Strongest Recorded Ground Motions

Every structure has a certain capacity to deform. If the deformation demand exceeds the deformation capacity, the structure collapses. This chapter deals with the deformation demand imposed by ground motion. Ground motions for engineering applications are measured by accelerometers (acceleration sensors) oriented in three orthogonal directions: usually east, north, and up. A linear-elastic structure can be represented by one or more single-degree-of-freedom systems. The tripartite plot is a very concise and elegant way of displaying the response spectrum of a ground motion. Acceleration-deformation plot of the response spectrum (ADRS) is helpful in estimating the response of nonlinear systems. When shaken strongly, a “ductile” structure yields on reaching its maximum strength. After yielding, the structure no longer behaves in a linear fashion. ADRS and cyclic-demand response spectra directly affect the response of structures.