Metal dome - Vitoria - Spanien

Abstract

This self-supporting dome, in the shape of a spheric cap and with a 5.850 m² surface, rests upon 36 concrete pillars, placed at an equal distance from each other in a circle with a diameter of 76 m and a corbeling of another 3 m. The clear height between the horizontal level of the supports up to the centre of the dome is 15 m and the total weight of the structure is 102 t. The dome is defined by a two layer tetrahedral grid framework. The supporting nodes belong to the inner layer which has a variable depth and it diminishes towards the crown as the loads it has to support become smaller. This is a logical result of the adopted triangulation which is made possible by the construction with sucessive rings. Consequently the assembly has been simplified and the construction time has been reduced. The assembly has been done constructing the first two rings in their final position and the rest of the dome in two parts. These were constructed on the ground and were then lifted by means of telescopic crane. The structure has been designed to stand a load of 120 kp/m² and was calculated by means of the assimilation method. This method determines the elastic constants of a continuous shell, with the same dimensions, shape and boundary conditions as those of the real dome, assuming the same deflections. From these forces in the ficticious assimilated dome, the tensile and compressive forces in the real grid framework can be worked out.