Research on the Seismic Performance-Based Design of Cast Steel Joints Based on the Capacity Spectrum Method

According to the capacity spectrum method, the general method for seismic performance-based design of the cast-steel joints is put forward, in which ductility is adopted as the performance index. The method includes three steps: 1) establishing the ductility capacity curve of the joint; 2) establishing the ductility demand curve of the joint; 3) calculating the performance points of the joint according to the capacity spectrum method. Taking the Y-type cast steel joint as an example in this study, the hysteretic curves of the joints with different design parameters were analyzed. Besides, the optimized design parameters for the joint under specific natural period were obtained. The results showed that: 1) Y-type cast steel joint showed a good ductility, as long as it could meet the requirements in Technical Specifiation for Application of Connections of Structural Steel Casting (CECS 235∶2008); 2) the optimal value of d/D was related to the basic natural vibration period of the structure, the d/D value specified in CECS 235∶2008 was not the optimal value for all structures; 3) after establishing ductility demand curves for structure systems with different damping ratios and site types, the numerical seismic performance design that based on the ductility could be carried out for regular cast steel joints by adopting capacity spectrum method.