Chapter 5: Structural dynamics and seismic analysis methods

Earthquake loading poses the structural analyst with one of the most challenging problems in engineering. A violent and essentially unpredictable dynamic ground motion imposes extreme cyclic loads on engineering materials, the response of which under such conditions is complex and incompletely understood. If this is the case, engineering designers for whom this book is written may wonder whether there is any point in their getting to grips with the complex underlying theory of dynamic seismic analysis. In fact, current methods of analysis provide important insights into the way that structures respond to earthquakes, and hence the ways in which designers can control this response. Moreover, a basic understanding of analytical principles is essential to enable an informed and critical use to be made of computer-generated results, which form the basis for most seismic analysis and design. Therefore, in the authors’ view, earthquake engineers must make the effort to understand the basics of dynamic seismic analysis.