1 soil-structure interaction (ssi),current situation and future direction

 soil -structure-interaction (ssi) effects may be either beneficial or detrimental to the performance of structures. when beneficial, by incorporating ssi effects in the seismic code calculations, more cost-effective designs are possible. for some situations, such as the design or retrofitting of bridges, dams or buried structures, etc., an appropriate inclusion of ssi effects in seismic calculations may bring large design cost savings to our society. there is an urgent need for performing comparative cost-benefit reviews with and without considering rigorously the ssi effects for different types of constructions. on the other hand, when it is determined by calculations that ssi effects can be detrimental to the performance of structures, by mere recognition and taking effective measures, safety and better performance can be achieved. a large number of research papers and several books have been written on soil- structure interaction analysis and site response due to earthquake loading. however, the majority of these publications have been restricted to the linear behavior of soil-structure systems. it is possible, with the use of the numerical methods currently available, to conduct accurate earthquake analysis of real soil-structure systems in the time domain, including many realistic nonlinear properties. in this paper a brief review of ssi and code provisions about this subject, current situation of ssi in engineering investigations and future researches are addressed.