## 5 Test Results and Analysis
### Test Results Stress Analysis of the Arc-Shaped Cut of the Diaphragm
2 Principal compressive stress under transverse loading conditions  
1 For the unreinforced 96# diaphragm, the curve of the test stress changing with the loading lateral position is shown in Figure 16. The horizontal loading position 0 in the figure was 30 cm directly above the A# attention diaphragm, and the left rear wheel of the loaded vehicle was located in the middle of the ribs of 17# and 18#U. The 17# and 18#U ribs were in the middle, and the maximum stresses of the two transverse loading tests were about \(-135\) MPa and \(-131\) MPa, respectively. Under the action of lateral loading, the stress amplitude in the unreinforced crack initiation zone was larger. 2 The stress curves before and after reinforcement of 100# cross-sectional plate reinforced by \"arc-cut optimization + steel plate reinforcement\" are shown in Figure 17. The figure shows that: (1) the maximum stress in the CI area before reinforcement is about \(-128\) MPa, and the maximum stress in the CI area after reinforcement is about \(-40\) MPa, with a reduction of 68.7%. In addition, the reinforcement makes the stress redistribution at the curved notch, and the stress is roughly uniformly distributed at the curved notch. Moreover, the stress-load location curve is smoother compared with that before reinforcement, which indicates that the optimization of the curved notch with steel plate reinforcement can effectively reduce the stress peak in the CI area and improve the stress distribution, thus improving the fatigue life of the structure. Figure 15: Longitudinal loading 105# Diaphrag (notch optimization) CI area measuring point stress-load position relationship curve: (**a**) Before optimization, (**b**) after optimization. 3 The stress curve at the curved notch of the 105# cross-sectional plate reinforced with the curved notch optimization is shown in Figure 18. The figure shows that the stress peak before reinforcement is \(-115\) MPa and after reinforcement is \(-58.5\) MPa, and the stress reduction only reaches 49.1%, which indicates that the arc cut optimization also has a better repair effect, but the effect is 1.40 times worse than that after steel plate reinforcement. Further, the stress-load location curves changed in the same trend before and after reinforcement, and the curved cut reinforcement only changed the stress amplitude. Under transverse loading conditions, according to the stress-load position curve of the principal compressive stress peak (measurement point in the crack initiation area) inside the arc-shaped incision, the following results were obtained: (1) The stress curve law of all measuring points was similar. The movement of the load had a wave peak. When the wheel load gradually moved away from the 17# and 18# U ribs, the measured stress value tend to zero. (2) During the horizontal loading process, the inner side of the arc-shaped incision bears compressive stress. Further, a strong correlation between the stress of the measuring point and the load on the bridge deck is observed. (3) The trend of the stress curve before and after reinforcement is similar, showing the law of first increase and then decrease, but the peak stress after reinforcement is reduced significantly, and the stress curve is also smoother compared with that before reinforcement. Figure 16: Transverse loading 96# diaphragm (unreinforced) CI area measuring point stress-load position relationship curve: (**a**) The first CI area, (**b**) the second CI area. Figure 17: Transverse loading 100# diaphragm (steel reinforcement) CI area measuring point stress-load position relationship curve: (**a**) Before reinforcement, (**b**) after reinforcement.