Seismic Retrofitting of Low-Rise Nonductile Reinforced Concrete Buildings by Buckling-Restrained Braces

Abstract eng:
An experimental study was carried out to examine the applicability of bucking-restrained braces (BRB) to seismic retrofit low-rise, gravity-load-designed, concrete frame buildings. In the first phase of the study, a simple but effective BRB made from encasing an unbonded flat bar section with grout fill in a hollow square-section steel tube was developed through a series of quasi-static cyclic loading tests. The original design of BRB test specimens was based on available design guidelines and past research reports. However, they were found to perform very poorly due to the occurrence of several unexpected failures in or near the end of yielding zone of BRB specimens. After correcting those details, the final BRB specimen was able to successfully yield in both axial tension and compression up to ductility ratio of approximately 16. In the second phase of the study, an assemblage of a reinforced concrete column with non-seismic detailing and a diagonally arranged BRB was tested under quasi-static cyclic load. The test results showed that the BRB effectively yielded at a lateral drift of about 0.3%, which is much lower than the drift at which the column reached the peak strength (about 1 %). The force-deformation of the assemblage displayed ductile stable hysteretic loops from small to large lateral drift levels, without any sign of degradation, until the complete failure of the column at the drift of 2.5%. The results clearly demonstrated the potential of BRB in seismic retrofitting of non-ductile, low-rise concrete frame buildings.

• Export as: BibTeX | MARC | MARCXML | DC | EndNote | NLM | RefWorks
• Add to your basket