Design of steel fiber reinforced concrete tunnel lining segments by nonlinear finite-element analysis with different safety formats

Abstract

The use of Nonlinear Finite Element Analysis (NLFEA) for the assessment of structures requires special considerations regarding the employed safety format. While some guidelines are available, the provided information is focused on Reinforced Concrete (RC) and the application for Steel Fiber Reinforced Concrete (SFRC) structures is not addressed. In order to evaluate the application of NLFEA and the use of SFRC as reinforcement scheme for segmental tunnel lining design, a multi-level model for the analysis of SFRC structures is used. This multi-level SFRC model allows to directly assess the influence of a chosen fiber type, content and fiber orientation on the structural response. The post-cracking behavior is captured by a discrete crack model based on cohesive interface elements. After a brief introduction of the numerical model and the use of safety formats in NLFEA, the influence of the applied safety format on the local structural response of a SFRC beam subjected to 3-point bending is investigated. The proposed multi-level SFRC model is used to carry out a full probabilistic analysis due to its capability to capture the influence and scatter of important SFRC parameters. Finally, a segmental lining ring subjected to earth & water pressure is designed using different safety formats. In order to discuss the influence of the reinforcement scheme, the design by NLFEA is carried out for SFRC as well as RC segments. It is shown that the use of NLFEA can result in a greatly increased design resistance and that SFRC segments offer a better performance compared to RC segments.