Study on dynamic constitutive relation and fiber pullout simulation of modified carbon fiber reinforcement concrete

In order to improve the weak binding force and easy pull-out of the traditional carbon fiber (CF) and concrete interface, this paper prepared three-dimensional multi-scale carbon nanotube-fiber (MCNF) by grafting carbon nanotubes on the surface of carbon fibers by electrophoresis, and carried out computer simulations. The results showed that compared with ordinary carbon fibers, the attraction between the MCNF fibers surface and the concrete interface is stronger, and it is not easy to pull out. At the same time, Plain concrete (PC), CF concrete (CF content as 0.1% of concrete volume) and MCNF concrete (MCNF content as 0.1% of concrete volume) were prepared, and dynamic mechanical tests were carried out by using a Φ100 mm Hopkinson pressure bar test (SHPB) experimental device., It is found that compared with carbon fiber, the interface between MCNF and concrete is more tightly bonded and difficult to pull out, so it has better effect on improving the mechanical properties of concrete. Finally, MCNF enhencement effect was introduced to simplify and modify the Zhu-Wang-Tang (ZWT) constitutive model which is the damage model of traditional and the simplified model conforms to the actual situation of MCNF concrete. The theoretical curve based on the constitutive model is also similar to the actual test curve, proving the correctness of the constitutive model.The research results provide references for improving the impact load resistance of concrete in practical engineering.