000013349 001__ 13349
000013349 005__ 20161114160337.0
000013349 04107 $$aeng
000013349 046__ $$k2009-06-22
000013349 100__ $$aSakellaraki, E.
000013349 24500 $$aOhba ohashi pile-supported bridge experiment revisited: paradoxes and new interpretations

000013349 24630 $$n2.$$pComputational Methods in Structural Dynamics and Earhquake Engineering
000013349 260__ $$bNational Technical University of Athens, 2009
000013349 506__ $$arestricted
000013349 520__ $$2eng$$aThe seismic response of an actual bridge supported on groups of steel piles in extremely soft clay (NSPT = 0) is investigated. The pier and its foundation were thoroughly instrumented in the early 1980’s by the Institute of Technology of Shimizu Corporation. This pioneering project provided several earthquake recordings, with peak accelerations in the free field as high as 0.11g. Two important observations were made: First, rock-to-surface amplification of peak horizontal acceleration varied significantly in the two horizontal directions, which is not compatible with vertically-propagating one-dimensional waves. The existence of a multi-dimensional wave field in Ohba Ohashi valley has been successfully demonstrated by earlier investigators. Second, the pile cap and bridge deck responded with a maximum acceleration of only 0.05g – as compared to an expected 0.15g or higher – a unexpected behavior that has not been explained/reproduced in a satisfactory manner to this day. An attempt is presented in this paper to reproduce the structural response using analytical tools. The relatively low level of peak strain in the soil (γ< 10-4), in conjunction with the high plasticity index of the clay material and the lack of damage in the structure justify the use of linear elastodynamic models. The effects of soil amplification, kinematic interaction, foundation compliance, pile-to-pile interaction and superstructure dynamics are considered. Pile group effects are treated both by simplified and rigorous elastodynamic numerical models. It is shown that records and predictions compare reasonably well when pertinent assumptions are introduced. Implications of valley effects, soil-structure-interaction, multiple-support excitation and structural connections on seismic response are discussed. The influence of kinematics of the movable bearings connecting the deck and the piers is investigated. A possible scenario for the deamplification of earthquake motion at the structure is proposed.

000013349 540__ $$aText je chráněný podle autorského zákona č. 121/2000 Sb.
000013349 653__ $$aSoil-Structure Interaction, Bridge Engineering, Pile Foundations, Earthquake Engineering Abstract. The seismic response of an actual bridge supported on groups of steel piles in extremely soft clay (NSPT = 0) is investigated. The pier and its foundation were thoroughly instrumented in the early 1980’s by the Institute of Technology of Shimizu Corporation. This pioneering project provided several earthquake recordings, with peak accelerations in the free field as high as 0.11g. Two important observations were made: First, rock-to-surface amplification of peak horizontal acceleration varied significantly in the two horizontal directions, which is not compatible with vertically-propagating one-dimensional waves. The existence of a multi-dimensional wave field in Ohba Ohashi valley has been successfully demonstrated by earlier investigators. Second, the pile cap and bridge deck responded with a maximum acceleration of only 0.05g – as compared to an expected 0.15g or higher – a unexpected behavior that has not been explained/reproduced in a satisfactory manner to this day. An attempt is presented in this paper to reproduce the structural response using analytical tools. The relatively low level of peak strain in the soil (γ< 10-4), in conjunction with the high plasticity index of the clay material and the lack of damage in the structure justify the use of linear elastodynamic models. The effects of soil amplification, kinematic interaction, foundation compliance, pile-to-pile interaction and superstructure dynamics are considered. Pile group effects are treated both by simplified and rigorous elastodynamic numerical models. It is shown that records and predictions compare reasonably well when pertinent assumptions are introduced. Implications of valley effects, soil-structure-interaction, multiple-support excitation and structural connections on seismic response are discussed. The influence of kinematics of the movable bearings connecting the deck and the piers is investigated. A possible scenario for the deamplification of earthquake motion at the structure is proposed.

000013349 7112_ $$aCOMPDYN 2009 - 2nd International Thematic Conference$$cIsland of Rhodes (GR)$$d2009-06-22 / 2009-06-24$$gCOMPDYN2009
000013349 720__ $$aSakellaraki, E.$$iMylonakis G., E.$$iKarabalis D., L.$$iSyngros, K.$$iTazoh, T.
000013349 8560_ $$ffischerc@itam.cas.cz
000013349 8564_ $$s586490$$uhttps://invenio.itam.cas.cz/record/13349/files/CD517.pdf$$yOriginal version of the author's contribution as presented on CD, section: Soil-structure interaction.
000013349 962__ $$r13074
000013349 980__ $$aPAPER