Seismic Loads E-Book

Victor M. Lyatkher

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch

Seitenzahl: 472

Veröffentlichungsjahr: 2015

Beschreibung

Earthquakes are a way of life on Earth, and, whether you live in an area that is often affected by earthquakes or not, every building, every road, every bridge, and, in fact, almost everything constructed by humans in which we walk, sleep, live, sit, or visit, has to be constructed to withstand an earthquake, by following local, regional, or national codes, laws, and regulations. Further to this, the science and engineering behind these constructions go further than what is mandated by government as a part of their practice. All construction, and, in general, all life on Earth, has some risk of seismic impacts. A comprehensive description of any seismic action may be given only on a probabilistic basis and, in general, is very bulky and quite uncertain. However, for a variety of structures or systems that meet fairly simple models of behavior during earthquakes, a general description of the seismic action is not required, for prediction of the status of such facilities or systems may be sufficient to define one or more common parameters of seismic impact. Thus, it makes sense to search for optimal parameters of influence in which optimality is understood with the greatest ease with sufficient information. This book contains a description of several models of seismic effects and examples of implementation of these models at specific sites. Using this information, scientists and engineers can design structures that are stronger, safer, and longer-lasting. It is a must-have for any scientist, engineer, or student working in or researching seismic loads and constructions with a view toward withstanding seismic activity.

Leseprobe

Contents

Cover

Half Title page

Title page

Copyright page

Preface

Chapter 1: Statement of the Problem

1.1 General Scheme of Estimation of Seismic Stability

1.2 Seismic Hazard

1.3 Variation of Seismic Hazard

1.4 Seismic Loads

Chapter 2: The Definition of Seismic Actions

2.1 The Probability of Loads During the Earthquake of a Given Intensity

2.2 Recognition of Earthquake Foci

2.3 The Calculation of Seism Caused by Movement in the Earthquake Focus

2.4 Physics of Focus and Control of Seismicity

2.5 Seismic Forces for a Fixed Position and Energy of the Earthquake Source

Chapter 3: The Influence of Topography and Soil Conditions. Secondary Processes

3.1 Influence of the Canyons

3.2 Dynamics of Water-Saturated Soil Equivalent Single-Phase Environment

3.3 Dynamics of Water-Saturated Soil as Multiphase Medium

3.4 The Real Estimates of the Property of Soils

3.5 Landslides and Mudflows

3.6 Waves on the Water

Chapter 4: Example of Determination of Seismic Loads on the Object in an Area of High Seismicity

4.1 Assessment of Seismotectonics and Choice of Calculation of Seismicity

4.2 The Parameters of Impacts

4.3 Selection of Unique

4.4 Numerical Models of the Focus

4.5 The Influence of the Shape of the Canyon

Chapter 5: Examples of Determination of Seismic Effects on Objects in Areas of Low Seismicity

5.1 Preliminary Analysis

5.2 Assessment of Seismic Risk on Seismological Data

5.3 Tectonic Structure of the Area

5.4 Recognition of Seismically Active Nodes’ Morphostructure

5.5 The Types of Computational Seismic Effects

5.6 Analog Modeling of Seismic Effects

5.7 Mathematical Modeling of Seismic Effects

Chapter 6: Stability of Structures During Earthquakes

6.1 Stability of Concrete Dams

6.2 Vibration and Strength Reserves of the High Dams

6.3 The Reliability of Groundwater Dams

6.4 The Stability of Underground Structures

6.5 Seismic Effects Caused by Missing Floods Through the Waterworks

Conclusion

References

Index

Seismic Loads

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Library of Congress Cataloging-in-Publication Data:

ISBN 978-1-118-94624-4

Preface

Tectonic mobility of the earth’s crust makes all construction and, in General, all life on Earth associated with some risk of seismic impacts. In some areas (seismic) this risk is greater, in others (aseismic) - less. Existing maps of seismic zoning and building codes of the different countries, to some extent, evaluate and regulate this risk is usually in an implicit form. Seismic risk for a single object or group of objects is determined primarily by seismic impact.

