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Über dieses Buch

This book addresses applications of earthquake engineering for both offshore and land-based structures. It is self-contained as a reference work and covers a wide range of topics, including topics related to engineering seismology, geotechnical earthquake engineering, structural engineering, as well as special contents dedicated to design philosophy, determination of ground motions, shock waves, tsunamis, earthquake damage, seismic response of offshore and arctic structures, spatial varied ground motions, simplified and advanced seismic analysis methods, sudden subsidence of offshore platforms, tank liquid impacts during earthquakes, seismic resistance of non-structural elements, and various types of mitigation measures, etc. The target readership includes professionals in offshore and civil engineering, officials and regulators, as well as researchers and students in this field.



Chapter 1. Introduction

No places on Earth are entirely free of the risk of earthquakes. Earthquakes are among the most destructive natural phenomena on the planet, having substantial social and economic consequences.
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Chapter 2. Offshore Structures Versus Land-Based Structures

Offshore structures (Fig. 2.1) with their facilities are used to drill wells, to extract and process oil and natural gas, or to temporarily store product until it can be brought to shore for refining and marketing.
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Chapter 3. Characterize Ground Motions

To determine the location of an earthquake occurrence, two geometric notations, namely hypocenter and epicenter, will be introduced first. Because the majority of earthquakes are caused by the rupture of the rock along a fault or multiple faults, and thousands of square kilometers of fault plane surface may be involved in this rupture, while it is important to define a location in a fault where the rupture initiates, this location is normally referred to as hypocenter or focus as shown in Fig. 3.1. From the hypocenter, the rupture spreads across the fault at velocities ranging from 2 to 3 km/s [1].
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Chapter 4. Determination of Site Specific Earthquake Ground Motions

Different from the loads generated by the wind, wave/current and ice, which are due to the external forces applied on structures, earthquake loads are purely induced by the ground accelerations transferred to the foundation of the structures. Therefore, the determination of the earthquake ground motion is an essential part of earthquake engineering.
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Chapter 5. Representation of Earthquake Ground Motions

It is noted that the most important parameters of an earthquake ground motions are its maximum motion, predominant period and effective durations [1]. However, different from other loadings, earthquake induced loading and ground motion cherish high uncertainties in these aspects, as well as, more broadly, on its occurrence, magnitude, frequency content and duration. The uncertainties come from many sources: the energy suddenly released during an earthquake is built up rather slowly through tectonic movements; historical records over a time span of a couple of hundred years do not provide a complete picture of the seismic hazard. Moreover, the rupture and faulting process during an earthquake is extremely complex and affected by many parameters that are difficult to predict [2].
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Chapter 6. Determining Response Spectra by Design Codes

Ideally, if one uses abundant ground motion records or converts those motions into many corresponding individual response spectra, and takes these records or response spectra as earthquake loads input for a structure, the response and strength evaluation for the structure can be relatively reliable. However, in reality, this is not feasible.
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Chapter 7. Record Selection for Performing Site Specific Response Analysis

Compared to the coded based simplified method (Sect. 6.​2), site specific response analysis (Sect. 4.​3) is a more refined method to determine ground motions. As presented in Sect. 3.​2.​1, even though the P-waves arrive first and cause the vertical shaking of the ground, it is normally the shear waves that cause strong horizontal ground motions and possible subsequent structural damage .
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Chapter 8. Spatial Varied (Asynchronous) Ground Motion

The spatial varied ground motions are categorized as either large scale (regional) or local scale seismic motion. The former refers to the attenuation relationship with a scale of 10 km, which describes the relationship between accelerations and site-to-source distance, as elaborated in Sect. 3.​6.
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Chapter 9. Seismic Hazard and Risk Assessment

Hazard is defined as inherent physical characteristics that pose potential threats to people, property, or the environment.
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Chapter 10. Influence of Hydrodynamic Forces and Ice During Earthquakes

Under strong seismic ground motion, the structure may undergo large motions. Compared to land-based structures, offshore structures cherish unique effects of fluid–structure interactions: the hydrodynamic forces due to the relative velocity and acceleration between structural members and their surrounding waters.
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Chapter 11. Shock Wave Due to Seaquakes

Note that both seaquakes and tsunamis are caused by the vertical deformation of seafloors.
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Chapter 12. Introduction to Tsunamis

Originally used to describe large amplitude resonance oscillation of waves in a harbor, tsunami is a Japanese word made from two word roots: “tsu” means harbor and “nami” means wave. The term sometimes refers to as tidal waves dominated by long period motions.
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Chapter 13. Earthquake Damages

Earthquakes can lead to various types of damages, including foundation damage , structural damage , non-structural component damage, and contents and furniture damage .
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Chapter 14. Design Philosophy

Design is a mixed decision made from an environment of partial truth, partial knowledge, and partial uncertainty . A structure subjected to seismic loads is required to have a certain amount of safety related to strength, ductility, deformation and energy absorption .
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Chapter 15. Seismic Analysis and Response of Structures

The major objective of seismic analysis is to develop a quantitative measure or a transfer function that can convert the strong ground motions at a structure’s foundation to loading and displacement demands of the structure, which provide essential input for a reliable assessment of structural capacity.
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Chapter 16. Sudden Subsidence and Its Assessment

