipped with buckling-restrained braces. Methods: The design method permits the peak seismic response to be predicted, as well as the dampers to be added in the structure to obtain a uniform distribution of the ductility demand. For that purpose, a pushover analysis with the first mode load pattern is carried out. The corresponding story pushover curves are first idealized using a degrading trilinear model and then used to define the SDOF (Single Degree-of-Freedom) system equivalent to the RC frame. The SDOF system, equivalent to the damped braces, is designed to meet performance criteria based on a target drift angle. An optimal damper distribution rule is used to distribute the damped braces along the elevation to maximize the use of all dampers and obtain a uniform distribution of the ductility demand. Results: The effectiveness of the seismic retrofit is finally demonstrated by non-linear time-history analysis using a set of earthquake ground motions with various hazard levels. Conclusion: The results proved the design procedure is feasible and effective since it achieves the performance objectives of damage control in structural members and uniform ductility demand in dampers.
Highlights
Many existing buildings in high seismicity regions were designed and constructed without any design provision for earthquake resistance
This paper presents an interesting application of a seismic retrofit design method to an existing reinforced concrete building using Buckling-Restrained Braces (BRBs)
The European codes still fail to give any design guidelines for steel dampers. Both American and Japanese standards propose design procedures that are mostly applied to steel building structures, while the applications to complex real reinforced concreted (RC) buildings are still lacking
Summary
Many existing buildings in high seismicity regions were designed and constructed without any design provision for earthquake resistance. The elasto-plastic (EP) axial steel dampers are extensively used in diagonal braces for the seismic energy dissipation (i.e., buckling restrained braces) since they significantly decrease both member forces and inter-story drifts under earthquake ground motion. Their practical design is more complex than other retrofit strategies since they significantly modify both stiffness and damping characteristics of the structure. Its application in current practice is rather limited since simple and efficient design methods are still lacking, and the more accurate time-history analysis is time-consuming and computationally demanding
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
