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Experimental and reliability assessment of fire resistance of glue laminated timber beams

Resilient Cities and Structures 2025年第1期4卷 101-114页

作者： Navaratnam, Satheeskumar Munmulla, Thisari Rajeev, Pathmanthan Ponnampalam, Thusiyanthan Tesfamariam, Solomon Federation University Australia BallaratVIC3353 Australia School of Engineering RMIT University Melbourne3000 Australia Department of Civil & Construction Engineering School of Engineering Swinburne University of Technology Australia Ronnie & Koh Consultants Pte Ltd 573972 Singapore Department of Civil and Environmental Engineering University of Waterloo WaterlooONN2L 3G1 Canada

Glue-laminated timber (GLT) is an engineered wood product widely used in mass timber construction for its strong structural and fire-resistant properties. However, the fire performance of GLT varies significantly due to the natural and uncertain phenomena (moisture, exposure time, isotropic, homogenous properties, etc.) of fire and timber. This makes it difficult to predict the fire behaviour of the GLT structural elements. To ensure building safety, it is crucial to assess GLT's fire behaviour and post-fire structural integrity during the design stages. This study conducted the experimental tests of GLT beams (280 mm × 560 mm) without loading (1.4 m) and under a four-point bending load (5.4 m). Tests identified thermal behaviour and charring rates of GLT beam. Then, the residual stiffness of the GLT beam was calculated, and the charring rates of the beams were compared with Australian and European standards. Reliability analysis was conducted for beams for a fire exposure of 120 min, considering the charring rates observed through the analysis and simulating the fire insulations. Results show that the charring rate of GLT made with spruce pine timber varied between 0.43 and 0.81 mm/min, with a mean rate of 0.7 mm/min, aligning with both Australian and European standards. However, considering timber density and moisture content, the charring rates in Australian standards were conservative. The study also found that structural capacity significantly degrades under fire, with a 22 % reduction in flexural stiffness after 120 min of exposure. Additionally, GLT beams can safely function for 30 min under 75 % of their design moment capacity and for 60 min under 50 % capacity. © 2025 The Author(s)

关键词： Glues

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Failure Envelopes of Single-Plate Rigid Helical Anchors for Floating Offshore Wind Turbine

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China Ocean engineering 2023年第6期37卷 1000-1010页

作者： CHEN Hong-zhen WANG Le TIAN Ying-hui ZHANG Chun-hui SHEN Zhi-chao LIU Meng-meng State Key Laboratory of Hydraulic Engineering Intelligent Construction and Operation Tianjin UniversityTianjin 300072China State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian 116024China Department of Infrastructure Engineering Faculty of Engineering and Information Technology The University of MelbourneVictoria 3010Australia School of Civil Engineering Hebei University of Science and TechnologyShijiazhuang 050018China Hebei Technological Innovation Center of Disaster Prevention and Mitigation Engineering of Geotechnical and Structural System Shijiazhuang 050018China School of Marine Science and Engineering South China University of TechnologyGuangzhou 511442China Institute of Ocean Energy and Intelligent Construction Tianjin University of TechnologyTianjin 300384China

Helical anchor is a kind of novel foundation for floating offshore wind turbines,which should be subjected to combined tensile loading caused by wind,wave and ***,the research about the capacity of helical anchor was mainly examined under uniaxial loading and scarcely explored under combined *** this study,three-dimensional finite element limit analysis is adopted to assess the bearing capacities of single-plate rigid helical anchors with different ratios of helix to shaft diameter,D_(H)/D_(S) and embedment ratios L/D_(S).Result shows that the vertical,horizontal and moment bearing capacities increase with increasing D_(H)/D_(S) and L/D_(S).The normalized V-H failure envelopes expands with increasing L/D_(S),while the normalized V-M failure envelopes tend to contract with the increase of D_(H)/D_(S).With increasing D_(H)/D_(S) or decreasing L/D_(S),the normalized H-M failure envelopes expand when the horizontal and moment loading act in the same direction and contract when they act in the opposite *** effect of D_(H)/D_(S) and L/D_(S) on the shape of H-M failure envelope become insignificant when L/D_(S)≥4.A series of failure mechanisms under different loading conditions were observed and can be used to explain the ***,a series of approximate expressions were proposed to fit the uniaxial bearing capacities and the failure envelopes.

