The use of PET bottles in civil construction has become very common, given that they can be used in the construction of walls, the manufacture of tiles, among others. There are already many studies that have verified the use of PET bottles as a component of the structure or construction itself and that show satisfactory results. The optimization of reinforced concrete parts to ensure weight reduction, as well as the reduction of materials used and, consequently, cost reduction, is a case that requires attention in the field of civil construction. Hollow or hollow beams are a good alternative for this optimization. The presence of shear reinforcement and the Stuttgart test model were studied, and a comparison of the load capacity between the tested beams was performed. Hollow or hollow beams behaved similarly to the reference beam. There was a reduction in volume and consequently in weight between the beams of approximately 15.3% and a loss of shear strength between the same beams of approximately 26.3%. The test results were compared with the recommendations of NBR 6118 (2014) and a similarity between the results was found.