Light, microreinforced UHPC shell structures optimised to deformations using the example of parabolic trough collectors in concentrating solar power plants

壳体结构由超高性能混凝土和微筋或玻璃钢网组成。根据“形式随力”的指导原则，已被证实是极细长、抗偏转和可生产的，在第一阶段具有打击表面的精度。人们刻意把焦点放在太阳能发电厂的抛物面壳槽上，这些槽能集中阳光以获得绿色能源。这些结构注定要用于基础和详细的研究，因为它对偏转限制的太阳跟踪、沙漠中的环境暴露和质量保证的系列生产的要求非常复杂。所采取的方法是互动、跨学科和多层次的，包括概念和组成部分设计以及详细的规定。科学分析伴随着实验验证和迭代优化，涉及一系列工程学科，如混凝土设计、结构力学和动力学、风能以及太阳能和材料工程。在当前运行期内，探讨了边界条件，调查了具体的影响条件，评估了精度要求，并开发了数值模型。对多准则优化算法进行了修改和测试，并对结构的刚度和振动安全特性进行了校核。在实验中，已经设计了足够的混凝土混合料，并建立了一套几何测量程序-能够验证外壳的形状精度-已经建立。最后，互动研究活动合并成一个由UHPC制成的抛物面槽式集热器的创新全尺寸原型。抛开抛物线槽的最新发展，可以显著增加长度和宽度，在这里，第二个阶段的基本创新旨在实现空心而不是引入预应力的单壁壳。这样，在保持甚至放大结构抗变形刚度的同时，结构的重量也会大大降低。此外，可以有效地提高UHPC的压缩性能比。应通过响应面上基于模拟的优化技术捕捉几何、材料和风荷载以及服役过程中结构退化引起的随机不确定性，以确保结构的稳健性。风洞试验将提供准静态但也可多准则的瞬变风压数据，用于全瞬变模式分析。试验部分包括空心网壳结构根据模板、制造工艺和加固技术所需的一般但具体的节点设计。最后，设想了一个具有摄影测量证明的表面精度并符合上述所有理论设计要求的全尺寸收集器原型。

Shell structures made from UHPC and micro-reinforcement or GRP meshes acc. to the guiding principle "form follows forces", have been confirmed to be extremely slender, deflection-resistant and producible with striking surface accuracy during the first period. Focus has purposely been laid on parabolic shell-troughs of solar power plants concentrating insolation to gain green energy. These structures are predestinated for fundamental and detailed research due to its very complex demands for deflection-restrained sun tracking, environmental exposure in deserts and quality assured serial production. The approach taken is interactive, interdisciplinary and multileveled, including conceptual and component design as well as detailing provisions. Scientific analyses accompanied by experimental verifications and iterative optimizations are performed involving a bunch of engineering disciplines, e.g. concrete design, structural mechanics and dynamics, wind as well as solar and materials engineering. In the currently running period boundary conditions are explored, specific impact conditions investigated, precision demands assessed and numerical models developed. Algorithms for multi-criteria optimization have been adapted and tested as well as checks on the rigidity and vibration safety features of the structure have been performed. In experiments adequate concrete mixtures have been designed and a geometric surveying procedure - able to approve the shell's shape-accuracy - has been established. Finally, the interactive research activities merged into an innovative full-scale prototype of a parabolic trough collector made from UHPC. With respect to recent developments of parabolic troughs aside, that enable notably increased lengths and widths, here the essential innovations of a second period aim at the realisation of hollow instead of single-walled shells introducing pre-stressing. This way structural weight should be significantly decreased while its stiffness against deformation can be maintained or even amplified. Furthermore, the performance ratio of UHPC in compression can be efficiently improved. Stochastic uncertainties in geometry, material and wind loads and also due to structural degradation during service shall be captured by simulation based optimisation techniques on response surfaces to ensure structural robustness. Wind tunnel tests will deliver quasi-static but also multi-criteria, transient wind pressure data for fully transient modal analyses. The experimental part comprises the general but specific nodal design required by a hollow shell structure in accordance to formwork, manufacturing process and reinforcing techniques. Finally, a full-size prototype collector with photogrammetric proven surface accuracy and conform to all theoretical design requirements laid out above is envisaged.