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Über dieses Buch

This book describes methods used to estimate forces and deformations in structures during future earthquakes. It synthesizes the topics related to ground motions with those related to structural response and, therefore, closes the gap between geosciences and engineering. Requiring no prior knowledge, the book elucidates confusing concepts related to ground motions and structural response and enables the reader to select a suitable analysis method and implement a cost‐effective seismic design.

Presents lucid, accessible descriptions of key concepts in ground motions and structural response and easy to follow descriptions of methods used in seismic analysis;Explains the roles of strength, deformability, and damping in seismic design;Reinforces concepts with real‐world examples;Stands as a ready reference for performance‐based/risk-based seismic design, providing guidance for achieving a cost-effective seismic design.

Inhaltsverzeichnis

Frontmatter

Chapter 1. Ground Motions from Past Earthquakes

Abstract
During earthquakes, the ground shakes in all three directions. The inertia of freestanding structures, such as buildings, bridges, and dams, prevents them from moving in unison with the ground. As a result, structures deform and develop stresses. This chapter discusses the ground motion characteristics which affect the response of structures. This chapter also explains how seismic loads are different from gravity and wind loads.
Praveen K. Malhotra

Chapter 2. Ground Motions for Future Earthquakes

Abstract
The time, location, and size of future earthquakes are uncertain. The ground motions produced by earthquakes of known magnitude and distance are also uncertain. This chapter discusses the uncertainty in future ground motions and the “acceptable” level of risk in seismic design. The design ground motions are expressed by their response spectra and/or time histories. Response spectra are needed for static analyses and time histories are needed for dynamic analyses.
Praveen K. Malhotra

Chapter 3. Seismic Response of One-Story Buildings

Abstract
The seismic response of a structure to a given ground motion depends on structure’s normalized strength, deformability, and damping. Normalized strength is its lateral load capacity divided by its weight. Minimum strength is needed to resist gravity and wind loads and to withstand frequent ground motions without damage. Deformability and damping are needed to withstand rare ground motions without collapse. Well-designed building frames can increase their deformability and damping through flexural yielding. Deformability and damping cannot be taken for granted. They are ensured through proper detailing and calculated through proper analysis. Different methods of analysis are discussed in the chapter.
Praveen K. Malhotra

Chapter 4. Seismic Response of Multistory Buildings

Abstract
As discussed in Chapters 2 and 3, the seismic performance of a structure depends on its normalized strength, deformability, and damping. Normalized strength is the lateral strength of a structure divided by its weight. Due to its much higher weight, a multistory building generally has smaller normalized strength than a one-story building. Due to cumulative nature of story deformations, a multistory building is much more deformable than a one-story building. Therefore, the height of a building does not make it more vulnerable to seismic shaking. Through flexural yielding in beams at various levels, a multistory building can significantly enhance its deformability and damping. Flexural yielding should not be confined to a single story and it should occur before brittle failures. This chapter discusses the seismic response of multistory building frames.
Praveen K. Malhotra

Chapter 5. Sliding of Objects During Earthquakes

Abstract
Flexural yielding in building frames is an excellent source of deformability and damping. While building frames continue to function after yielding, objects such as machinery and equipment cannot be expected to perform after yielding. In this chapter, sliding at the base of objects is shown to be an excellent source of deformability and damping.
Praveen K. Malhotra

Chapter 6. Rocking of Objects During Earthquakes

Abstract
Flexural yielding is a source of deformability and damping in building frames. Base sliding is a source of deformability and damping in broad unanchored objects. Slender objects have a tendency to rock than slide during earthquakes. Limited rocking can be a source of deformability for slender objects. Unlike sliding, rocking is not a significant source of damping. Rocking response is highly nonlinear. This chapter discusses nonlinear-static and nonlinear-dynamic analyses of base rocking. This chapter also introduces the concept of toppling response spectrum.
Praveen K. Malhotra

Chapter 7. Seismic Response of Storage Racks

Abstract
Sliding at the base of structures is an excellent source of deformability and damping. This chapter discusses sliding between the structure and its contents. In Chaps. 3 and 4, flexural yielding in building frames, with fully restrained connections, was shown to significantly increase their damping and deformability. While fully restrained connections are stronger than the members being, partially restrained connections are weaker than at least one of the members being joined. This chapter discusses the effects of yielding in partially restrained connections.
Praveen K. Malhotra

Chapter 8. Seismic Response of Liquid-Storage Tanks

Abstract
Relying solely on strength to resist ground motions can be expensive. A good seismic design utilizes deformability and damping to reduce the strength demand on a structure. A nonlinear analysis is needed to consider all sources of deformability and damping in a structure. Ground-supported, upright, cylindrical, liquid-storage tanks are massive structures. Strength demands on tanks can be quite high. Fortunately, there are some inherent sources of deformability and damping which can be utilized to significantly reduce the strength demand on tanks. This chapter discusses progressively refined analyses to capture various sources of deformability and damping in ground-supported liquid-storage tanks.
Praveen K. Malhotra

Chapter 9. Seismic Response of Gantry Cranes

Abstract
Gantry cranes are customized to meet specific requirements at a facility. Due to their unique configuration, prescriptive design, based on empirical rules, cannot be justified. Gantry cranes have some brittle elements (joints and connections) and some ductile elements (steel beams and columns). Brittle elements should be made stronger than the ductile elements to allow the ductile elements to yield, deform, and dissipate energy during seismic ground shaking. The deformation demands on ductile elements can be reduced by increasing their strength, but the brittle elements should always be stronger than the ductile elements. Due to their geometry, gantry crane models are nonlinear even when the structural members remain elastic. Therefore, linear analyses are omitted in this chapter. As in the case of liquid-storage tanks, discussed in Chap. 8, gantry cranes are fairly complex systems. Therefore, nonlinear-dynamic analyses are not practical for gantry cranes. In this chapter, both elastic and inelastic analyses are carried out by the nonlinear-static procedure.
Praveen K. Malhotra

Backmatter

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