Originally designed in the 1960s, Poultry Market Roof is a doubly curved elliptical paraboloid 76mm thin concrete shell spanning 70m by 40m. The structure remains one of the largest and shallowest of its kind and sits at the forefront of structural engineering. Sixty years later, and beyond the originally envisaged design life of the structure, the challenge was to develop a strategy to justify the continuing use of the roof while transforming the space below into the new London Museum.
This challenge was further heightened when a point-cloud survey showed the thickness and shape of the roof to be out of tolerance from the intended design, and material tests showed the concrete to be both weaker and less stiff than originally intended. The combination of material and geometric deviations, both of which impact the capacity of the structure, necessitated a detailed analytical investigation. An innovative approach, which assessed the behaviour of the roof probabilistically, was developed to meet the modern-day performance requirements without requiring strengthening works, achieving the most sustainable outcome.
This project highlights the pivotal and unique role structural engineers play in breathing new life into existing structures. The iconic roof required extensive structural engineering analysis and thoughtful consideration to prove that maintaining the existing structure was the safest and best solution.
The project showcases how to “do nothing” through deep engineering analysis and insight, showing a profound understanding of structure and a vision for making a positive impact to our environment. The structural engineers undertook exceptional forensic structural analysis and demonstrate significant decision-making skills and technical knowledge.