Influence of Geometrical Parameters on Behaviour of Reticulated Timber Domes: Fid-Bau Portal

Influence of Geometrical Parameters on Behaviour of Reticulated Timber Domes

Pan, Dan H. / Girhammar, Ulf Arne

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. These types of domes have high stiffness in all directions along the surface and are kinematically stable. The dome is subjected to uniformly distributed load over entire structure. The dome model is generated with a preprocessor program called DOME-IN and analysed with 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, H/D; (b) straight relative curved types of main beams in the triangular networks versus mesh density; (c) perpendicular relative parallel types of purlin arrangements in the triangular networks versus the number of purlins; and (d) mesh density of main network members or size of triangular networks. 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. It is found that: (a) the optimum height-diameter ratio is H/D ≈ 0.3; (b) that straight beams in the triangular networks are preferred to curved beams, especially for higher mesh densities;(c) that purlins perpendicular to the latitudinal beams are preferable to purlins parallel to the latitudinal beams if there is a decking that provides bracing to the system; and (d) mesh densities with six sectors (n = 6) (lowest number of practical interest) and as many divisions of the arc beam and of the sector of the ring beam (m = k > 4), which is necessary in order to meet the design criteria for the dome, can be recommended.