Abstract
Structures in service may be subject to blast loading, which can result in significant damage or even failure of critical structural elements. Understanding and mitigating such effects is crucial for ensuring structural resilience. This study conducts a comprehensive numerical analysis to evaluate the efficiency of carbon fiber reinforced polymer (CFRP) as a reinforcing solution for reinforced concrete (RC) beams under explosive loads. Finite element (FE) models were developed using LS-DYNA to analyze the structural response, failure mechanisms of RC beams under blast conditions. To verify the reliability of the FE models, numerical results were systematically compared with experimental data from existing literature. CFRP reinforcement significantly enhances the load-carrying capacity and energy absorption of RC beams while also reducing mid-span deflection. Given excellent agreement with experimental data, the study further explores the impact of different CFRP reinforcement strategies through numerical analyses, considering key factors such as CFRP thickness, the number of reinforcement layers, and various strengthening configurations. Additionally, numerical simulations were conducted to generate Pressure-Impulse (P-I) diagrams for CFRP-strengthened RC beams subjected to blast loading. These diagrams help establish correlations between blast-induced damage, measured in terms of mid-span displacement, and applied explosive loads, offering valuable insights for structural design and retrofitting.
Key Words
blast loading; FE simulation; fiber reinforced polymer; mid-span displacement; P-I diagram; RC beams
Address
Department of Civil Engineering, Seoul National University of Science and Technology, 232 Gongneung-ro, Nowon-gu, Seoul 01811, Republic of Korea
Abstract
Pervious concrete pavements offer stormwater management benefits but are limited by their low mechanical capacity. To address this issue, this paper introduces a hybrid paver composed of a 3D-printed paste frame and post-cast pervious concrete core. A comprehensive experimental program was conducted to investigate the effects of frame geometry (lattice, circular, hexagonal, and diamond), bottom-layer thickness (10-30 mm), aggregate gradation, and post-casting time on density, porosity, infiltration, and flexural performance. The results indicated that the frame geometry and bottom-layer thickness were the dominant factors governing the mechanical-hydraulic balance. Increasing the printed-layer thickness significantly enhanced the flexural strength by increasing the section stiffness and confinement, although it reduced infiltration owing to the formation of deeper constricted flow channels. Circular and diamond geometries provided superior confinement and strength, whereas the lattice and hexagonal patterns maintained higher drainage continuity. The hybrid system developed in this study demonstrated flexural strengths up to 4 MPa, exhibited performance consistent with the functional drainage standards and offering a designable platform to tailor pavement performance.
Address
Young Hwan Bae, Hong Jae Yim: Department of Civil Engineering, Pusan National University, Busan 46241, Republic of Korea
Noor Nabilah Sarbini: Faculty of Civil Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor, Malaysia
Abstract
Inspection information plays an important role in time-dependent reliability assessment of deteriorating
structures, and various types of inspection information can be incorporated into reliability updating. This study proposes a unified reliability-updating framework that systematically integrates both inequality-type inspection events and equality-type inspection data into the reliability analysis of deteriorating structures. Two illustrative examples are presented to demonstrate the applicability of the proposed framework. The first example illustrates an reinforced concrete (RC) bridge subjected to a coupled corrosion-fatigue deterioration process, in which inspection outcomes for no damage detection, corrosion pit detection, and fatigue crack measurement are investigated. The second example focuses on a steel bridge dominated by fatigue crack deterioration. The effects of multiple inspection events under various inspection strategies, including inspection timing, inspection intervals, inspection order, inspection quality, and correlation among inspection outcomes, are discussed. The results show that detailed inspection data, such as measured corrosion pit depth or fatigue crack size, significantly change the updated probability of failure, whereas qualitative inspection events, such as crack detection without size measurement, provide less constraining information compared to precise quantitative measurements, although they still contribute useful information for reliability updating. The proposed framework offers practical guidance for inspection planning and life-cycle reliability management of aging infrastructures.