On 7 May, 2001, a minor earthquake occurred in the vicinity of the Ekofisk oil-field (Fig. 1.​23) in the North Sea, which comprises several offshore jackets and tripod structures connected by bridges. During this earthquake, a permanent vertical movement of platforms occurred. The people on board the platforms and the platform connecting bridges felt a strong sudden vertical drop, which is often referred to as sudden subsidence or sudden drop . The vertical movement is estimated to have been approximately 80 mm. Assuming that the vertical displacement took place in a single motion with the acceleration of gravity (free drop), the duration of the sudden subsidence is estimated to have been 0.13 s. This is the only reported sudden subsidence event to have occurred offshore thus far. Such events can cause failures of structural members or even a collapse of topside and supporting structures, and may also influence the capacity of the foundation and grout connection of pile clusters, etc.
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Chapter 17. Tank Liquid Impact

Tanks are used in water distribution systems and in industrial plants for the storage and/or processing of a variety of liquids and liquid-like materials, such as oil, liquefied natural gas, chemical fluids and wastes of different forms, tanks are used and often constructed with thin shells due to efficiency of load carrying capacity, i.e. the strength properties of all materials can be used completely in tension or compression.
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Chapter 18. Selection of Computer System and Computation Precision

Advances in computer technology allow engineers to solve problems of increasing complexity in two aspects: first, it allows for the calculation of results based on classical solutions but with numerical evaluation of certain terms that cannot be expressed in a closed form; second, it also allows for the modelling of complex systems (structures, foundations, soils, or faults) using approximation methods such as finite element method and to perform numerical calculations to obtain the system’s response.
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Chapter 19. Avoid Dynamic Amplifications

Life is pretty simple: You do some stuff, most fails, some works.
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Chapter 20. Ductility Through Structural Configuration and Local Detailing

The conventional approach requires that structures can passively resist seismic loading through a combination of redundancy , strength, deformability , and energy absorption . In an earthquake prone area, a ductile structural system with minimal weight is preferred and is often the governing design principle.
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Chapter 21. Damping

A few thousand years ago, human beings began to use damping to control the motions of structures. For example, the columns in ancient Greece and the territories within the Roman Empire were typically composed of numerous masonry blocks of varying size and shape. The friction at the column segment connections (Fig. 21.1) and between the column and the foundation can provide significant damping, which is beneficial to dissipate seismic energy and to prevent structural collapse, at the cost of permanent displacement of the column.
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Chapter 22. Direct Damping Apparatus

Originally used in the automobile industry to decrease the dynamic response and fatigue loading on vehicles, damping apparatuses have also been recognized as an effective technique to mitigate dynamic seismic (from 1990s) and wind induced (from 1960s) response for structures.
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Chapter 23. Base and Hanging Isolation System

The base isolator was scientifically proposed by Skinner et al. (Earthq Eng Struct Dyn 3(3):161–201, 1975, [1]) as shown in Fig. 23.1. It possesses the following essential elements (Buckle and Mayes in Earthq Spectra 6(2):161–201, 1990, [2]): (1) a flexible mounting so that the period of vibration of the total system is lengthened sufficiently to reduce the force response; (2) a damper or energy dissipater so that the relative deflections between the building and ground can be controlled to a practical design level; (3) a means of providing rigidity under low (service) load levels due to mild wind and minor seismic ground motions.
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Chapter 24. Dynamic Absorber

To absorb the kinetic energy produced by dynamic loading such as wave, wind, earthquake and ice loading on a structure.
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Chapter 25. Load and Energy Sharing Mechanism

Load and energy sharing mechanisms aim to distribute seismic energy and load among more designated resisting structures or structural elements. Typical such mechanisms include the measures to connect a structure to adjacent structure(s) (Sect. 25.2), and lock-up and shock transmission units (Sect. 25.3).
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Chapter 26. Resistance of Non-structural Components

Non-structural components are physically connected to primary structures by various connections. They are normally not taken into account as a stiffness and/or damping contributor in a holistic structural analysis even though they increase a certain amount of damping and stiffness. However, they may behave unintentionally as structural elements by participating in the load path to transfer inertia forces and contributing accountable stiffness, strength and damping to structural elements. In this case, their contribution should be considered in the relevant seismic structural design.
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Chapter 27. Structural Health Monitoring and Earthquake Insurance

Structural Health Monitoring (SHM) or Structural Health Assessment (SHA) is the inspection of the structural soundness (conditions) and detection of damages at every stage during the service life of a structure. SHM carries out a diagnosis of the state of the constituent materials, of the different parts, and of the full assembly of these parts constituting the structure as a whole.
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Chapter 28. Control Techniques for External Damping Devices

For direct damping apparatuses , base isolation , hanging isolation , dynamic absorber and lock-up and shock transmission devices, three types of techniques are available for vibration control: passive, semi-active and active, which are illustrated in Fig. 28.1. Moreover, hybrid technique takes the advantages of both passive and active control technique.
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Chapter 29. Seismic Rehabilitation for Structures

Seismic rehabilitation includes all concepts associated with reparation, upgrading, retrofitting, and strengthening . They contribute to a reduction in the vulnerability of structures due to various reasons and motivations, such as a revision of design codes or earthquake damages, etc.
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