The rocking-dominated seismic response of reinforced concrete (RC) columns is a complex mechanism that entails P-Delta effects, concrete crushing and spalling, rupture and dislocation of steel bars and stirrups, as well as combined localized failures causing splitting and shear-flexure cracking. In this paper, we present a new meso-scale numerical modeling strategy for the detailed simulation of the rocking response of slender RC columns under seismic actions. This work advances the current state-of-the-art by exploring the unprecedented use of the Distinct Element Method (DEM), originally conceived for geotechnical studies and whose applicability in earthquake engineering has been primarily limited to the assessment of unreinforced masonry sub-structures. To decrease analysis time and enable the use of DEM for RC problems, concrete is herein idealized as an assembly of solid macro-block layers of size directly proportional to their distance from expected plastic hinges. These layers are connected by nonlinear interface springs to simulate tensile and shear cracking via a simplified Mohr-Coulomb criterion. Crushing of concrete in deformable blocks is modeled using the Feenstra and De Borst strain-softening linearized compression law, while confinement and combined failures are accounted for numerically through the explicit representation of longitudinal and transversal reinforcement bars, idealized as link elements. Previous experimental static and dynamic tests on full-scale RC column specimens and results from fiber-based Finite Element and sectional analysis models are used to evaluate DEM results and quantify the influence of key modeling parameters, including block number and deformability, as well as the amount of damping. The agreement between simulated failure modes and force and displacement capacities and their experimental counterparts demonstrate the applicability of the proposed approach, while demonstrating the pros and cons of simplified numerical methods.
A new Distinct Element meso-model for simulating the rocking-dominated seismic response of RC columns
Scattarreggia, N
;
2023-01-01
Abstract
The rocking-dominated seismic response of reinforced concrete (RC) columns is a complex mechanism that entails P-Delta effects, concrete crushing and spalling, rupture and dislocation of steel bars and stirrups, as well as combined localized failures causing splitting and shear-flexure cracking. In this paper, we present a new meso-scale numerical modeling strategy for the detailed simulation of the rocking response of slender RC columns under seismic actions. This work advances the current state-of-the-art by exploring the unprecedented use of the Distinct Element Method (DEM), originally conceived for geotechnical studies and whose applicability in earthquake engineering has been primarily limited to the assessment of unreinforced masonry sub-structures. To decrease analysis time and enable the use of DEM for RC problems, concrete is herein idealized as an assembly of solid macro-block layers of size directly proportional to their distance from expected plastic hinges. These layers are connected by nonlinear interface springs to simulate tensile and shear cracking via a simplified Mohr-Coulomb criterion. Crushing of concrete in deformable blocks is modeled using the Feenstra and De Borst strain-softening linearized compression law, while confinement and combined failures are accounted for numerically through the explicit representation of longitudinal and transversal reinforcement bars, idealized as link elements. Previous experimental static and dynamic tests on full-scale RC column specimens and results from fiber-based Finite Element and sectional analysis models are used to evaluate DEM results and quantify the influence of key modeling parameters, including block number and deformability, as well as the amount of damping. The agreement between simulated failure modes and force and displacement capacities and their experimental counterparts demonstrate the applicability of the proposed approach, while demonstrating the pros and cons of simplified numerical methods.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
