The stadium roof is undoubtedly the most technologically complex element of the entire building. Its design, which appears deceptively simple, resembles a tensioned veil supported by a series of vertical masts. Given the vast surface area to be covered—approximately 41,000 m²—the project required the most advanced structural modelling and mathematical engineering tools in order to achieve the extreme lightness and slenderness of its elements.
Structurally speaking, the roof follows a relatively straightforward principle: fifty steel columns support a balanced system made up of two main structural rings. The outer ring—also the primary compression ring—consists of thick steel beams working under intense compressive forces. The inner ring is far lighter, made up of a dual-layer cable system that works under high tension. These two rings are connected by fifty pairs of radial cables, joined by steel struts, which also work under tension—similar to the spokes of a wheel.
Once the inner ring is lifted into place using a pneumatic system (always anchored to the outer ring), the radial cables are pulled taut and the forces between both rings are balanced, forming a stable structure. At that point, a continuous surface can be installed—this is the actual element that provides protection from sun and rain.
This collaborative system of steel and cable enables the covering of large spans (up to 70 metres) with a minimal amount of material. The final roofing solution chosen for construction is a next-generation membrane, specifically designed for high tensile strength, contributing to the overall bracing of the steel structure. At the same time, it is extremely lightweight and durable, and thanks to its slight translucency, allows a certain amount of natural light to filter through.