Formulating Earthquake Resistant Design Criteria

The primary function of design criteria in general, and earthquake-resistant design criteria in particular, is to restate a complex problem that has unknowns and uncertainties into an unambiguous, simplified form having no uncertainties. The design criteria should provide clearly stated guidelines for the designers. For example, when actually designing a structure, an engineer needs to know the forces and deformations that the structure should be able to resist. Some of these forces, such as dead loads imposed by gravity, are well known, but others that result from transient actions of nature or man, such as earthquake, wind or live loads, are not known. This lack of knowledge must somehow be circumvented and a precise, unambiguous statement of the design conditions must be given to the design engineer. This is accomplished by means of the design criteria. The designer also needs to know the properties of the materials and structural elements that will be used, but as these are not precisely known, mainly because of imperfections in materials and workmanship, the design criteria must also take this into account. In the preparation of the design criteria, allowance must be made for the uncertainties, and it is necessary to be cognizant of all the unknowns for which allowances must be made

The Effect of Local Site Conditions on Recorded Strong Earthquake Motions

The subject of the effects o£ local soil conditions on strong ground motion is of particular interest now because of efforts underway to modify the building codes, new legislation concerning the aseismic design of hospitals, problems of earthquake-resistant design of nuclear power plants and a generally increasing sophistication of earthquake-resistant design procedures in structural engineering practice. As a result of these factors, many major projects now require geological and seismological studies, including some assessment of the expected earthquake motion at the site and an estimate of any probable effects of local site conditions on the expected motions

Comments on “Bedrock Intensity Attenuation and Site Factors from San Fernando Earthquake Records” by K. W. Campbell and C. Martin Duke

In the paper "Bedrock Intensity Attenuation and Site Factors from San Fernando Earthquake Records," by K. W. Campbell and C. Martin Duke, which appeared in the February, 1974 issue of the Bulletin, a correlation is made between a measure of intensity of recorded ground accelerations and four categories of soil, classified by increasing softness. The authors present different numerical site factors for each category and conclude that their results are sufficiently reliable to justify their use for purposes of zoning. The site factors and the conclusion are based mainly on the data presented in their Figure 5 and the lines of specified slope fitted by least squares to the data points. The set of lines in their Figure 6 present the authors' idealized relation between intensity, softness of ground, and distance from the source. The upper four lines in Figure 6 are taken from Figure 5

Memorial - Fritz Matthiesen (1926-1981)

R. B. "Fritz" Matthiesen died on 26 October 1981, at the age of 54, a victim of cancer, and his untimely death was a sad loss to his colleagues in earthquake engineering and seismology. We all miss his technical abilities, his sharp wit, and his irreverent ways of dealing with bureaucracy. Fritz had long been active in the affairs of the Seismological Society of America and was on the Board of Directors at the time of his death. His special technical interests were in the measurement and interpretation of strong ground motion and in the full-scale testing of structures such as buildings, dams, and nuclear reactors, and he was one of the world leaders in these fields. Until recently, he was Chief of the Seismic Engineering Branch of the U.S. Geological Survey, where he worked the past eight years of his career

Proceedings of the Fifth World Conference on Earthquake Engineering [Book Review]

The recently issued two-volume set of the Proceedings of the Fifth World Conference on Earthquake Engineering consists, essentially, of all the papers presented at the last world conference held in Rome in July of 1973. There are approximately 420 papers divided about equally between those 10 pages long and the shorter 4-page papers. The volumes include all the papers which were issued as preprints, a few submitted too late for preprinting, and some 30 discussions. Several of the discussions are categorized as free discussions, and are actually additional papers. Also included in the Proceedings is a list of the 850 participants from the 45 countries represented at the conference; an index of the papers, by session; an index of authors; and a brief section containing data about the International Association for Earthquake Engineering, the sponsoring organization. In the same section are the brief speeches given at the opening and closing ceremonies, administrative reports, and a few photographs. This general material comprises 168 pages, bringing the total for the volumes to nearly 3,200 pages. The massive volumes, 3½ in thick, are well-bound in maroon fabrikoid with gold lettering. The papers are reproduced photographically from originals supplied by the authors so there is considerable variation in typography. The quality of both the printing and the paper is very good, however, and the legibility of text, figures and photographs is at least equal to any of the Proceedings of previous world conferences

Distant motions from a building vibration test

Horizontal ground motion generated by vibration tests of the nine-story Millikan Library Building on the Caltech campus was recorded on the surface of the ground in the Pasadena area at distances up to 3 miles from the building. Later it was learned that the vertical component of the motion also was recorded by the seismograph on Mt. Wilson, 6.7 miles from the Library and 4,800 ft higher in elevation. The magnitude of the acceleration varied from 2.04 × 10-^(2)g at the excitation level on the ninth floor of the building to 3.2 × 10^(-7)g at Mt. Wilson. Simple calculations show that multistory buildings are particularly well-suited for inducing large dynamic forces in the ground with relatively small equipment

Engineering features of the San Fernando earthquake of February 9, 1971

Because of its consequences, the San Fernando earthquake was a major earthquake from the engineering point of view, even though it was only a moderate shock in seismological terms. As a result of the many effects of the earthquake, a large number of detailed studies and reports will be forthcoming from a wide variety of sources, and the papers collected in this volume are only preliminary studies of some of the more important and interesting engineering features of the earthquake. The papers were prepared by staff and students working in earthquake engineering within the Division of Engineering and Applied Science at the California Institute of Technology. The timely financial support of the Engineering Division of the National Science Foundation and the Earthquake Research Affiliates of the California Institute of Technology in conducting the research and preparing this report is gratefully acknowledged

George W. Housner (1910–2008)

George W. Housner, Carl F Braun Professor of Engineering, emeritus, died after a short illness on 10 November 2008, just a few weeks before his 98th birthday. He was in the retirement home in Pasadena where he had lived for several years. For all of us who knew George, this marked the end of an era. Few people have guided and nurtured a field the way George led earthquake engineering over a period of several decades. He had a profound effect on many people and will long be remembered. His impact was so pervasive that he earned the title "Father of Earthquake Engineering." This article records some of my thoughts about this remarkable man

Some Mechanics Problems in Earthquake Engineering

Since the beginning of earthquake engineering research in the United States in the 1920's, this discipline has proved to be a particularly fruitful source of interesting problems in applied mechanics. Some examples of the earliest such problems are the development of the response spectrum as a tool in analysis and design, the development of nonlinear hysteretic models of structural response for dynamic loading, and the application of the theory of stochastic processes to problems in modeling of strong ground motion and structural response. An additional class of problems has arisen from efforts to understand the effects of soil-structure interaction on structural response. The need for dynamic analyses in order to understand and simulate earthquake response has also been one of the major factors behind the development of modern computer codes for structural analysis

Some Simple Uses of Instrumental Data

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