Assessment of progressive collapse potential in corner floor panels of reinforced concrete buildings

The Department of Defense (DoD) document, UFC 4-023-23, which provides technical guidance for mitigation of progressive collapse, classifies buildings based on the desired level of protection. Medium and high levels of protection categories require the use of the Alternate Path (AP) method to investigate the capability of the structural system to transfer loads safely from a notionally removed column to the remaining structural elements. Certain columns and structural elements at prescribed locations must be investigated to determine the structural bridging capabilities over the removed column. Transfer of loads from a notionally removed corner column to the adjacent structural elements can impose significant stress/deformation demand on structural elements supporting the corner panel. When the panel area exceeds the floor damage limits, the panel and its structural elements must be designed to support the additional load or the loads must be transferred to adjacent columns. This paper investigates the implementation of UFC 4-023-23 to protect against progressive collapse of corner floor panels when their dimensions exceed the damage limits. A case study of a reinforced concrete building is analyzed, designed, and investigated using the AP method.