Trends in dynamics of civil engineering structures – solved and unsolved problems

The knowledge of the dynamic behaviour of modern civil engineering structures is becoming more and more important. Small dynamic loads can cause perceptible and/or audible vibrations. Strong dynamic loads often cause damage or collapse of structures. Vibrations propagating in different media before exciting a structure may be influenced by the dynamic properties of each medium. The dynamic behaviour of a structure is caused by mass, stiffness and damping. Mass and stiffness can be modelled well in most cases but the estimation of damping is today the weak point of the analysis. The methods in structural dynamics are layout and construction according to fundamental rules, dynamic calculations, dynamic in–situ tests and dynamic laboratory tests. Dynamics of dams, bridges and high–rise buildings are discussed. A dynamic method for the safety inspection of bridges is also presented. Finally the problem of perceptible and audible vibrations due to traffic, blasting and machinery is discussed.