A comprehensive description of the seismic action may be given only on a probabilistic basis and in the General case is very bulky and quite uncertain. However, for a variety of structures or systems that meet fairly simple models of behavior during earthquakes, a General description of the seismic action is not required. For prediction of the status of such facilities or systems may be sufficient to define one or more common parameters of seismic impact. Thus, it makes sense to search for OPTIMAL parameters of influence, in which OPTIMALITY is understood as the greatest ease when sufficient information.

This book contains a description of several models of job seismic effects and examples of implementation of these models at specific sites.

The main results obtained by the author and his colleagues during the work in the Research Sector (now JSC NIIAS) of Institute Hydroproject (Moscow) at 1968-2010 years. The names of the main participants of the works listed in the references joint publications. All these people the author is eternally grateful.

Work on the dynamics of water-saturated soil at 1974 received Award of the Indian Society of Earthquake Technology, Roorkee, India; research on the seismic stability of large dams in 1984 awarded the prize of the Council of Ministers of the USSR.

Chapter 1

Statement of the Problem

The description of loads on mass civil or industrial buildings can be limited to the consideration of the impacts and consequences on the average over the ensemble of objects and similar events on-site. The resulting gradation effects on INTENSITY (seismic scale scores and seismic intensity) includes not only the mechanical parameters of the motion of the ground during earthquakes, as reflected in the testimony of certified devices, but also the condition of the facilities after the earthquake, changing landscapes, people’s reactions, and animals.

Gradation of earthquakes may be different, seemingly unrelated to the earthquake, and characterize mechanical parameters according to a model of the phenomenon. It is clear that depending on the adopted model will change the form and content classification information. For example, in the simplest focal model input parameters are the ENERGY (magnitude M and class K are proportional to the logarithm of the energy of the earthquake source), geographic coordinates, and depth of focus. These parameters can be interpreted in terms of mechanics and serve as a basis for a mathematical model of seismic movements. The representation of the environment, two or three phase system, is very significant.

Any volume statistical information about seismic impacts that meet a certain score or magnitude (plus length and depth) can be significantly different for structures of different levels of responsibility. For mass civil and industrial buildings, construction regulations in many countries allow job seismic effects that match a specific seismicity (one factor seismicity) with the sense of mean-square acceleration, oscillations of the earth’s surface (in fractions of the acceleration of gravity), and the ensemble averaged data related to earthquakes fixed macro seismic intensity.

Similarly, sets and spectral properties of earthquakes are averaged for all of the observed effects. This approach, suggesting some variation degree (measure) fracture within one macro seismic area, bulk plants, apparently, can be considered acceptable.

The situation is different when considering seismic effects on structures, the destruction of which should be considered a catastrophe on a national or even international scale. Here, risk assessment must be specific and accurate. These objects include, nuclear power plants and large hydraulic and hydropower plants with large reservoirs. The design of such facilities in areas of seismic activity is a challenging task.

This task is complicated when the question of the earthquake pertains to existing structures. On the one hand, in this case, it becomes possible to obtain reliable data on the dynamic properties of the object. However, seismic evaluation and engineering conclusions, in this case, should be particularly reasonable, as changes in the structures are very complex, very expensive, or even impossible. Meanwhile, the problem in recent years has become relevant due to changes in the map of seismic zoning of Russia. For example, according to the normative documents in force for the period of design and construction of the Volga (Volgograd) HPP district, placement was considered virtually aseismic (five points or less). In accordance with the new map of general seismic zoning of the territory of Russia GSZ-97, included in new edition Russian standard (SNiP 11-7-81* M, 2002), in the region of the Volga, the hydroelectric power station assumes the possibility of occurrence of earthquakes with the intensity of shock in seven points on the MSK-64 scale with the repetition of such events one time in five thousand years. The increase in the background level of seismicity, up to seven points, requires estimates of the seismic safety of the main structures of hydroelectric power stations to take into account the existing regulatory documents. During engineering surveys for waterworks, similar works on the main site structures were carried out and organized the missing studies that were conducted in two areas: