The Peter Hall Performing Arts Centre is a new 400-seat theatre and teaching space for The Perse School, Cambridge. The triple-height foyer space has an exposed concrete frame with a two-way spanning timber diagrid roof, viewable from the courtyard through the double-height glazing above first floor level. The foyer operates as a café during the day, and a reception space for audiences during events. Materials have been selected for their robustness both as structural elements and to withstand the extensive use throughout a school day. Exposed concrete is used throughout the building, as the structural frame and architectural design, with the warmth, stability and acoustic benefits offered by timber exploited for the diagrid roof and its supports, and throughout the auditorium space.
The timber diagrid roof has 126 individual BauBuche Laminated Veneer Lumber (LVL) members connected at node points to create an elegant, efficient structure. The internal nodes have been designed as hidden moment connections, innovatively using glued-in steel rods bolted to bespoke octagonal steel nodes. A standard design code for this type of construction doesn't exist, and so testing at University of Bath was required to confirm the pull-out capacity of the threaded steel rods bonded into the LVL. The unique shape of the octagonal node, chosen for strength, required 3D analysis to rule out unwanted deflections and check stresses around the bolt holes.
The diagrid roof is supported by slender LVL columns and an exposed concrete structure along the edges. The perimeter connections are bolted steel flitch plates, designed as pins to allow the LVL columns to be as slender as possible. The roof is also supported by a single line of internal support from a double-height exposed concrete shear wall, which along with the surrounding concrete structure, provides stability to the foyer.