ULTIMATE SHEAR TESTS OF FULL-SIZED PRESTRESSED CONCRETE BEAMS

STATIC TESTS TO FAILURE OF FOUR FULL-SIZED PRESTRESSED CONCRETE BEAMS ARE DESCRIBED. TWO OF THE BEAMS WERE 18 INCH X 36 INCH I-BEAMS, TWO WERE 36 INCH X 36 INCH BOX BEAMS. THE BEAMS HAD VARIABLE AMOUNTS OF WEB REINFORCEMENT, MAKING IT POSSIBLE TO CONDUCT A TOTAL OF NINE ULTIMATE STRENGTH TESTS ON THE FOUR BEAMS. SHEAR SPAN TO EFFECTIVE DEPTH RATIOS RANGED FROM 2.92 TO 5.84. DIAGONAL TENSION AND FLEXURE SHEAR INCLINED CRACKING WERE OBSERVED. SIX SHEAR FAILURES AND TWO FLEXURAL FAILURES OCCURRED, AND IN ONE TEST THE SPECIMEN FAILED PREMATURELY, DUE TO DAMAGE SUSTAINED IN THE PREVIOUS TEST. RESULTS WERE COMPARED WITH A PREVIOUS INVESTIGATION WHICH USED SMALLER, 9 INCH X 18 INCH I-BEAMS. IT WAS FOUND THAT BOTH THE INCLINED CRACKING STRENGTH AND THE ULTIMATE SHEAR STRENGTH OF THE FULL-SIZED TEST BEAMS WERE SOMEWHAT LESS THAN THE STRENGTH OF THE SMALLER BEAMS. HOWEVER, THE PROPOSED SPECIFICATION FOR THE DESIGN OF WEB REINFORCEMENT, WHICH WAS CONSERVATIVELY BASED ON THE RESULTS OF THE SMALL BEAM TESTS, SATISFACTORILY PREDICTED THE ULTIMATE SHEAR STRENGTH OF THE FULL-SIZED BEAMS. /BPR/