The book provides a critical assessment of the current knowledge and indicates new challenges which are brought about at present times by fighting man-made and natural hazards in transient analysis of structures. The latter concerns both permanently fixed structures, such as those built to protect people and/or sensitive storage material (e.g. military installations) or special structures found in transportation systems (e.g. bridges, tunnels), and moving structures (such as trains, planes, ships or cars). The present threat of terrorist attacks or accidental explosions, the climate change which brings strong stormy winds or even the destructive earthquake motion that occurs in previously inactive regions or brings about tsunamis, are a few examples of the kind of applications addressed in this work. Problems of such diversity cannot be placed within a single traditional scientific discipline, but call for the expertise in probability theory for quantifying the cause, interaction problems for better understanding the physical nature of the problems, as well as modeling and computational techniques for improving the representation of inelastic behavior mechanisms and providing the optimal design.