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OCR for page 133
LYD I K S IEGUM FELDT J ACOBSEN
1897-1976
BY JOHN A. BLUME
YDIK SIEGUMFELDT JACOBSEN, Stanford University Prolessor
Emeritus, Member of the National Academy of Engineering, Past
President and Honorary Member of the Seismological Society of
America, and first President of the Earthquake Engineering Re-
search Institute, died on December 22, 1976, following a stroke.
Dr. Jacobsen was internationally known for his pioneering work
in determining the dynamic characteristics of buildings and other
structures and their response to earthquake ground motion and
other disturbances, as well as for his research and teaching in
vibrations and dynamics. He directed the Vibration Laboratory at
Stanford University from 1926 until his retirement, in 1962, and
was Head of the Mechanical Engineering Department from 1949
to 1961. He coauthored, with Robert S. Ayre, a standard text,
Engineering Vibrations (McGraw Hill, 1958), and he wrote many
technical papers.
Lydik Jacobsen was born June 17, 1897, in Nyborg, Denmark,
where his father owned a steam-powered flour mill. After complet-
ing the Danish equivalent of an American high school education,
Lydik worked in various flour mills and at a fish hatchery, where he
enjoyed manual labor. In 1917, his father, Hans Christian Jacob-
sen, sold his mill and took his wife and five children, including
Lydik, to California. Lydik began work in the Sperry Flour Mill in
Stockton, California, where he soon supervised all machinery on
one floor. Because of his growing interest in the mechanical aspects
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of milling, he was encouraged to attend Stanford, where he ob-
tained his Bachelor of Arts degree in mechanical engineering after
three years of accelerated study. In 1921 he became a junior
engineer with Westinghouse Electric Corporation in Pittsburgh,
Pennsylvania, where he worked with S. Timoshenko. In 1924
Professor Durand, another engineer who later became famous,
persuaded Lydik to return to Stanford for graduate study and
provided him with an instructorship as a source of financial aid.
In 1927 Lydik obtained his Doctor of Philosophy degree in
physics at Stanford and also became a U.S. citizen. That same year,
with some financial aid obtained by Dr. Bailey Willis, he started a
vibration laboratory at Stanford with a large shaking table. The
combination of the 1925 Santa Barbara earthquake, Dr. Willis' aid
and encouragement, and the opportunity to apply his knowledge
of vibration from physics and mechanical engineering all contrib-
uted toward developing Dr. iacobsen's interest in the problem of
how buildings respond to earthquake-induced ground motion.
In 1931 Dr. Jacobsen was awarded a Guggenheim fellowship in
applied mechanics that enabled him to visit universities and labora-
tories in five European countries. He became a Full Professor in
Mechanical Engineering at Stanford in 1936. He was a Visiting
Professor at the University of Michigan in 1938 and at the Illinois
Institute of Technology in 1941. During a leave from Stanford in
1953 and 1954, he was a Fulbright Professor at Den Polytekniske
Laeranstalt (the Danish Polytechnic Institute) in Copenhagen.
After he retired from teaching, in 1962, he cofounded Agbabian-
Jacobsen Associates, a consulting engineering firm, in which he was
active until he retired in 1969. He continued his individual consult-
ing practice until his death.
During World War II, he analyzed 271 U.S. Navy ships of all
types and served aboard 130 of them to study ways to reduce
sounds and vibrations and thus decrease detection by enemy sub-
marines. He left the service in 1946 as a Commander in the Naval
Reserve and with a U.S. Navy Commendation Medal.
Dr. Jacobsen published about forty scholarly, thorough, and
precisely written papers involving a great deal of thought and
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effort on new subject matter in whose development he, personally,
had played either a sole or a major role, including mechanics, stress
analysis, vibrations, models, dynamic behavior of models, damping,
shock, blast effects, ship vibrations, hydrodynamics, shaking table
research, mathematics, and earthquake motion. In addition to his
published works, he wrote many reports, both public and private,
for clients during his decades of consulting work for industry and
Government; such unpublished reports by a consultant of Dr.
Jacobsen's caliber often involved more complexity, discovery, and
innovation than was generally found in his published works.
Dr. Jacobsen received many honors and awards, but no doubt
fewer than he deserved because of his frank honesty in all matters
and also because his audience's understanding rarely matched his
own. He was a pioneer in earthquake dynamics, but he was also a
mechanical engineer, a mathematician, and a physicist who at-
tempted to explain new and complex building dynamics to struc-
tural engineers, architects, and public officials. The work was made
more difficult with waning public interest in such matters shortly
after each damaging earthquake.
He was elected to the National Academy of Engineering in 1975;
his citation was for '`outstanding research, teaching, practice, and
writing in mechanical and structural vibrations and shock." He
served as President of the Seismological Society of America from
1953 to 1955 and was elected an Honorary Member in 1974. He
was Chairman of the U.S. Coast and Geodetic Survey's Advisory
Committee on Engineering Seismology from 1947 to 1949. He was
one of the founders and the first President of the Earthquake
Engineering Research Institute in 1949 and was elected an Honor-
ary Member in 1969. He was a Fellow of the American Society of
Engineering Education. His accomplishments are listed in Who's
Who in America, Who's Who in Engineering, American Men of Science,
Blue Book of Denmark, and Danes in the World.
Lydik Jacobsen was a dynamic person in every sense of the
word intelligent, vigorous, enthusiastic, energetic, friendly,
fluent, greatly interested in people as well as in science and en-
gineering, and a dedicated worker with much endurance. He
135
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enjoyed his work, especially research or a challenging, difficult
problem. He was proud of the fact that, in 1975, eight of his former
students were members of the National Academy of Engineering.
Lydik Jacobsen was respected by all his peers, even those who
might not always agree with him. Some of Dr. Jacobsen's work for
example, his development of the phase-plane-delta method of
treating inelastic, nonharmonic, vibrating systems would have
been much more widely applied had it not been for the computer,
which later made such procedures unnecessary. The same is true of
his dynamic (mechanical) models of buildings tested on the shaking
table, which were replaced by electric analogs or by high-speed
digital computers. Nevertheless, the pioneering innovation was
there, and it helped to provide a solid base for later development
with more exotic equipment. Lydik Jacobsen's pioneering work in
vibrations and in approaching the earthquake problem as one of
dynamics rather than statics was a great milestone that shall always
be on record, remembered by all who knew him, and appreciated
in the future by those who did not know him.
Dr. ~acobsen's survivors, besides his widow Mary Louise of
Laguna Hills, California, include his first wife, Doris (Wetzel), of
Menlo Park; two sons, Erland, of Fresno, and Ian, of Honolulu;
and a daughter, Ellen Yazar, of Ankara, Turkey. His brother,
Theodor, a retired professor of astronomy, lives in Seattle; a sister,
Ingrid Wilson lives in Los Angeles; and two sisters, Kirsten Greger-
sen and Lisse Lindman, live in Santa Barbara.
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OCR for page 138
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