Advanced two-step integrated optimization of actively controlled nonlinear structure under mainshock–aftershock sequences

Abstract

In this paper, an attempt is made to examine a new method for designing and applying the active vibration control system to improve building performance under mainshock–aftershock sequences. In this regard, three different structures are considered; 5-, 10-, and 15-story buildings. Seven mainshock–aftershock sequences are selected from the Iranian accelerogram database for analyzing the structures. By implementing an advanced two-step optimization method, buildings equipped with the active vibration control system (linear–quadratic regulator (LQR) algorithm) are designed to withstand all events of mainshock–aftershock sequences. In the first optimization step, a multi-objective optimization with the genetic algorithm is performed and a set of optimal Pareto front results is obtained. In the next step, the life-cycle cost of each optimal design sample of the Pareto front is calculated by considering the cumulative damage and the design sample with the minimum cost is selected as a final optimal property. The results prove that the active vibration control system is capable of reducing structural responses, including acceleration, drift, and residual drift under mainshock–aftershock sequences, and consequently the life-cycle cost of buildings, especially the taller ones. In addition, obtaining the building design variables (story stiffness and yielding force) and active LQR algorithm properties simultaneously leads to a slightly softer final building model than the conventional structure designed by the common building design code. Moreover, it is revealed that, by considering the aftershocks, the building life-cycle cost increases significantly.

Seismic Risk Assessment of Optimally Designed Highway Bridge Isolated by Ordinary Unbounded Elastomeric Bearings

“…Various types of multi objective optimization methods can be used, e.g., criterion based, aggregated-based, and Pareto front [16]. The latter is selected for this study since it is more commonly used for vibration control systems and contains fewer limitations compared to the other methods [17][18][19]. Furthermore, this method can lead to a set of non-prior optimal results [20].…”

Performance-based active controller design for nonlinear structures using modified black hole optimization

“…This aspect is especially important from the performance-based seismic design standpoint where strict requirements are imposed on structural forces, drifts, and accelerations associated with various predetermined damage states (FEMA, 2018). In general, such requirements can be most effectively achieved by means of constrained multi-objective optimization of controller, control device(s), and/or structural system parameters (Azizi et al, 2019; Chen and Chien, 2020; Hosseini et al, 2021; Khansefid and Bakhshi, 2018; Kazemi and Behnamfar, 2020; Peckens et al, 2021; Efedali and Tavakoli, 2017).…”

An investigation of the structural nonlinearity effects on the building seismic risk assessment under mainshock–aftershock sequences in Tehran metro city

“…From the other side, to overcome this major shortcoming, an extensive effort has been launched to investigate the effect of aftershocks on the performance of different types of buildings (Han et al, 2014; Khansefid and Bakhshi 2019a; Luco et al, 2004; Li and Ellingwood 2007; Ruiz-García and Aguilar 2015; Zhou et al, 2013). Most of these works focused only on the changes in the structural responses of buildings taking into account the aftershocks’ effects while fewer research works dealt with the seismic loss and risk assessment of buildings under MA sequences considering the building nonlinear behavior.…”