Concrete-filled steel tube (CFST) structure has been widely used in civil engineering structures as it offers numerous structural benefits. The (CFST) columns’ behavior has been investigated intensively against axial and lateral impact loading. However, there is a lack of knowledge on the response of (CFST) columns when filled with different types of concrete. Therefore, in order to close this gap, experimental and numerical studies were carried out to investigate the performance of CFST members filled with four different types of concrete under the effect of lateral impact load. The concrete types were normal concrete, steel fiber concrete, and propylene fiber concrete all with average cubic strength of Fcu=45 N/mm2, except the last one was high strength concrete with Fcu=70 N/mm2. In high loaded members, the available standard tubes’ sizes available in domestic market won’t cover the required design size, hence emerged the need to fabricate the required size of pipe by welding. Consequently, the effect of using seam weld pipe instead of seamless pipe on the response of (CFST) under impact load was investigated in this study. Accordingly, eight specimens were tested divided into two groups, four specimens for each. The first group are fabricated from seam weld pipe and the other group from seamless pipe. The parameters studied were types of concrete and steel pipe. The failure mode and local damages of the specimens were thoroughly investigated. A finite element analysis (FEA) model was then performed to simulate the behavior of (CFST) members against lateral impact loading and validated with the corresponding experimental results. Wide range analyses of the (CFST) columns response against lateral 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 seam weld specimens have an almost equivalent lateral impact resistance as seamless CFST counterparts. (2) The lowest value for the total impact energy and maximum dynamic displacement were recorded for the specimens filled with polypropylene concrete specimens. While the maximum recovery energy was observed for the same specimens. (3) 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. |
