Disproportionate Collapse Robustness of Prestressed Steel Frames under Corner Column Removal Scenario

A steel frame is capable of resisting disproportionate collapse due to various natural mechanisms, such as Vierendeel action (VA), compressive arch action (CAA), and catenary action. Lacking these mechanisms in corner columns, the entire structure is more vulnerable to collapse with the removal of these columns than of columns in other locations. To evaluate the influence of prestressed tendons on resistance of prestressed steel frames caused by corner column loss, this study investigated eight two-span two-story steel frames (bare steel frames and prestressed steel frames). The experimental results demonstrated that the prestressed tendons introduced significant CAA, in addition to the VA, especially during the small deflection stage. The prestressed tendons enhanced the load resistance of steel frames with top-seat angle connections. However, prestressed tendons reduced load resistance with a welded connection. This reduction was caused by a significant tensile force occurring in the upper beam due to prestressed tendons, which resulted in the premature failure of the welded connection and a decrease in load resistance attributed to VA. Parabolic tendons were more effective than straight tendons in enhancing the load resistance of prestressed steel frames, particularly when the effective prestress was less than 0.4 f pu , where f pu is the ultimate tensile strength of the prestressing tendon.