## 4 Analysis of the Test Results
### Beam Deflection  
Figure 14a,b show the deflection time history curve of the beam body at the quarter point and the midspan of the test beam, respectively, in which the bearing settlement is not considered, and the upper arch of the beam body is positive, and the lower deflection is negative. It can be seen from the deflection curve of the beam at the quarter point, shown in Figure 14a, that with the increase in the ambient temperature, the beam gradually undergoes upper arch deformation under the action of the external temperature load. At 17:00, the upper arch value of the beam is the largest at approximately 0.020 mm; at 22:00, the deflection value of the beam changes from positive to negative, and the beam starts to change from deformation of the upper arch deformation to deformation of the lower arch; in the period from 2:00 to 5:00 the next day, the deflection amplitude of the beam is the largest at approximately 0.027 mm. According to the analysis of the curve in Figure 14b, the deformation of the upper arch of the beam body at the mid-span at 17:00 on the test day is the largest at approximately 0.40 mm. During the period from 2:30 to 5:30 on the next day, the deformation of the beam body tends to stabilize, with the largest deflection amplitude at approximately 0.75 mm. By comparing and analysing the deflection curves of the beams in Figure 14a,b, the following conclusions can be obtained: The deflection deformation of the test beams is sinusoidal and periodic, which is the same as the change trend of the ambient temperature; the deflection deformation of the beams in the middle of the span is far greater than that at the quarter point. When the ambient temperature is a maximum, the deflection of the beam body is less than that of the beam body, and the deflection of the beam body is less than that of the beam body. Figure 12: Displacement between the track slab and base plate. Figure 13: Longitudinal relative displacement between the CA mortar layer and base plate. the camber value at the quarter point and the midspan of the beam is a maximum. The deflection value of the beam is the highest when the ambient temperature of the next day is the lowest, and the deflection deformation of the beam at the two positions is slightly larger than that of the upper arch, due to the influence of the rise and fall of the ambient temperature. The longitudinal deflection curve of the beam at different times is drawn, as shown in Figure 14c. It can be seen from the analysis of the curve in the figure that the deflection deformation of the simply supported beam is symmetrical with respect to the midspan position of the beam body. The deflection deformation trend of the simply supported beam during the process of increasing temperature is opposite to that in the stage of decreasing temperature. During the period from 9:00 to 21:00, the beam body between the beam end and the quarter point experiences downward deflection, the deflection degree of the beam body at the quarter point is relatively large, and the beam body between 1/4 L and 3/4 L shows upper arch deformation with the maximum degree of camber in the middle of the span. From 21:00 to 9:00 the next day, the camber deformation of the beam body occurs between the end of the beam and the quarter point, the camber degree of the beam body at the eighth point is relatively large, and the middle part of the beam body presents deflection deformation; the maximum difference in the displacement of the beam body appears in the middle of the span in the whole test process at approximately 1.1 mm. In conclusion, under the condition of high temperatures and no direct sunlight in summer, the deflection of the beam changes in a sine curve period, and the peak value of deflection in the cooling stage is slightly larger than that in the heating stage. Due to the constraint of the bearing and adjacent  
Figure 14: Deflection curve of the beam body. (**a**) Quarter point; (**b**) midspan; (**c**) deflection curve.