Experimental and Numerical Study of a Tube in Tube Force Limiting Device

Abstract

The buckling and sudden capacity loss of the compression member can be prevented using a proposed tube in tube force limiting device (TTFLD). In this way, the brittle post-buckling behavior of the compression member can be converted into an elasto-plastic behavior. The TTFLD consists of two tubes with unequal diameter, one of which is placed into the other tube. The outer tube operates as a casing for the inner compression tube and the flexural stiffness of the outer tube restrains the buckling of the inner tube. The present study has experimentally investigated and evaluated a number of experimental specimens. Next, numerical analysis of these specimens has been done using finite element software. Further, the behavior of the tube in tube force limiting device have been investigated under important parameters such as the gap between the inner and outer tubes (gap), the inner tube or main member slenderness ratio (λ), and the ratio of outer tube length to inner tube length $$\left( {L_{2} /L_{1} } \right)$$ , by extending the numerical studies to further examples. Using this TTFLD is an effective, simple and economical method to prevent the buckling of compression member and can lead to a favorable increase in the bearing and deformability capacity of the compression members with different values of slenderness ratio. The compressive strength of the member will increase significantly, if the gap size is less than about 43% of the inner tube’s gyration radius, and the length ratio is greater than about 55%.