Dynamic Tensile Behaviors of HRB500E Connected with Extrusion Sleeves at Different Strain Rates

In this paper, the connection performance of extrusion sleeves and the strain rate effect on 500 MPa-grade hot-rolled ribbed bar(HRB500E) connected with extrusion sleeves under a range of testing strain rates from 1.079/sto1.395/s, similar to what would be caused by an impact, were explored. The test results showed that, under strain rates likely caused by aircraft impact, the specimens mostly failed due to breaking outside the joint length. Furthermore, there was no relative slip between the rebar and the extrusion sleeve, indicating that the connection was stable and reliable in the used experimental parameter field. The percentage total elongation at maximum force (Agt) of HRB500E spliced by the extrusion sleeve showed an exponential decline with the increase in the strain rate, indicating a clear strain-rate sensitivity. The average deviation between the dynamic increase factors (DIF) calculated using the modified Cowper-Symonds formulas and the experimental values was within 5.4%, which can better reflect the strain rate effect on the strength of the spliced connection. The DIFy of sleeve-spliced rebars was higher than that of unspliced rebars, and the ratio of the DIFy of sleeve-spliced rebars to the DIFy of unspliced rebars increased with the strain rate. The experimental results can provide a basis for an optimized design of the aircraft impact-resistant extrusion sleeve rebar connections.