This project focuses on the structural design of a set of stairs forming part of the DTU 313 building at the Technical University of Denmark (DTU), located in Kongens Lyngby, Denmark. The stairs are integral to the architectural layout of the building and consist of three main sections, each developed to meet the spatial and structural requirements of the project.
The first section is a single-flight stair connecting levels E1 and E5. Structurally, each stair is formed by two 120 mm CLT lateral panels that act simultaneously as the main load-bearing elements and as parapets. Between these panels, a series of 180 mm CLT transverse panels serve as the steps while also contributing to the overall structural stability. The stair is connected to the main building beams through the 120 mm CLT panels using screw connections, ensuring both rigidity and ease of assembly.
The second section is a double-flight stair connecting the ground floor to level E1. The height difference required the design of two runs separated by an intermediate landing, allowing a change in direction between flights. Another landing is located at the top of the upper flight. Structurally, the intermediate landing consists of a 180 mm CLT panel supported by steel beams, which are anchored to a concrete wall on one side and suspended from the main glulam beams by steel hangers on the opposite side.
Each flight in this section follows the same structural system as the single-flight stair: 120 mm CLT lateral panels act as both load-bearing elements and parapets, with 180 mm CLT treads connecting them transversally. The flights are fixed to the main structure by means of screwed connections. In this configuration, the CLT slab panels span between steel cantilever beams supported on the surrounding concrete walls for the two lower flights. The upper flight slab is supported on one side by a 120 mm CLT panel spanning between the highest cantilever beam and the main ground floor structure, while on the opposite side it rests on a steel beam designed by others.
Degree of Freedom was responsible for the structural design and detailing of all stair elements.
