La evaluación y gestión de estructuras en servicio: ¿Un arte o una técnica?

The evaluation and manegement of existing structures: Art or technique?

In this article the most important differences between structural evaluation of an existing bridge and the design of a new structure are identified. So that, there is need to develop a methodology for structural evaluations which take into account the abovementioned differences and to optimize the avaliable and limited economical sources instead of the criteria specified by the prevailing design Codes. Due to the uncertainly related with the physical variables involved in the structural evaluation (resistance, loads, etc.) only the methods using the Reliability Theory can solve it with a scientific criteria. A guideline of the fundamental definitions and methodology based on this theory to obtain the Reliability Index (failure probability) are presented. Ultimate live load carrying capacity taking into account the possible redistribution of internal forces should be included in the reliability analysis for Ultimate Limit States to evaluate the system response. Finally, the article includes the procedure to take into account the failure probabilities of existing structures for the development of rational criteria based on the economical expected cost.