## 5 Impact of BFRP Design Parameters on Transverse Crack Behavior of CRCP
### Reinforcement Content of BFRP  
The variation in reinforcement content of BFRP can be related to both the bar spacing and diameter of BFRP. The influence of the bar spacing and diameter of BFRP on crack spacing and crack width are shown in Figures 8 and 9, respectively. As described in Figure 8, the more the spacing of the BFRP, the higher the crack spacing and crack width of CRCP. When the bar spacing increases from 6 to 14 cm, the crack spacing experiences a serious increase from 3.43 to 7.18 m, while the crack width increases sharply as well, from 1.36 to 2.87 mm. This can be attributed to the decrease in the reinforcement content of the BFRP bar. Given the bar spacing ranging from 6 to 14 cm, the corresponding reinforcement content decreases from 0.72% to 0.31%. Therefore, in order to achieve a lower crack spacing and crack width of CRCP, a reasonable bar spacing of BFRP needs to be carefully considered.  
As expected, the diameter of BFRP bars also has great impact on both of the crack spacing and the crack width, with the higher the BFRP diameter, the lower the crack spacing and crack width of CRCP, as shown in Figure 9. Given an increase in the BFRP diameter from 10 to 18 mm, the corresponding reinforcement ratio of BFRP increases from 0.38% to 1.2%, resulting in a decrease of 55.9% (from 5.69 to 2.51 m) and 55.5% (from 2.27 to 1.01 mm) for crack spacing and crack width, respectively. Therefore, a rational increase in the BFRP diameter is an effective way to reduce the crack spacing and width of the CRCP with BFRP bars.  
Figure 7: Impact of elastic modulus of BFRP on the crack spacing (**left**) and crack width (**right**) of CRCP with BFRP bars.  
With the aforementioned range of BFRP spacing (6, 8, 10, 12, and 14 cm) and BFRP diameter (10, 12, 14, 16, and 18 mm), the reinforcement content for each combination of spacing and diameter can be calculated within the range of 0.22% to 1.63%. The relationship between the reinforcement content of BFRP and the crack spacing and width are presented in Figure 10. In general, both the crack spacing and crack width show a significant drop with an increase in the reinforcement content of BFRP bars. Since the reinforcement content is related to both the spacing and diameter of BFRP, the impact of different bar spacing and diameter given the same or similar reinforcement content on crack spacing and crack width was conducted to optimize the BFRP design in CRCP with BFRP bars.  
Table 5 summarizes a similar reinforcement content with various combinations of BFRP spacings and diameters as well as the results of the crack spacing and width in CRCP with BFRP bars. Given reinforcement contents of 0.30% and 0.31%, the smaller BFRP spacing and BFRP diameter (10 cm and 10 mm, respectively) produced a lower crack spacing and width compared to the combination of 14 cm spacing and 12 mm diameter of BFRP. Interestingly, this relationship can also be found in reinforcement contents around 0.42%, 0.50%, 0.75%, and 0.98%, as presented in Table 5, indicating that closely spaced BFRP with a lower bar diameter can result in a lower crack spacing and crack width, given a similar reinforcement content of BFRP. For CRCP, a wider crack width is one of the distresses and is a key factor in the development of punchout. Therefore, given the same or similar reinforcement ratio, a smaller BFRP spacing and BFRP diameter are recommended to achieve better CRCP performance because of its contribution to the lower crack spacing and crack width.  
Figure 8: Impact of BFRP spacing on the crack spacing (**left**) and crack width (**right**) of CRCP with BFRP bars.  
Figure 9: Impact of BFRP diameter on the crack spacing (**left**) and crack width (**right**) of CRCP with BFRP bars.