The failure behavior of beam-to-column connections can be minimized or avoided to some extent by using PET waste fibers. With the change of composition, different seismic performances of concrete joints can be adjusted. FEM analysis was performed in ABAQUS software to compare the performance of concrete beam-to-column connections reinforced with conventional concrete fibers and waste PET under cyclic loading. The concrete mix is designed to achieve a concrete grade of M25. Seven figures of the external beam-to-column connections were modeled as a quarter of the architectural prototype. The first joint is conventional concrete and designed according to IS 1893 (Part 1):2022 and the reinforcement in the joint part are specified according to the ductility requirements of IS 13920:2016. Six other samples were designed to contain different PET waste fibers (0.25% to 1.50%) in the seam area. Beam-to-column connections have 0.75% to 1.25% PET fiber inclusions that have better performance in terms of strength, load-carrying capacity, energy dissipation capacity, joint shear strength, and ductility in the joint area. Incorporating PET waste fibers into concrete can provide the best solution for waste management, and also has the potential to reduce the cost of reinforced concrete by 15%-20% holds economic significance, and concrete with PET waste fibers indeed demonstrates better seismic performance, and could lead to increased safety and longevity of structures in seismic-prone areas. This suggests that experimental work or studies might have explored how these fibers affect the concrete's properties, strength, durability, and other characteristics.