effect of structural height on the location of key element in progressive collapse of rc structures

After the failure of an element in a structure, its loads should be redistributed on the other elements and the structure must provide some new paths to carry the load. if such new load paths are not provided, collapse progression will begin in the structure. as the beginning of progressive collapse in a structure is more sensitive to the missing of an element, the location of that element is more important to be found. the most sensitive element is called the key element. in this paper, sensitivity analysis is modified following gsa and dod guidelines and used for finding the key element of symmetric structures with different heights. four structures with different heights have been analyzed for every column missing event and the load carrying conditions of the structures have been monitored. the results showed that the location of the key element in the plan and height of the structure is different in structures with different heights.