Development of a Risk Framework for Forecasting Earthquake Losses in Port Systems

Abstract

Ports play a critical role in transportation infrastructure but are vulnerable to seismic hazards. Downtime and reduced throughput from seismic damage in ports results in significant business interruption losses for port stakeholders. Managing risks from systemwide disruptions resulting from earthquake damage has been studied as a central element of a project sponsored by the National Science Foundation Network for Earthquake Engineering Simulation (NEES) program. Presented are the concepts and methods developed for the seismic risk management of a portwide system of berths. The framework used to calculate port losses is discussed, particularly the use of spatially correlated ground motion intensity measures that estimate damage to pile-supported wharves and container cranes, the repair costs and downtimes subsequently determined via repair models for both types of structures, and the impact on cargo handling operations calculated via logistical models of the port system. Results, expressed in the form of loss exceedance curves, are calculated.

Optimal Seismic Upgrade Timing in Seaports with Increasing Throughput Demand via Real Options

“…respectively, within the performance-based earthquake engineering risk assessment framework for ports developed by Burden et al (2016). In the last two equations, λX(x) denotes the MAF of the event {X>x}, that is the random variable X exceeds a particular value x, G(u|v)=Pr(U>u|V=v) denotes the conditional complementary cumulative distribution function signifying the probability of the event {U>u} given the event {V=v}, im denotes an intensity measure of an earthquake (e.g., peak ground acceleration), edp is an engineering demand parameter representing a measurable structural response to an earthquake (e.g., peak deformation of a critical member in a seaport structured facility/component), dm is a damage measure converting the edp of choice to a quantifiable damage state commonly done through component-specific fragility curves (e.g., Na andShinozuka 2009, Shafieezadeh andBurden 2014), and rr represents component-specific repair requirements due to a sustained dm.…”

“…Nevertheless, if deemed essential, multi-intensity ground shaking can be accounted for more rigorous decisionmaking through the definition of the reference seismic event using loss curves. In this setting, full probabilistic loss analysis for the existing port needs to be undertaken involving, apart from a hazard curve obtained from regional PSHA, fragilities for the different infrastructure and simulation-based tools to predict downtime/loss of service (see e.g., Burden et al 2016). Nevertheless, such information and analyses may be too costly to obtain and therefore out the reach of most stakeholders.…”

“…The values of the parameters for this example are shown in Table 3. Three cases of increasing downtime, retrofit, and repair costs are considered, in order to assess the sensitivity of the optimal retrofit time to these parameters, obtained from probabilistic seismic loss analyses for seaports as in Burden et al (2016). In cases 1 and 2, the repair cost is equal with the retrofit cost.…”

“…More importantly, within such an environment there is an opportunity to combine seismic structural upgrades with investments to increase the seaport capacity to meet increased throughput demands. In typical medium-to-large capacity seaports, the latter investments are commonly undertaken every 20 years or so and involve strengthening, deepening, and/or extending berth quay walls and wharf foundations, that is, the same key infrastructure at container terminals that are known to be the most seismically vulnerable (see e.g., Na and Shinozuka 2009, Scharks et al 2014, Shafieezadeh and Burden 2014, Burden et al 2016. Such investments involve high capital costs and can cause partial temporary operational disruption in the terminal operation.…”

“…It then uses a series of simplification assumptions to evaluate this option, accounting for earthquake loss due to a reference seismic event having a specific annual probability of occurrence. Notably, the developed RO formulation accounts for changes in earthquake loss in line with increasing cargo throughput demand: this is an important consideration for the problem at hand, since the largest portion of earthquake loss in seaports is due to downtime (i.e., business interruption) rather than to repair cost (see e.g., Na and Shinozuka 2009, Shafieezadeh and Burden 2014, Burden et al 2016. The conceived RO formulation is solved in discrete-time by considering a simple lattice (tree)-based approach.…”