Effect of the location of the first stirrup on the shear strength of reinforced concrete beams

Resumen

The objective of this research was to determine the effect of the distance of the first stirrup on the shear strength of reinforced concrete beams. Although Peruvian standards indicate that the distance of the first stirrup in beams should be less than or equal to 10 cm, in practice there are discrepancies in this distance, which usually ranges from 2.5 to 10 cm, but its effect on shear strength is unknown. Therefore, in this experimental research, scale frames were constructed with the intention of having beams that work in the condition of fixed supports. The spacings of the location of the first stirrup were 2.5, 5, 7.5, and 10 cm, and three frames were made for each distance. These prototypes were subjected to point loads at a distance of 15 cm from the support, equivalent to the camber of the beam. This was done in order to determine the shear strength. These tests were carried out on the Universal Machine of the Materials Testing Laboratory of the Faculty of Engineering of the National University of Cajamarca. The results obtained for the location of the first stirrup at 2.5 cm, 5 cm, 7.5 cm, and 10 cm determined resistances of 5.51, 4.98, 4.53, and 4.28 tons, respectively. Finally, it was concluded that the location of the first stirrup has an effect on the shear strength of reinforced concrete beams, since the closer the first stirrup is, the greater the beam's shear strength.