Experimental Study on Shear Behavior of Prestressed Concrete Beams

Two simply supported beams with a shear span to depth ratio of 2.2 were tested, one with straight prestresssing tendons and the other without for reference. The shear behavior and the prestressing effect are focused on. The test results showed that the prestressed concrete (PC) beam has a significant arch effect, and the prestressing could greatly increase both the cracking load and the shear strength. Besides, the Modified Strut-and-Tie Model (MSTM) and the sectional design method from China Code (GB 10) and ACI318-08 have also been adopted for predictions. The comparisons indicates that the MSTM can not only well predict the shear strengths of PC beams with a small shear span to depth ratio, but also well account for the prestressing effect, while the sectional design method seems so conservative due to its not properly considering the shear mechanism of such beams. It can be concluded that the MSTM is capable of predicting the shear strength of PC beams with significant arch effect and thus can be employed in practical designs.