Numerical Modeling of Additive Joints Made from SFRC for the Reuse of RC Components

For a sustainable design, the equivalent reuse of reinforced concrete (RC) components helps to significantly reduce waste and \(\hbox {CO}_2\) -emissions from construction. A key task is the development of new connections for the modules transmitting internal forces and shaping the new structure. In this contribution, the derivation of an additive joint for RC beams using steel-fiber reinforced concrete (SFRC) and additional steel reinforcement is presented. The geometry of the cut-out for jointing thereby relies on the maintenance of load-bearing capacity and serviceability with respect to a complete beam, which is experimentally investigated. The tests were performed in full scale and holistically measured, e.g., using digital image correlation to monitor deformations and growth of crack widths. The experiments revealed that the additive beam exhibits a 20% higher load-bearing capacity than the complete beam due to the SFRC joint. In numerical investigations a finite element (FE) model is built up and validated with the experiments. The FE simulation bases on cohesive interface elements, employing a traction-separation law. The numerical investigation possesses good accordance with experimental results for both, the load-bearing behavior and even more for the crack distribution. By means of a global sensitivity analysis (GSA) based on the FE model the influence of the additional reinforcement, material parameters, and joint roughness are quantified. It reveals that the fibre content and the length of the additional reinforcement are decisive for the load-bearing capacity.