ABSTRACT
The existence of aging bridges in the road network and the damages resulting from everyday operation and earthquake activity demonstrate the need for timely and effective maintenance and rehabilitation of them. The importance of bridges in operational, economic, and social terms makes the evaluation of the seismic risk an objective of particular research and practical interest. It is necessary, however, that bridge operation and management is not only directed to ensure durability in their service life but also to minimize the adverse impacts on society, environment, and the economy (Dong et al. 2014).
The aim of this research is the development of a computerized management system for assessing optimal maintenance and rehabilitation strategies for road bridges in their life-cycle aiming at minimizing the seismic risk within the framework of sustainability. The system development takes into account the design and structural characteristics of bridge elements (foundation, substructure, superstructure) combined with age and exposure to earthquake activity, the performance of bridge elements in time as a result of seismic actions and operational loads, feasible maintenance and rehabilitation treatments (repair, reinforcement, replacement), the traffic disruption as a result of bridge closure, and the importance of the bridge within the road network. The bridge response to seismic loads is modeled through finite element analysis and vulnerability (fragility) curves are developed for each bridge element describing the probability of damage as a result of a specific seismic parameter.
Optimal maintenance strategies are sought for a bridge network in time to ensure the minimization of potential impacts that are due to seismic risk, efficient use of resources, and the reduction of social and environmental impacts subject to operational, safety, and budget availability constraints. Due to the large size and complexity of the problem, the optimization is done employing an appropriately designed genetic algorithm. The system implementation was performed in Microsoft Excel™ environment while the genetic algorithm was developed in Visual Basic for Applications (VBA). The result of the optimization is a maintenance and rehabilitation plan which minimizes either the seismic risk parameter or the cost associated with the proposed interventions or the combination of the two (Figure 1). Trade-off between maintenance cost and seismic risk. https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315207681/cd556cd4-4dcf-4efe-8e29-56fc67b8bfbd/content/fig237_1.tif"/>
The system has been applied to existing bridges with highly diverging characteristics. The application indicated that the proposed maintenance strategies are in good agreement with the structural and functional characteristics of bridges, the estimated condition worsening in time, the seismic hazard in the area where the bridge is built, and the bridge importance within the road network. The results of the investigation are found reasonable and indicate that the methodology can be effective in assisting bridge maintenance and management decisions in regions with high seismic activity.
