## 3 Results and Discussion
### Crack Pattern from Field Inspection  
Field inspections are essential for checking the cracking positions on these base plates inferred from the monitoring strain rate. During the 150 days long field test, two field inspections were conducted at the ages of 65 and 130 days, respectively. Figure 13 shows the pattern of the visible cracks on the top surfaces of all the field base plates. Note that the blue lines represent the cracks found by the first inspection, and the red lines represent the cracks observed at the second inspection. In order to clarify crack propagation, the positions of the embedded VWSGs and the detected time of cracking at each position are also marked on the drawing from which it is easy to observe where and when the crack appeared. As observed from Figure 13, the development of transverse crack in all field base plates followed a similar mode. Regardless of the duration of sealed-curing period, a majority of transverse cracks were localized at the mid-length of the plate, i.e., the crack concentration region. However, the number of the transverse cracks significantly decreased with prolonged sealed curing time. Clearly, transverse cracks originated from the plate edge on both sides of the plate and propagated toward the plate center. The easily incurred edge cracking, most likely located in the 2000 mm range in the middle area along the length, may be attributed to rapid drying at the edge and strong restraint of deformations in this area. It was observed from Plate I-a and Plate I-b that parallel short cracks formed alongside a from a main crack near the centerline, which were nearly uniformly spaced along the plate length. This finding reveals that although stress is relieved at a crack, cracking phenomenon affects the surrounding area only in a limited distance. Hence, transverse cracks can occur at close  
Figure 12: Initial cracking time at Positions A (plate center) and B (plate edge) deduced from the field measured strain rate curves (as illustrated in Figure 11). spacings. In contrast to Series I, Series II, III, and IV had a much better crack pattern, where the number of transverse cracks was less than two for each plate. Figure 13: Crack patterns observed from field inspections. Calculated Stress Development in Base Plates under Different Temperature and Humidity Boundary Conditions  
As discussed earlier, the different crack patterns on the four test series of base plates can be attributed to the different curing/environmental boundary conditions that existed during the test. In this section, the effects of various environmental boundary conditions on transverse crack initiation are numerically analyzed from the perspective of temperature-induced and humidity-induced stresses. Since the transverse cracks are always initiated at the plate edge, it was taken as the region of interest in the analysis. The temperature-induced stress simulation only considered the effect of the temperature field. Figure 14 shows the inputted historical data of air temperature and solar radiation for the temperature field simulation, which were obtained from a meteorological information website. The temperature-induced stresses of the different series of base plate were calculated with the same meteorological data, but the temperature boundary condition was altered according to the curing regime adopted for each series. Figure 15 shows the calculated temperature-induced longitudinal stresses at Edge-top (mid-length) and Edge-bottom (mid-length). The measured tensile strength of base plate concrete was also indicated in the figure, which was obtained by using a direct tension testing machine. As observed from Figure 15a,b, the geotextile covering effectively reduces not only the magnitude but also the amplitude of temperature-induced stress. After the geotextile cover was removed at 20 or 45 days, the temperature gradient in the base plate becomes larger and gives rise to the fluctuation of temperature stress.