8/8/2019 Abstract for_SECED_YEC

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SECED - Society for Earthquake and Civil Engineering Dynamics Young Engineers Conference - 2010

DYNAMIC RETAINING WALL-SOIL-STRUCTURE INTERACTION:BENEFICIAL OR DETRIMENTAL?

G. Papazafeiropoulos

Civil Engineer (M.Sc.), Ph.D. Candidate, Division of Mechanics, Department of Applied Sciences,Technical University of Crete, Greece

Email: gpapazafeiropoulos@yahoo.gr

ABSTRACT

The issues of the dynamic interaction of retaining walls with the retained soil (Wall-Soil Interaction) and of structures with the soil underlying their foundation (Soil-Structure Interaction) have been examined by anumber of researchers in the past. Besides this, a usual problem faced by structural and/or geotechnicalengineers in densely populated areas is the construction of buildings near existing structures. Often in suchcases, there is not enough room to efficiently eliminate the interaction between the two structures, and theengineer has to take into account the phenomenon of retaining wall-soil-structure interaction. Of much interestis the dynamic version of this phenomenon (which incorporates the static version), where all the threecomponents (wall, soil, structure) respond dynamically and affect the response and distress of each other.Dynamic Wall-Soil-Structure Interaction (denoted from now on by DWSSI) is present when the foundation of astructure is relatively close to the basement wall of an adjacent structure, close to a gravity or cantilever wallretaining soil or even close to a bridge abutment during a seismic event. DWSSI has not been investigated yetand is either ignored or considered beneficial by the majority of the seismic norms worldwide. In general,engineering practice follows these trends. In the present study, using numerical two-dimensional simulations,the influence of the flexibility of the wall, the type of the wall-retained soil interface, the flexibility of thefoundation and the relative distance of the structure from the wall on the modified equivalent soil impedances(springs and dashpots) and on the wall distress is addressed. Emphasis is given on the variation of the complex-valued soil impedances with frequency. Subsequently, a structure founded on the retained soil is included in the

numerical models, as a single-degree-of-freedom system (SDOF) and its dynamic distress and response arestudied. Despite the fact that DWSSI is affected by many interrelated factors, the numerical results of thecurrent study provide a clear indication of the direct dynamic interaction between a retaining wall and itsretained structures. It is shown that DWSSI may be either beneficial or detrimental, according to thecircumstances. Therefore, neglecting DWSSI or assuming that it is beneficial can sometimes result in unsafeseismic design and dangerous situations. In this study diagrams are presented which can be used for the seismicdesign of retained structures. Nevertheless, a more elaborate consideration of the interrelated phenomena on theseismic design is necessary, not only for the retaining walls but for the nearby structures as well.

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