TY - CONF A1 - Auersch, Lutz A1 - Markfort, Greta T1 - Static and dynamic behaviour of pile foundations in homogeneous and inhomogeneous soils T2 - Computational Methods in Structural Dynamics and Earthquake Engineering N2 - Offshore wind energy towers are dynamically loaded by waves and wind. Pile foundations provide stiffness and damping and should be properly calculated. A combined finite-element boundary-element method for the dynamic interaction of flexible structures and the soil has been developed. The flexible structures such as single piles or complete wind energy towers are modeled by the finite element method whereas the homogeneous or layered soil is modeled by the boundary element method which uses the Green’s functions for interior loads in the layered half-space to establish the dynamic stiffness matrix of the soil. Soils with a stiffness that is continuously increasing with depth can be modeled as multi-layer soils with step-wise increasing stiffness. The effects of different parameters such as the stiffness of the soil, the axial and bending stiffness of the pile, and the radius of the cylindrical contact area will be analysed for the different components of excitation (vertical, horizontal, rotation and coupling). The results can be determined as specific power laws which are different for the different load cases and for the different soil models (Winkler support, homogeneous continuum, continuum with increasing stiffness). The dynamic effect of radiation damping will be analysed by the frequency-dependent compliance functions. A clear layering of the soil can cause noticeable changes in the dynamic compliances as reductions of the stiffness and the damping in certain frequency ranges (below and around layer resonance frequencies). The distribution of the displacements along the pile help to explain the observed laws. An example of an offshore wind energy tower has been modeled and calculated for wind, wave and weight loads. The resonances of the tower are usually limited by the radiation damping which is strongest for a soft soil. T2 - COMPDYN 2017 CY - Rhodes, Greece DA - 15.06.2017 KW - Pile foundation KW - Finite-element boundary-element method KW - Pile bending stiffness KW - Soil stiffness KW - Continuously inhomogeneous soils KW - Layered soils KW - Wind energy tower PY - 2017 SP - 4675 EP - 4690 PB - NTUA CY - Athens AN - OPUS4-42089 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Auersch, Lutz T1 - Response to harmonic wave excitation of finite or infinite elastic plates on a homogeneous or layered half-space JF - Computers and geotechnics N2 - The soil–structure interaction of elastic plates on homogeneous or layered soils excited by horizontally propagating waves is analysed. Large plates are modelled by a combined finite-element boundary-element method (FEBEM), whereas the response of infinitely long plates is calculated by a numerical integration in the frequency–wavenumber domain. The finite-element boundary-element method yields the complete soil–plate transfer function of frequency and distance whereas the frequency–wavenumber solution of the infinitely long plate can serve as an approximation for long distances on a finitely long plate. The soil–plate transfer function starts to decrease strongly at the coincidence frequency, where the bending stiffness equals the plate inertia. A strong decrease follows at mid frequencies and a strong reduction of less than 0.1 of the ground vibration is reached at high frequencies. Rules for the characteristic frequencies are derived from the numerical results clearly indicating the strongest influence of the soil stiffness and the weaker influence of the bending stiffness of the plate. The influence of the mass, length and width of the plate are shown to be limited in case of realistic parameters, but it should be noted that the reduction effects are less effective for layered soils and for nearer observation points. KW - Plate-soil interaction KW - Wave excitation KW - Flexible plate KW - Layered soil KW - Vibration reduction KW - Finite-element boundary-element method KW - Frequency-wavenumber method PY - 2013 DO - https://doi.org/10.1016/j.compgeo.2013.02.001 SN - 0266-352x VL - 51 SP - 50 EP - 59 PB - Elsevier Appl. Sci. Publ. CY - Barking AN - OPUS4-27983 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz ED - Náprstek, J. ED - Horácek, J. ED - Okrouhlík, M. ED - Marvalová, B. ED - Verhulst, F. ED - Sawicki, J.T. T1 - Reducing ground-borne micro-vibrations by plate foundations T2 - Vibration problems ICOVP 2011 - 10th international conference on vibration problems (Proceedings) T2 - Vibration problems ICOVP 2011 - 10th international conference on vibration problems CY - Prague, Czech Republic DA - 2011-09-05 KW - Plate-soil interaction KW - Wave excitation KW - Vibration reduction KW - Finite-element boundary-element method PY - 2011 SN - 978-94-007-2068-8 SN - 0930-8989 N1 - Serientitel: Springer proceedings in physics – Series title: Springer proceedings in physics VL - 139 SP - 329 EP - 335 PB - Springer AN - OPUS4-24804 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz ED - M. Papadrakakis, ED - D.C. Charmpis, ED - N.D. Lagaros, ED - Tsompanakis, Y. T1 - Simple and advanced boundary-element method for the soil and its application to railway dynamics T2 - COMPDYN 2007 - Computational methods in structural dynamics and earthquake engineering (Proceedings) T2 - COMPDYN 2007 CY - Rethymno, Crete, Greece DA - 