Pseudo-double impulse for simulating critical response of elastic-plastic MDOF model under near-fault earthquake ground motion

• Published in: Soil dynamics and earthquake engineering (1984) Vol. 150; p. 106887
• Main Authors: Akehashi, Hiroki, Takewaki, Izuru
• Format: Journal Article
• Language: English
• Published: Barking Elsevier Ltd 01-11-2021; Elsevier BV
• Subjects: Acceleration; Critical excitation; Double impulse; Earthquakes; Elastic limit; Elastic-plastic earthquake response; Ground motion; Influence coefficient; Near-fault ground motion; Nonlinear resonance; Plastics; Pseudo-double impulse; Seismic activity; Sine waves; Critical excitation; Double impulse; Elastic-plastic earthquake response; Near-fault ground motion; Pseudo-double impulse; Nonlinear resonance
• ISSN: 0267-7261; 1879-341X
• DOI: 10.1016/j.soildyn.2021.106887

A pseudo-double impulse (PDI) is proposed as an extension of the ordinary double impulse (DI) as a substitute of a one-cycle sine wave. PDI is treated as a set of impulsive lateral forces while the ordinary DI was introduced as an impulsive ground acceleration. The deformation and acceleration responses of multi-degree-of-freedom (MDOF) models under DI largely exceed those under the corresponding one-cycle sine wave as a main part of a near-fault ground motion. This is because DI has multiple frequency components and the higher-mode responses are excited. While the influence coefficient vector of the ordinary DI consists of 1 at every component, the influence coefficient vector of PDI is set to be proportional to the undamped fundamental natural mode. Therefore, the fundamental-mode response is mainly excited and the higher-mode responses are hardly excited by PDI. The displacement responses, the velocity responses and the input energy under DI and those under PDI are derived here for both elastic proportionally and non-proportionally damped MDOF models. The critical timing under PDI is also derived. The critical timing can be obtained by the time-history response analysis without repetition. It is demonstrated through the time-history response analysis that the distributions of interstory drifts and floor accelerations under the critical PDI correspond well to those under the critical one-cycle sine wave. Moreover, it is shown that, as far as the input level is large, the critical input period of PDI and that of the one-cycle sine wave correspond well. Since this procedure is not limited to elastic models, the proposed procedure helps to efficiently estimate the critical responses under the one-cycle sine wave for elastic-plastic MDOF models. Finally, the responses under recorded near-fault ground motions are compared with those under PDI. It is shown that the correspondence of the response under PDI and that under the recorded ground motions is fairly good although recorded ground motions are not always critical inputs for elastic-plastic MDOF models.
•A pseudo-double impulse (PDI) is proposed as an extension of the ordinary double impulse (DI).•The fundamental-mode response is mainly excited and the higher-mode responses are hardly excited by PDI.•The critical PDI can efficiently estimate the critical responses of elastic-plastic MDOF models and the critical period.•PDI can capture the critical input period of a one-cycle sine wave without repetition and evaluate the maximum acceleration.