Existing Reinforced Concrete (RC) structures designed for gravitational loads only are generally vulnerable to seismic events. They do not generally comply with the more advanced seismic safety standards and are often in need for retrofitting. The introduction of diagonal steel bracings is among the most common technical solution for improving seismic performance of existing RC structures. Nevertheless, several issues dealing with both analysis and design of RC frames strengthened by steel bracings under seismic action are still open. This paper presents the numerical simulation of existing RC frames retrofitted by using steel bracing with different arrangement and distribution throughout the structure. The nonlinear analyses performed in OpenSEES by using the model generated by CDSwin focuses on RC structures retrofitted with concentric X-braces which are often employed for seismic strengthening of existing structures. After a short overview of the most recent contributions on the above mentioned aspect, the paper outlines the numerical models employed for simulating the behaviour of both RC frames and steel bracings. Then, the results of seismic nonlinear analyses are carried out for demonstrating the facility and effectiveness of the two software in modelling and simulating nonlinear behaviour of diagonal steel braces. Moreover, the effect of bracing patterns is investigated and the most effective one in the case of a relevant case-study is pointed out.
Seismic analysis of RC framed structures retrofitted with steel braces
FAELLA, Ciro;LIMA, CARMINE;MARTINELLI, Enzo;REALFONZO, ROBERTO
2012
Abstract
Existing Reinforced Concrete (RC) structures designed for gravitational loads only are generally vulnerable to seismic events. They do not generally comply with the more advanced seismic safety standards and are often in need for retrofitting. The introduction of diagonal steel bracings is among the most common technical solution for improving seismic performance of existing RC structures. Nevertheless, several issues dealing with both analysis and design of RC frames strengthened by steel bracings under seismic action are still open. This paper presents the numerical simulation of existing RC frames retrofitted by using steel bracing with different arrangement and distribution throughout the structure. The nonlinear analyses performed in OpenSEES by using the model generated by CDSwin focuses on RC structures retrofitted with concentric X-braces which are often employed for seismic strengthening of existing structures. After a short overview of the most recent contributions on the above mentioned aspect, the paper outlines the numerical models employed for simulating the behaviour of both RC frames and steel bracings. Then, the results of seismic nonlinear analyses are carried out for demonstrating the facility and effectiveness of the two software in modelling and simulating nonlinear behaviour of diagonal steel braces. Moreover, the effect of bracing patterns is investigated and the most effective one in the case of a relevant case-study is pointed out.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
