Master dissertation by Cédric Van Roy

La Tour du Midi is a 1960s office skyscraper distinguished by its complex, column-free structural system. This dissertation investigates the use of Preflex beams within the tower’s structural typology. Through a structural analysis of the building, it seeks to understand why this particular application of Preflex beams in high-rise suspended structures has remained a singular example, a question only partially explored in architectural discourse and here re-examined through the lenses of structural engineering and construction history. The study examines, through archival research, the rationale for implementing Preflex beams and their implications for structural complexity and the construction process. This is complemented by step-by-step calculations of residual stresses, highlighting the innovative character of the system. In addition, a comparative analysis of the Preflex beam system and an alternative steel solution is conducted to critically assess the claimed advantages of the Preflex approach in terms of structural efficiency. Finally, the research situates La Tour du Midi within its broader architectural and engineering context to identify additional influences on its structural design and to address what makes this typology unique. By reassessing this exceptional case, the dissertation demonstrates how innovative structural engineering methods can expand the boundaries of architectural possibility, while also showing how architecture and engineering can be shaped by the drive for innovation.