Historical records indicate that strong earthquakes are usually accompanied by aftershocks with large peak ground accelerations. Structural damages caused by the mainshock can be further aggravated by aftershocks, which can lead to structural collapse. Current structure seismic design practices generally consider the mainshock effects only. Performance of buildings subjected to mainshock-aftershock sequential ground motions, should always be fully investigated. Previous studies on sequential ground motion focus mainly on frame structures. There is a paucity of publications addressing other type of structures, especially high-rise buildings. The reasons for this omission have been identified as the complexity of high-rise buildings and unaffordable computational costs related to the nonlinear dynamic analysis of long duration sequential ground motions. Thus, the authors used Tianhe-2, once known as the fastest supercomputer in the world, to conduct nonlinear dynamic analysis of a typical 20-story frame-core tube building subjected to sequential mainshock-aftershock ground motions. This study focuses on 104 mainshock and aftershock ground motions from four different sites. Thus, the effects of mainshocks only and sequential ground motions of a frame-core tube structure at four different sites were analyzed in this study’s finite element model. The Performance of these structures under mainshocks and sequential ground motions are compared in terms of inter-story displacement ratio, hysteretic energy and damage index based on the Park-Ang model. The results prove that a supercomputer can be used to solve the computational cost issue in structural engineering and emphasize that the effects of sequential earthquakes need to be considered in structural design, even for frame-core tube structures with lateral resisting members.

Introduction

Earthquakes are one of the most serious disasters that endanger the safety of people’s lives and properties. The mainshock and aftershocks forms sequential ground motions. In recent years, sequential mainshock-aftershock seismic activity has caused tremendous losses to society. The compounding effect of the damage and disruption caused by earthquake sequential ground motion reactions have made seismic history in Chi-Chi (1999) [1], Wenchuan (2008) [2], Christchurch (2010–۲۰۱۱) [۳], Tohoku (2011) [4], and Nepal (2015) [5]. These are just a few examples of major earthquakes that have caused tremendous human loss and cost. Based on a 2012 report by the Center for Disaster Management and Risk Reduction (CEDIM) in Germany, in 2011 alone, worldwide seismic loss included 133 earthquakes (including aftershocks) and their consequences (i.e., tsunamis, landslides, ground settlements) caused $365 billion worth of damage including the death of 20,500 people and the loss of homes to approximately one million people. CEDIM shared the assessment of the Tohoku earthquake damage, where the tremendous loss from the Tohoku earthquake was said to be mostly due to “aftershocks” [۶]. Therefore, understanding the sequential ground motions and the response of the structure subjected to sequential ground motions in perspective is of great significance to the improvement of planning for seismic events and the development of post-earthquake emergency responses and recovery strategies.