Cyclic Behavior of Reinforced Concrete Flexural Members to Changing Design Parameters

An experimental study was conducted to evaluate the cyclic behavior of reinforced concrete (RC) flexural members with different design parameters. Twenty-five large-scale beam specimens were tested under lateral displacement reversals using a test setup intended to impose single-curvature deformation. Test parameters investigated include: 1) specimen aspect ratio, a/d; 2) designated shear stress demand, [??]; 3) spacing of transverse reinforcement, s; 4) diameter of longitudinal reinforcement, [d.sub.b]; and 5) tension-to-compression reinforcement ratio. All specimens were designed in compliance with ACI 318-19 using Grade 60 ([f.sub.y] = 60 ksi [414 MPa]) reinforcing steel and a specified concrete strength of 4 ksi (27.6 MPa). Test results indicated that specimen peak lateral strength, [V.sub.peak], can be acceptably estimated by [V.sub.Mn], the shear corresponding to the development of the nominal flexural strength at the beam fixed end. The [V.sub.peak]/[V.sub.Mn] ratio increased as the normalized peak shear stress, [Please download the PDF to view the mathematical expression], decreased, where [b.sub.w], d and [f.sub.cm] were the beam width, effective depth, and concrete cylinder strength, respectively. Specimen ultimate drift, [d.sub.u], was also found to be more sensitive to the normalized peak shear stress, [V.sub.peak]/[b.sub.w]d[??]. Specimen ultimate drift, [d.sub.u], tended to increase as the [V.sub.peak]/[b.sub.w]d[??] decreased. The average normalized energy dissipation capacity generally increased as the specimen normalized peak shear stress decreased, the aspect ratio increased, and the spacing of transverse reinforcement was reduced. Finally, specimen effective lateral stiffness increased as the shear span decreased or the reinforcement ratio on the tension side increased. Keywords: aspect ratio; deformation; diameter of longitudinal reinforcement; energy; reinforcement ratio; shear stress; stiffness; strength; transverse reinforcement spacing.