# Study of Innovative Connector for Steel-Concrete Composite Structures
## 3 Results
### Push-Out Test
#### 3.2.2 Mechanical Properties  
Displacement-force diagrams for all analyzed samples are shown in Figure 13. Based on the results from the preliminary test (Figure 13a), the maximum force of 210 kN was determined, transmitted by the model with fasteners in the form of sheets with a thickness of 1.00 mm and four nails. Thanks to this, the characteristic values of 5% (10 kN) and 40% (80 kN) of the expected failure force of the samples in model no. 2, which were built of nominally identical connectors as in model 1, were determined.  
Figure 12: Failure mode of model no. 3 and 4 (consisted of 2 shot nails): (**a**) front view; and (**b**) rear view.  
Figure 13: Load–slip curves from push-out tests: (**a**) model no. 1; (**b**) model no. 2; (**c**) model no. 3; and (**d**) model no. 4.  
The maximum shear forces transferred by the samples of model no. 2 are 180, 190, and 200 kN. The displacement-force diagrams (Figure 13b) show that the curves for individual samples coincide in the elastic range, ranging from 0 to about 100-120 kN. After exceeding the yield point, the curves cease to coincide and their curvature can be observed. After exceeding the forces by about 160 kN, 180 kN, and 195 kN by samples 2A, 2B, 2C, respectively, there is a significant increase in displacement (by about 5.0 mm) in relation to a small increase in load (by about 20 kN). This phenomenon occurs until the forces destroying the sample are reached. The displacement of samples of model no. 2 at the moment of reaching the maximum load was in the range of 7.0-7.82 mm.  
Analyzing the results from the push-out tests of model no. 3 (Figure 13c), in which fasteners made of sheet, 1.00 mm thick, and 2 nails were used, the convergence of the displacement-force curves was observed almost to the breaking strength of the samples. The maximum shear force transmitted by specimen 3A is 120 kN, while the maximum shear force transmitted by specimens the 3B and 3C is 125 kN. The shape of the displacement-force curves is similar to the curves in model no. 2. Initially, an increase in load causes a linear increase in displacement until the yield point is reached, corresponding to a load of about 60 kN. Further increasing the load causes the displacement to increase nonlinearly up to the breaking point. The displacement of model no. 3 samples at the moment of reaching the maximum load was in the range of 11.3-12.5 mm.  
The results for model no. 4 samples built with fasteners in the form of 1.25 mm sheet and 2 pcs. of nails are shown in Figure 13d. The maximum shear forces transferred by samples 4A and 4B are 140 kN, and the breaking force of sample 4C is 130 kN. The displacement-force diagrams show that the curves coincide in the elastic range, i.e., up to the load value of about 70 kN. After exceeding the yield point, the curves cease to coincide, and their curvature can be observed. Then, after exceeding the force of 110-120 kN, there is a significant increase in displacement (by about 10.0 mm) in relation to a small increase in load (by about 20 kN). The displacement of model no. 4 samples at the moment of reaching the maximum load is in the range of 11.0-12.8 mm.