Pushover Analysis of Shear-Critical Frames: Formulation

An analytical procedure is presented for the nonlinear analysis of reinforced concrete frame structures consisting of beams, columns, and shear walls under monotonic and pushover loads. The procedure is capable of accurately representing shear-related mechanisms coupled with flexural and axial behaviors. The formulation described herein uses linear-elastic frame analysis algorithms in a nonlinear mode based on an unbalanced force approach. Rigorous nonlinear sectional analyses of concrete member cross sections, using a distributed-nonlinearity fiber model, are performed based on the disturbed stress field model. The proposed method is distinct from existing methods in that it allows for the inherent and accurate consideration of shear effects and significant second-order mechanisms within a simple modeling process suitable for practical applications. Decisions regarding the anticipated behavior and failure mode or the selection of appropriate analysis options and parameter values, or additional supporting calculations such as the moment-axial force or shear force-shear deformation responses, are not required.