Performance-oriented seismic retrofit of a Cliff-mounted steel–glass observation platform under near-source ground motions: viscous damping strategies and targeted section enhancement

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Kiral A., Tonyali Z., Farzam M. F.

ENGINEERING SCIENCE AND TECHNOLOGY, AN INTERNATIONAL JOURNAL, cilt.83, sa.1, ss.1-28, 2026 (SCI-Expanded, Scopus)

Özet

Cliff-mounted steel–glass observation platforms may be earthquake-sensitive because of their slender supports, low inherent damping, and elevated mass. This study presents a numerical proof of concept for retrofitting the Oylat Glass Observation Platform in Türkiye with fluid viscous dampers (FVDs). To the authors' knowledge, and within the literature reviewed, this is the first reported FVD retrofit study for a freestanding or cliff-mounted steel–glass observation platform. Three spectrally matched near-source records from the 2023 Kahramanmaraş earthquake sequence were applied simultaneously in two horizontal directions. Direct-integration response-history analyses were performed. Four strategies were compared. Strategy 1 used all feasible external and internal FVDs. Strategy 2 controlled the columns first and then added deck dampers one at a time. Strategy 3 used only external FVDs to control the columns. Strategy 4 combined external FVDs with ring-beam strengthening. In each strategy, Design Methodology II (DM-II) iteratively adjusted the active damper coefficients using the governing demand-to-capacity (D/C) ratio. Strategies 1, 2, and 4 kept all audited members at D/C ≤ 0.80. Their maximum D/C ratios were 0.7991, 0.7820, and 0.7882, respectively. Strategy 3 met its column-control objective but did not control the full deck. Its maximum D/C ratio was 2.8292. Strategy 2 gave the lowest maximum D/C. Strategy 4 gave the most uniform outer-deck displacement. These results establish a proof-of-concept benchmark for future FVD placement and sizing algorithms.