Seismic collapse assessment of archetype frames with ductile concrete beam hinges

Abstract

Highly ductile cement-based materials have emerged as alternatives to conventional concrete materials to improve the seismic resistance of reinforced concrete (RC) structures. While experimental and numerical research on the behavior of individual components has provided significant knowledge on element-level response, relatively little is known about how ductile cement-based materials influence system-level behavior in seismic applications. This study uses recently developed lumped-plasticity models to simulate the unique failure characteristics and ductility of reinforced ductile-cement-based materials in beam hinges and applies them in the assessment of archetype frame structures. Numerous story heights (four, eight, and twelve), frame configurations (perimeter vs. space), materials (conventional vs. ductile concrete), and replacement mechanisms within the beam hinges are considered in the seismic analysis of the archetype structures. Results and comparisons are made in terms of the probability of collapse at 2% in 50-year ground motion, mean annual frequency of collapse, and adjusted collapse margin ratio (ACMR) across archetype structures. The results show that engineered HPFRCCs in beam plastic-hinge regions can improve the seismic safety of moment frame buildings with higher collapse margin ratios, lower probability of collapse, and the ability to withstand large deformations. Data is also reported on how ductile concrete materials can reduce concrete volume and longitudinal reinforcement tonnage across frame configurations and story heights while maintaining or improving seismic resistance of the structural system. Results demonstrate future research needs to assess life-cycle costs, predict column hinge behavior, and develop code-based design methods for structural systems using highly ductile concrete materials.