Effect of soil–structure interaction on a masonry structure under train-induced vibrations

This paper presents an experimental investigation to assess the influence of soil–structure interaction (SSI) on an unreinforced masonry structure under train-induced vibrations. For this purpose, a structure near a railway line was instrumented and monitored when subjected to five railway traffic vibrations. The measured vibrations were used to estimate the modal properties using a frequency domain decomposition technique. The variation in estimated modal properties against varying excitations indicated that the dynamic response depends on the source of excitation. Two finite-element (FE) models were also developed and updated through manual tuning, one with a fixed base and the other with a flexible base accounting for SSI. The modal properties and response time histories measured through experimentation were compared to those predicted by detailed three-dimensional FE models. A comparison between the base input force, base moment and peak displacement of both FE models was also performed. The results indicated that the effect of SSI on the fundamental mode shape and in the prediction of accurate response time histories of the investigated structure was significant. However, the effect on modal frequencies, base input force, base moment and peak displacement of the investigated structure under train-induced vibrations was observed to be very low.