Title:
Flexure-Shear Interaction of Reinforced High Strength Concrete Beams
Author(s):
Shuaib H. Ahmad and D. M. Lue
Publication:
Structural Journal
Volume:
84
Issue:
4
Appears on pages(s):
330-341
Keywords:
beams (supports); flexural strength; high-strength concretes; reinforced concrete; shear strength; span-depth ratio; tests; Structural Research
DOI:
10.14359/1662
Date:
7/1/1987
Abstract:
Fifty-four reinforced concrete beams using high-strength concrete (f'c > 6000 psi [42 MPa]) were tested under monotonically increasing loads to determine the effect of shear on the flexural resistance capacity and failure mode. The beams were singly reinforced without shear (web) reinforcement. The concrete strength was not a prime variable and varied from 9000 to 10,000 psi (63 to 70 MPa). The beams were tested for six shear-to-depth a/d ratios and six percentages of tensile steel content {rho}. Test results indicate that shear reduces the flexural resistance of the beams. A "valley of diagonal failure" is clearly observed when the relative flexural strength Mf / Mfl is plotted against the shear span-to-depth ratio a/d. Test results suggest that the relative flexural strength of high-strength concrete beams is inversely proportional to steel ratio and directly proportional to the concrete strength f'c for tensile steel ratios less than 1.88 percent. On the basis of experimental results of this investigation, an analytical flexure-shear interaction model for reinforced concrete beams using concretes of higher compressive strength is proposed. The proposed model compares favorably with the results of reinforced concrete beams of normal concrete strength beams (f'c = 4000 psi [20 MPa]) reported in the literature.