This paper presents an investigation of the behavior of CFDST members under low velocity lateral impact using ABAQUS, where nonlinear material behavior and strain rates of steel and concrete are included. The finite element analysis (FEA) models of CFDST members are described and verified using existing experimental results. Strain and stress states of concrete and steel tube in CFDST members are analyzed over the full loading range, followed by a parametric study investigating the influence of impact height, hollow ratio, nominal steel ratio, diameter-to-thickness ratio of inner steel tube and strength of materials on the impact force and global residual lateral deformation. Furthermore, the dynamic increase factor (DIF) of CFDST members under lateral impact is proposed, and the influence of the confinement factor on the dynamic increase factor (DIF) is analyzed. The results show that when the confinement factor is larger than 1.03, the dynamic increase factor needs to be considered to accurately estimate the dynamic resistance capacity of CFDST members subjected to lateral impact. (C) 2015 Elsevier Ltd. All rights reserved.