Zhu & Zhang 2008
The authors propose a special type of bracing element termed a SFDB. A seismic design procedure for the SFDB is then developed. The purpose of this structural system is to minimize residual drifts and create a damage-free structure after frequent and design based earthquakes. SFDB are typically installed in CBF buildings as part of the bracing system which resisted lateral loads. SFDB frames are capable of achieving a seismic control level comparable to that of buckling-restrained braced frames, while having significantly reduced residual inter-story drift after earthquakes. SFDB devices are reusable after frequent design based earthquakes. In order to explain the displacement based seismic design approach for SFDB frames, two design examples are used: a 3-story and a 6-story SFDB frame.
System Concept
The SFDB re-centers itself through the use of superelastic SMA wire strands. Moreover, it can also dissipate energy through friction.
Design Procedures, Results, and Discussion
A 3-story and a 6-story SFDB frame were used as prototype buildings for displacement-based seismic design approach. Non-linear dynamic analyses were applied to two prototype buildings. In the design steps, the drift target in the design of SFDB frames was selected based on primary performance objectives. Both high damping and low damping were considered for hysteretic behavior of the SFDB. Frames were also designed both with (SFDB) and without (SFDB-NF) friction dissipation at the sliding surface. The 3-story building, including both the SFDB and SFDB-NF frames, could meet the design target performance. The 6-story building, underestimated the peak inter-story drift ratios and brace ductility demands for both the SFDB and SFDB NF frames. Nonlinear dynamic analyses results show that SFDB frames designed using the DBD procedure can achieve the target displacement parameters with a high degree of accuracy, however, caution should be exercised in the design of medium-rise buildings since the design procedure tends to underestimate values of maximum story drift ratios and brace ductility demands.
Reference
Zhu, S. and Zhang Y. (2008). “Seismic Design of Steel Concentrically Braced Frame System with Self-Centering Friction Damping Braces,” Proceedings of the 14th World Conference on Earthquake Engineering 2008, Beijing, China, October 12-17.