Experimental Study of a Pre-Compressed Self-Centering Brace

Several self-centering systems have been developed and tested so far, and all of them confront problems. Several problems like stress relaxation, elongation capacity and high post-yield stiffness are some of the problems, which should be addressed. The aim of this study is to find a solution to these problems. To this end, a new pre-compressed self-centering system has been proposed, tested and studied. Pre-compressed springs have been used to provide the required restoring force. Since the spring is under pressure and it has a high elastic capacity, the problem related to limited elongation capacity no longer exists. The experimental result indicates that the proposed self-centering brace has complete self-centering behaviour and low postyield stiffness. The proposed self-centering system produces less secondary stiffness compared to other systems. The effect of secondary stiffness on the drift and base shear was studied. Results of the numerical models indicate that high secondary stiffness does not decrease the drift of the structure, it only increases the base shear. Therefore, to attain an economical design, using the proposed self-centering system with slight secondary stiffness is suggested.