Failure mechanism and seismic performance evaluation of steel frame using rocking truss

To mitigate the deficiency of the conventional steel frames, a novel steel frame system using rocking truss (SFWRT) and self-centering energy dissipative devices (SCED) was developed. The SCED consists of structural members, pre-tension tendons, abutting element and friction dissipation devices, which exhibits excellent self centering and energy dissipation capacity. This new structural system is analyzed using Incremental Dynamic Analysis method (IDA). A scaled earthquake acceleration response spectrum from a specified ground motion was used in this analysis. It is found that the formation of the plastic hinges of the structural components includes four stages: emergence, developing, degradation and completely bearing capacity loss. A comparative study is also made to investigate the development of these plastic hinges under different ground motions in both traditional steel frame and SFWRT. The results for evaluating the lateral collapse resistance capacity indicate that the rocking truss can significantly decrease the structural dynamic response and improve the seismic performance of buildings. The collapse probability curves of the steel frame and SFWRT based on three limit states are compared. It is found that the rocking truss is helpful to reduce the collapse probability under earthquakes. The damage of the steel frame as well as the expected loss of the main structure after an earthquake can be significantly reduced with the help of rocking truss, which would also reduce the repair cost and improve the structural resilience under earthquakes significantly.