Research On The Impact Performance Of Concrete Filled Steel Tubes With FRP Composites

Concrete filled steel tube with FRP (carbon/glass fiber reinforced polymer) is a composite structure composed of the concrete filled steel tube with external FRP wrapped shell. Due to the reinforcement and anti-corrosion of the FRP in the structures, the comprehensive performance of the concrete filled steel tube was improved effectively. Based on the current researches, the experimental and numerical researches were conducted to study the impact performance of the specimens, which provided scientific evidence to the engineering design and application.1. Impact test on concrete filled steel tube with FRP. Lateral impact test was carried out using a drop-weight impact test machine with 80kg impact weight.11 specimens including 8 concrete filled CFRP-steel tubes,2 concrete filled GFRP-steel tubes and 1 concrete filled steel tube were tested, with the same diameter and thickness of steel tubes. The time-history curves of impact force, acceleration, deflection and strain were recorded. Based on the deformations and energies consumption of the specimens, the influence of the FRP types, wrappings, thicknesses, axial loadings on the impact performance of the concrete filled steel tube with FRP were analyzed. The relation between the local contact stiffness of the impact site and the impact response was also researched.2. Impact test on corrosive concrete filled steel tube with FRP. This paper reports an experimental study of concrete filled steel tubes with FRP to investigate the effect of FRP wraps on impact response after corrosion. Before the specimens were subjected to a process of electrochemical corrosion in 5-fold simulated seawater, they were impacted twice by 80kg and 100kg impact weights, with the same diameter and thickness of steel tubes but various lengths, thicknesses of FRP and axial pressure. The time-history curves of impact force, acceleration and the final deflection were recorded. Attenuation degrees of the deformations and the energies consumption of the specimens were compared before and after corrosion to evaluate the anti-corrosion performance of concrete filled steel tube and concrete filled steel tube with FRP.3. The numerical simulation of the lateral impact of the concrete filled steel tube with FRP. Using ABAQUS software, the finite element analyses were conducted to the lateral impact behaviors of the concrete filled steel tube with FRP. For the local damage behavior of the FRP on the impact site, the 2D-Hashin failure criteria of the FRP was modified to 3D-Hashin rules. The Vumat subroutine was written to achieve 3D-Hashin rules. Compared with the test data,3D-Hashin rules can simulate failure behaviors of the matrix compaction and fiber breakage better during direct impact, realizing the simulation of the impact process of the complex structures.4. The parameters influence analysis and the example of engineering. This paper presented a penetrating analysis of the impact performance of the concrete filled steel tube with FRP. The influence laws of the impact response including impact energies, FRP thicknesses and wrapping types, the thicknesses of the steel tubes, the strength grades of the concrete, the lengths of the specimens were analyzed. Finally, based on Xie Tang bridge, the finite element model of the pier of the concrete filled steel tube with FRP impacted by the boat was established. To compare the impact force and the impact deformation of the concrete filled steel tube, the evaluation of the enhancement the impact performance on FRP reinforcement was conducted.