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All Journal Civil Engineering Journal
Saito, Taiki
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Civil Engineering, Building, Construction & Architecture

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An Investigation of Dynamic Soil-Structure Interaction on the Seismic Behavior of RC Base-Isolated Buildings Santoso, Alvin K.; Saito, Taiki
Civil Engineering Journal Vol 10, No 11 (2024): November
Publisher : Salehan Institute of Higher Education

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.28991/CEJ-2024-010-11-01

Abstract

Soil-structure interaction (SSI) can significantly influence earthquake responses in base-isolated (BI) buildings, yet it is often overlooked in practice due to the high computational demands of complex analyses. This study investigates SSI effects on reinforced concrete (RC) base-isolated buildings, idealizing SSI with a cone model. Three BI building models of varying heights and soil characteristics were analyzed using modal and nonlinear time history analysis. The base isolation system incorporated elastic sliding bearings, lead rubber bearings, natural rubber bearings, and oil dampers. The SSI model was idealized considering hard, medium, and soft soils. To simulate earthquake input, three artificial ground motions with different phase characteristics were generated to match the design response spectrum according to the Japanese code. The seismic responses of the base-isolated building models with SSI were compared to those of models without SSI. Modal analysis showed that the natural period increased with softer soil profiles. In the first and second modes, the natural period lengthened as the building’s aspect ratio increased. Conversely, in the higher modes with a rocking pattern, the building with the lowest aspect ratio exhibited the longest natural period. Overall, implementing SSI generally reduced seismic responses, notably lowering story drift, acceleration, and force, particularly for buildings on soft soil. However, the SSI effect significantly increased the base rotation angle in high aspect ratio buildings on soft and medium soils. These findings indicate that including SSI in analysis is essential for more realistic seismic response predictions, especially for tall, slender base-isolated buildings. Doi: 10.28991/CEJ-2024-010-11-01 Full Text: PDF
Shaking-Table Test on a Multi-Story Continuous Vibration-Control System Employing Pulley Amplification Mechanism Majima, Ryo; Yamasaki, Yasuo; Saito, Taiki
Civil Engineering Journal Vol 11, No 1 (2025): January
Publisher : Salehan Institute of Higher Education

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.28991/CEJ-2025-011-01-02

Abstract

This study proposes an innovative passive vibration-control system, named the Pulley Damper Multi-story System (PDMAS), which incorporates pulley tackles installed at multiple stories in the successive stories to amplify inter-story displacement. This configuration significantly enhances the energy absorption efficiency of the linked dampers at the middle of the cable by utilizing the cumulatively amplified story displacements via a continuously stretched cable across the entire structure. The proposed system shows notable potential for controlling responses induced by higher vibration modes by customizing the wire installation layout. The aim of this study is to introduce PDMAS and to investigate its seismic-mitigation effectiveness. As a primary investigation of this new system, comparative experimental studies were conducted through shaking-table tests on nine specimens featuring various cable layouts optimized for the first and second structural vibration modes, with or without dampers, under harmonic waves, white-noise waves, and simulated seismic waves. The experimental results demonstrate that the PDMAS effectively accommodates the cumulative amplified story displacement across the structure to match theoretical damper values. Furthermore, the specimens employing PDMAS with a wire layout optimized for the first structural mode reduced both acceleration and displacement by nearly half compared to specimens without PDMAS. Doi: 10.28991/CEJ-2025-011-01-02 Full Text: PDF
Development and Validation of a Seismic Index for Assessing the Vulnerability of Low-Rise RC Buildings Sharafi, Sayed Q.; Maulana, Taufiq I.; Saito, Taiki
Civil Engineering Journal Vol 11, No 3 (2025): March
Publisher : Salehan Institute of Higher Education

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.28991/CEJ-2025-011-03-016

Abstract

This research develops a comprehensive framework for evaluating the seismic vulnerability of Afghanistan's low-rise reinforced concrete (RC) structures, aiming to enhance urban resilience and mitigate seismic risks. The primary objective is to improve structural safety and reduce economic losses and casualties during devastating earthquakes. Utilizing a database of low-rise RC buildings constructed between 2001 and 2022 by the Ministry of Urban Development and Housing (MUDH) and the Ministry of Education (MOE), the study analyzes structures with varying materials, architectural styles, construction years, and number of stories. The methodology integrates a modified Japanese Is Index, refined using statistical techniques to incorporate local seismic data and building characteristics across diverse seismic zones. Advanced analyses, including the Capacity Spectrum Method (CSM) and dynamic analysis using STERA 3D software, support the development of the Afghanistan Seismic Index (ASI). Findings confirm ASI’s reliability by comparing it to existing seismic assessment methods, demonstrating its suitability for region-specific evaluations. The research proposes a novel, tailored seismic index (ASI) for assessing seismic vulnerability and addressing gaps in Afghanistan’s building code (ABC) and standards. This framework enhances structural performance and informs future policy, providing a foundation for safer urban environments and sustainable infrastructure development in earthquake-prone regions. Doi: 10.28991/CEJ-2025-011-03-016 Full Text: PDF
Co-Authors Majima, Ryo Maulana, Taufiq I. Santoso, Alvin K. Sharafi, Sayed Q. Yamasaki, Yasuo