City Quay Gardens is a unique urban design intervention that regenerates and reinvents Belfast’s historic docklands situated adjacent to the Belfast Harbour Commissioners Building. The architectural design by Gillespies enhances the garden with playful elements, among which is the eye-catching ‘Gateway Nest’.

The Nest is a sculptural installation composed of interwoven oak glulam rings, evocative of a bird’s nest, suspended between four angled steel columns. Engineered by Mule Studio, the structure employs an innovative lateral load transfer strategy to reduce the size of the slender curved glulam sections (200x91mm) and minimize connection points, particularly under wind loads. Reflecting this structural clarity, each ring segment is fixed using a single bolt, directly expressing the pin-like behavior within the smallest timber sections.

Karamba3D played a central role in Mule Studio’s structural design process, particularly in addressing the project’s tight timeline and complex design constraints. It enabled the team to rapidly iterate and  quickly assess a range of structural options. Early in the project, Karamba3D was used to understand the sculpture’s global behavior under gravity and wind loads. As the design progressed, the combination of Karamba3D simulations and hand calculations allowed the team to identify and focus on critical stress zones.

One of the principal challenges was managing the lateral loads with very small glulam elements and managing the feasibility of timber-to-timber and timber-to-steel connections within small sections. Karamba3D allowed very fast exploration of the releases between elements and of the load path optimization for minimum connection forces. Cycling through different options and seeing the member forces allowed for the engineering to achieve its aims. In the end the primary support connection was visually expressed as a single pin in the realized structure, mirroring the analysis assumptions explored with Karamba3D.