Behavior Of Tubular Structures Research Articles

Study of effect of provision of cut-outs on axial collapse behaviour of circular aluminium tubes

Geometrical modification of thin-walled tubular structure is one of the innovative ways in the development for vehicle safety design. This research is developed in accordance with the need of investigation on behaviour of tubular structures with geometrical modifications like cut-outs under dynamic loading technique. Diamond and elliptical cut-out shapes are provided in multiple number arranged circumferentially in a single row on a tube surface. Tubes with cut-outs are loaded axially at three different velocities, corresponding to three different strain rates. Energy absorption characteristics like energy efficiency, specific energy absorption, peak collapse force, mean collapse force and efficiency of peak force reduction at the initiation of tube deformation are calculated and compared using finite element (FE) based ABAQUS/Explicit® software. Split-Hopkinson Pressure Bar (SHPB) is modelled in the FE software to understand the material behaviour under high strain dynamic loading. Johnson-Cook material model parameters are incorporated in the study to understand the strain rate sensitive behaviour of aluminium alloy material. Results revealed that providing diamond and elliptical cut-outs on tube is much efficient than providing circular cut-outs on tube, in terms of percentage peak load reduction as well as energy efficiency of structure. It was observed that number of cut-outs influences the polygonal deformation pattern of tube with cut-outs. Overall study significantly helps to achieve the aim of improving vehicle crashworthiness characteristics by implementing cut-outs in a crash frame.

Effect of Column Shortening on the Behavior of Tubular Structures

This paper presents the column shortening effect on the behavior of Tubular, Tube in tube and Bundled tube structure. Frame tube buildings consist of closely spaced column connected by deep spandrel beams placed on the perimeter in plan. A Tube in tube and Bundled tube structure of 50 storeys with storey height of 4 m is considered for the study, RC columns and spandrel beams are modelled with M70 and M110 concrete mix. Models are developed using ETABS software and the effect of elastic shortening of the RC column is included in the analysis to study the behavior by calculating member forces. From the analysis, the effects due to elastic shortening in parameters such as axial force, shear force, bending moment and time period are obtained and compared between the tubular, tube in tube structure and bundled tube structure, there is a variation of about 25%, 20%, 23% and 74% and 23%, 17%, 25% and 57%. 19%, 15%, 31% and 60% respectively, which results in the reduction of member size, which ultimately reduces the dead load and the cost of construction.