关键词： helical anchors bearing capacity failure envelope clay

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Research Progress on the Influence of Varying Fiber Contents on Mechanical Properties of Recycled Concrete

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Structural Durability & Health Monitoring 2023年第3期17卷 239-255页

作者： Zhenqing Shi Guomin Sun Jianyong Pang College of Civil and Architecture Engineering Chuzhou UniversityChuzhouChina Engineering Research Center of Underground Mine Construction Ministry of Education(Anhui University of Science and Technology)HuainanChina

Applying recycled concrete for engineered projects not only protects the ecological environment but also improves the utilization rate of waste concrete to satisfy sustainable development ***,the mechanical properties of recycled concrete are not as good as those of ordinary *** enhance the former’s performance and increase its popularity and application in engineeringﬁelds,notable advances have been made by using steel,synthetic,plant,and mineralﬁber *** materials are added to recycled concrete to improve its mechanical *** have shown that(1)steelﬁbers have a distinct reinforcing effect and improve the strength,toughness,and elastic modulus of recycled concrete;(2)the addition of syntheticﬁbers can improve the tension,crack resistance,and durability of concrete,but the size effect needs to be further explored and elaborated;(3)plantﬁber concrete is lightweight and environmentally friendly and provides high toughness and good thermal insulation,but theﬁbers corrode in alkaline environments;in addition,plantﬁbers have high water absorption capacity,which leads to wet expansion and dry shrinkage phenomena,which need to be further studied;and(4)the cost of basaltﬁber,a mineralﬁber,is relatively low,and a suitable basalt content can improve the mechanical properties of recycled concrete to a certain extent.

关键词： Recycled concrete fibers mechanical properties overview

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Experimental investigation on the effect of hoop spacing and crosstie configuration on the cyclic performance of reinforced concrete beams

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Advances in Structural engineering 2024年第7期27卷 1115-1129页

作者： Lee, Tai-Kuang Chen, Cheng-Cheng Architecture and Building Research Institute Ministry of the Interior Sindian New Taipei Taiwan Department of Civil and Construction Engineering National Taiwan University of Science and Technology Taipei Taiwan

According to ACI 318-19(SI), in the plastic hinge zone of RC beams, the longitudinal reinforcement at each corner and every other longitudinal reinforcement must be enclosed by the corner of the closed hoop or the hooks of crossties. However, in RC construction practice, the longitudinal reinforcement of RC beams is densely arranged, making construction difficult. In this study, four large RC beam specimens were designed and fabricated to conduct experiments to verify the effect of hoop spacing and crosstie configuration on the cyclic performance of reinforced concrete beams. It is found that: (1) The crosstie configuration with seismic hook engaging the longitudinal reinforcement at the bottom is recommended and that during construction, within the range of twice the beam depth from the RC column outer face, the bottom and side formwork should be completed after the crossties are assembled, which should solve the problem of difficult construction. (2) The transverse reinforcement spacing between 4 and 6 times the smallest longitudinal reinforcement diameter of RC beams may have no significant effect on the cyclic performance of RC beams. (3) The requirement that in the plastic hinge zone of RC beams, every corner and alternate longitudinal bar on the perimeter must have lateral support provided by the corner of a tie or crosstie in ACI 318-19(SI) may not have a major impact on the cyclic performance of the RC beam. (4) The ultimate drift angle of each specimen in the negative direction was between 4.3% rad and 4.5% rad;thus, all the specimens satisfied the ACI requirement. However, the cyclic performance (plasticity rotation angle) of all specimens basically did not meet the requirement of 3.0% rad for earthquake-resistant structures. © The Author(s) 2024.

关键词： Reinforced concrete

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Strength And Stability Of Concrete Samples Produced With Electric Arc Furnace Slag 9

Strength And Stability Of Concrete Samples Produced With Ele...

