Evaluation of Dynamic Amplification Factor for Moment Resisting Frames in Progressive Collapse

Abstract

Progressive collapse has been a prevalent research topic since a gas explosion caused the collapse of the Ronan Point apartment building in 1968. Progressive collapse occurs when an
instantaneous loss of a supporting element causes failure in adjacent members leading to a large-scale collapse of the structure.

The General Services Administration GSA and the Department of Defense DoD have provided design guidelines regarding progressive collapse mitigation.

The guidelines provide requirements for setting up static and dynamic, linear and nonlinear analyses. In particular, a dynamic amplification factor DAF of 2 is recommended to account for the dynamic effects when performing a static analysis. Recent studies have determined that the GSA and the UFC guidelines provide an overly conservative dynamic amplification factor.

 In this thesis, various frames were analyzed using SAP2000 for all four analysis methods and the results were used to make recommendations regarding a more appropriate dynamic amplification factor. Additionally, the role of dynamic and nonlinear effects was observed and compared for the four different analysis methods.
By looking at the different frames, it is evident that the dynamic amplification is consistently less than 2, this is true for all the frames analyzed except for the 2x2 span frame with an interior column removed where the DAF is exactly 2. It is reasonable for the dynamic amplification to be higher for a frame with two spans because when a column is damaged and removed in this frame, there are only two columns remaining to take all the load.

Also, the DAF is significantly larger for the deflections than the moments.