# Revisiting Cracking in Reinforced Concrete Beams: An Updated Analysis
## 3 Experimental Procedure
### Beams  
Regarding the beams, the authors tried to select the most diverse parameters: normal and reduced dimensions, different curing ages, ER (cold worked steel) and NR (hot rolled steel) ribbed steels, different (geometric) reinforcement ratios, different spacing of transverse reinforcement, and different cover. For the selected reinforced concrete beams, Table 1 specifies the geometric characteristics (L indicates the length of the beam; b the width of the rectangular cross section; h the corresponding height), the day of the test T and the value (average) expected compressive strength of concrete f\({}_{\rm c}\). For beams tested in the short-term (less than 60 days of curing), the f\({}_{\rm c}\) value is determined by a logarithmic curve (Neville methodology [30]), which, in turn, results from a huge set of tests on different cubes of concrete with a 150 mm edge, carried out on different days. In general, more than 20 cubes, tested in groups of 3, were tested in a longer time interval. For long-term beams,the methodology indicated in EC2 [1] (exponential curve) was used, which included cover of 20 mm for normal beams and 10 mm for Group VIII of beams. Table 2 shows the reinforcement amounts of the selected beams: the type of steel in the \"steel\" column, the amount of tensile reinforcement A\({}_{s}\), the corresponding reinforcement ratio \(\rho\), the amount of compressive reinforcement A\({}^{\prime}\)\({}_{s}\), the corresponding reinforcement ratio \(\rho^{\prime}\), and the transverse reinforcement in the lateral and central zones, A\({}_{\rm sw1}\) and A\({}_{\rm sw2}\), respectively. Note that the load scheme adopted, with 4 points, determines two lateral zones and a central zone in the span of the beam (see Figure 2). For example: A\({}_{s}\) = \"2f10\" means 2 longitudinal bars with a diameter of 10 mm located in tensile reinforcement; A\({}_{\rm sw}\) = \"f6@180\" means vertical stirrups with 2 legs spacing 180 mm apart along the axis of the beam; and \"AR50\" means axial restraint with an initial axial force of \(\sim\)50 kN. \begin{table}
\begin{tabular}{c c c c c c} \hline
**Group** & **Beam** & **L (mm)** & **b/h (mm)** & **T (Days)** & \(\ell_{c}\) (MPa)** \\ \hline I & B01.ER.2f8.2f10.6f@180 & 3000 & 205//310 & 33 & 24.4 \\  & B02.NR.2f8.2f10.6f@180 & 3000 & 205//310 & 33 & 24.4 \\  & B03.ER.2f10.2f10.6f@180 & 3000 & 205//310 & 32 & 24.3 \\ II & B04.NR.2f10.2f10.6f@180 & 3000 & 200//305 & 32 & 24.3 \\  & B05.ER.6f12.2f10 & 3000 & 210//305 & 31 & 24.3 \\  & B06.NR.6f12.2f10 & 3000 & 203//297 & 31 & 24.3 \\ III & B07.ER.6f12.2f10.6f@60 & 3000 & 192//305 & 28 & 24.0 \\  & B08.NR.6f12.2f10.6f@60 & 3000 & 200//305 & 27 & 23.9 \\  & B09.ER.6f12.2f10.6f@180 & 3000 & 200//275 & 26 & 23.8 \\  & B10.NR.6f12.2f10.6f@180 & 3000 & 200//305 & 26 & 23.8 \\  & B11.NR.3f16.2f10.6f@180 & 3000 & 202//301 & 379 & 33.9 \\ IV & [EMAIL_ADDRESS] & 3000 & 204//302 & 379 & 33.9 \\  & [EMAIL_ADDRESS] & 3000 & 204//302 & 382 & 33.9 \\  & [EMAIL_ADDRESS] & 3000 & 205//305 & 382 & 33.9 \\  & [EMAIL_ADDRESS] & 3000 & 207//303 & 42 & 29.3 \\ V & B16.NR.3f12.2f8.6f@60 & 3000 & 202//302 & 41 & 29.2 \\  & [EMAIL_ADDRESS] & 3000 & 207//303 & 40 & 29.0 \\  & B18.NR.3f12.2f8.6f@180 & 3000 & 200//303 & 41 & 29.2 \\  & [EMAIL_ADDRESS] & 3000 & 201//299 & 761 & 34.4 \\ VI & [EMAIL_ADDRESS] & 3000 & 201//299 & 762 & 34.4 \\  & B21.NR.3f12.2f8.6f@180 & 3000 & 202//307 & 54 & 36.6 \\ VII & B22.NR.3f12.2f8.6f@60 & 3000 & 200//306 & 54 & 36.6 \\  & [EMAIL_ADDRESS] & 3000 & 202//303 & 50 & 36.1 \\  & B24.ER.2f6.2f6.4f@70 & 1500 & 98.1//152 & 34 & 41.6 \\ VIII & B25.ER.3f6.2f6.4f@70 & 1500 & 100//153 & 34 & 41.6 \\  & B26.ER.4f6.2f6.4f@70 & 1500 & 100//154 & 36 & 41.8 \\  & B27.NR.3f8.2f6.4f@70 & 1500 & 101//153 & 37 & 42.0 \\ \hline \end{tabular}
\end{table} 
Table 1: Description of RC beams. Figure 2: Test set-up. The 27 beams were divided into 8 different groups. Although some beams from a given group may be related to beams from another group, the main distinction between groups lies in their construction and essential characteristics.