Optimization approaches for robust and durable reinforced concrete and fibre concrete structures under consideration of scale bridging polymorphic uncertainty modelling

该项目的总体目标是为钢筋和钢纤维混凝土结构的面向寿命的设计开发计算可靠性和优化方法，从而可以在结构的整个寿命期间跟踪多态不确定性的影响。相互作用的负载和环境引起的恶化过程和传播的不确定性，通过多个空间和时间尺度的比例桥接模型结合物理健全的模型钢筋和纤维增强混凝土和多场结构分析。考虑多态不确定数据（随机，区间和模糊数的组合，以及广义不确定性模型）和概率荷载模型的结构水平，而采用计算模型来表示结构退化过程在较低的尺度导致了高度增加的复杂性的问题。为了科普这种复杂性，并减少建模工作，计算策略，其特点是在结构的关键位置结合高保真度模型（热点）和低保真度模型，并结合能够考虑到时间依赖性和高维输入空间的模型简化技术，必须开发结构一级的模型。·材料尺度的不确定性（纤维分布、裂缝粗糙度、钢-混凝土粘结性能）和人为引起的不精确性（例如钢筋位置）如何通过空间和时间尺度传播并影响结构可靠性？·FRC结构的铸造过程模拟是否有助于减少FRC结构设计中的不确定性？·混凝土和钢筋设计（纤维与传统钢筋和混合设计）以及相关的不确定性水平如何影响结构的耐久性和寿命？·考虑到钢筋设计、开裂和腐蚀性物质进入之间的不确定相互作用，是否有可能确定优化耐久性设计的混凝土保护层尺寸？·使用高性能FRC材料的预应力混凝土结构的（改造）设计如何影响疲劳性能，从而影响结构的预期寿命？将通过一个参考桥梁项目对考虑RC和FRC结构设计中多态不确定性的计算方法进行测试，该参考桥梁项目的特点是UHPFRC和RC桥面板和预应力梁的组合，材料数据和湿度监测数据可用。

The overarching objective of this project is the development of computational reliability and optimization methods for the lifetime-oriented design of reinforced and steel fibre concrete structures, which allow to follow the influence of polymorphic uncertainties throughout the life of the structure. Interacting loading and environmentally induced deterioration processes and the propagation of uncertainties through multiple spatial and temporal scales are accounted for by scale bridging models in conjunction with physically sound models for reinforced and fibre reinforced concrete and multifield structural analysis. Consideration of polymorphic uncertain data (combinations of stochastic, interval and fuzzy numbers as well as generalized uncertainty models) and probabilistic load models on the structural level while employing computational models to represent structural degradation processes at lower scales leads to a highly increased complexity of the problem. To cope with this complexity and to reduce the modelling effort, computational strategies, characterized by combining high fidelity models at critical locations of the structure (hot spots) and low fidelity models at the structural level in conjunction with model reduction techniques able to account for time dependence and high dimensional input spaces must be developed.Taking into account the results achieved in the 1st funding phase, the following main scientific questions are addressed in the 2nd phase of the project:• How do uncertainties at the material scale (fibre distribution, crack roughness, steel-concrete bond properties) and human induced imprecisions (e.g. position of reinforcement) propagate through spatial and temporal scales and affect the structural reliability?• Can simulations of the casting process of FRC structures help reducing uncertainties in the design of FRC structures?• How does the concrete and reinforcement design (fibres vs. conventional reinforcement and hybrid designs) and the associated levels of uncertainty affect the durability and lifetime of a structure? • Is it possible to determine the concrete cover size for an optimized durability oriented design, considering uncertain interactions between reinforcement design, cracking, and the ingress of corrosive substances? • How does a (retrofitting) design of a prestressed concrete structure, using high performance FRC materials, affect the fatigue performance and, consequently, the expected lifetime of the structure?The computational methods considering polymorphic uncertainties in the design of RC and FRC structures will be tested by means of a reference bridge project, which is characterized by a combination of a UHPFRC and a RC bridge deck and prestressed girders, for which material data and data from moisture monitoring are available.