Du Xiuli

Seismic retrofit priority assessment of highway networks based on multi-indices analysis

Seismic retrofit priority analysis of roads and bridges is essential for seismic fortification and emergency relief preparation of highway networks. First, four types of network component importance ranking indices, including beweenness centrality, network connective reliability sensitivity, post-earthquake travel time delay and normal travel time delay of components are employed in this paper to calculate the seismic retrofit importance values of bridges and roads. Second, according to the component importance values of each individual index, the integrated importance values of components were evaluated by a multi-attribute decision method based on TOPSIS. Then, the seismic retrofit priorities of transportation network components are determined by the integrated importance measures. In case study, the characteristics of these indices are analyzed by results comparisons, and differences between the component importance ranking by one index and the integrate indices are also explored. The results of the case study show that the integrated importance measure has combined the impacts of network topology, component seismic response, component transportation capacity and OD trips, and provides the fundaments for comprehensive component retrofit ranking of the highway transportation systems.

A heuristic search space reduction method for water distribution system seismic design optimization

In the seismic design optimization model of urban water distribution system (WDS), the design objective is seismic performance requirement of user nodes, the design parameters consist of the water supply network topology and the seismic capacity of pipeline structures. The selection of optimal design parameters is a combinatorial optimization problem. This paper presents a two-stage search space reduction strategy for WDS seismic design using GA. In the first stage, the initial population is generated by degree constrained connected graph, which narrowed the optimization search space at the beginning of GA. A genetic individual repair strategy is proposed for individuals violate constraints in the evolutionary process, which achieved search space reduction during GA operation. The proposed method processes better efficiency in WDS seismic optimized design using GA and also provides a reference for other constrained optimization problems.