Folded-plate and curved sandwich panels made of high performance materials for long-span roof elements

由非腐蚀性高性能材料制成的混凝土层的夹层结构，便于轻质、耐用和整体建筑结构按形式随力。建于20世纪初的壳体结构属于单功能建筑构件的范畴。然而，在承载能力和细长方面的巨大潜力是显而易见的。壳体和夹层结构的结合产生了结构构件，具有资源消耗小、能源效率高、模块化、隔音和防火等特点。在第一个和第二个资助期，研究了先张法折板和双曲线夹层结构的基本原理。除了开发一种可重复使用的碳纤维增强聚合物(CFRP)锚具外，还对高性能混凝土中先张法CFRP的粘结性能进行了表征，并确定了无裂缝传递区的最小厚度。在拉伸和剪切载荷下的成分测试中，核心层显示出很高的潜力，这些芯层是以包装的形式发泡的。折板、双曲先张法单壳梁和夹层壳梁的短时受弯试验表明，该设计具有较高的设计能力。本课题的目标是开发面向实际的生产技术，并与工业伙伴合作，建立由薄壁锯齿形屋面梁和双曲壳梁组成的大跨度带面板夹层单元的基础。为此，设计了中跨(约15m)和大跨度(约25m)结构。在第二步中，开发了一种适用于预制件厂的CFRP加固夹紧技术。对于薄壁折板和双曲混凝土面板，设计了CFRP钢筋网架，并需要开发特殊的模板。开发了大尺寸元件在聚氨酯包装中发泡的连接工艺。为了确保高的夹层作用，测试了销钉和连续剪切连接件的应用，这些连接件还适用于承载发泡过程中产生的负载。在数值模拟以及构件和大型实验测试中，几何形状和材料组合(UHPC、TRC、PU、连接装置、先张法CFRP)是不同的，以根据形式随力实现荷载传递。在分析了单层荷载传递机理的基础上，建立了考虑短期荷载和长期荷载的折板和双曲夹层梁工程模型。

Sandwich constructions with concrete layers made of non-corrosive high performance materials, facilitate light, sustainable and integral building structures according to form follows force. Shell structures built in the early 20th century belong to the group of mono-functional construction members. Nevertheless a high potential regarding load carrying capacity and slenderness is obvious. The combination of shells and sandwich constructions leads to structural members, which exhibit coexisting features, namely small consumption of resources, high energy efficiency and modularity as well as sound insulation and fire protection.In the first and second funding period the basic principles for the establishment of pre-tensioned folded plate and doubly-curved sandwich structures have been investigated. Besides the development of a reusable anchorage for CFRP (carbon fibre reinforced polymer), the bond behaviour of pre-tensioned CFRP in high performance concrete was characterised and a minimum thickness for a crack-free transmission zone was determined. In component tests under tension and shear loading, a high potential of core layers, which were foamed in pack could be shown. Flexural testing under short-time loading on folded-plate and doubly-curved pre-tensioned single shell beams and sandwich shell beams already showed a high capability of this design.The goals of the requested project are the development of practice-oriented production techniques and to establish the basis of long-span sandwich elements with facings made of thin-walled sawtooth roof beams and doubly-curved shell beams in cooperation with industrial partners. For this purpose, designs of medium-span (c. 15 m) and long-span (c. 25 m) structures are worked out. In the second step a clamping technology for CFRP reinforcement for the application in precast-plants is developed. For thin-walled folded-plate and doubly-curved concrete facings CFRP reinforcement grids are designed and special formwork needs to be developed. The joining process of large-sized elements by foaming in pack of polyurethane is developed. To ensure high sandwich action, the application of pin and continuous shear connectors is tested, which additionally are appropriate to carry loads induced due to the foaming process. In numerical simulations as well as component and large-scale experimental testing geometries and material combinations (UHPC, TRC, PU, connecting devices, pre-tensioned CFRP) are varied to achieve a load transfer according to form follows force. After the characterisation of single load transfer mechanisms, an engineering model for folded-plate and doubly-curved sandwich beams is derived, which accounts for short-term and long-term loading.