Location: Bregenz, Austria
Market: Arts & Entertainment
Product: Type AAF Girder Clamps
Client: Bregenzer Festspiele GmbH
Engineer & Contractor: Biedenkapp Stahlbau GmbH

The Bregenzer Festspiele (Bregenz Festival) is world-renowned for its open-air opera productions set directly on Lake Constance. Every two years, the iconic floating lake stage undergoes extensive structural modifications and reconfigurations to accommodate new, visually complex set designs for upcoming theatrical seasons.

For the structural reconfiguration of the stage's substructure, the contractor, Biedenkapp Stahlbau GmbH, required a highly durable and adjustable clamping solution to connect the supporting steel frame. Crucially, parts of the installation had to be carried out underwater, where beam-to-beam sections joined the submerged frame and anchored into timber support piles below the water’s surface. Traditional field welding or drilling was unsuitable due to environmental restrictions, limited visibility, and the logistical challenges of working underwater.

Lindapter worked alongside Biedenkapp Stahlbau GmbH, providing technical support and connection drawings to engineer a high performance clamping detail using Type AAF adjustable girder clamps. To construct the substructure, girder clamps in an 8-bolt configuration were used for 90-degree cross-over beam connections, while 4-bolt girder clamp configurations secured steel saddles directly to the underwater timber support piles. All supplied Type AAF clamps were hot dip galvanized to deliver the required corrosion resistance in the lake’s marine environment.

Specialist diving contractors wearing wetsuits installed the clamps directly underwater using simple hand tools. The adjustability of the Type AAF allowed divers to easily manipulate and align the heavy structural members underwater before applying the specified torque, enabling fast and straightforward assembly without requiring field drilling or specialized submerged welding equipment.

By eliminating the need for drilling or welding, the installation avoided damage to anti-corrosion coatings and eliminated environmental risk to Lake Constance. The robust, hot dip galvanized connections provided the necessary load capacity and long term durability to safely support the floating stage frame throughout the festival's demanding performance schedule.

• High Adjustability: Lateral alignment flexibility allowed divers to easily position beams and overcome site conditions underwater.
• No Field Welding or Drilling: Avoided hot work and drilling in sensitive underwater environments, preserving structural integrity.
• Corrosion Resistance: Hot dip galvanized finish ensured robust protection against long term exposure to water and weather elements.
• Fast & Safe Installation: Simplified underwater assembly for specialist divers using standard hand tools to achieve required clamping force.
• Full Technical Support: Lindapter provided detailed connection drawings and engineering advice to ensure precise, code compliant structural joints.