Wrapped Hybrid Tubes

为了用混凝土建造轻质结构，必须发展新的建造理念来取代传统的重型建筑技术来建造混凝土结构。这些建筑理念导致了形式优化结构(形式追随力)，但也在材料选择上产生了新的组合，即材料追随力。除了有利的生产条件外，这两个原则相结合的思想构成了本申请的核心思想。Funa和Flora证明，除了贝壳原理外，管的原理是自然轻量化施工中最有效的方法之一。管子的原理以其中空的圆柱形为特征。在加载时，由于其恒曲率，应力分布不会出现峰值。此外，筒体结构还具有承载能力与重量之比低的特点。这一自然现象在林德舒尔特的论文中被采纳，并导致了高性能混凝土结构的发展。在本项目中，这种现象甚至被用来通过额外的碳纤维缠绕来推进结构设计。因此，本研究项目的目的是对缠绕混杂管件进行优化设计，使其成为与材料和形状相关的轻质结构。包括了相关的极限荷载和剩余荷载的计算方法。作为该设计的一个特殊特点，横截面中的每个单独组件在荷载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相对较薄的高性能混凝土核心层形成的。核心层的主要任务是接收压应力。核心由内外两块钢板包围。这些钢板通过支撑作用创造了一定的延性。此外，这些板还可用作永久模板。自己的初步工作表明，如果支撑在纵向尽可能柔软，在圆周方向尽可能坚硬，则支撑效果最好。这种各向异性行为可以通过纤维增强聚合物作为额外包裹的材料来实现。为了建立描述中心荷载和偏心荷载作用下混合缠绕管承载性能的模型，相关的三种结构构件(混凝土芯材、钢板和碳纤维缠绕)将在试验和数值研究中有所不同。材料模型将被用于海上风能建设中灌浆接缝的数值计算，这些模型已经在LUH成功使用。这样，一种新型的混凝土轻质结构将被建立起来。

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.