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SOFT ACTOR-CRITIC REINFORCEMENT LEARNING FOR ROBUST ACTIVE STRUCTURAL VIBRATION CONTROL

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Active structural control systems are among the most effective technologies for suppressing vibrations in civil engineering structures subjected to dynamic loads such as earthquakes and wind. However, conventional active control methods often suffer from performance degradation due to time delays, measurement noise, and changing operational conditions. To overcome these limitations, data-driven control strategies based on reinforcement learning have emerged as promising alternatives. This study introduces advanced soft actor-critic (SAC)– based control approaches designed to enhance adaptability and robustness in complex real-world environments. Challenges in Traditional Active Control Systems Traditional controllers, such as linear quadratic Gaussian (LQG) control, rely on predefined system models and fixed parameters. In practical applications, uncertainties such as sensor noise, communication delays, and environmental variability can significantly reduce their effectiveness. Thes...
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FOAMED GLASS AGGREGATE AS A LIGHTWEIGHT SUSTAINABLE GEOMATERIAL FOR GEOTECHNICAL INFRASTRUCTURE

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Foamed glass aggregate (FGA) is an innovative lightweight geomaterial manufactured from recycled glass through a sinter-foaming process. As sustainability becomes a central priority in civil engineering, FGA has emerged as a promising alternative to conventional granular fills. Its highly porous cellular structure results in extremely low density, excellent thermal insulation, and efficient drainage performance. These characteristics make FGA particularly suitable for applications such as embankments, backfills, retaining structures, and foundation systems where weight reduction and environmental benefits are essential. Production Mechanisms and Microstructural Formation The engineering performance of FGA originates from its manufacturing process, in which glass particle size, sintering temperature, and foaming agent dosage interact to create a controlled cellular microstructure. During sintering, gas released from the foaming agent becomes trapped within softened glass particles, f...
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NON-DESTRUCTIVE ESTIMATION OF UNSATURATED HYDRAULIC CONDUCTIVITY USING TIME-LAPSE GEOPHYSICAL METHODS

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Accurate estimation of soil unsaturated hydraulic conductivity is essential for understanding vadose zone flow, groundwater recharge, contaminant transport, and broader subsurface hydrological processes. Conventional point-scale measurements are typically invasive, labor-intensive, and limited in spatial and temporal coverage, making them inadequate for capturing natural field heterogeneity. To address these limitations, non-destructive geophysical techniques offer a promising alternative for continuous, large-scale monitoring of soil moisture dynamics and hydraulic behavior. Integrated Geophysical Framework This study introduces an innovative framework that integrates time-lapse ground penetrating radar (GPR) and electrical resistivity tomography (ERT) with an improved instantaneous profile (IIP) inversion approach. By combining electromagnetic and electrical measurements, the method captures changes in soil moisture and pore-water distribution over time. This integrated approach e...
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BRIDGE DIGITAL TWINS AND THE ROLE OF LOAD TESTING IN LIFECYCLE MANAGEMENT

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Bridge digital twins represent a transformative approach in bridge engineering, enabling the creation of virtual replicas that mirror the physical structure throughout its lifecycle. Originating from advancements in other industries, digital twin technology integrates real-world data with computational models to support monitoring, analysis, and decision-making. In bridge applications, digital twins promise enhanced safety, predictive maintenance, and optimized asset management, making them a critical component of next-generation infrastructure systems. Concept of Digital Twins in Bridge Engineering A bridge digital twin combines geometric information, material properties, sensor data, and operational conditions into a unified virtual model. By linking physical bridges with Building Information Modeling (BIM) and Finite Element (FE) models, engineers can simulate structural behavior under varying loads and environmental influences. This integration enables continuous assessment of p...
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ANISOTROPIC SHEAR BEHAVIOR OF BAMBOO SCRIMBER FOR STRUCTURAL APPLICATIONS

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 Bamboo scrimber (BS) is a high-performance engineered bamboo material gaining recognition as a sustainable alternative to conventional structural materials. Produced through the densification and resin impregnation of bamboo fibers, BS exhibits excellent strength, durability, and resource efficiency. Despite its promising mechanical properties, the anisotropic nature of bamboo—stemming from its fibrous structure—leads to direction-dependent behavior that is not yet fully understood, particularly under shear loading. This knowledge gap presents a critical challenge for the reliable structural design of BS components subjected to shear forces. Experimental Investigation of Shear Properties To address this challenge, the study conducted an extensive experimental program involving 250 shear tests performed under five distinct loading orientations. This comprehensive testing approach enabled the systematic evaluation of how fiber alignment and loading direction influence shear perfor...
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TRIBOELECTRIC-FUNCTIONALIZED APCY CEMENT: SMART CORE–SHEATH YARN-BASED CEMENTITIOUS COMPOSITES FOR ENERGY-AUTONOMOUS INFRASTRUCTURE

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Advanced cementitious composites are rapidly evolving beyond traditional load-bearing functions to incorporate multifunctional smart capabilities such as self-sensing and ambient energy harvesting. These next-generation materials are designed to support intelligent infrastructure systems capable of structural monitoring, data transmission, and autonomous energy supply. This study introduces triboelectric-functionalized cementitious composites reinforced with smart core–sheath braided yarns (APCY), aiming to enable large-scale deployment of energy-autonomous and self-powered civil infrastructure. Fabrication of Smart Core–Sheath Yarns via Braiding Technology The APCY yarns are manufactured using advanced braiding technology to produce a core–sheath configuration optimized for mechanical durability and functional performance. A surface roughening modification applied to the guide holes significantly enhances yarn hairiness, thereby increasing effective surface contact area for triboele...
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SLAM-CENTRIC FRAMEWORK FOR PRECISE AND PLATFORM-AGNOSTIC ROBOT-AIDED INFRASTRUCTURE INSPECTION

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Robot-aided inspection has emerged as a promising solution for enhancing safety, efficiency, and objectivity in infrastructure assessment. However, existing approaches often suffer from inconsistent mapping accuracy, unreliable defect measurements, and platform-specific system designs that limit scalability. This study investigates whether a SLAM-centric (Simultaneous Localization and Mapping) framework can overcome these limitations and enable precise, repeatable, and platform-agnostic visual inspections across diverse infrastructure environments. Integrated Lidar–Camera–Inertial SLAM Architecture The proposed framework integrates lidar, camera, and inertial measurement unit (IMU) data within a unified SLAM pipeline to ensure robust localization and mapping under real-world conditions. Multi-sensor fusion enhances pose estimation accuracy and resilience to environmental challenges such as lighting variation, occlusions, and geometric complexity. By centering the inspection workflow...
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