Abstract – In this paper, experimental and numerical studies were carried out to investigate the performance of normal concrete (N.C), polypropylene fiber concrete (P.F.C), steel fiber concrete (S.F.C), and high strength concrete (H.S.C) filled steel tubes under lateral impact loading. A total of eight specimens were tested divided into two groups, four specimens for each for the four types of concrete. The first group the specimen’s dimension were 114.3 mm diameter and 4 mm thickness, and the other group with dimension of 88 mm diameter and 4 mm thickness. The average cubic strength for all concrete was Fcu=45 N/mm2, except for the high strength concrete was Fcu=70 N/mm2. The specimens were tested using drop-weight impact test rigs with fixed- sliding boundary conditions at ends. The parameters studied were types of concrete, the length to diameter aspect ratio, and the confinement factor effect. The failure mode and local damages of the specimens were thoroughly investigated. A finite element analysis (FEA) model was also performed to simulate the performance of (CFST) members against lateral impact loading and the predicted results from the FEA model were validated with the corresponding experimental results. Wide range analyses of the (CFST) specimen’s response against impact loading were then carried out using the validated FE models to examine the deformation and the energy dissipation of each concrete type. The main findings are as follows: (1) The lowest value for the total impact energy and maximum dynamic displacement were recorded for all specimens filled with polypropylene concrete specimens. While the maximum recovery energy was observed for the same specimens in group (I). (2) Nearly the same value for the total impact energy and maximum dynamic displacement were recorded for the specimens filled with ordinary concrete and high strength concrete, which mean that no benefit was gained form increasing the concrete strength. On the other hand, it may have triggered brittle failure for the concrete core. (3) high strength concrete specimens has The lowest values of constraining factor (ξ) , which behave in the most brittle failure pattern. so, Ductility of the tested specimens increase with the constraining factor (ξ). |
