# Revisiting Cracking in Reinforced Concrete Beams: An Updated Analysis
###### Abstract  
As materials and structural optimization continue to be important in design, structural safety checks for service limit states have become increasingly important. One key aspect of these checks is the controlling of cracks to prevent them from affecting the structure's function or appearance. However, the authors have found that current regulations do not accurately reflect the reality of crack behavior. This is the case of the crack spacing. To address this issue, the authors conducted experiments on 27 reinforced concrete beams to investigate crack location, cracking moment, corresponding deflection, and crack width values as sag increases. Their main finding was that cracks tend to appear at the stirrup locations, and that crack width increases linearly with the sag-to-free-span ratio up to the yielding point. They also concluded that increasing the amount of tensile reinforcement is an effective way to reduce crack width for the same sag. cracking; RC beams; Crack position; crack spacing; crack width; Moment of cracking; cracking deflection; experimental work 202313392620231339262023139262023139262023133926202313926202313392620231339262023139262023139262  
In fact, to calculate the deflection, for example, EC2 [1] proposes an interpolation between the elastic deflection and the deflection in a fully cracked structure. Among other parameters, this interpolation depends on the cracking moment of the section. Cracking, in particular, is caused by different factors, conditioning both the stiffness and durability of structures. Cracking is normal in reinforced concrete structures subject to bending, shear, torsion, or tension resulting from either direct loading or restraint or imposed deformations. Cracks may also arise from other causes such as plastic shrinkage or expansive chemical reactions within the hardened concrete [1]. Such cracks may be unacceptably large, but this issue is outside the scope of this work. Anyway, cracking reduces stiffness of RC members, and increases deformation when loads act on the structure. The study of cracking, particularly crack width and spacing, has been a topic of investigation for long time. In 1943, [PERSON] [3] conducted one of the earliest works on the subject, where he tested axially reinforced cylinders by applying tensile forces to the reinforcement and observing the resulting deformations of the concrete, including crack width and spacing. Even then, [PERSON] concluded that crack width is proportional to tension in the reinforcement after cracking begins. Additionally, he suggested that new cracks will not appear if the tensile strength of the concrete is not exceeded, although he did not explicitly state this. However, several works [4; 5] involving deep beams appeared. These tests involved supposedly bending beams: in fact, the arching effect was not negligible, with slenderness ratios of L/h = 5.7 and L/h = 6.2. As a result, the shear effects on the web of the beams were significant, and this caused cracking that was different from the cracking observed in normal beams subject to bending. These works exhibited a relevant characteristic in the methodologies used to control cracking, which are similar to those currently employed in regulations [6]. In particular, the evaluation of crack width was heavily dependent on the steel stress, whereas the bond between steel and concrete, cover, and reinforcement ratio were primarily considered in the assessment of crack spacing. A little later (1983), [PERSON] et al. [7] used a theoretical formulation (using the energy criterion of fracture mechanics as well as the strength criterion) to estimate crack width and spacing in RC elements under pure tension. The proposed theoretical formulation was confirmed by experimental results obtained by other authors. It should be emphasized that the real unknown in the study was the crack spacing, which was found to be a function of several factors, including the axial strain of the bars, bar spacing, bar diameter, fracture energy of concrete, and its elastic modulus.