Responses of concrete-filled FRP tubular and concrete-filled FRP-steel double skin tubular columns under horizontal impact

This paper presented the experimental and analytical results of concrete-filled fiber-reinforced polymer (FRP) tubes (CFFTs) and concrete filled GFRP-steel double skin tubular columns (DSTCs) under horizontal impact loads. The influences of the thickness of FRP tubes and impact velocity were discussed. The thickness of the FRP tubes had insignificant influence for both the peak impact force and the maximum displacement. Under the same applied impact energy, the maximum displacement of concrete filled FRP-steel DSTC specimens was similar to 40% smaller than that of CFFT specimens. The impact velocity had more influence on the peak impact force than the duration. Three-dimensional finite-element (FE) models were developed to simulate the impact behavior of two types of composite columns and the numerical results are compared with the test data. Then, the verified FE model was used to conduct parametric study. Moreover, analytical solutions for lateral displacement of composite columns under impact were obtained, in which the effect of impact damage was considered by introducing reduction factors into the vibration equations. The comparison between analytical results and test results showed that the maximum displacement can be accurately predicted by the proposed theoretical model.