Wrapped Hybrid Tubes

为了用混凝土建造轻质建筑，必须开发新的建筑概念，以取代传统的混凝土结构重型建筑技术。这些建筑概念导致了形式优化的建筑（形式遵循力），但也导致了材料选择中的新组合，即材料遵循力。除了有利的生产条件之外，将这两个原理结合起来的思想形成了本申请的核心思想。Funa和植物群表明，除了壳的原理外，管的原理是自然轻质结构中最有效的方法之一。管的原理是以其中空的圆柱形为特征。在加载时，由于其曲率恒定，应力分布不会出现峰值。此外，管状结构的特征还在于承载能力与重量之间的低比率。这一自然现象在Lindschulte的论文中被采用，并导致了高性能混凝土制成的高效结构的发展。在这个项目中，这种现象被用来通过额外的CFRP包裹来推进结构设计。因此，本研究的目的是开发一个优化设计的缠绕混合管作为轻质结构有关的材料和形状。包括相关的极限荷载和剩余荷载计算方法。作为这种设计的一个特点，横截面中的每个单独的组件在载荷传递过程中都被分配了特定的角色。该结构的主要组成部分是由一个相对较薄的高性能混凝土核心层。芯层的主要任务是接收压缩应力。核心是由内外钢板包围。这些钢板通过支撑作用产生一定的延展性。此外，这些板还用作永久模板。自己的初步工作表明，如果支承在纵向方向上尽可能软，而在周向方向上尽可能硬，则支承效果最有效。这种各向异性行为可以通过纤维增强聚合物作为用于附加包裹的材料来实现。为了推导出描述缠绕混合管在中心和偏心法向载荷下的承载性能的模型，三个相关的结构部件（混凝土芯、钢板和CFRP缠绕）将在实验和数值研究中变化。将使用材料模型，该模型已在LUH成功用于海上风能建筑中灌浆接头的数值计算。这样，将建立一种新型的混凝土轻质结构。

In order to build lightweight constructions with concrete, new construction concepts must be developed to substitute the traditional heavy building technique for concrete structures. These construction concepts lead to form optimized constructions (form follows force), but also to new combinations in the material choice in the sense of material follows force. In addition to favorable production conditions, the thought of uniting both of these principles forms the core ideas of the present application. Funa and Flora show that besides the principle of shell, the principle of a tube is one of the most effective methods in natural lightweight construction. The principle of tube is characterized by its hollow circular cylindrical shape. While being loaded there will occur no peaks in the stress distribution, because of its constant curvature. In addition, tubular structures are also characterized by a low ratio between load bearing capacity and weight. This nature phenomenon was taken up in the dissertation Lindschulte and led to the development of highly efficient structures made of high-performance concrete. In this project this phenomenon is used to even advance the structural design by an additional CFRP wrapping. Therefore, the aim of this research project is to develop an optimized design for wrapped hybrid tubes as lightweight structures relating to material and shape. Associated ultimate and residual load calculation methods are included. As a special feature of this design, each individual component in the cross section is assigned a specific role in the process of load transfer. The main component of the structure is formed by a relatively thin core layer of high-performance concrete. The main task of the core layer is to receive the compression stresses. The core is surrounded by an inner and outer steel plate. These steel plates create certain amount of ductility by supporting effects. Additionally the plates serve as a permanent formwork. Own preliminary work have shown that the supporting effect is most effective if the supporting is as soft as possible in longitudinal direction and as stiff as possible in circumferential direction. Such an anisotropic behavior can be achieved by fiber reinforced polymer as a material for an additional wrapping. In order to derive models for the description of the bearing behavior of wrapped hybrid tubes under centric and eccentric normal loads, the three relevant structural components (concrete core, steelplates and CFRP wrapping) are going to be varied in experimental and numerical studies. Material models will be used, that already are successfully used at the LUH for numerical calculations of grouted joints in offshore wind energy constructions. In this way, a new type of lightweight structures made of concrete will be established.