Keywords: space structures, lattice domes, varax domes, geometric configuration, node coordinate generation, Formian generation.

Varax domes are special lattice domes built up of a network of equilateral triangles of straight or curved beams and a decking supported by straight purlins. The geometry of a typical varax dome is obtained by projecting the plane network of equilateral triangles onto the spherical surface of the dome. The projection is defined by rays that originate at the centre of the sphere. Thus, all beam elements and structural nodes lie in great circle planes and have the same radius of curvature.

Formian is a special program developed at the Space Structures Research Center, University of Surrey, UK, to generate coordinates for advanced space structures [1,2]. It is based on formex algebra [3] and has been proven to be a powerful tool. However, the Formian program cannot handle the special features of varax domes. It is necessary to implement new functions related to varax domes within it, which is the focus of this paper. After having done so, all other functions and tools in the Formian program are available for application to varax domes.

Functions and procedures for generating varax dome configurations have been developed and implemented into this professional program for space structures, Formian, to be able to generate any shape of varax domes and to use the results as input variables to a finite element program for analysis purposes. Thus, the Formian program used in this paper is adapted to be applicable also to varax domes. The details of the computer functions and programming are found in [4,5]. In this paper, the procedures and applications of this Formian program adapted to varax domes are described and illustrated.

The principles and procedures for generating different configurations of varax domes are presented in the paper. The computer schemes necessary to accomplish these kinds of dome shapes are illustrated. Varax domes with different numbers of sectors, different numbers of divisions of the arc length and the bottom beam, and with and without an apex ring are presented. Also, different arrangements of the purlins are illustrated as are applications of inherent Formian functions to generate special shape effects on varax domes.

1

H. Nooshin, P. Disney, "Formian 2", Multi-Science Publishing Co Ltd, 1997.

2

H. Nooshin, P. Disney, "Formex Configuration Processing", International Journal of Space Structures, Special issue, 15(1), 2000. doi:10.1260/0266351001494955; 16(1), 2001. doi:10.1260/0266351011495313; 17(1), 2002. doi:10.1260/026635102760123042

3

H. Nooshin, "Formex Configuration Processing in Structural Engineering", Elsevier Applied Science Publishers, London, 1984.

4

U.A. Girhammar, D.H. Pan, "Implementing Varax Dome Functions into Formex Configuration Processing" (to be submitted).

5

U.A. Girhammar, D.H. Pan, "Generating Varax Dome Configurations using Adapted Formian Program" (to be submitted).

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