An important challenge in damage detection based on the curvature mode shape (CMS) method is recognizing damage severity in damaged structures. Here, an efficient approach is proposed based on the finite element (FE) method, which detects the existence, location and severity of damage using the distributed genetic algorithm in conjunction with CMS. First, using the mode shape of the structure, curvature is calculated at the nodes of the structure in the FE model. By comparing the curvature between the intact and damaged structures, the existence and location of damage are determined. Next, by defining an optimization problem, damage severity in the damaged elements is determined. Results of applying the proposed approach on beam and frame structures under various damage scenarios and an experimental set-up show that this method is very effective in damage detection of such structures. Furthermore, the performance and accuracy of the proposed method are examined for various noise levels.