The feasibility of CFT frames forming column yield mechanism

As well known, concrete-filled tubular (CFT) have excellent capacities for the plastic deformation and energy absorption even under high compression. In order to use the capacities of CFT columns in moment-resistant frames, a new yield mechanism is proposed where some columns are permitted to yield (WCM). In that case, the attention should be paid for the frame instability such as story pancake crush. A column-to-beam strength ratio (R_FCB) will be one of the effective parameters to control the frame stability. From this point of view, the minimum requirement of the ratio is investigated by time-history dynamic responses of the maximum deformation and the damage in CFT columns of frame models with various numbers of stories or bays, and arrangement of columns to permitted to yield, and the ratio of 1.5 will be enough, because the damage of the columns will not decrease if the R_FCB increases over 1.5. Furthermore the frame stability is verified by experiment.