Keywords: reticulated domes, non-linear analysis, geometrical parameters.

Domes are very efficient structural systems for long clear span buildings. The introduction of laminated timber highlighted the economic advantages of this material and led to the use of timber domes even for very large spans. In this paper, reticulated timber domes of triangular network shape with decking and bottom tension ring are considered [1]. These types of domes have high stiffness in all directions along the surface and are kinematically stable. The dome is subjected to evenly distributed load over entire dome. The dome model is generated by a preprocessor program DOME-IN [2] and analysed by ABAQUS.

The focus of this paper is to evaluate the behaviour of reticulated timber domes with respect to (a) height-diameter ratio of the dome, ; (b) straight relative curved types of main beams in the triangular networks versus mesh density; and (c) perpendicular relative parallel types of purlin arrangements in the triangular networks versus the number of purlins. The influence of these parameters on relative maximum deflection of the dome, relative critical pressure for global buckling of the dome, relative maximum axial forces and relative maximum bending moments in the network members, is evaluated.

In a companion paper, the ring beam stiffness effect on the behaviour of the reticulated dome is evaluated [3].

It is found that the optimum height-diameter ratio is . For higher mesh densities or in other words for greater number of divisions, the difference between using straight or curved beams is negligible, except with respect to bending moments. The use of straight beams gives always much lower values of bending moments than what is obtained in case of curved beams for all mesh densities. Then, for higher mesh densities, straight network beams are preferred.

Concerning purlin arrangements, purlins perpendicular to the latitudinal beams in the triangular networks is generally preferable to purlins parallel to the latitudinal beams. The difference between the two arrangements is negligible with respect to buckling load and normal forces, but significant regarding deflections and very big concerning bending moments.

1

Girhammar, U.A. et al., "Design of a Glulam Dome in Borlänge of 123 m Span Length", Martinson AB, Teknisk rapport 88:2, Bygdsiljum, Sweden, 1988 (in Swedish) (internal report).

2

Pan, D.H., "Dome-In - A Preprocessor Program for Reticulated Dome Calculations", Report 2001:1, Civil Engineering, Department of Applied Physics and Electronics, Umeå University, Umeå, Sweden 2001.

3

Pan, D. and Girhammar, U.A., "Ring Beam Stiffness Effect on Behaviour of Reticulated Timber Domes", TProceedings of The Sixth International Conference on Computational Structures Technology, Topping, B.H.V and Bittnar, Z, (Editors), Paper 126, Civil-Comp Press, Stirling, UK, 2002. doi:10.4203/ccp.75.126

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