Impact response of stainless steel tube locally-strengthened by concrete-filled steel tube.

• A new locally-strengthened method was developed for steel tube. • Impact tests were conducted on the locally-strengthened steel tube. • The failure mode, impact force, displacement and energy absorption were studied. • Analytical model was proposed to predict impact force and displacement responses. This paper proposes a novel stainless-steel tube locally strengthened by a concrete-filled steel tube to resist impact loads. A drop hammer impact test system was used to determine the failure modes, impact forces, and displacement responses of the strengthened tubes under an impact load. The effects of the strengthening length and thickness of the concrete and outer steel tubes on the impact responses of the strengthened tubes were investigated. The impact resistance was found to improve with an increase in the thickness of the concrete and outer steel thickness. The test results also indicated that the strengthened tubes exhibited a flexural failure mode with a combination of local and global deformations. An analytical model for predicting the dynamic responses of the locally strengthened tubes was established based on an equivalent two-degree-of-freedom (TDOF) model. The analytically predicted results were compared with the experimental results, and the good consistency between these two results demonstrated the accuracy of the established analytical model. [ABSTRACT FROM AUTHOR]