Simulated Behavior of Rectangular Reinforced Concrete Columns under Seismic Loading

To address the need for enhancing the resiliency of existing building infrastructure under strong earthquake motions, this study objective is to quantify the seismic behavior of concrete columns for all critical strength degradation modes using an extended dataset for column tests, referred as UTSA Reinforced Concrete (RC) Column Database. Novel metrics for quantifying behavior are proposed using a mix of mechanics and statistic-based methods, including the force deformation envelopes, degradation triggers, cyclic/hysteresis parameters, and strength damage. The UTSA Column Database has been expanded by over 100 additional column tests with a variety of properties. Novel data include: 1) complete set of lateral force versus lateral drift envelope metrics, 2) novel cyclic behavior metrics, 3) a collection of digital images of damage condition/progression. A comprehensive set of rectangular RC column lateral force versus deformation envelope parameters are calibrated using the UTSA column database. The modeling parameters defining a multi-linear envelope response include an elastic stiffness, degrading stiffness, strength and deformation capacity at yield, peak, capping, and residual points. The parameters are calibrated for all column lateral-degradation modes, classified as: flexure, flexure-shear, splice, and shear controlled using its prominent properties. Similar approach is used to calibrate the cyclic/hysteresis and strength damage parameters. A novel mathematical model using cubic spline curves representing three physically meaningful parameters is proposed. The parameters are identified as unloading stiffness, reloading stiffness, and Energy Ratio, which represents a measure of dissipated energy. The parameters are found to be correlated with the secant stiffness, which represents column's deformation level.