SHEAR BEHAVIOR OF STEEL BEAMS STRENGTHENING BY PRESTRESSING STRANDS

Seven simply supported steel beams were tested to explain the effect of existence of external prestressing strands on the shear behavior of steel beams. All of these beams have the same steel section, clear span length and strengthening by two external prestressing strands. The tested beams are divided into two groups according to existence of external prestressing strands, the first group consists of one steel beam as a reference, while, the second group deals with six steel beams strengthening by external prestressing strands divided according to the eccentricity location of prestressing strand (e) ranging from (0 to 165) mm at jacking stress (fpj=814.589 MPa). During the test, it was found that the shear load strain curves for tested beams were slightly stiffer than the reference beams and the percentage of stiffening increase with increase the eccentricity locations from the effective depth for shear zone, while, the maximum shear load increased about (0.173%, 26.086%, 33.043%, 48.521%, 13.739% and 69.565%) with increase the eccentricity location from (0 to 165) mm respectively as compare with the reference beam. On the other hand the maximum shear strain was decreased to 0.507%, 1.015%, 20.304%, 1.776% 25.634% and 28.172% with increase the eccentricity location from (0 to 165) mm respectively as compare with the reference beam.