The objective of having a diagnosis of a bridge is to generate a technical study to verify that the stability and mechanical resistance of the structure comply with the current safety requirements and regulations. A diagnosis involves assessing and studying existing damage, recalculating the structure if necessary, and considering all physical and chemical environmental factors that may have contributed to damage to the structure.
The elaboration of a diagnosis on a bridge allows to deliver of an integral quantitative evaluation of the “health status” of its different elements. This allows the owner and managers to have fundamental information to adjust maintenance cycles or make decisions related to when to undertake corrective actions in the structure or the establishment of new control measures for further monitoring of the bridge, all to ensure the bridge’s future performance.
The diagnosis of bridges aims to determine the pathologies that they present, which can affect the characteristics of resistance and serviceability of a bridge. Additionally, after having a diagnosis, a prognosis should be performed, which is intended to predict what the future behaviour of the structure will look like, so that it may be determined what monitoring the structure requires in the present and when actions, such as repairs, will be required in the future.
With this information, a strategy should be designed, and appropriate measures should be undertaken. It must be determined when the repairs and other corrective actions should be performed to achieve the economical optimum. In some cases, these interventions need to be immediately foreseen and executed, intervening in an early way before the intervention becomes more complex and increases even more its cost. But in other situations, interventions can be delayed until a point is reached at which deterioration would begin to progress to the extent that it would reach the stage described above, that further delay would increase the complexity and cost of the repair.
In addition, to schedule this type of intervention, all types of situations need to be evaluated, affecting the decision on when to undertake the intervention. For example, it may happen that due to the progression of the deterioration, it is possible to wait longer to intervene, but just a window of time is found in which the traffic on the bridge can be cut off with no problems. Here the decision can be made to take advantage of this opportunity to intervene immediately. In short, very careful consideration must be given to when to act, evaluating all scenarios.