An Energy-Based Assessment on Dynamic Amplification Factor for Linear Static Analysis in Progressive Collapse Design of Ductile RC Frame Structures

Abstract

Progressive collapse is a mechanical process that exhibits nonlinear and dynamic characteristics. The nonlinear dynamic effect on the progressive collapse resistance demand can be accurately evaluated by the nonlinear dynamic (ND) method. In engineering practice, however, the simplified and easy-to-use linear static (LS) method is often adopted. That is accomplished by using a dynamic amplification factor (DAF) to correct the LS resistance demand to approximate the true ND resistance demand. In this paper, the analytical expression of the DAF is established based on the energy conservation principle. The collapse-resisting substructure is firstly simplified as a single-degree-of-freedom (SDOF) equivalent. Then the energy conservation equation and the static balance equation of the SDOF equivalent are established to obtain the ND and LS demands. Finally, the DAF is obtained by dividing the ND demand by the LS demand. The DAF is validated through a series of the numerical examples including a SDOF system, a 3-storey planar frame and an 8-storey 3-D RC frame model structures.