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SUMMARY:Performance-Based Design of Geotechnical Structures: Recent Advanc
 es - Professor Susumu Iai\, Disaster Prevention Research Institute\, Kyoto
  University
DTSTART:20100305T163000Z
DTEND:20100305T173000Z
UID:TALK22709@talks.cam.ac.uk
CONTACT:Zelda Stuck
DESCRIPTION:An overview is presented on the recent advances in earthquake 
 geotechnical engineering with respect to the seismic design of geotechnica
 l structures. In conventional seismic design\, many factors that should be
  considered for design are specified rather than evaluated. The principles
  in performance-based design presented in this lecture are much more gener
 alized and allow the experienced practicing engineers and code writers go 
 back to the critical issues in design\, including performance criteria to 
 specify the design parameters. The modern principles in seismic design pre
 sented in this lecture allow a sophisticated approach to deal with the unc
 ertainty. The life-cycle cost approach is an promising approach. The optim
 um design in the life-cycle cost approach has a certain probability of fai
 lure. This probability is not prescribed by an authority (such as 10% over
  50 years) but rather determined as a result of the minimum life-cycle cos
 t procedure. \n\nStrong non-linearity in site-response recorded through in
 struments during earthquakes is different from the view based on the equiv
 alent linear or non-linear models without the effect of dilatancy. The non
 -linearity does not diminish the high frequency nature of the accelerogram
 s\, or necessarily reduce the peak acceleration that can exceed 1g as mani
 fested by the strong motion record during the 2004 Niigataken-chuetsu and 
 the 2008 Iwate-Miyagi inland earthquakes. \n\nStrong non-linearity in soil
 -pile interaction is identified as the manifestation of strain localizatio
 n in the vicinity of the pile side. Load-displacement curves of a pile for
  saturated sand deposit follow a hardening-spring type shape similar to th
 e stress strain curve during cyclic mobility of saturated sands. The effec
 ts of soil-pile separation are significant in the behavior of a single and
  group piles. These facts direct us to a critical view on the conventional
  design recommendations for designing pile foundations. \n\nFacing with th
 e highly non-linear response of soil-structure systems during strong earth
 quake motions recorded in recent years\, we may well be going back to the 
 basics of understanding the mechanism of soil-structure interaction as is 
 rather than hastily jumping into adopting a simplified method and trying t
 o temper the model parameters in order to get the simplified model fit the
  recorded case histories.\n\nCombined hazards\, such as those at the 2004 
 Sumatra earthquake\, poses a new challenge to the geotechnical earthquake 
 engineers. The use of  design charts\, that reflect a series of comprehens
 ive parametric studies based on the effective stress analysis\, may be one
  of the efficient approach to meet this challenge.\n
LOCATION:Engineering Department - LR6
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