Starting situation

For the atmosphere measurement on the Cape Verdian islands a flexible tower was planned. The minimum lifetime of the tower was expected with 10 years. The corrosion protection of the tower and the prestressed ropes was to be laid out for the increased salt concentration due to the near sea and for the increased abrasion due to the sand content of the steady wind from Africa (Sahara). Because of missing wind standards for the Cape Verdians the load assumptions for the maximum wind forces were derived from wind measurements given from an approximately 20km distant airport.

Description

The mast is prestressed with 12 ropes and consists of usual scaffold components. All components can be easily separated from each other allowing an easy disassembly. The plattform at the height H=30m is equipped with changing measurement instruments and easily can be reached by an integrated staircase.

What we did

We designed and verified the complex system of the scaffold components and the prestressed ropes. All stiffening components of the tower were idealized considering their nonlinear stiffnesses at the joints. The stresses and strains were calculated for the imperfect system including the nonlinear geometry (Th.III.O.) for the ropes considering also snap through due to lifting wind loads.