# An Integral Fuzzy Model to Evaluate Slab and Beam Bridges with a Preventive Approach
## 2 State of the Art
### Classical Approach  
The classical approach is the most widely used method for determining the condition of bridges. This approach involves manual inspection and assessment by experts who provide a judgment on the overall condition of the bridge. This section analyzes seven international manuals that provide guidelines for carrying out this type of assessment, each with different methodological approaches. From a comparative analysis of these documents, two predominant approaches emerge: corrective and preventive. The preventive approach aims to identify the progressive deterioration of bridge elements at early stages, allowing for timely interventions to be planned that extend their useful life and reduce long-term maintenance costs. In contrast, the corrective approach allows deterioration to progress to a more severe level before action is taken, which can compromise structural safety and result in higher repair costs. To begin our analysis, we reviewed the manual corresponding to Mexico [16], which establishes the criteria for evaluating the overall condition of a bridge using a corrective approach based on visual inspections and assessments. This methodology considers the deterioration of the bridge's construction materials, as well as the impact of external factors that may accelerate this deterioration. The assigned ratings depend on the inspector's judgment, introducing a high level of subjectivity into the evaluation. Furthermore, the methodology generates a final rating that represents the overall condition of the bridge but masks the specific influence of individual elements. This can make it difficult to identify the relationship between localized deterioration and the bridge's overall condition, limiting the accuracy of the diagnosis. In Colombia, the manual [17] establishes the criteria for evaluating bridges using a corrective approach. Its methodology treats the bridge as a single component, without considering the influence of individual deteriorations on the bridge's overall performance. This approach places significant responsibility on the evaluator, who must determine both the type of maintenance required and the urgency of its application. It is essential to note that the manual does not provide maintenance recommendations, leaving this decision entirely to the professional's discretion. On the other side, the Ontario Structure Inspection Manual (OSIM) [4] presents criteria for the individual evaluation of bridge elements, assigning a final rating to each and determining the necessary maintenance work based on this evaluation. However, it lacks an integral approach that considers the overall performance of the bridge, which makes its evaluation method corrective and limits its ability to identify early-stage deterioration. In Costa Rica, the manual [18] establishes criteria for evaluating the condition of certain individual bridge elements using a corrective approach. Although it includes an inventory and a section describing the degree of damage to the elements, the system does not explain how the overall bridge evaluation process is conducted. Furthermore, the manual does not provide recommendations regarding the maintenance work required for the deteriorated elements. In Peru, the manual [5] focuses on assisting in the evaluation of bridges, considering both certain deterioration that may affect the bridge elements and external factors that can accelerate their progression. This manual establishes relationships between the different bridge elements to assign an overall rating to the structure. Additionally, it includes recommendations for periodic, preventive, and corrective maintenance. However, its application relies on the personal judgment of the evaluator who is responsible for assessing and estimating the resources required for the structure's preservation. The AASHTO manual from the United States [3] initially evaluates the individual elements of the bridge before assigning an overall rating to the structure.