From Jointing Systems to Light-Weight Structures: Hybrid, dry-fit beam, surface and spatial structures made of UHPFRC

作为正在进行的SPP1542的一部分，申请者正在进行子项目：开发用于几何复杂表面和由超高性能混凝土制成的梁单元的新型连接系统。研究的重点是开发用于传递压力、弯矩和剪力的超高性能混凝土薄壁构件的干配合连接系统。主要的方法是通过提高接合区的精度和几何复杂性来实现高机械效率。除了精确的装配外，构件还采用整体筋单元施加轴向预应力。目前正在开发用于以下超高性能混凝土构件的新型连接系统：用于传递压力的轴向加载和干配合薄壁管，用于梁结构中导向力的薄壁管的弯曲刚度节点单元，以及用于精确组装分段壳体构件的线形干配合连接系统。第一笔资金中确定的目标在第一个研究期结束时达到。到目前为止，这些结果已经发表了几次。后续应用的目标是将之前开发的超高性能混凝土构件的新连接原理转化为强大的轻质梁、面层和空间结构。其目标是通过将单个模块化梁和壳单元智能地耦合成杂交的、协作的支撑单元和系统来提高结构部件和系统的承载能力。通过结合与抗剪、平面或曲面单元相关的干配合杆，可以实现各种相关的建筑结构类型，主要是从弯曲承重结构到优化壳体。第一个项目阶段的前提条件仍然有效：使用超高性能混凝土来改善抗拉性和后开裂性能，通过预应力进行干配合连接和高效的材料利用。由于在本研究项目中并不是所有可能的梁和壳的几何组合都可以研究，因此从可能的支撑单元组合中选择了三个相关的施工实例：将梁和壳单元组合成单轴预应力梁单元、将梁和壳单元组合成正交双向预应力面层结构和将梁和壳单元组合成曲线空间结构。根据几何约束，三维空间中的杂交结构体系和单元可以作为梁和曲面，主要作为受弯构件或作为膜结构。

As part of the ongoing SPP1542 the applicants are working on the subproject: development of novel jointing systems for geometrically complex surfaces and beam elements made of UHPC. Focus of the investigation is the development of dry fit jointing systems for thin UHPFRC components for the transmission of compression, bending and shear forces. The main approach is to achieve a high mechanical efficiency through increased precision and geometric complexity in the jointing area. Besides precise fitting the components are axially prestressed by integrated tendon elements. The novel jointing systems are being developed for the following UHPFRC components: Axial loaded and dry fit thin walled pipes for the transmission of compressive forces, bending stiffness node elements of thin walled tubes for guiding forces in beam structures, as well as line shaped dry fit jointing systems for accurate assemble of segmented shell components. The objectives identified in the first funding are reached by the end of the first research-period. The results so far have been published several times. The aim of the subsequent application is now to transfer the previously developed new jointing principles for UHPFRC components into powerful light weight beam, surface and spatial structures. The goal is to increase the load bearing capacity of structural components and systems by intelligent coupling of individual modular beam and shell elements into hybrid, cooperating supporting elements and systems. By combining dry fit rods associated with shear resistant, flat or curved surface elements a variety of relevant building structure types can be realized mainly from the bending load bearing structures towards optimized shells. The preconditions of the first project phase remain valid: Using UHPFRC to improve tension resistance and post cracking behaviour, dry fit jointing and efficient material utilization through prestressing. Since in this research project not all possible combinations of beams and shells in their geometric diversity can be investigated, exemplified three relevant construction practice cases from the possible support element combinations for the research program are selected: combination of beam and shell elements into a uniaxial prestressed girder element, combination of beam and shell elements into an orthogonal biaxial prestressed surface structure and combination of beam and shell elements into curved spatial structures. Depending on the geometric constraints the resulting hybrid structural systems and elements in three dimensional space can work as beams and surfaces as mainly bending loaded component or function as membrane structure.