Seismic Behavior of Steel Reinforced Concrete Beam-Columns and Frames

The ability to perform accurate nonlinear simulations is a key component in the assessment of the behavior of seismic force resisting systems. A three-dimensional distributed plasticity formulation for composite beam-columns suitable for nonlinear static and dynamic analyses of composite seismic force resisting systems has been developed. New uniaxial constitutive relations are developed for the concrete and steel elements to simulate the cyclic response of steel reinforced concrete (SRC) members. The relations account for the salient features of each material, as well as the interaction between the two, including for concrete: varying levels of confinement within a section, cracking, crushing, and spalling, and for steel: cyclic plasticity and residual stresses. The accuracy of the formulation is validated against a comprehensive set of results from monotonically and cyclically loaded beam-column specimens. The formulation is suitable for use in parametric studies to quantify the seismic performance factors of special moment frames using steel reinforced concrete columns and structural steel beams following recommendations of the recently released FEMA P695 report.