On the importance of energy-based parameters

In the Energy Based Design methodology damage is directly related to the input energy. The potential for an earthquake ground motion to damage a specific structure is closely associate with the energy input to that structure and its energy dissipative capacities. In Performance-Based Seismic Engineering (PBEE), seismic hazard is computed through a parameter that is usually indicated as Intensity Measure (IM), which should comprehensively define seismic input to the structure. The development of an energy-based framework for PBEE requires, among other steps, the characterization of the relationships between IMs and with suitable engineering demand parameters (EDPs). A promising parameter for assessing the damage potential of these motions is the input energy that takes into account the contribution of amplitude, frequency content and duration of ground motion. Moreover, the effects of inelasticity and ground motion duration that are overlooked by the more conventional spectral parameters are instead implicitly captured by input energy, that is directly related to the number and amplitudes of the cycles of oscillator response: hence, it conveys information on the ground motion duration, reflecting cumulative effects by virtue of the integration over time that is involved in their computation. In this paper, by using energy-based parameters, we intend to highlight the contribution of energy IMs in describing several effects of seismic action in simple and more complex structures. To this purpose IMs in predicting strength, energy and deformation levels for a structure will be established, in order to identify parameters providing the best levels of correlation to structural damage measures also in presence of site effects.