An analytical model for Tensairity girders

Thin-Walled Structures, 2011

The load bearing behavior of an asymmetric spindle shaped Tensairity girder is studied experimentally and compared to finite element analyses. The influence of the air pressure on the stiffness of the structure is investigated for homogeneous distributed load, asymmetric distributed load and a local load at the center of the structure. An overall good correlation between experiments and finite element predictions was found. An analytical model based on two coupled ordinary differential equations is presented and solved for the homogeneous distributed load case. The role of the form of the Tensairity girder on the stiffness is investigated by comparing the load-deflection behavior of the asymmetric spindle shaped girder with a cylindrical shaped girder.

Tensairity is a new light weight structural concept. It is a unique combination of pneumatic structures and cable-strut structures. The core principle of a tensairity structure is to use the low pressure air inside the hull element to stabilize the compression element from being buckled. The new light weight structure has a variety of applications ranging from wide span roof structures to temporary bridges. In this paper, non-linear static and dynamic analysis of a tensairity spindle shaped beam is done by dividing the thickness of hull element into three layers of equal thickness with different orientation in each layer. The paper also determines the maximum load carrying capacity of a spindle shaped tensairity beam before buckling for different parameters.

Tensairity is a new light weight structural concept. It is a unique combination of pneumatic structures and cable-strut structures. The core principle of a tensairity structure is to use the low pressure air inside the hull element to stabilize the compression element from being buckled. The new light weight structure has a variety of applications ranging from wide span roof structures to temporary bridges. In this paper, the load displacement response of a spindle shaped tensairity beam made with composite hull element is determined for different parameters.

Tensairity is a new light weight structural concept. It is a unique combination of pneumatic structures and cable-strut structures. The core principle of a tensairity structure is to use the low pressure air inside the hull element to stabilize the compression element from being buckled. The new light weight structure has a variety of applications ranging from wide span roof structures to temporary bridges. In this paper, modal analysis of a spindle shaped tensairity beam made with composite hull element is done and natural frequencies are obtained for different parameters.

2012

An analytical approach to torsion of thin-walled beams of open section with one plane of symmetry is considered. The theory of torsion of thin-walled beams of open section with influence of shear, based on the classical Vlasov's theory of thin-walled beams of open section, as well as the Umansky's theory for closed-open sections, is applied. The general transverse loads act in the beam walls, reduced to the moments of torsion with respect to the principal pole (torsion/shear centre) only. The beam will be subjected to torsion with influence of shear with respect to the principal pole and in addition to bending due to shear in the horizontal plane trough the principal pole. The obtained analytical expressions for displacements are applied in the analysis of displacements of the modern container ship hull girder subjected to torsion, as well as in the parametric analysis of simple U sections. Comparisons with the finite element method by applying shell elements are provided.

Engineering Structures, 2009

Tensairity is a new lightweight structural concept consisting of struts and cables stabilized by a textile membrane, which is inflated by low pressurized air. In order to estimate the potential of Tensairity beams towards applications including axial compressive loads, full-scale compression experiments were conducted on a simply-supported spindle shaped Tensairity column. The column was subjected to axial compressive loading for various levels of internal air-pressure in order to quantify its effect on local and global response, and it was found that the axial stiffness of the column increases with air-pressure and eventually reaches a plateau. Displacements were measured in several positions along the span, whereas axial forces were experimentally determined by strain gauges measurements. The experimental results were compared to finite element and analytical predictions, yielding good correlation for low air-pressure levels, whereas for higher ones, local imperfections led to significant deviations. Comparisons of the Tensairity column to similar truss-type structures with comparable stiffness revealed the superiority of the concept in terms of transportation volume and in-situ deployment.

Marine Structures, 2014

The hull girder moment capacity of a very large crude oil carrier (VLCC) called Energy Concentration (EC), for which many benchmark studies have been carried out using the simple progressive collapse method (SPCM), is predicted. In this study, three approaches are used to represent the load-shortening behavior, socalled average compressive strength, of a stiffened panel, comprising the hull section: 1) kinematic displacement theory (KDT); 2) nonlinear finite element analysis (FEA); and 3) simple formulas in the common structural rule (CSR) for tankers. Loadshortening curves for various kinds of stiffened panels in EC are compared for five different scenarios with variations of loadshortening approaches and initial imperfections. In order to verify the effect of load-shortening on the prediction accuracy of the hull girder moment-carrying capacity, load-shortening curves are imported into an SPCM-based in-house program called Ultimate Moment Analysis of Damaged Ships (UMADS). Comparison of the hull girder ultimate strength for general heeling conditions, including hogging and sagging conditions, reveals that the loadshortening curves significantly affect the hull girder momentcarrying capacities. Based on our comparison of these capacities with other benchmark results, it is concluded that nonlinear FEA provided the most conservative results, KDT provided the second most conservative results, and the CSR formulas predicted the upper bound.

Tensairity is a new light weight structural concept. The key principle of Tensairity is to use low pressure air to stabilize compression elements against buckling. The basic Tensairity structure is a beam with the properties of a simple airbeam as light weight, fast set up and compact storage volume but with the load bearing capacity of conventional steel girders. Ideal applications of the Tensairity technology are wide span roof structures, temporary buildings and footbridges.

Ships and Offshore Structures, 2008

A method is presented to estimate the ultimate moment based on a simplified approach to represent the behavior of stiffened plate columns. The assessment of the strength of a very large crude carrier is performed and compared with the moment at failure in hogging estimated by other methods applied to the same case. The proposed method allows the prediction of the degradation of the strength due to corrosion and residual stresses. It also allows the evaluation of the strength of the hull at several heeling conditions. Finally, an analysis of the efficiency of the high tensile steel is carried out. * The elements into which the cross section is subdivided are considered to act and behave independently. 60 MARCH 1996 0022-4502/96/4001-0060$00.45/0 JOURNAL OF SHIP RESEARCH