| In this study, an analytical model to compute the lateral-force response of large stubby reinforced concrete structures with cylindrical and box sections is derived. Three displacement components, flexure, bar slip, and shear, are considered under monotonically increasing load and load reversals.;Displacement due to bar slip is computed by calculating the average slip of the tensile reinforcement, which caused the element to rotate with respect to the centroid of the compressive reinforcement.;Up a shear stress of 4Vf(,c)(''),(' )f(,c)('') in psi, the shear stiffness is assumed equal to the shear modulus of rigidity of concrete, G. Beyond this cracking shear stress, the shear stiffness is computed using empirical formulas based on results of tests performed by Vecchio. No attempt was made to derive an expression for the shear strength of the specimen. The envelope of the cyclic shear model is the same as the monotonic shear model. Unloading is assumed to converge to the point of zero stress-zero strain as observed by Vecchio.;Test results for beams, walls, cylindrical and box section specimens obtained by other investigators are used to calibrate the model developed in this study. The effect of prestressing steel is also examined by analyzing a prestressed concrete containment vessel model subjected to lateral load.;Flexural displacement is computed from the curvature distribution along the structural element. A criterion defining the beginning of the inelastic curvature (and the plastic hinge) is introduced. An empirical formula to calculate curvature of a section based on nonlinear compressive strain distribution is used to account for the needed concentrated flexural rotation in the critical region(s). The maximum curvature is assumed to be spread along the length of the plastic hinge(s). The inelastic curvature is assumed comprised of recoverable and nonrecoverable curvatures. During unloading, only recoverable curvature is used in simulating the moment-curvature relationship under load reversals. Rules for hysteretic behavior of concrete and steel reinforcement are also introduced. |
