# Revisiting Cracking in Reinforced Concrete Beams: An Updated Analysis
###### Abstract
Afterwards, they were adapted to beams in bending. All ignored the possible presence of transverse reinforcement in beams. In general, the crack spacing started to be determined from a sum of 2 terms: one directly proportional to the cover; the other directly proportional to the \(\phi/\rho_{\text{eff}}\) ratio [16]. An interesting particularity is that, by observing the photos of beams tested by various authors [15,17,18], and taking into account the number of cracks and the spacing of the stirrups, most likely, the location of the cracks coincided with the position of the stirrups, although it is not possible to fully confirm this conclusion. On the other hand, [PERSON] [19], using computational analysis, determined cracks positioned between stirrups. In [PERSON]'s PhD thesis [11], the issue of the effects of the presence of stirrups on RC elements under (variable) bending was addressed. [PERSON] wrote: \"Occurrence of flexural cracks at constant spacings in varying moment regions,..., has been observed by many investigators\". In this regard, he cites [PERSON] [20] and [PERSON] [21]. [PERSON] completed, \"This fact is often correlated to the spacing of stirrups, assuming that the presence of a stirrup makes the section 'weak'.\" In [PERSON]'s work, resorting to a figure where he geometrically shows the \"Progressive development of primary cracks in a varying moment region\", he justifies: \"the stress distributions shown in figure clearly indicates that the primary crack spacing in a varying moment region is constant even if the strength along the member is unchanged.\"  
In turn, in [PERSON]'s [20] work, it is written: (i) \"Visual inspection of the specimens has shown that flexural cracks are greatly affected by the location of the stirrups and are forming in their vicinities\"; (ii) \"Clearly, the crack spacing can be directly correlated to the spacing of the stirrups used in the specimens\". These are the only sentences that the authors found in the bibliography that relate the positioning of the cracks with the placement of the stirrups. However, [PERSON] was not assertive enough, because he writes (only) in the conclusions of the work: \"Results of Groups A and B indicate that spacing of the cracks is most probably governed by stirrup spacing\". Regarding [PERSON]'s work [21], the authors only found a reference to stirrups, when [PERSON] writes: \"However, the presence of stirrups or the load history may alter the theoretical regular evolution of the cracks.\" However, despite the fact that, in this work, a regular spacing between cracks was verified, this fact could not have been caused by the stirrups because, purely and simply, they did not exist. Another important issue in cracking, namely, in the evaluation of the crack width is the crack width variation along the concrete cover depth. In this work, only the crack widths on the outer surface of the RC beams were measured. In this regard, [PERSON] [22], based on experimental work on RC elements subjected to pure tension, indicates that the crack width at the reinforcement is typically smaller than the crack width at the external concrete surface. This observation is similar to the findings in the previously mentioned experiments reported by other authors. This reduction depends on the reinforcement cover and the type of steel, whether smooth (plain surface) or with a rough surface (ribbed). In the case of steels with rough surfaces (high bond bars or ribbed) and with cover greater than 30 mm, the crack width on the surface of the steel can be only \(\sim\)25% of the crack width on the external surface of the concrete. In the case of steels with a smooth surface, the reduction is not significant, or it may not even happen. [PERSON] adds two important sayings. The first: \"The crack width at the reinforcement is independent of the concrete cover depth\". Second: \"When primary cracks are developing, the tensile strain in reinforcement exceeds the ultimate tensile strain of the surrounding concrete.