Virtual Design Laboratory for Sustainable Fiber Reinforced Concrete Structures: From Discrete Fibers to Structural Optimization Under Uncertainty

Concrete is one of the most used materials worldwide with a high environmental impact. Over past years, numerous attempts to minimize the associated effects on the environment by using more sustainable materials or by improving the performance of the material (e.g. high strength concrete, fiber reinforcement) have been introduced. The increase in material performance must be accompanied by better models and design approaches to take full advantage of the potential benefits. In this contribution, a discrete fiber and a multi-level model for the analysis of SFRC structures are used to assess the influence of a chosen fiber type, content, and orientation on the structural response. Zero-thickness cohesive interface elements capture the post-cracking behavior. The discrete fibers are modeled using truss elements. The bond between fibers and concrete is modeled using an elastoplastic bond-slip law, and the effects of fiber bending, friction, and matrix spalling are accounted for using a sub-model at the level of the interface element. The predictive capabilities of both models are validated and compared with fiber pull-out experiments. Finally, the prospects of applying complex FE models in conjunction with methods of optimization to design an SFRC tunnel lining segment are discussed. The objective is to minimize the total segment thickness and the fiber content while a constraint ensures that the required failure probability is retained.