Flexural behavior of Prestressed Self Compacting Concrete Beams with Openings

In many structures, openings within reinforced concrete beams are essential.Apertures are necessary for bypassing a variety of utility services, such as air conditioning units, electrical lines, water pipes, and network connections. Buildings may now have lower story heights, which results in substantial cost savings. In this study, the flexural behavior of simply supported post-tensioned self-compacting concrete beams with rectangular openings is evaluated through an experimental test program. The use of self-compacting concrete was adopted regarding its efficiency to fill the forms in the tight portions around the openings. The tested beams included one control beam without openings, one post-tensioned control beam without openings and three post-tensioned beams with different opening configurations. While, the first beam was provided with a small opening in the middle third of the span, the second had a relatively larger opening and the third beams had two small openings in the shear span. The test results showed that post-tensioning effectively increased the cracking and ultimate loads as the ultimate load was almost twice as that of the control beam without openings. The deflection values during the whole loading course were reduced, while the ductility index values indicated a convenient structural behavior. It was found that the one opening around the middle of the span or two openings within the shear spans had a slight influence on the structural behavior as long the opening height is no more than one third of the beam height and the opening length is about 7 percent of the clear span.