Nonlinear Finite Element Analysis of B-C Connections: Influence of the Column Axial Load, Jacket Thickness, and Fiber Dosage

Abstract

The behavior of beam-column (B-C) connections received thorough investigation during the past decades focusing on critically-detailed connections before and after strengthening. Various techniques for strengthening of the B-C connection were previously evaluated using high performance concrete jackets (HPCJ), carbon-fiber reinforced polymer (CFRP) composites, or external steel plates. In this study, systematic nonlinear finite element analyses (FEA) were conducted using ANSYS to evaluate the effects of the fiber content and thickness of the HPCJ as well as the level of the column axial load, which is a parameter difficult to evaluate experimentally due to limitations in loading machines and requirement for complicated testing setups. A total of twenty nonlinear FEA models were created, calibrated and properly verified with reputable experimental literature results. The nonlinear FEA results showed that both the HPCJ thickness and fiber content significantly affect the cracks distribution, failure mode, ultimate load capacity, and ductility of the B-C connection. Column axial load levels up to 75% were advantageous to the behavior of virgin B-C connections. In strengthened B-C connections with HPCJ, column axial load levels of 50% and 75% besmirched the behavior compared with 25%. The use of 1% volumetric fiber fraction within the HPCJ results in comparable performance as 2%. The lateral load capacities, net drifts, hysteresis loops, cracks distribution, energy dissipation, stiffness degradation, and failure modes were presented.