Optimal seismic upgrade timing in seaports with increasing throughput demand via real options

A real options (RO) formulation is proposed for decision-making on the timing to upgrade the seismic performance of existing seaports with increasing throughput demand in earthquake prone areas. The pay-off of the seismic upgrade investment option is estimated based on projected net earnings, repair cost, and downtime for a damaging reference seismic event having a pre-specified annual probability of occurrence. These projections inform a discrete-time RO binomial tree, following the American option valuation framework, which propagates the probability of the reference seismic event assuming Poisson temporal distribution of earthquake occurrence. The net present value of the expected annual payoff of the considered investment is used as an index supporting risk-informed decision-making discounted by the weighted average cost of capital (WACC). Numerical examples pertaining to decision makers with different capital cost, namely port authorities and terminal operators, operating in different economic environments typical of developed and developing countries are furnished to illustrate the applicability of the proposed RO formulation. It is found that high WACC and/or low throughput growth bring the optimal seismic upgrade timing forward, while earthquake consequences and upgrade cost have almost no influence on this timing

Simulation framework of port operation and recovery planning

This study proposes a framework of simulation tool suites for ports to evaluate their response to disaster crisis and port security policies. The focus is containerized cargos that are imported through ports in the U.S. with final destinations also in the U.S. A crisis, such as a man-made or natural disaster, may cause a delay at the seaport. The down time of ports may result in severe economic losses. Thus, when a seaport cannot normally operate, it is important to minimize the impact caused by the disrupted freight flow. Port security policies also have a significant impact on the port operation efficiency. This model developed in this study evaluates the performance of re-routing strategies under different crisis scenarios and can help the user to find an effective re-routing decision and analyze security policies of a port. This model also analyzes security policies of the simulation port

Common Case Studies of Marine Structural Failures

Marine structures are designed with a requirement to have reasonably long and safe operational life with a risk of catastrophic failures reduced to the minimum. Still, in a constant wish for reduced weight structures that can withstand increased loads, failures occur due to one or several following causes: excessive force and/or temperature induced elastic deformation, yielding, fatigue, corrosion, creep, etc. Therefore, it is important to identify threats affecting the integrity of marine structures. In order to understand the causes of failures, structure’s load response, failure process, possible consequences and methods to cope with and prevent failures, probably the most suitable way would be reviewing case studies of common failures. Roughly, marine structural failures can be divided into structural failures of ships, propulsion system failures, offshore structural failure, and marine equipment failures. This book chapter will provide an overview of such failures taking into account failure mechanisms, tools used for failure analysis and critical review of possible improvements in failure analysis techniques

Recent Studies on Seismic Centrifuge Modeling of Liquefaction and Its Effects on Deep Foundations

The effects of liquefaction on deep foundations are very damaging and costly, and they keep recurring in many earthquakes. The first part of the paper reviews the field experience of deep foundations affected by liquefaction during earthquakes in the last few decades, as well as the main lessons learned. The second part of the paper presents results of physical modeling of deep foundations in the presence of liquefaction conducted mostly in the U.S. and Japan in the 1990’s, with emphasis on the work done by the authors and others at the 100 g-ton RPI centrifuge. Centrifuge models of instrumented single piles and pile groups embedded in both level and sloping liquefiable soil deposits have been excited in-flight by a suitable base acceleration. End-bearing and floating piles with and without a pile cap, with or without a mass above ground, free at the top or connected to a lateral or rotational spring to simulate the superstructure\u27s stiffness, with the foundation embedded in two- or three-layer soil profiles, have been tested. Tests with a mass above ground have allowed backfiguring the degradation of the lateral resistance of the loose saturated sand against the pile as the soil liquefies, while tests in sloping ground without a mass have allowed studying the effect of lateral spreading. Interpretations of these centrifuge experiments and their relation to field observations, soil properties, theory and analytical procedures are also discussed

Recent Studies on Seismic Centrifuge Modeling of Liquefaction and Its Effects on Deep Foundations

The effects of liquefaction on deep foundations are very damaging and costly, and they keep recurring in many earthquakes. The first part of the paper reviews the field experience of deep foundations affected by liquefaction during earthquakes in the last few decades, as well as the main lessons learned. The second part of the paper presents results of physical modeling of deep foundations in the presence of liquefaction conducted mostly in the U.S. and Japan in the 1990’s, with emphasis on the work done by the authors and others at the 100 g-ton RPI centrifuge. Centrifuge models of instrumented single piles and pile groups embedded in both level and sloping liquefiable soil deposits have been excited in-flight by a suitable base acceleration. End-bearing and floating piles with and without a pile cap, with or without a mass above ground, free at the top or connected to a lateral or rotational spring to simulate the superstructure\u27s stiffness, with the foundation embedded in two- or three-layer soil profiles, have been tested. Tests with a mass above ground have allowed backfiguring the degradation of the lateral resistance of the loose saturated sand against the pile as the soil liquefies, while tests in sloping ground without a mass have allowed studying the effect of lateral spreading. Interpretations of these centrifuge experiments and their relation to field observations, soil properties, theory and analytical procedures are also discussed

Ground Improvement by Deep Vibratory Methods

Vibro compaction and vibro stone columns are the two dynamic methods of soil improvement most commonly used worldwide. These methods have been developed over almost eighty years and are now of unrivalled importance as modern foundation measures. Vibro compaction works on granular soils by densification, and vibro stone columns are used to displace and reinforce fine-grained and cohesive soils by introducing inert material. This second edition includes also a chapter on vibro concrete columns constructed with almost identical depth vibrators. These small diameter concrete piles are increasingly used as ground improvement methods for moderately loaded large spread foundations, although the original soil characteristics are only marginally improved. This practical guide for professional geotechnical engineers and graduate students systematically covers the theoretical basis and design principles behind the methods, the equipment used during their execution, and state of the art procedures for quality assurance and data acquisition. All the chapters are updated in line with recent developments and improvements in the methods and equipment. Fresh case studies from around the world illustrate the wide range of possible applications. The book concludes with variations to methods, evaluates the economic and environmental benefits of the methods, and gives contractual guidance

Ground Improvement by Deep Vibratory Methods

Vibro compaction and vibro stone columns are the two dynamic methods of soil improvement most commonly used worldwide. These methods have been developed over almost eighty years and are now of unrivalled importance as modern foundation measures. Vibro compaction works on granular soils by densification, and vibro stone columns are used to displace and reinforce fine-grained and cohesive soils by introducing inert material. This second edition includes also a chapter on vibro concrete columns constructed with almost identical depth vibrators. These small diameter concrete piles are increasingly used as ground improvement methods for moderately loaded large spread foundations, although the original soil characteristics are only marginally improved. This practical guide for professional geotechnical engineers and graduate students systematically covers the theoretical basis and design principles behind the methods, the equipment used during their execution, and state of the art procedures for quality assurance and data acquisition. All the chapters are updated in line with recent developments and improvements in the methods and equipment. Fresh case studies from around the world illustrate the wide range of possible applications. The book concludes with variations to methods, evaluates the economic and environmental benefits of the methods, and gives contractual guidance