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Effect of CFRP confinement on bond-slip behavior of steel rebar in low-strength concrete: Experimentation, prediction and parametric study

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Construction and Building Materials 2025年 477卷

作者： Jafari, Abouzar Shahmansouri, Amir Ali Abdulridha, Hayder A. Issa, Baqer I. Bengar, Habib Akbarzadeh State Key Laboratory of Disaster Reduction in Civil Engineering Tongji University Shanghai200092 China Department of Civil and Environmental Engineering Washington State University PullmanWA99164 United States Department of Civil Engineering Faculty of Engineering and Technology University of Mazandaran Babolsar Iran

The bond strength between steel rebar and low-strength concrete (LSC) is critical for the structural integrity of reinforced concrete structures, particularly in seismic regions where weak bonding can compromise load transfer and overall stability. To address this issue, an experimental study was conducted on 216 unique pullout specimen designs, incorporating concrete compressive strengths of 5, 10, 15, 20, 25, and 30 MPa, rebar diameters of 12, 16, and 20 mm, concrete cover sizes of 25, 35, 45, and 55 mm, and CFRP confinement conditions (unconfined, and confined with one or two CFRP layers). Using the LASSO optimization algorithm, a closed-form solution was developed to predict bond strength, integrating key influencing parameters. The results demonstrated that CFRP confinement significantly enhanced bond strength, with a maximum improvement of 184 % for specimens with two CFRP layers. The increase in concrete cover led to a rise in bond strength, with a maximum recorded bond strength of 24.72 MPa in CFRP-confined specimens. Conversely, increasing rebar diameter from 12 mm to 20 mm resulted in a bond strength reduction of up to 27.7 %, highlighting the inverse relationship between rebar size and bond performance. The parametric sensitivity analysis revealed that compressive strength had the most substantial effect on bond strength (81.8 %), followed by concrete cover (23.5 %) and CFRP confinement (13.6 %), while rebar diameter had a negative impact (-18.9 %). The developed predictive model provides a practical and reliable tool for estimating bond performance, demonstrating that CFRP confinement can enhance the bond strength of LSC to levels comparable with higher-strength unconfined concrete. These findings offer valuable insights into the design, assessment, and strengthening of reinforced concrete structures, contributing to the development of efficient retrofit strategies for improving structural resilience. © 2025 Elsevier Ltd

关键词： Sensitivity analysis

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Data set from quasi-static cyclic tests of scoured 2 × 3 pile-group foundations for bridge structures

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Earthquake Spectra 2025年

作者： Huang, Zeanran Ye, Aijun Wang, Xiaowei Department of Bridge Engineering Tongji University Shanghai China State Key Laboratory of Disaster Reduction in Civil Engineering Tongji University Shanghai China

Scour has been reported a critical factor in aggravating the seismic vulnerability of pile-group foundations for bridges. A handful of theoretical and experimental studies have been reported focusing on nonlinear behavior and damage mechanisms of scoured pile-group foundations. However, there is a lack of well-documented, publicly accessible datasets that can facilitate numerical model validation and associated in-depth studies. To this end, this article describes the development of a dataset from a pair of quasi-static cyclic tests on two specimens of scoured 2×3 reinforced concrete (RC) pile-group foundations characterized by different aboveground heights of piles embedded into homogeneous sandy deposits. This dataset is useful for the development and validation of analytical and numerical models, especially for capturing the highly nonlinear behavior of RC piles and soils. This work details specimens and sandy deposits, together with instrumentation and data processing. The organization of the dataset and indicative results are illustrated for expediency of implementation. The dataset can be accessed in Zenodo via https://***/10.5281/zenodo.13762253. © The Author(s) 2025.

关键词： Pile foundations

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Experimental investigation on the anti-detonation performance of composite structure containing foam geopolymer backfill material

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Defence Technology(防务技术) 2025年第1期43卷 304-318页

作者： Hang Zhou Hujun Li Zhen Wang Dongming Yan Wenxin Wang Guokai Zhang Zirui Cheng Song Sun Mingyang Wang School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing 210094China College of Civil Engineering and Architecture Zhejiang UniversityHangzhou 310058China Institute for Composites Science Innovation School of Materials Science and EngineeringZhejiang UniversityHangzhou310027China School of Safety Science and Engineering(School of Emergency Management) Nanjing University of Science and TechnologyNanjing 210094China State Key Laboratory of Disaster Prevention and Mitigation of Explosion and Impact Army Engineering University of PLANanjing 210014China

