Experimental study on the effect of strain rate on the eccentric compression performance of FRP-ECC-steel double-skin tubular columns

FRP-ECC-steel double-skin tubular columns (DSTC-ECCs) demonstrate greater deformability, which enhances the cracking resistance of the FRP tubes and Normal Strength Concrete (NSC) in FRP-NSC-steel double-skin tubular columns (DSTC-NSCs). This paper investigates the compressive properties of 54 DSTC specimens. The key factors studied include strain rate, eccentric distance, hollow ratio, and the type of interlayer material (with the same compressive strength). The results show that under the same conditions, compared with DSTC-NSCs, the tensile side of the sandwich material of DSTC-ECCs exhibits more intensive cracking, and ductility index ( DI ), and energy dissipation ( E d ) of the composite short columns are significantly improved. Additionally, the study clarifies the effects of eccentricity, hollow ratio, and strain rate on the peak load, DI , and E d of the composite short column specimens, and a compressive strength model for DSTC-ECC composite short columns, considering the eccentric distance, strain rate, and concrete compressive strength, is proposed.