| Abstract: | Crack Formation and Tensile Behaviour of Concrete Members Reinforced with Rebars and Fibres exemplified by Ultra‐High‐Performance Concrete Part 1: Crack Mechanical Relationships When combining conventional non‐pre‐stressed or pre‐stressed reinforcement with fibres, differences in the load‐carrying and deformation behaviour arise in comparison to the well‐known reinforced and pre‐stressed concrete. This fact holds true comparably for all concrete classes. However, it is of special interest for ultra‐high‐performance concretes (UHPC), because fibres are added to these concretes generally to improve ductility. With regard to durability, the positive influence of the fibres on the crack formation process and the crack widths in the serviceability range is significant. Especially for enhanced requirements concerning the crack width (order of magnitude: 0.1 mm) with combined reinforcement of rebars and fibres an essential improve compared to reinforced concrete can be achieved. The analysis of the crack formation process presumes the understanding of the different behaviours of the two reinforcing elements ”rebars” and ”fibres”. In part 1 of this contribution, the therefore required mechanical relationships are presented and linked with each other considering equilibrium and compatibility. In part 2 the derived relationships are validated on the basis of experimental investigations on tensile members with combined reinforcement made of UHPC. The application is furthermore illustrated by means of two examples. Because of its universal formulation, the presented proposal is generally applicable to all types of concrete reinforced with rebars and fibres, i.e. it is not limited to ultra‐high‐performance concrete. |
