The paper in hand investigates the nonlinear behavior of strengthened steel I-beams with web opening using externally bonded Carbon Fiber Reinforced Polymer (CFRP) composites. Two different web opening shapes; circular and rectangular; in two different positions; shear zone and mid-span; were concerned in the analysis. The finite-element analysis was conducted using ANSYS V.15. It was found that the existence of web opening not only reduced the capacity of the steel I-beam but also caused stress concentration around the opening, especially in shear zone which led to vierendeel failure mechanism. Thus, CFRP composite plates with different lengths were used above and below the opening to recover the original beam capacity. The results revealed that all the strengthened steel I-beams showed a better performance and presented a higher capacity. The adequate length of CFRP plates related to opening dimensions for each position and shape are demonstrated in detail.