Sandwich panels with folded plate and doubly curved UHPFRC facings

Sandwich-structured composites represent an efficient method to establish building envelopes which concurrently satisfy several demands. Besides low self-weight with high load-bearing capacity, sandwich panels provide sufficient physical properties, such as heat and sound insulation. In general, sandwich panels for applications in building industry are made of flat or thin profiled metal sheets or thick concrete facings. However, standard elements are limited to short spans. In contrast, spatially shaped concrete structures with folded plate or curved geometry provide high stiffness and load-carrying capacity even for thin elements. The application of folded plate and curved concrete structures to sandwich panels combines the advantages of both construction methods. To realize thin facings in various shapes, high performance cementitious composites are advantageous. Ultra-high performance fiber reinforced concrete (UHPFRC) provides high compressive and tensile strengths with ductile material behavior. The application of non-corrosive reinforcement, for example, carbon fiber reinforced polymer (CFRP), allows for filigree concrete elements with a thin concrete cover to only fulfill bond requirements. For sandwich panels with folded plate or curved facings, new production methods are necessary to account for cross-sections in various shapes. This paper introduces the basic ideas of non-planar concrete sandwich elements for long-span roof structures and the developed production methods.