Optimized Building Envelope: Lightweight Concrete with Integrated Steel Framework

This study presents a novel construction method for prefabricated wall elements by integrating a framework made of thin-walled sheet steel profiles into an optimized thermally insulating lightweight aggregate concrete (LAC) building envelope. The load-bearing function of the framework is provided by cold-formed Sigma-profiles, which are spot-welded to non-load-bearing U-profiles at the vertical ends. The LAC shapes the wall and stabilizes the thin-walled steel profiles against buckling, but has no further load-bearing function, thus allowing the reduction of its necessary compressive strength and subsequently minimizing its density. As a result, the LAC exhibits strength and density values well beyond existing standards, providing highly competitive thermal conductivity values that meet today's energy requirements without the need for additional insulation materials. Tailored composite specimens verify the stabilization of load-bearing sheet steel profiles by the LAC, which not only prevents buckling but also increases the load-bearing capacity of the overall system. The feasibility of this approach is validated by the production of two prototypes, each comprising a full-sized wall, in two different precast plants using distinct process technologies.