The compression and energy absorption properties of foam geopolymers increase stress wave attenuation under explosion impacts,reducing the vibration effect on the *** tests were conducted using several composite structure models,including a concrete lining structure(CLS)without foam geopolymer and six foam geopolymer composite structures(FGCS)with different backfill parameters,to study the dynamic response and wave dissipation mechanisms of FGCS under explosive ***,strain,and vibration responses at different locations were synchronously *** damage modes and dynamic responses of different models were compared,and how wave elimination and energy absorption efficiencies were affected by foam geopolymer backfill parameters was *** results showed that the foam geopolymer absorbed and dissipated the impact energy through continuous compressive deformation under high strain rates and dynamic loading,reducing the strain in the liner structure by 52%and increasing the pressure attenuation rate by 28%.Additionally,the foam geopolymer backfill reduced structural vibration and liner deformation,with the FGCS structure showing 35%less displacement and 70%less acceleration compared to the *** FGCS model with thicker,less dense foam geopolymer backfill,having more pores and higher porosity,demonstrated better compression and energy absorption under dynamic impact,increasing stress wave attenuation *** analyzing the stress wave propagation and the compression characteristics of the porous medium,it was concluded that the stress transfer ratio of FGCS-ρ-579 was 77%lower than that of CLS,and the transmitted wave energy was 90%*** results of this study provide a scientific basis for optimizing underground composite structure interlayer parameters.

关键词： Explosion load Composite structure Geopolymer foam Energy absorption

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A Full Three-Dimensional Model for Positive Long Air Gap Discharge Simulation

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IEEE Transactions on Dielectrics and Electrical Insulation 2025年

作者： Peng, Changzhi Dong, Xuzhu Sabariego, Ruth V. Zheng, Yu Deng, Yongqing Xie, Pengkang Wuhan University State Key Laboratory of Power Grid Environmental Protection School of Electrical Engineering and Automation Wuhan430072 China Genk3600 Belgium State Grid Hunan Electric Company Disaster Prevention and Reduction Center State Key Laboratory of Disaster Prevention & Reduction for Power Grid Transmission and Distribution Equipment Changsha410129 China

Long air gap discharge is one of the fundamental issues in high voltage engineering. The simulation of long air gap discharge can provide essential data for designing ultra-high voltage transmission and serves as the foundation for lightning protection. This study introduces an enhanced numerical model for simulating long air gap discharge, accounting for time-varying leader charge density and streamer region with direct experimental extraction. The comprehensive three-dimensional (3-D) model integrates novel parameters, including the streamer region angle, direction, and stochastic leader development, surpassing mere empirical descriptions. Additionally, the updated methodology for determining the streamer region makes the model adaptable to symmetric and asymmetric geometric engineering structures. Simplifying assumptions render the model computationally lightweight in full 3-D demand. The model simulated the current, velocity, and leader path of long air gap discharge under various voltages, then compared with experimental results. By incorporating new physical quantities, the model exhibited improved accuracy and precisely predicted current and velocity. Furthermore, the model calculated the breakdown voltage of typical engineering gaps, yielding results closely aligned with experimental data, with an accuracy exceeding 90%. © 1994-2012 IEEE.

关键词： Digital elevation model

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Dynamic response analysis of cross-fault tunnel considering source-to-structure seismic input and near-fault effect

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Tunnelling and Underground Space Technology 2025年 162卷

作者： Li, Liqun Chen, Zhiyi Lu, Ping Huang, Yu Department of Geotechnical Engineering Tongji University Shanghai200092 China State Key Laboratory of Disaster Reduction in Civil Engineering Tongji University Shanghai200092 China College of Surveying and Geo-Informatics Tongji University Shanghai200092 China

Tunnels crossing active faults are vulnerable to severe damage under near-fault earthquakes due to the combined effects of co-seismic dislocation and complex ground motion wavefields. To capture the spatiotemporal features of near-fault ground motion and their effects on tunnel structures, this study proposes a physics-based source-to-structure simulation framework. A frequency-wavenumber (F-K) integration method is used to reconstruct broadband seismic wavefields (0.1–10 Hz) based on the finite-fault source model of the 2022 Mw 6.6 Menyuan earthquake. These waveforms are discretized and applied to a nonlinear finite element model of the Daliang Tunnel, which experienced severe damage during the event. The simulated displacement time histories match well with classical finite fault solutions, and the spatial distribution of co-seismic displacements shows good agreement with InSAR observations, especially in amplitude and trend. Within 50 km of the epicenter, the simulated peak ground accelerations (PGAs) agree closely with strong motion records, and the Fourier spectra below 1 Hz are consistent with observed data. Directional velocity pulses and fling-step effects are captured by analyzing PGV/PGA ratios in strike and normal directions, and further confirmed by wavelet transform analysis of near-fault station responses. Structural analysis reveals that fault-crossing segments experience quasi-static shearing dominated by dislocation, while segments farther from the fault are mainly affected by directional velocity pulses. The dynamic stress induced by these pulses accounts for up to 57.1 % of the quasi-static stress. The results highlight the critical importance of low-frequency ground motion components and directional effects in evaluating the seismic response and damage mechanisms of cross-fault tunnels. © 2025 Elsevier Ltd

