Chunlu Liu

Multiobjective optimization of bridge deck rehabilitation using a genetic algorithm

The solution methods of multiobjective optimization have undergone constant development over the past three decades. However, the methods available to date are not particularly robust. Because of the complicated relationship between the rehabilitation cost and deterioration degree of infrastructure systems, it is difficult to find a near-optimal solution using common optimization methods. Since genetic algorithms work with a population of points, they can capture a number of solutions simultaneously and easily incorporate the concept of Pareto optimality. In this paper a simple genetic algorithm with two additional techniques, Pareto optimality ranking and fitness sharing, is implemented for the deck rehabilitation plan of network-level bridges, aiming to minimize the total rehabilitation cost and deterioration degree. This approach is illustrated by a simple example and then applied to a practical bridge system with a large number of bridges.

Information technology applications for bridge maintenance management

Infrastructure maintenance management has become a challenge field for civil engineers and government managers because of the increasing number of deteriorated structures, their complicated spatial locations, the improved service requirements, the limited maintenance budgets and so on. Therefore, maintenance management approaches have been developed for civil infrastructures such as bridges and roads over the past several decades, but most of such approaches focused on one specific structure only – project‐level maintenance management. Now, there are increasing demands and appropriate conditions for network‐level maintenance management for civil infrastructure systems. Aims to explore such a maintenance management approach by integrating and applying the current information technologies, which include the database management system, geographic information system, genetic algorithm and the Internet. Several possible applications of each technology are discussed for solving real‐world problems.

Comparative study of optimized and conventional bridges: Life cycle cost and environmental impact

In recent years, environmental problems have become serious issues in the whole world. Researchers and practical engineers in civil engineering have to pay enough attention to the environmental impacts as well as to the function, safety, cost and aesthetics at all lifecycle stages of civil infrastructures. In this study, the estimation is made for the lifecycle CO2 emission, and the lifecycle cost of both the conventional bridges and the minimum maintenance bridges. According to the results concluded from this research, the lifecycle environmental analysis and the lifecycle cost analysis may deduce various conflicting bridge design and management schemes, therefore, the bridge engineers and government managers should consider the environmental impact as a fundamental criterion in addition to the lifecycle cost during the decision-making process for the bridge lifecycle management. In addition, the characteristics of lifecycle environmental impact and lifecycle cost of bridges using new technologies have advantages compared with those of the conventional bridges.