# Revisiting Cracking in Reinforced Concrete Beams: An Updated Analysis
## 5 Discussion  
In this work, the authors revisit the issue of cracking in Civil Engineering structures. As it is known, cracking is a \"necessary\" phenomenon in RC elements, namely, in beams in order to take advantage of the potential of the reinforcement bars (strength). However, it is essential to find a way (controlling the crack widths) that prevents an unacceptable aesthetic of the structures and that might ensure a desired durability (protection of the reinforcement) throughout the working life of the structure. Although this topic has been extensively studied in the literature, the article focuses on aspects that have received limited attention in previous research. The main objective of the authors was to show the location of the main cracks in reinforced concrete beams subjected to bending. The primary finding was that the cracks predominantly occur in the position of the shear reinforcements, contrary to the commonly known concept of \"crack spacing\". The study visually demonstrates that the location of the main cracks is closely linked to the positioning of the stirrups. The authors are aware of the avant-garde aspect of the results. In fact, these results will have influence on the usual computing procedures of crack width based on crack spacing. However, the authors reaffirm that this is the result of many years of experimental investigation, which are now unveiled. This article has been in preparation for a long period of time. The study evaluated the cracking moment of reinforced concrete beams and determined that the mean flexural tensile strength of concrete should be used for this calculation. Neither the mean nor the characteristic value of axial tensile strength of concrete provided acceptable results for cracking moment evaluation. Additionally, the cracking moment was found to be strongly dependent on the tensile reinforcement ratio \(\rho\), with a potential doubling of the cracking moment value for a 1.1% increase in the reinforcement ratio. The study also revealed that the deflection at the onset of cracking increases slightly with an increase in the tensile reinforcement ratio \(\rho\), with a 3% increase observed for every 0.1% increase in \(\rho\). An important conclusion drawn from this study is that crack width increases almost linearly with the sag/free span ratio during the development of cracks until yielding occurs. This relationship, which can be expressed in a dimensionless manner, depends on several key parameters, including (mainly) the tensile reinforcement ratio, the amount of compressed reinforcement, stirrup spacing, and axial confinement of the beam. This point is very important. If, in the specialized bibliography and in the codes of practice and standards, the crack width was calculated based on crack spacing (see Equation (1)),  
Figure 19: Cracking width. Beams in Group VIII. and if this spacing is called into question in this work, then it is important to indicate an alternative way to carry out the calculation of the crack width. The study suggests that increasing the tensile reinforcement ratio or providing axial confinement to the beam are effective methods for reducing crack widths. Conversely, increasing the amount of compressed reinforcement may result in wider cracks. As previously mentioned, for the same value of the deflection (that is, the same curvature), if the amount of reinforcement \(\mathrm{A_{s}}\) increases, the horizontal balance of forces in the cross section is achieved with greater compression in the concrete (greater strains) and smaller strains in the tensioned steel--therefore, with a smaller crack width. On the contrary, for the same value of the deflection (same curvature), if the amount of reinforcement \(\mathrm{A_{s}^{\prime}}\) increases, the balance in the cross section is achieved with less compression in the concrete (lesser strains) and greater steel strains--therefore, with a larger crack width.