Seismic vulnerability assessment of wharf structures
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Serving as critical gateways for international trade, seaports are pivotal elements in transportation networks. Any disruption in the activities of port infrastructures may lead to significant losses from secondary economic effects, and can hamper the response and recovery efforts following a natural disaster. Particularly poignant examples which revealed the significance of port operations were the 1995 Kobe earthquake and 2010 Haiti earthquake in which liquefaction and lateral spreading of embankments imposed severe damage to both structural and non-structural components of ports. Since container wharf structures are responsible for loading and unloading of cargo, it is essential to understand the performance of these structures during earthquakes. Although previous studies have provided insight into some aspects of the seismic response of wharves, limitations in the modeling of wharf structures and the surrounding soil media have constrained the understanding of various features of the wharf response. This research provides new insights into the seismic behavior of wharves by using new and advanced structure and soil modeling procedures to carry out two and three-dimensional seismic analyses of a pile-supported marginal wharf structure in liquefiable soils. Furthermore, this research investigates the interaction between cranes and wharves and closely assesses the role of wharf-crane interaction on the response of each of these systems. For this purpose, the specific effect of wharf-crane interaction is studied by incorporating advanced models of the crane with sliding/uplift base conditions. To reduce the computational time required for three-dimensional nonlinear dynamic analysis of the wharf in order to be applicable for probabilistic seismic demand analysis, a simplified wharf model and an analysis technique are introduced and verified. In the next step probabilistic seismic demand models (PSDMs) are generated by imposing the wharf models to a suit of ground deformations of the soil embankment and pore water pressure generated for this study through free-field analysis. Convolving PSDMs and the limit states, a set of fragility curves are developed for critical wharf components whose damage induces a disruption in the normal operation of ports. The developed fragility curves provide decision makers with essential tools for maximizing investment in wharf retrofit and fill a major gap in seismic risk assessment of seaports which can be used to assess the regional impact of the damage to wharves during a natural hazard event.