关键词： Seismic response

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Reliability-informed design table for optimizing tuned mass-damper-inerter systems to improve structural seismic performance

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Probabilistic engineering Mechanics 2025年 80卷

作者： Sun, Peifang Peng, Yongbo State Key Laboratory of Disaster Reduction in Civil Engineering Tongji University 1239 Siping Road Shanghai200092 China College of Civil Engineering Tongji University 1239 Siping Road Shanghai200092 China Shanghai Institute of Disaster Prevention and Relief Tongji University 1239 Siping Road Shanghai200092 China

As a promising device for seismic mitigation of structures, the tuned mass-damper-inerter (TMDI) has attracted considerable attention in recent years. However, existing design methods of TMDI such as the fixed-point theory-based formulas and stochastic optimization methods, often suffer from insufficient control gains or excessive computational demands. To address these issues, this study develops a reliability-informed multi-parameter design table (MPDT) for optimizing TMDI in a fast, accurate, and non-iterative manner. The MPDT is developed through repeated reliability-based design optimization (RBDO), integrating the probability density evolution method (PDEM) with genetic algorithms. It ensures robust TMDI performance under stochastic ground motions and facilitates efficient selection of key parameters, including mass ratio, inertance-to-mass ratio, damping ratio, and frequency ratio, across varying structural periods and seismic conditions. Additionally, it provides guidance for rational selection of TMDI topology, such as TMD, TID, or full TMDI. The MPDT is validated via case studies on a base-isolated structure and a five-story shear frame structure with various TMDI configurations. The results demonstrate that the MPDT-based TMDI designs achieve comparable control performance to full RBDO designs while significantly reducing computational effort. key influences such as structural modal frequency, inerter connection, and TMDI placement are examined, revealing the robustness of the proposed method even if the design assumptions are partially fulfilled. Furthermore, design trends, such as the relationship between inertance and structural period are uncovered. Overall, the MPDT provides a reliable, efficient, and scalable framework for performance-based seismic design of TMDI systems, supporting practical engineering applications. © 2025 Elsevier Ltd

关键词： Seismic design

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A scaling-based generalizable integrated ML-mechanics model for lateral response of self-centering walls

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engineering Structures 2025年 336卷

作者： Shahmansouri, Amir Ali Jafari, Abouzar Akbarzadeh Bengar, Habib Zhou, Ying Taciroglu, Ertugrul Department of Civil and Environmental Engineering Washington State University PullmanWA99164 United States State Key Laboratory of Disaster Reduction in Civil Engineering Tongji University Shanghai200092 China Department of Civil Engineering Faculty of Engineering and Technology University of Mazandaran Babolsar Babolsar Iran Department of Civil and Environmental Engineering University of California Los AngelesCA90095 United States

This study proposes an integrated solution that combines a multilayer perceptron (MLP) model with a mechanics-based approach to predict the lateral response of self-centering walls. The solution is then coupled with a scaling concept to address the locality limitations inherent to machine learning (ML) models. The MLP model was trained on a comprehensive synthetic dataset and validated using test data from laboratory experiments to estimate post-tensioning (PT) tendon stresses. The MLP predictions are then used in the mechanics-based solution to calculate concrete strain distribution, compressive length, and lateral capacity. By applying the scaling concept, a wall with configurations beyond the collected dataset is mapped to the available data. The proposed solution predicts the scaled response, which is then rescaled to derive the original response, enhancing the model's generalizability, as validated through blind testing. The developed MLP model demonstrates excellent prediction accuracy for PT tendon stress across varying drift levels, outperforming existing solutions. Furthermore, integrating the MLP model into the mechanics-based solution enables accurate predictions of wall compressive length and lateral capacity. The overall model exhibited excellent performance in validation with physical test data, and additional uncertainty quantification analyses using Monte Carlo simulation and Bootstrap sampling confirmed the robustness and stability of the proposed solution. © 2025 Elsevier Ltd

关键词： Blind validation Machine learning Post-tensioning Scaling Self-centering walls Uncertainty quantification

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Non-synergistic effect of marginal distribution and dependence structure of extremes triggering the future risk of compound dry-hot events in Yellow River, China

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Stochastic Environmental Research and Risk Assessment 2025年 1-14页

作者： Xu, Pengcheng Zhu, Tong Wang, Dong Wang, Yuankun Singh, Vijay P. Lu, Miao Fu, Xiaolei College of Hydraulic Science and Engineering Yangzhou University Yangzhou China Key Laboratory of Surficial Geochemistry Ministry of Education Department of Hydrosciences School of Earth Sciences and Engineering State Key Laboratory of Pollution Control and Resource Reuse Nanjing University Nanjing China School of Water Resources and Hydropower Engineering North China Electric Power University Beijing China Department of Biological and Agricultural Engineering Zachry Department of Civil and Environmental Engineering Texas A & M University College StationTX77843 United States National Water and Energy Center UAE University Al Ain United Arab Emirates National Key Laboratory of Water Disaster Prevention Nanjing Hydraulic Research Institute Nanjing China

