Keywords: space structure, aluminium alloy, three-dimensional mesh, extruded bars and nodes, finite element model.

Reticular space structures are very popular in covering large open areas with few or no internal supports, as a result of their main distinguishing features, such as ease of transportation, speed of erection, light weight construction and their pleasant appearance. These structural systems, basically composed of bars and nodes developing a very efficient three-dimensional mesh of various shapes, have recently been enriched by interesting applications based on the use of aluminium alloys [1]. In particular, the use of aluminium alloy extrusions for both bars and nodes can be used for obtaining simple and economic connections, which are the distinctive element of the most commonly adopted spatial systems [2].

Under these premises, a new aluminium alloy reticular space structure based on extruded components is proposed in the present paper with the aim of defining a possible alternative to the classical systems made of steel.

The first step of the present work is represented by the preliminary numerical qualification of the proposed system, that is the evaluation of its performance in terms of structural safety and reliability [3]. Such a target has been pursued by means of a wide numerical investigation, where after an initial identification of the geometrical application fields for the reticular space structure under study, the sizing of the constitutive components has been performed.

Later on, a reticular space structure has been proposed. Therefore, the system components have been subjected to accurate numerical simulations for defining both the optimal shape configuration of the bar ends and the node behaviour under the forces transferred by bars. In particular, the flattening of the tube ends has been proposed for simplifying the connection between bars and nodes. In addition, for avoiding the high strain state identified by the numerical analysis, an alternative tube configuration has been proposed, it being based on an extruded profile which does not require the end flattening for connecting the bar to the nodal plates.

The results obtained from the numerical tests performed have been used both to allow the fabrication of the real prototypes and to evaluate the stress and strain concentration into the nodal system.

Finally, the numerical study can be considered as a pilot application for the next analysis phase, where the selected system components will be assembled into a full-scale reticular space structure to be tested up to collapse in both an experimental and a numerical way. In such a way, the complete qualification of the innovative aluminium alloy reticular space structure proposed in the paper will be performed.

1

F.M. Mazzolani, "Design Criteria for Aluminium Structures: Technology, Codification and Applications", in Aluminium Structural Design, CISM Course No. 443, F.M. Mazzolani, editor, Springer, New York, 2002.

2

F.M. Mazzolani, V. Piluso, "The possibilities to use aluminium alloys in the field of reticular space structures", (in Italian), L'Edilizia e l'Industrializzazione, n.6, 1988.

3

F.M. Mazzolani, A. Formisano, "Numerical simulation of the node-bar system for an aluminium alloy reticular space structure", (in Italian), Proc. of the XX C.T.A. Congress, "Advances in steel constructions", Ischia, Italy, pp. 603-610, 2005.

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