Impact behaviours of partially encased steel-concrete composite members: Finite element simulation and analytical modelling

This study investigated the lateral impact behaviour of partially encased steel–concrete composite (PEC) members through finite element (FE) simulation and analytical modelling. A detailed FE model was developed and validated against available experimental data. The mean predicted-to-tested ratios of the peak impact force, mean impact force and maximum mid-span displacement were 1.01, 1.01 and 0.99, respectively, indicating accuracy of the FE model. Based on the validated FE model, the dynamic response characteristics, energy dissipation and internal force evolution of PEC members were analysed. Parametric studies were conducted to obtain the effects of axial force, flange thickness, web thickness and flange-to-web area ratio. The results showed that the presence of axial force increased the initial peak impact force but reduced the impact resistance owing to the second-order effect. Increasing the flange and web thicknesses improved impact resistance and reduced maximum displacement, whereas the flange-to-web area ratio had a non-monotonic influence owing to the competing effects of bending and shear resistance. Moreover, a two-degrees-of-freedom model considering second-order and strain-rate effects was proposed. The analytical predictions showed well agreement with FE results.