Key Words
corrosion; coupled corrosion-fatigue; deteriorating structures; fatigue crack; inspection; probability of failure; reliability; updating
Address
Baixue Ge, Yiyi Chen: College of Engineering, Sanda University, 201209, Shanghai, China
Jiaqi Bai: International School of Transportation, Shijiazhuang Institute of Railway Technology, 050000, Shijiazhuang, Hebei, China
Sunyong Kim: Department of Civil and Environmental Engineering, Wonkwang University, 460 Iksan dae-ro, Iksan, Republic of Korea
Abstract
Accurate prediction of fire-damaged RC structural behavior is essential for safety assessment; however, traditional numerical analysis becomes computationally intensive due to complex thermo-mechanical responses including non-mechanical strains at elevated temperatures. This study develops ML surrogate models (NN, XGB, LGBM) to predict RC member fire endurance time using a 4.37 million-point dataset generated from P-M diagrams obtained via high-fidelity numerical analyses. Tree-based ensembles outperformed NN in large-data regimes (test error <1%, geometric fitness >96%), providing superior interpretability through feature importance and monotonic constraints. Specifically, by defining the input conditions through a flexible 7-variable framework (B, H, BN, HN, M, P, R), this study enables the direct generation of P-M interaction diagrams under any arbitrary loading scenarios. Frame-level validation comparing predictive model and numerical analysis results on a 1-bay, 1-story RC frame confirmed applicability of proposed model with consistent column failure patterns, enabling very rapid predictions showing similar trends.
Key Words
extreme gradient boosting (XGB); fire-damaged RC; fire analysis; fire endurance time; neural network (NN)
Address
HyunKyoung Kim: Department of Civil and Environmental Engineering, Korean Advanced Institute for Science and Technology, Daejeon 34141, Republic of Korea
Ju-young Hwang: Department of Civil Engineering, Dong-Eui University, Busan 47340, Republic of Korea
Abstract
This study aimed to develop a methodology to predict the bending and shear P-I diagrams for any arbitrary RC columns based on a simple linear interpolation approach, which eliminates the need to conduct multiple blast analyses through rigorous nonlinear time-history approaches. The bending and shear P-I diagrams for the 15 RC column section are incorporated into the database, which covers the typical range of office buildings. The effectiveness of the proposed interpolation approach has been validated through comparisons between the interpolated P-I diagrams and those directly derived from trial-and-error-based blast analysis. The proposed methodology can be effectively used to assess whether to remove or retain the RC member that experienced the explosive loading, when the bending and shear P-I diagrams are not available, and to determine the required section dimensions and reinforcement ratios of RC columns during the explosion-proof design process.
Address
Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
Abstract
The construction industry is seeking automation-based solutions to overcome labor shortages, improve construction quality, and reduce waste in production. Although 3D concrete printing (3DCP) has shown potential for automated on-site fabrication, the conventional layer-deposition approach faces limitations in reinforcement integration, pumping requirements, size constraints, and surface quality. This study, as an alternative, proposes a slipform-based vertical printing method specifically designed for fabricating precast concrete elements in a single process. A prototype vertical printing device was developed at the lab scale, and the printability of cementitious materials, produced with various water-to-binder ratios and high-range water-reducing admixture dosages, was evaluated through the channel flow tests and printing experiments. Consequently, yield stress criteria were established: An initial yield stress of 85 Pa or lower is required to ensure gravity-driven flow of material into the nozzle, whereas an increase in yield stress to 240 Pa after a 20 min waiting time is necessary to satisfy adequate shape stability for vertical precast printing. The printing materials satisfying both criteria were successfully printed at 30 mm/min. In addition to the printability, surface wrinkles and air voids observed during printing were effectively handled by applying localized vibration (4 V, 60 s), which improved filling ability of the material around the embedded rebar substitute. These results demonstrate the feasibility of the proposed non-layered vertical printing process and provide quantitative rheological criteria for material design in the proposed vertical precast printing method.
Key Words
3D concrete printing; flowability; rheology; shape stability; slipform; vibration
Address
Gwang Min Park, Jae Hong Kim: Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea
Tae Yong Shin: Environment Research Laboratory, Research Institute of Industrial Science and Technology, Pohang, Republic of Korea
