Fragility Analysis of Pile-Supported Wharves and Piers Exposed to Storm Surge and Waves

Abstract

Ports are located in areas often susceptible to storm surge and flooding from severe storms as well as the potential impacts of climate change, such as sea level rise. Although there is a significant body of work addressing the vulnerability of ports subjected to earthquakes, models that support risk assessment of ports subjected to storm surge and waves from coastal hazards, including hurricanes, are scarce. This study presents a methodology for fragility analysis of wharf/pier structures typical in port facilities that are subjected to hurricane-induced storm surge and wave loading. Such models enable future risk assessment of these structures when exposed to current or projected storm conditions. The framework presented first utilizes Latin hypercube sampling within a Monte Carlo simulation to estimate uncertain vertical and horizontal demands from surge and wave loading, along with uncertain capacities associated with uplift, shear, and flexural failure. Fragility surfaces are then generated, expressing failure probability given wave height and relative surge elevation. Furthermore, stepwise logistic regression is applied to derive the parameterized deck–pile connection fragility functions for ready application in regional risk assessment. The proposed approach is applied to four alternative deck–pile connections typically found in wharves/piers: a full moment connection with dowels inside of the compression zone, a full moment connection with dowels outside of the compression zone, a partial moment connection with dowels inside of the compression zone, and a partial moment connection with dowels outside of the compression zone. The results suggest that the dominant structural failure mode for all of the examined cases is uplift. Furthermore, the partial moment connections are more vulnerable to storm surge and waves compared to full moment connections. Although providing sufficient clearance is a preferred method for port safety, it is not always possible to keep the wharf/pier deck sufficiently elevated above the sea level. Given the criticality of these structures to maintain port operations posthazard event, this paper offers a method for efficiently estimating their hurricane fragility that can be extended in the future to a portfolio of portstructures and applied for current hazard conditions or future scenarios including the effects of climate change.