@conference {3484, title = {Sensitivity Analysis of Track Vibrations due to Vertical Stiffness Variation in High-Speed Railways}, booktitle = {Computational Methods in Structural Dynamics and Earthquake Engineering, COMPDYN}, year = {2007}, address = {Rethymno, Crete}, author = {Z. Dimitrovov{\'a} and Varandas, J.N. and Almeida, J.R. and Silva, M. A. G.} }