Analytical modeling of inelastic seismic response of R/C structures

An analytical modeling scheme is developed to assess the damageability of reinforced concrete buildings experiencing inelastic behavior under earthquake loads. The structural model used to discretize a building is capable of integrating ductile moment-resisting frames with shear-wall models and out-of-plane transverse elements to allow simulation of special interactions that are important in modeling overall structural behavior. The structural model is achieved using a combination of concentrated plasticity at member ends and a distributed flexibility rule that accounts for the spread of plasticity based on the variation of the contraflexure point during dynamic response. The inelastic behavior of components is monitored using a new hysteretic model that utilizes a nonsymmetric trilinear envelope and permits the modeling of stiffness degradation, strength deterioration, and pinching, respectively. The structural parameters, such as moment-curvature envelopes, etc., required for the inelastic seismic response analysis are computed in-core, using mechanical models and empirical equations that emerge from identification studies. The results of the response analysis are expressed as damage indices using a calibrated damage model based on energy and ductility. This enables the estimation of energy and strength reserves in the structure before collapse. Several examples are presented to illustrate the versatility of the proposed modeling schemes.