A reminder that the 15th World Conference in Earthquake Engineering, is held in Lisbon, Portugal from September 24 to 28, 2012. Registrations using the conference Online registrations website feature are still possible until September 17th, 2012. Registration at the conference is also available. Conference cost is about E 600 (Euros).
The inaugural World Conference in Earthquake Engineering was held in Berkeley, California in June, 1956, to coincide with the 50th anniversary of the Great 1906 San Francisco Earthquake and Fire. The event was co-sponsored by the (then) fledgling Earthquake Engineering Research Institute (EERI) and by the Department of Engineering, University of California through the offices of University Extension. The National Science Foundation helped to support the conference financially. The 1956 organizing committee included R.W. Binder, J.A. Blume, W.K. Cloud, R.W. Clough, H.J. Degenkolb, C.M. Duke, A.L. Miller, H.C. Powers, and was chaired by J.E. Rinne. George W. Housner was EERI President and unofficial conference chairman. The printed Proceedings of the World Conference on Earthquake Engineering were made available by Karl V. Steinbrugge, EERI Secretary ($8.50 – to cover printing costs). These individuals represent a ‘who’s who’ of earthquake engineering in the USA at that time. Like today, although at a much smaller scale, the 1956 conference was international in scope with representations from USA, Japan, New Zealand, Chile, Mexico, Colombia, Turkey, Pakistan, Greece, Italy, Germany, and India. Participants provided 38 technical papers, two formal panel discussions, and conference organizers allowed for wide consultation among the conference registrants. To understand the style of the conference, a small portion of the final panel discussion (John A. Blume on Structural Design and Practice) from the 1956 conference is reproduced below. Some of the themes remain remarkably resilient today:
Question: Is building design to resist earthquakes often done with the aid of dynamic methods including dynamic model experiments?
Minami (Japan): Only in exceptional cases.
Pinzon (Colombia): In Colombia we do not as yet design by dynamic methods, although I understand Venezuela is conducting some research along those lines.
Barnes (U.S.): Until dynamic methods are available which can be done in the time for which engineers can get compensated, I think the nearest approach which static methods can provide will be generally used.
Blume (U.S.): In the United States the codes are being modified to simulate dynamic conditions for average structures by static methods. Special structures require special treatment for satisfactory and economic results.
Question: In Japan, do you ever set out to design beyond the elastic limit or is compliance with the building code the usual limit of design?
Minami: The use of basic seismic coefficients of 20% of gravity or more and allowable steel stresses of 34,000 psi bring us to the yield point. However, if some earthquakes are more severe than we anticipate, the steel would go into
the plastic range.
Rinne (U.S.): Many of us feel that a better balanced design will be obtained with higher coefficients and higher allowable stresses. This, of course, approaches a kind of limit design.
Blume: It can be shown by simple arithmetic that members carrying only lateral forces have less residual strength, not to mention energy absorbtion value, compared to other basic members under the low stress increases in codes.
Rosenblueth (Mexico): The Mexican code generally follows American codes, but some engineers raise stresses up to 100% or to the yield point, often with greater seismic coefficients. There are various practices.
Question (Binder from audience): Mr. Blume, in the December 23, 1948, Engineering News Record you listed some unsolved or controversial problems. Have these matters been resolved in the meantime?
Blume: A copy of that article is here. I shall first read and then comment briefly on each problem listed.
(1) “Design of all structures on the basis of a percentage of weight as an assumed lateral force.” This has been discussed a great deal at this conference. Modern codes vary the percentages for various conditions to better simulate dynamic phenomena. Great progress has been made.
(2) “The percentages required by various codes for such forces.” This has also been discussed, especially in the last panel question. Damping, energy absorbtion, allowable damage, etc., are all involved.
(3)“The way such percentages are reduced according to the number of stories for high buildings, regardless of width or other dynamic characteristics.” Same reply as for (1) above.
(4)“The amount of live load required by various codes to be included m the weight used in seismic computations.” Progress is being made on this also. The trend in recent codes is to approach actual average live loading.
(5)“The variation of coefficients for soft ground conditions.” This item is still controversial no doubt because many generally unrecognized factors enter the problem. American codes have in recent years tended to eliminate or reduce former variations in coefficients with ground conditions.
(6)“The amount of stress increase permitted under earthquake motion.” This has been widely discussed at this conference, particularly on this panel.
(7)“The handling of the overturning (cantilever) moment problem for high buildings or units thereof which act structurally for many stories.” This item, which is still controversial, has also been discussed on this panel. More research is indicated.
(8)“Design practice does not adequately differentiate between flexible and rigid structures.” This is still a problem although recent codes, particularly the new San Francisco code, approach the matter more realistically.
(9)“The definition of a diaphragm as a horizontal distributing element.” This problem has been worked on perhaps more than the others. I’ll ask Mr. Barnes to discuss this.
Barnes: A diaphragm is essentially a horizontal girder to distribute horizontal forces to the various vertical resisting elements. In addition to strength, there should be certain limitations on deflections of these diaphragms in order
that the vertical elements not be subjected to movement which would cause distress or failure.
Blume: In summary, may I say that progress has been made on these problems as-well as others. This conference has also contributed in no small degree toward the ultimate solution of many important matters in seismological engineering. There is, however, a great deal more to be done.
The Board of the International Association for Earthquake Engineering awarded the 16th WCEE to the Chilean Association of Seismology and Earthquake Engineering and the 2016 WCEE will be held in Santiago, Chile.