## 1 Introduction
According to CSA S474 [53], the average crack distance \((S_{m})\) is calculated as follows:  
\[S_{m,CSA}=2(c+0.1s)+\frac{k_{1}k_{2}d_{b}h_{eff}b}{A_{st}}, \tag{1}\]  
where \(c,s,b,d_{b}\) and \(A_{st}\) are the reinforcement cover (mm), outer rebar's layer distance (mm), cross-section width (mm), rebar diameter (mm) and outer area of the tension rebar's layer (mm\({}^{2}\)), respectively. Furthermore, \(k_{1}\) refers to the participation rate and boundary condition coefficients for rebars, which are considered equal to 0.4 and 0.8 for smooth and conventional rebars, respectively; \(k_{2}\) is the strain coefficient, which is equal to \(0.25(\varepsilon_{1}+\varepsilon_{2})/2\varepsilon_{1}\), where \(\varepsilon_{1}\) and \(\varepsilon_{2}\) are the highest and lowest effective strains in the tensioned area, respectively. Moreover, \(h_{eff}\) is the effective tensioned depth (mm) and is considered equal to the largest amount of either \(a_{1}+7.5d_{b}\) or \(a_{2}+7.5d_{b}\). Furthermore, it should not be much larger than the tensioned area or half the height of the section, according to CSA S474 [53]. Furthermore, it should not be much larger than the area of the tension or half the thickness as shown in Figure 1.  
NS 3473E [54] presents a similar equation for calculating the average crack distance, as follows:  
\[S_{m,NS}=2(c+0.1s)+\frac{k_{1}k_{2}d_{b}}{\rho_{{}_{\rm NS}}}, \tag{2}\]  
where \(c\) and \(s\) are the concrete cover's and the outer rebar layer's distance (mm), respectively. \(k_{1}\) is an environmental factor that is based on the rebar's corrosion, which is equal to 0.4 for ribbed rebars;  
Figure 1: Thickness of the buried area according to CSA-S474-2044 [53]. \(k_{2}\) is a strain factor equal to \(0.25(\varepsilon_{1}+\varepsilon_{2})/2\varepsilon_{1}\), where \(\varepsilon_{1}\) and \(\varepsilon_{2}\) are the highest and the lowest effective strains in the tensioned area, respectively. \(\rho_{t_{NS}}\) is the effective rebar's ratio, equal to \(A_{st}/A_{ct}\), where \(A_{ct}\) is the effective cross-section area of concrete and \(A_{st}\) is the area of the tensile rebars (Figure 2). CSA S474 [53] and NS 3473E [54] propose a similar formula to anticipate the crack spacing, with little variance in the slope of strain, which calculates the effective rebar's section. According to NS 3473E [54], the crack spacing is determined using the following relationship. \[W_{k,NS}=1.7W_{m,NS};W_{m,NS}=rw\varepsilon_{1}S_{m,ns}, \tag{3}\]  
\[r=1-\frac{\beta}{2.5k_{1}}\bigg{(}\frac{\sigma_{sr}}{\sigma_{s}}\bigg{)}^{2} \geq 0.4, \tag{4}\]  
where the correction coefficient \(r\) represents the plasticisers' impact on the hardened concrete's strain. \(\varepsilon_{1}\) is the tensile strain in the outer tensile rebar's layer, according to a non-axial stress distribution, with the main stress direction parallel to the longitudinal reinforcement, \(\varepsilon_{1}=\varepsilon_{S}=\sigma_{S}/E_{S}\). \(\sigma_{S}\), \(E_{S}\) and \(S_{m}\) are the steel rebar's stress, the steel rebar's modulus of elasticity and the average distance between cracks, according to Equation (2), respectively. Furthermore, \(\beta\) is the conditional factor, which is defined according to the environment condition (in a natural condition with no humidity, it is considered equal to 1), and \(k_{1}\) is equal to 0.4 for ribbed rebars. CSA-S474-04 [53] recommends calculating the average crack spacing according to average crack spacing as in Equation (1). According to EC2 [55], the concrete cover is the first parameter that affects the flexural crack's spacing. According to this standard, the average flexural crack's spacing can be obtained using the following formula:  
\[S_{m,EC2}=2C+k_{1}k_{2}\frac{d_{b}A_{ct}}{4A_{st}}, \tag{5}\]  
where \(C\) and \(d_{b}\) are the reinforcement cover and diameter (mm), respectively. \(A_{st}/A_{ct}\) is the effective cross-section rebar's ratio. \(k_{1}\) is equal to 0.8 and 1.6 for ribbed and smooth rebars, respectively.