Identification of critical members for progressive collapse analysis of single-layer latticed domes

This paper presents a method to identify the critical member in a single-layer latticed dome, which in the context of progressive collapse is defined as the member whose removal causes the most severe damage. The distribution of critical members in four typical types of single-layer latticed domes, including the Kiewit dome, the Ribbed dome, the Schwedler dome and the Lamella dome, is investigated through a comprehensive Alternate Path analysis scheme composed of hundreds of individual dynamic nonlinear analyses. The Alternate Path analyses also confirm the progressive collapse mechanism of single-layer latticed domes, i.e., the nodal snap-through buckling at either end of the initially removed member. On this basis, a critical member identification method is established, using an index that implicitly estimates the relative vulnerability to node buckling following the removal of a member to determine the criticality of this member. This method along with two other methods, using either static axial force or free vibration response, are evaluated via comparison against the nonlinear dynamic Alternate Path analysis results, and this proposed method shows a beyond-compare accuracy. Furthermore, based on the established understanding of the progressive collapse mechanism and the factors influencing the node buckling resistance, three methods for increasing the progressive collapse resistance of single-layer latticed domes are presented.