TORSIONAL BEHAVIOR OF NORMAL-STRENGTH REINFORCED CONCRETE BEAMS

الملخص

Recent methods for torsional design of reinforced concrete beams tend to the use of space truss analogy,instead of the earlier skew bending theory. A total of (101) rectangular beams made of normal strengthconcrete (NSC) that failed under pure torsion are considered in this work. NSC is defined as having thecylinder compressive strength f’c ≤ 40.1 MPa. These have been taken from the literature.Regression analysiswas performed on the results to obtain two representative equations to predict: cracking torsional moment (Tcr)and torsional resistance moment (Tr). The first equation is based on (3) major parameters that include concretecompressive strength (f’c) and sectional dimensions, while the second one is based on (7) major parameterswhich include the quantification of the influence of both transverse and longitudinal reinforcement.When theexisting code design methods were applied, they gave a coefficient of variation (COV) value ranges between(20.9-33.1) percent for the ratio of tested / calculated torsional strength (Tu-test / Tr-calc.). In contrast, theproposed equation has led to a COV of (12.9) percent.