Finite element analysis of RC beams strengthened in flexure with CFRP rod panels

The carbon fiber reinforced polymer (CFRP) rod panel technique has recently been introduced as an efficient and economical retrofit option for concrete structures. In a previous study, an experimental testing was carried out on RC beams strengthened with several rod panel configurations (continuous, overlapped, and overlapped with fabric end-anchorage). The current study presents comprehensive FE models of the tested beams, developed to provide an in-depth examination of the rod panel and its interaction with the concrete substrate. The FE models considered different material models and presented methodologies for simulating the failure modes experienced in the tests [intermediate crack-induced debonding (ICID) and concrete cover separation (CCS)]. Various comparisons with the experiments, such as ultimate load, load mid-span deflection history, failure mode, demonstrated the validity the FE models. This study reported on vital data, such as tensile stress distribution in the rod panel, maximum interfacial shear and normal stresses at the panel-concrete interface, and location of maximum stresses. It was found that high shear stresses exist at the end of the continuous and overlapped rod panels, and high normal stresses at the edge of the rod finger joint. Wrapping the panel's ends with fabrics resulted in reduction of end shear stresses and contributed to the prevention of CCS failure and the increase in the ultimate load. For field applications, the study recommends using the fabric wraps at the panel ends to prevent premature failures.