## 4 Test Results and Analysis of Time-History Curve  
### Strain Time-History Curve  
According to the data from the test, the strain versus time curve of each measuring point of each test piece under different impact heights was obtained through the data acquisition system and software analysis. The W1 specimen was used as a typical specimen  
Figure 11: Damage diagrams of W2, W3 and W4 specimens after being impacted. (**a**) W2; (**b**) W3; (**c**) W4. Figure 10: Destruction morphology diagram of W1 specimen. Figure 9: Test process diagram of W2, W3 and W4. (**a**) W2; (**b**) W3; (**c**) W4. for experimental analysis under the impact of an impact height of 1 m. The strain time-history curves of each measurement point of the W1 to W4 specimens are shown in Figure 12.  
As shown in Figure 12, the changes in strain of each measurement at any moment were recorded by the instrument. In order to distinguish and describe the strain curves for each measured point, the curves were processed through different colors and different shapes of icons. In Figure 12a, the record starts from the effective contact time of 0.6 s. The damaged W1 specimen was analyzed by the strain time0 history curve of other specimens and failure forms. Figure 12 indicates that falling objects collide with the contact surface of the wall within a short contact time in the range of 0.61 s to 0.62 s and the strain of the measuring point increases rapidly. However, the curve of measuring point 8 showed an upward phenomenon and did not appear in a descending stage. The strain gauge was damaged due to the crack development of measuring point 8, which caused the strain change to exceed the measuring range of the strain gauge. The result was basically in line with the test. Furthermore, the strain change from measuring point 1 to measuring point 7 was similar to measuring point 8, but the change was relatively small. Analyzing the failure morphology of W1, the cracking failure from measuring point 1 to measuring point 7 developed rapidly; the panel cracking released most of the energy, and the crack development did not pass through the measurement area of the strain gauge. The results were basically consistent with the test. Moreover, as shown in Figure 12, the trend of tensile tension and compression of these strain curves was different as these strain gauges were glued to the specimens in a horizontal and vertical manner. In order to obtain the maximal response variable, we only  
Figure 12: Strain time-history curves of W1 to W4. (a) W1; (b) W2; (c) W3; (d) W4. explored the increment in the strain gauge of each measuring point. The further cases of strain change were analyzed as follows. Comparing and analyzing the strain time-history curves of W2, W3 and W4 specimens, the time-varying law was similar. In the test, the W4 specimen was taken as a typical specimen for test analysis and description. The strain time-history curves of W4 at the impact height of 1 m and the impact height of 1.5 m are shown in Figure 13.  
Figure 13 illustrates that the impact height of the sandbag was proportional to the degree of strain change. The strain at the measuring point changed sharply until reaching the top, and then it decreased rapidly. After the wall was impacted, the elastic deformation was recovered slowly, the strain decay rate gradually decreased, and the change in the strain value gradually became stabilized after a short period of aging. The strain value after the test of each measuring point was different from the initial strain, which indicates that a certain small residual deformation occurred after the composite wall was impacted. Through comparative analysis of the results of the strain time-history curves of each specimen, the strain change degree of W4 was found to be higher than that of W2 and W3. The analysis showed that the influencing factors were mainly related to the light steel formwork and the strength of the poured concrete.