EXPERIMENTAL STUDY OF RESISTING MULTI-HITTING CAPACITY ON FRP CONFINED CONCRETE ON CONDITION OF INDIRECT DAMAGE BY WEAPONS

Based on the quasi-static and rapid loading test results of short cylindrical concrete specimens wrapped with fiber reinforced plastic (FRP) under three different constraint ratios(ξ), the multi-hitting test and quasi-static loading test after multi-hitting were conducted. The test results show that FRP confined concrete is a kind of material which can well resist multi-hitting. The stiffness of FRP confined concrete decreases along with increasing hitting times and also gradually converges. The final residual stiffness decreases along with ξ and η(ratio between maximum hitting stress and strength of FRP confined concrete) increase. For FRP confined concrete damaged by multi-hitting, compared with intact specimens, the elastic modulus decreases, while the strength is nearly unchanged and the ultimate strain increases. Ductility of FRP weak-confined concrete damaged by multi hitting obviously increases. The slope of linear strengthening of the stress-strain curve of FRP well-confined concrete damaged by multi-hitting increases along with the damage degree increasing and the final stress-strain curve of FRP well-confined concrete gradually approaches to linear elastic. This work provides the basis for further research on application of FRP confined concrete to defending structures.