The effect of the masts and cables is to more than double the span of this same frame without cables. The shape of the cable-stayed frame follows the general pattern of the bending movement in a portal frame with pinned feet and deep haunches. The snow load of 410 kg per sq m is taken by axial forces in the cables and bending of the ridge beam and, if the load is asymmetrical, causes some cables to go slack. Load effects then become non-linear, that is the effects of different load cases may not be simply added together. Linear analysis is sufficiently good for the analysis of dead load effects however. The masts receive compression forces of up to 1100 tonnes from the cables. With wind forces acting at right angles to the main axis of the building, the lateral stabilising system allows the cable anchorage points to move up to 226mm in the east-west direction. As in any large structure, the increase of forces due to temperature variations is decreased as far as possible, in this case by pinned connections and sliding joints. However the main cable-stayed frame is internally indeterminate and has to absorb these forces; the transverse frames are flexible and bend under temperature stresses so that the concrete corner supports do not receive excessive horizontal force.
The total period of construction was 24 months. Steelwork was brought onto site in large sections and welded up in position.
With heavy snow loading a structure of strength and rigidity was required. However reasonable economy has been achieved by the elimination of ground anchors, the use of a continuous ridge member and the careful selection of angles and prestressing force in the cables. Higher prestressing forces would have increased the size of the ridge beam.
Notes:
axial force осевая сила
cable-stayed frame балочно-вантовый каркас
haunch n. консольный выступ
indeterminate adj. неопределённый
linear adj. линейный
go slack провисать
sliding joint подвижное соединение