On progressive damage phenomena of structures

For more than 50 years, the technology of linear damage processes has been known and mastered. Strong, progressive damage processes have recently been discovered on various types of structures, for which a uniform theory has been unavailable. A common feature of these processes is the wide-band excitation of the dominant forces (ocean waves, storm, traffic), a shift of the structural response spectrum into domains of higher excitation caused by degrading structural stiffness, as well as a damage-controlled self-adaptation phenomenon. Any numerical investigation of progressive damage phenomena should be based on the load- or time-evolution of the global stiffness matrix. The eigenvalues or natural frequencies of this stiffness matrix offer a decision basis regarding the damage-induced change of structural features.