Application of Nonlinear Finite Element Analysis (NLFEA) is lagging behind the many digital advances in the structural engineering practice. This is due to the need for codes and standards. To help development of these codes and standards, 119 solution strategies were developed with different assumptions and choices for the concrete constitutive model, the finite element discretization, the way of modelling the reinforcement and the incremental-iterative procedures. The constants aspects of the constitutive model, like confinement and the reduction compressive strength due to lateral cracking, are based on the RTD1016 Dutch Guideline. All models are two-dimensional with a plane stress assumption and in all cases the analysis is force controlled with the application of an arclength method. This is done to increase the value of results for application in practice, as generally displacement loading is hard to apply in a real-life structure. The strategies were benchmarked with 101 experiments on reinforced concrete beams selected from literature. Those beams cover a broad range of design aspects, failing both in shear and bending, reinforcement configurations with- and without shear reinforcement, both prestressed and conventional reinforcement and heights ranging from 90 to 1200 mm. This resulted in 1919 NLFEAs which were performed with an automated approach in the DIANA multi-purpose finite element software package. It was concluded that the failure load and failure mode of the experiments can be approximated with a mean uncertainty of 1.05 with a coefficient of variation around 10 percent, provided that an appropriate solution strategy is applied. It is possible to assign an appropriate solution strategy when the structural design is known, where the main influence is the presence of shear reinforcement. Beams with stirrups are robustly modelled by a rotating crack model, while beams without stirrups were found to be better approximated by a fixed crack approach with specific choices regarding reinforcement modelling and equilibrium. To have a more objective way of judging the ductility of a failure, a measure of the dissipated energy in the reinforcement was implemented in the DIANA code. It was found that the mean model uncertainty of a ductile failure can be as low as 1.045, with a coefficient of variation around 10 percent. Brittle failures showed a mean uncertainty of 1.131, with a coefficient of variation just below 16 percent. Therefore the ductility index was found to be a valid way to judge the reliability of an NLFEA result. This study has demonstrated the applicability of force controlled NLFEA for reinforced concrete beams. The derived properties of the model uncertainties are a crucial input for safety formats.

A series of accelerated corrosion tests were done by SGS INTRON (commenced by Combinatie Aanpak Maastunnel, constructor of the Maastunnel project) to investigate for a proper repair material for the deteriorated concrete floor in the Maastunnel at Rotterdam. Five types of fiber reinforced mixtures with different tensile behavior ranging from SHCC (strain-hardening cementitious composite) to ON06 (similar tensile behavior as normal concrete) were designed. Different cracking behavior was observed due to the different tensile behavior in the repair mortar. It is of utmost importance to investigate if the cracking behavior can be simulated by numerical modeling and if in the future, the parametric analysis might be performed without large experimental series. Two types of numerical models are implemented in this master thesis, namely the lattice model and the continuum model. The lattice model can simulate the crack pattern of different materials in the accelerated corrosion test. The continuum model cannot show the behavior of decreasing number of cracks with decreasing fracture energy in the strain-softening materials due to the bifurcation problem brought by its incremental solution method. However, the lattice model shows the trend to underestimate the crack width of the strain-softening material. The continuum model has better performance in predicting the crack width. Also, the lattice model can predict the influence of the repair mortar-substrate bond strength on the crack pattern. Meanwhile, the continuum model always shows a complete failure in the repair mortar-substrate interface. The boundary conditions at the bottom edge are observed to influence the direction of the bottom cracks. The edges of the specimen are kept free in the experiment. However, the repaired area is constrained by the surrounding concrete in reality. This indicates that the laboratory test may not represent the cracking behavior of the concrete floor in the tunnel accurately. SHCC is observed to be more sensitive to the repair mortar-substrate bond strength than material with lower stain capacity. Extra caution on the bond quality is advised while applying SHCC in a concrete repair system. From the material point of view, with increasing fracture energy and strain capacity, more but thinner cracks can be performed in the accelerated corrosion test. SHCC material can perform the distributed crack pattern with a maximum crack width of 0.1mm which is ten times smaller than normal concrete. This behavior of SHCC is very suitable for being applied to a concrete repair system. The distributed cracks with smaller crack width can effectively limit the possibility of further corrosion. Besides SHCC, some strain-softening (under direct tension) materials can also show the deflection-hardening behavior in the bending test and produce the distributed crack pattern. SHCC and fiber reinforced concrete with deflection-hardening behavior in the bending test are suggested to be used in the concrete repair system.