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Oakland, CA, United States

Burden L.I.,University of Virginia | Rix G.,Georgia Institute of Technology | Werner S.,Seismic Systems and Engineering Consultants
Earthquake Spectra | Year: 2016

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. © 2016, Earthquake Engineering Research Institute.


Werner S.,Seismic Systems and Engineering Consultants | McCullough N.,CH2M HILL | Bruin W.,Halcrow | Rix G.,Georgia Institute of Technology | And 2 more authors.
Earthquake Spectra | Year: 2011

The Port de Port-au-Prince is the largest seaport in Haiti, and is essential to the country's economy. The Haiti earthquake severely damaged the Port, which disrupted the transport of cargoes into Haiti that were vital to the country's emergency response and post-earthquake recovery. Major contributors to this damage were widespread soil liquefaction, the poor performance of batter piles, and the poor pre-earthquake condition of many components of the Port's waterfront structures. Immediately after the earthquake, a U.S. military task force was deployed to the port to perform emergency repairs needed to reestablish cargo throughput. These repairs restored a significant cargo-throughput capacity at this small but vital seaport within weeks after the earthquake. © 2011, Earthquake Engineering Research Institute.


Yang C.S.W.,Georgia Institute of Technology | Werner S.D.,Seismic Systems and Engineering Consultants | DesRoches R.,Georgia Institute of Technology
Engineering Structures | Year: 2015

Skewed bridges are often encountered in the highway bridge system when the geometry cannot accommodate straight (unskewed) bridges. The objective of this study is to investigate the influence of skew angle on the seismic response of bridges using nonlinear time-history analysis and probabilistic seismic assessments. Six types of skewed and straight bridges (including multi-span simply supported, multi-span continuous, and single-span skewed bridges with steel or concrete girders together with non-integral abutments) commonly used in the central and southeastern United States (CSEUS) are considered for establishing three-dimensional numerical bridge models. The six bridge types are further categorized as: (1) non-seismically designed (NSD) bridges, (2) bridges with seismically designed (SD) columns, (3) bridges retrofitted by (i) column jackets, (ii) isolator bearings (IBs) and keeper plates (KPs), (iii) restrainer cables (RCs) and shear keys (SKs), or (iv) seat extenders (SEs) and shear keys (SKs). Probabilistic seismic demand models incorporating geometric and material uncertainty parameters for the bridges under a suite of ground motions are established to develop corresponding sets of fragility curves in terms of vulnerable bridge components. System fragility curves are further developed through a combination of the component fragility curves in the bridges. Comparisons of the fragility curves between the straight and skewed bridges indicate that the larger the skew angle, the more vulnerable the bridges, regardless of NSD bridges, bridges with SD columns, and retrofitted bridges. Formulas that consider effect of skew on the values of fragility parameters in the fragility curves are derived for each bridge class, component type, and limit state. Finally, the retrofit of columns and seismically designed columns can reduce column damage probabilities without significantly increasing demands to the other bridge component types, leading to a lower bridge system risk than that for the NSD bridges. However, although the other three retrofits (IB&KP, RC&SK, and SE&SK) can reduce transverse and/or longitudinal demands on the bearings, the column demands remain a similar or worse damage level than that for the NSD bridges, resulting in a similar or higher risk for the three retrofitted bridge systems. © 2014 Elsevier Ltd.


Shafieezadeh A.,Ohio State University | Desroches R.,Georgia Institute of Technology | Rix G.J.,Georgia Institute of Technology | Werner S.D.,Seismic Systems and Engineering Consultants
Journal of Structural Engineering (United States) | Year: 2013

Abstract Seismic performance evaluation of wharf structures constitutes the core of the vulnerability assessment of seaport infrastructure exposed to seismic events. Because this performance will depend on complex interactions between the surrounding potentially liquefiable soils and wharf foundation and structure, detailed and careful implementation of advanced modeling techniques is needed. These models are required to capture such highly nonlinear phenomena as permanent seaward deformation of embankment soils, soil-structure interaction in liquefiable soils, spread of plasticity in prestressed piles, and force-deformation of pile-deck connections. This study utilizes such modeling approaches to investigate the three-dimensional (3D) nonlinear response of a typical pile-supported container wharf structure in liquefiable embankment soils. Input excitations for this analysis consist of embankment soil deformations for a far-field and an impulsive near-field ground motion. These excitations are derived using two-dimensional (2D) plane strain free-filed analyses for transverse (seaward-landward) and vertical directions and a spectral matching technique for the longitudinal (parallel to shoreline) direction. Results of these 3D analyses show that the oscillating component of embankment deformations is the primary contributor to the maximum response of the piles sections and pile-deck connections, and that effects of permanent deformations of the embankment soil are much smaller. The analysis results also demonstrate the importance of the structure's 3D response characteristics, including longitudinal and torsional responses of the structure that are comparable to the transverse wharf responses during large amplitude oscillating embankment deformations owing to impulsive near-field motions. These important 3D response characteristics are not captured by more typical 2D wharf response analyses. Detailed comparisons of the responses of the 3D wharf model to corresponding responses from the 2D model of the wharf are provided. © 2013 American Society of Civil Engineers.


Ivey L.M.,Georgia Institute of Technology | Rix G.J.,Georgia Institute of Technology | Werner S.D.,Seismic Systems and Engineering Consultants | Erera A.L.,Georgia Institute of Technology
Geotechnical Special Publication | Year: 2011

Ports play a critical role in transportation infrastructure, but are vulnerable to seismic hazards. Current risk management practices focus on the effect of seismic hazards on individual port structures. However, damage and downtime of these structures has an impact on the overall port system's ship handling operations and the economic impacts that result from extended earthquake-induced disruption. The following paper overviews the concepts and methods developed for the seismic risk management of a port-wide system of berths. In particular, the use of spatially correlated ground motion intensity measures to estimate damage to pile-supported marginal wharves and container cranes via fragility relationships developed by project team members. Additionally, the repair costs and downtimes determined via repair models for both types of structures. Finally, the impact on ship handling operations calculated via logistical models of the port system. The paper also discusses how the results from such an analysis might be used by port decision makers to make more informed decisions in design, retrofit, operational, and other seismic risk management options. © 2011 ASCE.

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