A building whose functions are converted in which their volumes are improved, for example, a four-story building transformed into a five-story building, resulting in a dead load improvement of its structural self-weight, obviously requires strengthening in order to avoid the possibility of structural failures. This paper focuses on a nonlinear finite element analysis conducted using the ATENA program on T-section reinforced concrete beams strengthened in the negative moment region with wire ropes and an addition of steel rebars at the compression block. The results are then compared with the results of the previously conducted experiments. The specimen models consist of control beams (BK), strengthened beams with wire ropes at the tension block (BP1), and strengthened beams with wire ropes at the tension block and steel rebars at the compression block (BP2). The results show that the ratios of the load-carrying capacity against those of the experimental results are 1.25, 1.23, and 0.89 respectively for BK, BP1 and BP2. The effective stiffness ratios to those of the experimental results are 1.45, 1.15, and 1.86, while the ductility index ratios against the experimental results are 1.11, 0.63, and 1.01 respectively for BK, BP1, and BP2. The crack patterns of the nonlinear finite element analytical results revealed that all specimen models experience flexural failure.