Compound dry-hot extremes (CDH) cause devastating socio-economic impacts on society and ecosystems. Univariate risk assessment might not catch the potential impacts of CDH. Considering the negative correlation of average summer temperature and precipitation, this study developed two kinds of copula-based likelihood multiplication index, such as the whole likelihood multiplication index () and the second likelihood multiplication index (), to enumerate the attribution and projection of compound dry-hot events in Yellow River Basin (YRB) of China. Observed datasets show that the areas influenced by the CDH within YRB are increasing, and the most-extreme CDH event was observed several decades ago. Comparison of natural-only and all forcing-based CMIP6 data show that anthropogenic factors are causing the increasing trend of affected areas. Results of analysis showed that changes in the risk of CDH events could depend on not only the temporal variation of the marginal distribution but also the change in the dependence structure between variables. By comparing the difference between and, all grid-based areas in YRB were classified into five cases of combined effects which would help identify the synergistic and non-synergistic contribution of variations in marginal distribution and dependence structure of variables on risk of CDH events. Under Shared Socioeconomic Pathways scenarios (SSPs), the likelihood of concurrent dry-hot extremes is expected to increase in more than half of YRB while small parts of YRB would also experience decreasing likelihood of CDH events with 38.2% of grids under SSP1-2.6, 37.4% under SSP3-7.0 and 36.9% under SSP5-8.5 belonging to case 3 and 6. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2025.

关键词： Risk assessment

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DICTIONARY-LEARNING-BASED DATA PRUNING FOR SYSTEM IDENTIFICATION

arXiv

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arXiv 2025年

作者： Wang, Tingna Zhang, Sikai Sun, Limin Department of Bridge Engineering Tongji University Shanghai China Baosight Software China Shanghai Qi Zhi Institute Shanghai China State Key Laboratory of Disaster Reduction in Civil Engineering Tongji University Shanghai China

System identification is normally involved in augmenting time series data by time shifting and nonlinearisation (via polynomial basis), which introduce redundancy both feature-wise and sample-wise. Many research works focus on reducing redundancy feature-wise, while less attention is paid to sample-wise redundancy. This paper proposes a novel data pruning method, called (mini-batch) FastCan, to reduce sample-wise redundancy based on dictionary learning. Time series data is represented by some representative samples, called atoms, via dictionary learning. The useful samples are selected based on their correlation with the atoms. The method is tested on one simulated dataset and two benchmark datasets. The R-squared between the coefficients of models trained on the full and the coefficients of models trained on pruned datasets is adopted to evaluate the performance of data pruning methods. It is found that the proposed method significantly outperforms the random pruning method. © 2025, CC BY-NC-ND.

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Integrated assessment method for carbon emission and cost throughout the life cycle of office buildings: A comparative study of steel structure and timber structure

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Structures 2025年 77卷

作者： Bian, Ji Yi, Duhang Yao, Enming Yu, Hanying Li, Zheng Department of Structural Engineering Tongji University Shanghai200092 China China Overseas Grand Oceans Lowcarbon Technology Co. Ltd Shenzhen518030 China State Key Laboratory of Disaster Reduction in Civil Engineering Tongji University Shanghai200092 China

Quantifying carbon emission and cost throughout a building's life cycle is essential for enhancing energy efficiency and reducing emissions in the construction sector. However, life cycle cost (LCC) analysis often receives less attention than life cycle assessment (LCA), primarily due to insufficient information on actual cost throughout the life cycle. This study addresses this limitation by developing a cost calculation model that follows carbon trading and carbon tax systems, to propose an integrated LCA-LCC assessment method for office buildings. A comprehensive analysis was performed to compare the carbon emission and cost associated with steel structure and timber structure over their life cycles, providing a detailed quantification of their respective emission and cost characteristics. The results reveal that, throughout the life cycle, a timber structure emits 13 % less carbon than a steel structure, and a reduction that increases to 20 % when accounting for the embodied carbon of wood;The higher traditional costs of timber structures, compared to steel, are primarily driven by the stringent processing requirements for wood as a building material. Nevertheless, the carbon-related cost of the timber structure is still 20 % lower over the life cycle due to the characteristics of wood. This study offers a methodological insight for integrated assessment of carbon emission and cost, offering substantiated suggestions for advancing emission reduction strategies within the building industry. © 2025 Institution of Structural Engineers

关键词： Cost benefit analysis

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