City officials in Teichland, Germany, wanted an icon and landmark for a future recreation area.
By Jan M. Brenny
That’s the impetus behind the construction of an 18-story, fabric-enclosed observation tower near the village of Teichland, Germany, about 60 miles (100km) southeast of Berlin.
The tower, completed in July, 2010, is one of the manmade features being built on a former open-pit coal mining site. Local officials are developing the area into a recreation destination; ultimately, planners will flood an excavated section of the site, creating a 4,700-acre lake. The tower sits on a future shoreline of that lake.
An affinity for fabric
In 2007, as the renovation project was being planned, local officials decided to sponsor a tower design contest. The announcement intrigued Daniel Slota, a student studying architecture at the technical university in nearby Cottbus. One year earlier, he had designed an ice and wool membrane sculpture for a Moscow snow festival. The experience exposed him to the potential of fabric in architectural applications.
“I found you could easily spin and morph shapes from one contour to another,” he says. As a result, Slota was inspired to try fabric “sculpting” on a grander scale and decided to enter the Teichland competition. After he spent three months designing the concept, city officials chose his rendering of a membrane-encased tower over other designs of wood and steel.
A team of experts
With concept in hand, officials next put together the project team. As membrane engineer, they chose Leicht Structural Engineering and Specialist Consulting GmbH; as architect, AWB Architekten; as fabricator, Taiyo Europe GmbH; for installation, Seilpartner GmbH; and as project manager/civil engineer, GRBV Ingenieure GmbH.
Slota had definite ideas about how he wanted the tower to look. He designed the membrane “with as few horizontal sections as possible,” he says. “For me, the continuous line from top to bottom was very important.”
To accomplish that, instead of working from the inside out—first designing the support structure and then the outer skin—the team considered the outside appearance first and then built the inside support structure accordingly, Slota explains.
“The architects and I explained to Leicht what we wanted,” he says. “They, together with Taiyo and Seilpartner, came up with the solution.”
Nuts and bolts
The tower’s concrete core holds an interior staircase, allowing visitors to climb to the top. Windows along the way provide views of surrounding landscapes through 8-inch (20cm) gaps between the fabric pieces.
Slota originally wanted one continuous membrane encircling the tower, but that wasn’t practical, he says. Views would have been blocked. “We first tried designing holes in the fabric, but that looked strange,” he says. Installation would also have been a problem, he says. Instead, three fiberglass pieces, each measuring half the length of a football field (51.23yd/47m) long and just over 6 yards (6m) wide, encase the structure. Teflon® and titanium dioxide coatings help protect the fiberglass from weathering and enhance its color.
Fixed rings at the tower’s top and base secure the material to the structure. Space between the concrete and fabric ranges from about 2 feet (23.6in/60 cm) at the tower’s midsection to approximately 10 feet (3m) at the base.
An underlying web of cables and braces keeps the fabric in place, yet still allows it to shift slightly. The slight movement creates a play of changing convex and concave shapes, according to Slota.
Several vertical cables are embedded in each of the three fabric pieces. Although not designed originally, the cables became necessary for stabilization and helped during installation, when springtime winds hindered the process, Slota says. And there was an additional benefit.
“The ropes create small light and shadow effects on the membrane,” he says. “We didn’t design it that way, but I’m glad to have them.”
Slota’s original concept differed from the actual tower in other ways. Initially, the core was to be steel instead of concrete. An early version also featured exterior ornaments, but they interfered with the viewing gaps, Slota says. Since the tower is a tourist attraction, designers added a 30-person-capacity observation deck at the top. Visitors who make the daunting 272-step climb are rewarded with panoramic views.
A museum, also not originally planned, occupies the base of the tower. Exhibits depict the history of open-pit coal mining in the area and offer a look at the history of other types of energy, such as wind and solar power.
The only horizontal pieces of fabric used are located at the base of the tower—mainly for practical purposes, Slota says. The first 10 feet (3m) of fiberglass are exposed to the most traffic, so they were designed to be replaceable. “We can change that membrane without having to change the entire thing,” Slota says. Otherwise, the tower is there to stay.
After his fabric education from this project, Slota has become even more of a fabric aficionado and says he will likely use it in future projects. He spent this past summer freelancing on various projects around Berlin. One was a temporary fabric pavilion.
“Membranes are one easy way to make complicated, organic forms,” he says. “You never imagined them before, so in the next project you make more complicated organic forms, and you grow to understand them.”