IMPEDANCE FUNCTIONS OF ADJACENT STRIP FOUNDATIONS WITH DIFFERENT DEPTHS OF EMBEDMENT Vasiliki G. Terzi 1 1 Laboratory Teaching Staff Laboratory of Statics and Dynamics of Structures, Civil Engineering Department, 54124, Thessaloniki, Greece e-mail: terziv@civil.auth.gr Abstract The present study refers to the interaction between two adjacent strip foundations that have different depths of embedment. In particular, one foundation is characterized as deep and is embedded in an elastic isotropic soil layer which is resting on a rigid substratum, while the other foundation is characterized as surface and is resting on the soil layer’s surface. The two foundations have an equal value of half-width, B and the embedment depth, D of the deep foundation is equal to B. The distance ratio S/L, where S is the distance between the founda- tions and L is the width of each foundation receives the values of 0.5,3,5 and 10. In order to investigate the effect of the soil layer’s depth H, the distance ratio is kept constant and equal to 0.5 while the H/B ratio receives the values of 2, 4, 8 and 32. The main target is the calculation of the impedance matrix of the two interacting foundations and is achieved by the use of the finite element method. The accuracy of the finite element model is verified by comparison studies with the rigorous results from the boundary element method, concerning a single strip foundation, embedded or surface. Each strip foundation has three degrees of freedom; the vertical translation, the horizontal translation and the rotational one. Therefore, harmonic type of loading is applied at each foundation for each degree of freedom and the flexibility matrix is calculated for a normalized frequency range of 0.1<αο<2, where αο=ωB/Vs; ω is the loading frequency and Vs is the shear wave velocity. The final flexibility matrix is a 6x6 symmetric matrix, which consists of terms referring to the deep or surface foundation response and the coupled response between them. The flexibility functions are presented for typical values of S/L and H. The main conclusions are focused on the comparison between the response of each founda- tion which belongs to the system of the two and the response of a single foundation, deep or surface. Additional comments refer to the effect of the soil layer’s depth on the coupling terms of the flexibility matrix of the two adjacent foundations. Keywords: Structure-soil-structure interaction, Strip footings, Finite Element Method. 5622 COMPDYN 2019 7 th ECCOMAS Thematic Conference on Computational Methods in Structural Dynamics and Earthquake Engineering M. Papadrakakis, M. Fragiadakis (eds.) Crete, Greece, 24–26 June 2019 Available online at www.eccomasproceedia.org Eccomas Proceedia COMPDYN (2019) 5622-5639 ISSN:2623-3347 © 2019 The Authors. Published by Eccomas Proceedia. Peer-review under responsibility of the organizing committee of COMPDYN 2019. doi: 10.7712/120119.7332.18921