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This is the first paper in a series of papers that are intended to cover the present state of knowledge in the field of formex configuration processing. This field of knowledge has been developed during the last three decades and has now reached a level of maturity that makes it an ideal medium for configuration processing in many disciplines. In particular, it provides a rich assortment of concepts that are of great value to the engineers and architects involved in the design of space structures.

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This is the third paper in a series of papers that are intended to provide a comprehensive coverage of the concepts of formex configuration processing and their applications in relation to structural configurations. In the present paper, the attention is focused on structural forms that are based on hyperbolic paraboloidal, hyperboloidal and annular surfaces. It is shown that these categories of structural forms include many exciting possibilities for lattice and shell structures. The paper also includes sections on structural forms that may be obtained from combinations of simpler forms or through certain composite transformations that are called paragenic transformations.

This is the second paper in a series of papers that are intended to provide a comprehensive coverage of the concepts of formex configuration processing and their applications in relation to structural configurations. In the present paper, attention is focused on the configuration processing for a number of families of space structures, namely, pyramidal forms, towers, foldable systems and diamatic domes . Also included is a section on information export as well as an Appendix on basic formex functions. The section on information export describes the manner in which the information about the details of a configuration, generated by the programming language Formian, can be exported to graphics, draughting and structural analysis packages.

In this paper, the method of genetic algorithm is used as a search technique to find the stability characteristics of simultaneously statically and kinematically indeterminate structures The genetic algorithm is used to find out if there is a solution for a specific quadratic form which has to be satisfied in order to guarantee the statical stability. The genetic algorithm is a search technique that imitates nature in selecting and optimising towards an aim. The use of the genetic algorithm in the search for the stability of pin-jointed structures is found to be simple and powerful. A computer program called STAPS (Stability of Pin-jointed Structures) has been developed using the genetic algorithm. This program firstly identifies the independent mechanisms and states of self-stress, if any, in a structure. Then, the program searches for any state of self-stress that can stabilise all the mechanisms of the structure. STAPS program is a powerful tool for finding the stability of 2D and 3D pin-jointed structures. The program can be used for investigating the stability of space trusses and cable structures like cable nets, cable-strut and tensegrity structures1,2. Section 1 of this paper contains a brief introduction. Section 2 discusses the background of what is called ‘product forces’. Also, in Section 3 the stabilisation of mechanisms of pin-jointed structures is discussed. Section 4 introduces the method of genetic algorithm and how it is used in the search for stability of pin-jointed structures. Section 5 introduces the STAPS program together with illustrative examples of its application. Finally, Section 6 gives a conclusion of the work presented in this paper.

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Dynamic response of large complex space structures under wind loading is important in terms of performance and safety. Conventional method of wind loading calculation has been used successfully in codes to analyze large space structures. The method can be applied by approximating the air pressure, induced by wind, on the surfaces of structures. Although this replaces a wind loading test using complicated wind tunnel tests for any structural systems, the accuracy of the method, in the case of complex geometry guyed tower structures, is a matter of consideration. Hence, it is desirable to search for a procedure with more accuracy and reliability. In this respect, attention is paid to the advanced spectral element method and the computational fluid dynamics. Using the proposed formulation, a material and geometric nonlinear dynamic analyses have been performed to simulate post-buckling behaviours and also collapse modes for series of Manitoba Hydro's guyed towers under extreme wind loading conditions. Résumé : La réponse dynamique de grandes structures tridimensionnelles complexes sous des charges exercées par le vent est importante en termes de rendement et de sécurité. La méthode conventionnelle de calcul des charges dues au vent a été utilisée avec succès dans les codes pour analyser des grandes structures tridimensionnelles. La méthode peut être utilisée en appliquant une approximation de la pression d'air, induite par le vent, sur la surface des structures. Bien que cela remplace un essai des charges exercées par le vent qui utilise des essais compliqués en soufflerie pour tout système structural, il faut tenir compte de l'exactitude de la méthode dans le cas des tours haubanées, qui sont des structures géométriques complexes. Il est donc désirable de rechercher une procédure plus exacte et plus fiable. Concernant ces points, nous portons notre attention sur la méthode avancée des éléments spectraux et la dynamique des fluides numérique. En utilisant la formulation proposée, une analyse des matériaux et des analyses géométriques non linéaires ont été effectuées pour simuler le comportement post-flambement ainsi que les modes d'effondrement pour des séries de tours appartenant à Manitoba Hydro sous des conditions extrêmes de charges dues au vent.Mots clés : dynamique des fluides numérique, charge exercée par le vent, mode d'effondrement, analyse non linéaire, post-flambement.[Traduit par la Rédaction]