Cyclic Compressive Behavior and Stress-Strain Model of Large-Rupture-Strain and Conventional FRP-Strengthened Circular Columns
Presented By: Mohanad Abdulazeez
Affiliation: University of Missouri - Kansas City
Description: This paper presents a numerical investigation into the behavior of circular concrete columns confined with Polyethylene Terephthalate (PET), Polyethylene Naphthalate (PEN), and conventional Glass Fiber Reinforced Polymer (FRP). The columns were experimentally tested under cyclic compression loads to evaluate their seismic resilience and performance. Experimental results reveal that control columns exhibited lower ductility and peak lateral strength compared to FRP-confined columns, which demonstrated enhanced energy dissipation and improved ductility. Notably, this research is the first to investigate the cyclic performance of PET FRP-confined concrete columns, with particular emphasis on the stress drop phenomenon. To further elucidate the material behavior, numerical simulations were conducted using LS-DYNA software, with 18 distinct models analyzed. A parametric study was performed to assess the effectiveness of PEN and PET FRP strengthening, evaluating key factors such as failure modes, displacement ductility, axial cyclic load-displacement response, stiffness degradation, and energy dissipation capacity. Based on experimental and numerical results, a novel cyclic constitutive model is propose, incorporating adjustments for plastic strain and stress degradation. The proposed model accurately captures the stress drop phenomenon and provides valuable insights for the design and application of low-resistance (LRS) FRP confined concrete columns under seismic and cyclic loading conditions.
FE Simulation of Concrete Hydraulic Facilities Affected by Alkali-silica Reaction: From Material to Structure
Presented By: Mahdi Ftima
Affiliation: Polytechnique Montreal, Montreal, Canada
Description: This study focuses on an existing hydroelectric facility affected by alkali-silica reaction (ASR). The long-term objective is to predict the future performance of the structure and evaluate its integrity and functionality under the combined effects of ASR-induced expansion and mechanical loading. To achieve this, a phenomenological finite element framework is proposed, incorporating hygro-chemo-mechanical coupling tailored for ASR modeling in mass concrete hydraulic structures. The methodology involves three main stages: transient thermal analysis, transient moisture (hygral) analysis, and a final multi-physics analysis that accounts for mechanical loads.
Application of this modeling approach to the real structure demonstrated its practical relevance in an industrial context. The simulation results reproduced damage patterns that closely matched observed cracking, thereby enhancing confidence in the model and contributing to a better understanding of the structure’s complex long-term behavior. Comparison of displacement model predictions and available monitoring data allowed to assess an important size effect between laboratory and in-situ expansions.
Finite Element Analysis of Seismically Retrofitted RC Walls Presenters
Presented By: Ioannis Koutromanos
Affiliation: Virginia Tech
Description: This presentation will focus on recently implemented capabilities for nonlinear analysis of reinforced concrete walls. A set of element formulations, together with constitutive laws for the concrete, reinforcing steel, retrofit materials and the interface between retrofit overlays and existing concrete have been combined to provide an analysis framework in a freely available research code. The framework is combined with pre- and post-processing capabilities, greatly facilitating the model definition, which would otherwise be a challenge due to the presence of multiple fixtures (interfaces between materials, dowels, anchors, etc.). Two different levels of model fidelity can be pursued, namely, a higher-fidelity, three-dimensional, continuum-based approach, or a simplified, yet highly accurate approach, based on shell macroelements using the truss analogy for reinforced concrete. The capabilities of the method in capturing the response and damage mechanisms of walls retrofitted with FRP or concrete overlays are validated using the results of a recently completed experimental test project, focused on the performance of unretrofitted and retrofitted RC walls under cyclic lateral loads. The analytical models provide unique insights on the contribution of retrofit overlays to the resistance and deformability, including unexpected experimental observations.
Use of Finite Element Analysis for Penetration Detailing Around Openings in Steel-plate Composite Structural Elements for Nuclear Application Presenters
Presented By: Ahmed Elremaily
Affiliation: Sargent Lundy
Description: This study uses nonlinear FEA to develop alternate detailing around openings in steel-plate composite structural elements for nuclear application.