Aseismic Structural Systems for Buildings
International Institute of Seismology and Earthquake Engineering, Building Research Institute, Ministry of Construction, 2-25-5 Tokiwadai, Itabashi-ku, Tokyo, Japan
When structures are subjected to earthquake motions, the principal factors controlling their behavior are i) dynamic characteristics of the structure ii) characteristics of the input earthquake motions. In this sense, it is essential, first of all, to be acquainted with general dynamic properties. Let the simple structure – single degree of freedom system – as illustrated in Fig. 1 be considered. Spring, mass, and damper are the three elements which characterize the system. If to this system, an initial displacement is applied, then set it free, the time history of the displacement, velocity and acceleration will be as shown in Fig. 2. In Fig. 2 the basic concepts of period, frequency and circular frequency of the system are also explained.