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Öğe Modelling non-linear dynamic behaviour of rocking bridge piers with shape memory alloys(Emerald Group Publishing Ltd, 2023) Kocakaplan, Sedef; Ahmadi, Ehsan; Kashani, Mohammad M.In recent years, accelerated bridge construction has led to the substantial application of precast post-tensioned segmental (PPS) bridge piers. However, PPS piers are not widely used in high-seismicity regions due to their low energy-dissipation capacity (EDC). To address this deficiency, a series of shape memory alloy (SMA)-concrete composite PPS piers were examined in this work. Non-linear static and dynamic analyses were performed on experimentally validated finite-element models of the SMA-concrete composite piers and the results were compared with those of piers without SMA bars. It was found that the length, area and post-tensioning ratio of the SMA bars affected the EDC of the piers, and an optimal design of the bars is required to reach the highest EDC possible. The effects of SMA bars on the frequency response functions of piers were investigated for the first time in this study and it was found that, unlike the piers without SMA bars, sub-harmonics and super-harmonics were not seen in the responses of the SMA-concrete composite piers, mainly the drift responses. Furthermore, the SMA-concrete composite piers experienced a significant reduction in drift responses compared with piers without SMA bars.Öğe Nonlinear seismic fragility analysis of a resilient precast post-tensioned segmental bridge pier(Taylor & Francis Ltd, 2022) Ahmadi, Ehsan; Kocakaplan, Sedef; Kashani, Mohammad M.The use of precast post-tensioned segmental (PPS) piers is growing in the bridge industry, particularly in Accelerated Bridge Construction (ABC). To increase their use in high-seismicity regions, this study focuses on the seismic performance of the PPS piers under pulse-like near-field earthquakes. Two ensembles of 40 pulse-like near-field ground motions and 44 far-field ground motions along with three bridge piers of various heights are used in a series of incremental dynamic analyses. The piers are analysed under the original pulse-like near-field ground motions, their extracted pulse ground motions, and their corresponding non-pulse ground motions. It is found that the effect of the pulse ground motion is pronounced, when the pulse period is in proximity to the natural period of the pier. It is also seen that pulse-like near-field and far-field ground motions generally have similar effects on the response of PPS piers.Öğe Seismic performance of resilient self-centering bridge piers equipped with SMA bars(Emerald Group Publishing Ltd, 2025) Kocakaplan, Sedef; Ahmadi, Ehsan; Kashani, Mohammad M.This study examines the seismic behavior of precast post-tensioned segmental (PPS) bridge piers that are equipped with Shape Memory Alloy (SMA) bars. PPS piers are designed to minimize overall and localized damage to bridges by incorporating natural hinges and rocking mechanisms. The introduction of super-elastic SMA bars has the potential to enhance the use of PPS piers in high-seismic regions. A parametric study is conducted to identify piers with the highest energy dissipation capacity, which are then subjected to dynamic analysis. The aim is to assess the energy dissipation capability of these systems by subjecting the selected piers, both with and without SMA bars, to far-field ground motions using a Finite Element (FE) framework. The seismic performance of the piers is evaluated using Incremental Dynamic Analysis (IDA) curves, which are obtained from analyzing the piers under 44 far-fault ground motions. The IDA results indicate a significant reduction in the drift responses of the piers when SMA bars are utilized.Öğe Time-domain acceleration-based pulse characterization of 2023 Kahramanmaraş earthquakes(Springer, 2024) Sezgin, Sedef Kocakaplan; Ahmadi, Ehsan; Kashani, Mohammad M.On February 6, 2023, two significant earthquakes struck the region of Kahramanmara & scedil;, T & uuml;rkiye. The first earthquake, with a magnitude of 7.7 and a depth of 8.6 km, occurred in Pazarc & imath;k, and the second earthquake, with a magnitude 7.6 and a depth of 7.0 km, struck Elbistan. These two devastating events led to the loss of lives and massive destruction of civil infrastructures. In this work, pulse components of the ground motions for both earthquakes are characterized through a multi-pulse decomposition method developed by the authors. The work particularly focuses on cumulative energy, period, and amplitude of dominant pulse components using two extensive ground motion ensembles: (1) 103 ground motions from the Pazarc & imath;k earthquake, and (2) 79 ground motions from the Elbistan earthquake. It is found that, for the Pazarc & imath;k earthquake, pulse cumulative energy is more pronounced for the ground motions in proximity to the rupture lines. However, for the Elbistan earthquake, pulse cumulative energy is not significant for the ground motions in a specific area and is roughly uniformly distributed across all the ground motions and the entire region. It is also seen that dominant pulse periods lie predominantly within the range of 0.5-1.5 s for both earthquakes highlighting the significant damage caused. Finally, the pulse amplitudes exceed 0.5 g for several ground motions of the Pazarc & imath;k earthquake while all the amplitudes fall below 0.5 g for the Elbistan earthquake.
