A novel friction self-centering damper using nitrogen gas springs: Development, experiments, and seismic response control

Abstract

A novel nitrogen gas spring (NGS) friction self-centering damper (NGS-FSCD) is proposed to overcome the drawbacks of conventional self-centering dampers, including high post-yield stiffness and complicated assembly. The damper employs an NGS with low post-yield stiffness, no additional pre-compression, and excellent fatigue performance as the self-centering module, arranged in parallel with a friction damper. Quasi-static, low-cycle fatigue, and dynamic cyclic loading tests were conducted to investigate the influence of parameters such as NGS stroke, initial force, and friction bolt preload on the hysteretic performance of the damper. The experimental findings reveal that, under equivalent energy dissipation and restoring force, the post-yield stiffness of the NGS-FSCD is only 10–20 % of that of self-centering dampers using disc springs (DS) or shape memory alloys (SMA). The post-yield stiffness of the NGS-FSCD increases with the initial force of the NGS and decreases with it stroke. A multi-story braced frame structure was developed using OpenSees software. A comparative analysis was conducted among the buckling-restrained brace (BRB), the NGS friction self-centering brace (NGS-FSCB) with a post-yield stiffness equivalent to that of the BRB, and the DS and SMA friction self-centering braces, both exhibiting higher post-yield stiffness. The NGS-FSCB frame achieves reductions in base shear by 16.6 % and 27.2 %, and in peak roof acceleration by 16.4 % and 31.7 %, compared to the DS and SMA friction self-centering brace frames, respectively, under the design basis earthquake level. This confirms its effectiveness in minimizing residual deformation and enhancing overall seismic performance.