## 3 Result Analysis
### Analysis of the Time History Curves for Impact and Support Response Forces
(A) The peak and attenuation segments of each support response force can be separated from the varying trend, which has less variation than the impact force-time history curve. The starting and ending points of each segment are shown in Figure 11b. When the stress wave shifts from the top span of the beam to the support, the support response force rapidly develops and rapidly reaches the first wave peak between 579 and 800 kN. Then, the curve oscillates and experiences two wave peaks with different amplitudes, and then the impact force peak segment ends. The three wave peaks of different sizes are obtained from the stress wave in the main peak section of the impact force transmitted to the support. The fact that the transmission path of the stress wave mainly consists of the propagation of the wave along the direction of the beam height and length shows how complicated the propagation path of the stress wave in the beam is. As a result, the peak segment of the support reaction force lasts longer and can last up to 14 times longer than the primary peak segment of the impact force, showing that the inertial force effect has less impact on it. (B) Attenuation segment: after three wave peaks in an oscillation period with a small amplitude and one or two wave peaks with a small value, the support reaction force manifests itself as a result of the propagation of the stress wave during the oscillation segment and the secondary wave peak segment of the impact force to the support. The oscillation amplitude and peak values of the support reaction force are currently quite low. This is because the stress wave in the beam body is continuously reflected along the height direction during this time, and the beam body loses a lot of energy due to the development of cracks, flexural deformation, and peeling of the steel plate from the concrete. At this time, the lower energy of the lowered stress wave can no longer significantly increase the support response force. At the end of the impact phase, the time history curve of the support response force tends to zero. There are three peaks in each of the support reaction force-time history curves for the A1, B1, and B2 test beams. The first two peaks of beam A1 have comparable values. The values of the three peaks of beams B1-B3 drop essentially linearly, with the third peak having a smaller value. The complex stress wave propagation path to the support is the cause of the three peaks, and the first wave peak is formed by the stress wave that moves rapidly and directly away from the impact site to the support. The support response force is triggered to act by this stress wave. However, the second wave peak is created by the longer transmission path of the stress wave, which travels in the direction of the beam height. The stress wave propagates laterally along the width direction of the beam, first propagates to the vicinity of the support pressure beam, and then propagates to the support along the height direction, resulting in the generation of the third wave peak. After the steel plate is bonded, the values of the first two wave peaks have a significant decrease. This is because, after the steel plate is joined, the beam body has a greater energy dissipation impact on the vertically transmitted stress wave, resulting in a significant decrease in the support and reaction force values. The primary and secondary peaks of the support reaction forces both increase to some extent with the installation of the U\(-\)shaped steel plate hoops, and the secondary peak increases by 26.62% when comparing the time history curves of the support reaction forces of the B1 and B3 test beams. This is because the first two peaks of the support response force are significantly influenced by the primary peak wave segment of the impact force. In addition, after the U\(-\)shaped steel plate hoops have been installed, the support reaction force response caused by the stress wave transmitted along the height direction of the test beam is more prominent.