2007-06-13 KW - Finite-element boundary-element method KW - Explicit Green´s functions KW - Track vibration KW - Tunnel vibration KW - Vehicle-track-soil interaction KW - Radiation damping PY - 2007 SP - 1 EP - 12 CY - Athen AN - OPUS4-15015 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Auersch, Lutz T1 - Static and dynamic soil-structure interaction of finite and infinite beams and plates, tracks and piles T2 - EURODYN 2008 - 7th European Conference on Structural Dynamics, July 7-9, 2008, Southampton, UK T2 - 7th European Conference on Structural Dynamics, EURODYN 2008 CY - Southampton, UK DA - 2008-07-07 KW - Soil-structure interaction KW - Wave-number integrals KW - Finite-element boundary-element method KW - Moving loads on tracks KW - Pile-soil interaction PY - 2008 SN - 9780854328826 IS - E 102 SP - 1 EP - 12 AN - OPUS4-18236 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz ED - Papadrakakis, M. ED - Papadopoulos, V. ED - Plevris, V. T1 - How to quantify the vibration reduction of railway tracks T2 - COMPDYN 2013 - 4th ECCOMAS Thematic conference on computational methods in structural dynamics and earthquake engineering (Proceedings) T2 - COMPDYN 2013 - 4th ECCOMAS Thematic conference on computational methods in structural dynamics and earthquake engineering CY - Kos Island, Greece DA - 2013-06-12 KW - Railway induced ground vibration KW - Mitigation measures KW - Railway tracks KW - Finite-element boundary-element method KW - Wavenumber integrals KW - 1-D insertion loss PY - 2013 SP - 1 EP - 19 AN - OPUS4-29313 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Auersch, Lutz A1 - Markfort, Greta T1 - Static and dynamic behaviour of pile foundations in homogeneous and inhomogeneous soils N2 - Offshore wind energy towers are dynamically loaded by waves and wind. Pile foundations provide stiffness and damping and should be properly calculated. A combined finite-element boundary-element method for the dynamic interaction of flexible structures and the soil has been developed. The flexible structures such as single piles or complete wind energy towers are modeled by the finite element method whereas the homogeneous or layered soil is modeled by the boundary element method which uses the Green’s functions for interior loads in the layered half-space to establish the dynamic stiffness matrix of the soil. Soils with a stiffness that is continuously increasing with depth can be modeled as multi-layer soils with step-wise increasing stiffness. The effects of different parameters such as the stiffness of the soil, the axial and bending stiffness of the pile, and the radius of the cylindrical contact area will be analysed for the different components of excitation (vertical, horizontal, rotation and coupling). The results can be determined as specific power laws which are different for the different load cases and for the different soil models (Winkler support, homogeneous continuum, continuum with increasing stiffness). The dynamic effect of radiation damping will be analysed by the frequency-dependent compliance functions. A clear layering of the soil can cause noticeable changes in the dynamic compliances as reductions of the stiffness and the damping in certain frequency ranges (below and around layer resonance frequencies). The distribution of the displacements along the pile help to explain the observed laws. An example of an offshore wind energy tower has been modeled and calculated for wind, wave and weight loads. The resonances of the tower are usually limited by the radiation damping which is strongest for a soft soil. T2 - Compdyn 2017 CY - Rhodes, Greece DA - 15.06.2017 KW - Pile foundation KW - Finite-element boundary-element method KW - Pile bending stiffness KW - Soil stiffness KW - Continuously inhomogeneous soils KW - Layered soils KW - Wind energy tower PY - 2017 AN - OPUS4-42486 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Auersch, Lutz T1 - Compliance and damping of piles for wind tower foundation in nonhomogeneous soils by the finite-element boundary-element method JF - Soil Dynamics and Earthquake Engineering N2 - A combined finite-element boundary-element method for the dynamic interaction of the soil with flexible structures such as single piles or complete wind energy towers has been developed. Flexible piles in different soils are analysed in frequency domain. The different parameters such as the stiffness of the soil, the bending stiffness and the radius of the hollow pile are analysed for their influence on the complex compliances. The results have been determined as specific power laws which are different for the different load cases (horizontal, rocking, coupling) and for the different soil models (Winkler, continuum with constant, root-parabolic and proportional-linear stiffness variation). The strongest influence of the soil stiffness can be found for the homogeneous soil and the horizontal component. Winkler soils have a weaker influence than the corresponding continuous soils. An offshore wind energy tower has been modeled and calculated for wind and wave loads. KW - Pile foundation KW - Finite-element boundary-element method KW - Pile bending stiffness KW - Soil stiffness KW - Continuously inhomogeneous soils KW - Layered soils KW - Wind energy tower PY - 2019 DO - https://doi.org/10.1016/j.soildyn.2018.12.005 SN - 0267-7261 VL - 120 IS - 5 SP - 228 EP - 244 PB - Elsevier CY - London AN - OPUS4-47891 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -