## 4 Results of Numerical Simulation
### Anchorage with Supplementary Reinforcement  
Specimen 1B was chosen as the default specimen for numerical model calibration and other simulations of anchorage with supplementary reinforcement. The comparison between the experiment result and the numerical simulation is shown in the graph in Figure 17. The relationship between load and displacement for the experiment and the numerical simulation shows an excellent agreement. The correlation coefficient is 0.98. Figure 15: Comparison of results of the experimental test with numerical simulation—specimen without supplementary reinforcement. The process of deformation of the anchoring zone together with the development of the cracks whose width exceeds 0.5 mm is shown in Figure 18. Based on the distribution and position of the cracks, it can be stated that an essential part of the supplementary reinforcement is not only the stirrups around the anchor but also the other additional longitudinal rebars. Study of the Influence of Fundamental Parameters on the Load-Displacement Behavior of the Anchorage  
Based on the initial simulations, a parametric study was created in order to determine the influence of selected input parameters on the final resistance and stiffness of anchorage with and without supplementary reinforcement. A series of numerical simulations were performed to demonstrate the effect of concrete strength on the load-displacement behavior of short-headed anchor without any supplementary reinforcement. The disproportional  
Figure 16: Deformation of the anchorage area and the formation of cracks with a width greater than 0.5 mm—anchor without supplementary reinforcement. Figure 17: Comparison of results of the experimental test with numerical simulation—specimen with supplementary reinforcement. Figure 18: Deformation of the anchorage zone and the formation of cracks with a width greater than 0.5 mm—anchor with supplementary reinforcement (the picture does not show the longitudinal and shear reinforcement of the specimen). increase in the resistance and changing of the load-displacement behavior depending on the concrete's compressive strength is shown in the graph in Figure 19.  
Similarly, a series of numerical simulations were performed on an anchor model with supplementary reinforcement. The anchor's size and position and the specification of additional reinforcement (\(\mathcal{O}\) 10 mm,\(f_{y}\) = 500 MPa) remained as constant parameters. The graph in Figure 20 presents the influence of concrete strength on the resistance and stiffness of anchorage with supplementary reinforcement. The effect of the supplementary reinforcement's diameter on the anchor system's resistance and stiffness was another parameter that was investigated. However, the other parameters were retained: the arrangement of the reinforcement, the material characteristics of the reinforcement (\(f_{y}\) = 500 MPa) and the concrete (\(f_{c,cube}\) = 30 MPa), as well as the overall  
Figure 19: Influence of concrete compressive strength on the resistance of the anchor without supplementary reinforcement. Figure 20: Influence of concrete compressive strength on the resistance of the anchor with supplementary reinforcement. arrangement of the test setup and the test method. The increase in anchorage resistance on the change of the supplementary reinforcement diameter is shown in the graph in Figure 21.  
The results of the numerical analysis are shown in the graphs in Figure 15:0 They present an increase in the maximum achieved anchorage resistance and the corresponding displacement. Figure 15:1 The effect of the supplementary reinforcement diameter on the resistance of the anchorage system. Figure 15:2 _Cont._  
The graph in Figure 23a shows the proportional percentage increase in anchorage resistance concerning the concrete strength class. It also shows the relationship between the increase in concrete strength and the increase in anchorage resistance.