Load tests and modal analysis of bridges

This paper describes the static, dynamic and long-term tests of bridges in situ, which have been performed in the Czech and Slovak Republics since 1968. The standard methods are supplemented with the criteria for the elastic and permanent deformations, natural frequencies and the dynamic impact factors. The monitoring of stresses under usual traffic loads provides important data for the fatigue of bridges, for the estimation of their residual life and for the determination of inspection intervals. Modal analysis and identification ascertain the characteristic properties of bridges from their response. The damage in bridges may be reflected in the changes of their natural frequencies or modes of natural vibration.