Load-bearing behavior of shape-optimized struts made of UHPC

Under Priority Program 1542 “Concrete light. Future concrete structures using bionic, mathematical and engineering formfinding principles”, funded by the Deutsche Forschungsgemeinschaft (DFG), the aim of the subproject “Shape optimized filigree rods made of UHPC and non-corrosive CFRP-reinforcement for variable three-dimensional trusses” is to develop shape-optimized struts and prestressed ties made of innovative materials in accordance with the principle “form follows force”. By theoretical and experimental investigations on these two components fundamentals for the realization of modularly constructed slender concrete truss supporting structures shall be created. This paper gives an overview of the investigations that have already been carried out on the shapeoptimized struts. First, the key ideas of the entire subproject are briefly presented. Subsequently, relevant material-specific characteristics of ultra-high performance concrete (UHPC) and carbon-fiber-reinforced polymers (CFRP) are illustrated and fundamentals concerning the load-bearing behavior of slender concrete struts are discussed. Essential objectives referring to the development of the struts, their optimized shapes, deduced by numerical analyses, and the results of finite element analyses for unreinforced and reinforced optimized and cylindrical struts with identical volume are shown. Finally, the paper gives details of the planned test scheme and the production process as well as the conclusions from first component tests on optimized and cylindrical struts.