Soil-structure interaction in the time domain using the BEM

The accurate analysis of the dynamic response of structures, especially that of lifeline structures in case of earthquakes, is becoming increasingly important in civil engineering. The structural response to dynamic excitation can be influenced to a significant extent by the interaction of the structure with the foundation soil or rock. The development of an efficient and robust procedure, that allows the accurate treatment of soil-structure interaction in the time domain, is the primary aim of this project. The simulation of the foundation soil and rock is based on the Boundary Element method (BEM) which has some considerable advantages compared to other techniques like the Finite Element method (FEM) for the treatment of unbounded media. Not only is the problem dimension reduced by one order of magnitude, thereby significantly reducing the number of unknowns and facilitating the problem discretisation, but also the obtained results are more accurate than those of the FEM, since the effects resulting from the infinite extent of the soil or rock mass are automatically included in the Boundary Element solution. An error due to mesh truncation is avoided completely. A new computational approach for the treatment of dynamic problems with the BEM will be developed, increasing its efficiency and generality. Finite Elements, on the other hand, are ideally suited for the treatment of non-linear phenomena, that are likely to occur in the vicinity of the analysed structure or within the structure itself. In order to unite "the best of both worlds", the procedure will allow the coupling between BEM and FEM. The resulting analysis software is intended to significantly reduce the effort required for the numerical simulation of soil-structure interaction problems and to increase its accuracy, thus augmenting the safety of structures subjected to dynamic loading..