The shape of the sculpture can be seen from the cross-section above.
The external curved surface is shaped as a spherical cap, where the diameter of the sphere is 88m. The diameter of the cap at ground level is 60m. Staircases 10m wide are built into the spherical cap facing each of the four corners of the globe. The staircases have very large steps (about twice the size of a normal staircase). The staircases end in a platform about 11m over ground level. The interior of the sculpture can be viewed through an opening in the spherical cap measuring 10m x 10m.
Four pillars are placed at the corners between the staircases. The pillars rise about 30 m above ground level and are topped with red domes, illuminated from below and equipped with spires to attract lightning.
The base of the sculpture is constructed as the spherical cap, where the sphere has a diameter of 220m. Consequently, the centre of the base is 4m below ground level.
The floor of the sculpture is finished with an asphalt coating.
The external spherical cap, the staircases and the four pillars are constructed of steel. All visible surfaces are finished with black paint. A fifth pillar is placed in the middle of the four pillars. A gas burner is located in the fifth pillar, about two meters under the viewing platform.
At random intervals, the gas burner shoots a pillar of flame about one meter wide and 8.4m high up between the pillars. The gas flame is ignited by a sensor-controlled computer – once within an 18-day period. Each time, the flame burns for about 25 seconds.
The pillars are earthed so that they can function as lightning attractors. In the event of a lightning strike, there will be a powerful resonant sound effect in the interior of the sculpture.
The individual steel units have been sandblasted and then treated with a rust prevention coating of 15-20 µ zinc primer. After assembly of the units in the engineering workshop, the pre-treatment was repaired along all seams.
When the steel construction had been assembled and all seams completed, there were further repairs to the pre-treatment prior to the final treatment. The final treatment consists of at least 30 µ epoxy-polyurethane or acrylic, three coats being applied to all exterior and interior surfaces. The steel columns were similarily treated prior to being erected.
The surface treatment has a maximum lifespan of 15-20 years, provided that any damage is repaired completely and promptly.
The technical specifications for the gas flame are contained in the report from Naturgas Midt-Nord, which has made technical calculations in respect of gas and safety.
The pillars were prefabricated in a factory. Each pillar has a diameter of 2m at the base and 1.6m at the top. The steel pillars are topped with red glass domes with internal illumination.
A damp course has been formed under the asphalt base by laying down a 15cm layer of shingles. The drain pipe system is constructed as a percolation drain, which is led to the municipal rainwater system.
The construction of the drain pipe system has been based on the soil and ground water situation at the site. Drainage from the exterior of the dome is through a rock filling along the circumference of the sculpture with the rainwater being drained off to the public rainwater system.
The steel dome is supported partly by four steel pillars and partly by the circular continuous footing. The foundations for the pillars and the continuous footing are cast on site in excavations to frost-free depth.
The width of the continuous footing varies from 0.8 to 1.0 metres, depending upon the bearing capacity of the soil. The foundations for the pillars and continuous footing were cast in situ in shuttering.
Each of the four pillars has a lightning conductor. The lightning conductors are connected to a common earth which is integrated into the foundations of the pillars and the continuous footing.
A hollow pillar is situated in the middle of the dome. This pillar contains the machine room for the gas installation. A gas burner is located on top of the pillar, approximately 2 m under the top of the steel dome.
The curved surface of the sculpture is fabricated from 5-6mm sheet steel which is stiffened with rolled IPE 360 profiles (radial) and HE 140 A profiles (circular). The staircase is also constructed of 5-6 mm sheet steel.
All fabrication of sheets and profiles, and of the components of the sculpture (stringers and steel pillars) was carried out in engineering workshops. All components were fabricated in the maximum size suitable for transportation. The assembly of these components to form the completed sculpture was undertaken on site with the assistance of mobile cranes.
All seams between the steel sheets are welded and the joints between the sheets sealed with weld beads prior to surface treatment.
The steel construction is secured to the continuous footing by fittings cast in the concrete. Likewise, there is a solid connection to the four steel pillars. Other than these connections, the steel construction is self-bearing.
The total amount of steel used is about 400 tonnes.
In order to avoid any misunderstandings, it must be emphasised that it is extremely dangerous – and may have fatal consequences – to be on or near the sculpture during thundery weather conditions.
© Ingvar Cronhammar