## 3 Experimental Results and Discussion  
### Dynamic Response and Residual Impact Capacity  
The damage to the beams was compared by studying crack widths and inclination for diagonal cracks. Cracks wider than 0.1 were annotated and measured using an electronic calliper. The inclination of diagonal cracks wider than 0.1 mm were also annotated, and the inclinations were determined by drawing a secant line between an approximate start and end of the crack. The degree of damage to Beam A1 in Figure 8a was less than expected, and the mass of the striker was thus proactively increased for all subsequent tests. This mass increase from 60 to 70 kg induced what is deemed a total flexural shear failure for Beam A2. Beams A1 and A2 showed steep diagonal cracks with inclinations close to 45 degrees on the west side of the mid-point, while less steep diagonal cracks appeared on the east side of the mid-point. A local shear plug damage mode and global flexural shear damage thus occurred. Beam A2 showed that the global flexural shear damage is critical, as this diagonal crack resulted in the compressive zone's failure and the beam's complete failure. Wide and steep diagonal shear cracks formed for Beams B1, B2, C1, and D1, close to 45 degrees in inclination, accompanied by wide flexural cracks. The damage patterns showed significant shear plug and flexural damage, corresponding to a hybrid response. Beam C2 instead responded with a wide global flexural shear crack on the west side and small flexural cracks; thus, the response is shear-dominated. B2 showed a similar global flexural shear crack as C2, but this crack did not open to the same extent, although the shear reinforcement was less for B2. The reason for the larger shear capacity of Beam B2 was that the diagonal shear crack propagated across two stirrups instead of only one, which was the case for C2. The damage due to sequential impact testing is evaluated by comparing the damage after the first impact test to the impact test where the beam failed, as presented in Figure 9. Beam A2 failed after the first impact and thus needs no comparison. The results for Beam B2 in  
was deemed to have failed since the concrete in the compressive zone showed significant spalling; it is therefore a local failure. The spalling is possibly a result of local compressive failure at the impact zone from the impact load. However, the global flexural shear crack on the east side propagated to the crushed zone, implying that this may also be a reason for the spalling. Significant flexural damage was accumulated by the five impacts, as shown by the sizeable residual curvature presented in the picture of the beam and also by the large width of the flexural cracks after the fifth impact test. The sequential impacts also widened the steep diagonal and global flexural shear cracks. Significant flexural and shear damage thus occurred, indicating a hybrid response mode of Beam B2. Figure 9b shows that Beam C2 failed by the second impact. The critical global flexural shear crack on the west side opened significantly, resulting in spalling around the tensile reinforcement and significant permanent shear deformation of the beam. Beam D2 in Figure 9c showed to withstand six impacts before local failure occurred. The beam failed by spalling around the tensile reinforcement and in the compressive zone. This beam showed a flexure-dominated response for all impacts by opening wide flexural cracks, which is supported by the sizeable residual curvature presented by the picture of the beam. The full signal measured at the west accelerometer was compared for the beams during the first, second, and fifth impact test in Figure 10. Beam A1 in (a) showed its second prominent peak due to a second impact during the first test earlier than the other beams. The smaller spring-back indicates more damage to Beam A1 and a different response than the other beams, as less energy was imposed on the striker after the first impact with the beam.