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9th International Conference on Applying New technology in Green Buildings, ATiGB 2024

作者： Vo, Duy-Hai Vo Duyen Anh, Huynh Hwang, Chao-Lung Lu, Chien-Ming Truong, Thi Thu Ha Tran, Thanh-Quang The University of Danang University of Technology and Education Department of Civil Engineering Danang Viet Nam The University of Danang - University of Technology and Education Civil Engineering Department Danang Viet Nam National Taiwan University of Science and Technology Department of Civil and Construction Engineering Taipei Taiwan

ISBN: (纸本)9798331505042

This research investigated the hardened properties of concrete specimens produced with electric arc furnace (EAF) slag as aggregate. The concrete mix proportions were calculated following the Densified Mixture Design Algorithm (DMDA) method with various water-to-binder (w/b) ratios at 0.3,0.4 and 0.5. To examine the hardened characteristics, the strength development including compressive strength, splitting tensile strength, and ultrasonic pulse velocity (UPV) tests were conducted, while the expansion under autoclave conditions was observed to the stability of concrete samples. The concrete specimens exhibited a compressive strength range of 19.1-57.9 MPa and splitting tensile strength of 1.76-3.82 MPa at 28-day, significantly reducing with increasing w/b ratio. The UPV results were higher than 3660m/s, while the concrete samples were stable in shape under the autoclave condition test. © 2024 IEEE.

关键词： Electric arc furnaces

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Influence of freeze-thaw damage gradient on stress-strain relationship of stressed concrete

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Frontiers of Structural and civil engineering 2023年第9期17卷 1326-1340页

作者： Xiguang LIU Yongjie LEI Yihao SUN Jiali ZHOU Ditao NIU College of Civil Engineering Xi’an University of Architecture&TechnologyXi’an 710055China Institute for Interdisciplinary Innovation Research Xi’an 710055China Shaanxi Construction Engineering Group Co. Ltd.Xi’an 710055China XAUAT Engineering Technology Co.Ltd.Xi’an 710055China

Freeze-thaw damage gradients lead to non-uniform degradation of concrete mechanical properties at different depths.A study was conducted on the stress-strain relationship of stressed concrete with focus on the freeze-thaw damage *** effects of relative freeze-thaw depths,number of freeze-thaw cycles(FTCs)and stress ratios on the stress-strain curves of concrete were *** test results demonstrated that freeze-thaw damage was more severe in the surface layers of concrete than in the deeper *** relative peak stress and strain of concrete degraded bilinearly with increasing *** stress-strain relationship of stressed concrete under FTC was established,and it was found to agree with the experimental results.

关键词： freeze-thaw damage stress ratios stress-strain relationship damage variable

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Studying the usability of recycled aggregate to produce new concrete

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Journal of engineering and Applied Science 2024年第1期71卷 129页

作者： Qasim, Ola Adel Hilal, Nahla Al Biajawi, Mohammad I. Sor, Nadhim Hamah Tawfik, Taher A. College of Engineering University of Information Technology and Communications Baghdad Iraq Scientific Affairs Department University of Fallujah Fallujah Baghdad Iraq Faculty of Civil Engineering Technology Universiti Malaysia Pahang AL-Sultan Abdullah Persiaran Tun Khalil Yaakob Gambang Pahang26300 Malaysia Civil Engineering Department University of Garmian Kurdistan Region Kalar46021 Iraq Department of Civil Engineering Harran University Sanlıurfa63510 Turkey Department of Construction and Building Engineering High Institute of Engineering October 6 City Egypt Institute of Construction and Architecture Slovak Academy of Sciences Dúbravskácesta 9 Bratislava845 03 Slovakia

One of the most significant environmental issues worldwide is garbage, particularly waste from construction materials, which is generated in substantial numbers. However, in the building industry, the significant extraction of natural resources such as cement, natural sand, and natural gravel poses a critical environmental challenge, depleting these resources at an alarming rate. There are some solutions that developed countries are resorting to, namely the division of construction waste into groups, where it is reused under the name of recycling construction waste to produce new, environmentally friendly building materials. The aim of this research includes a laboratory process study as it includes the use of the following ratios: 0, 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100%, under the process of replacing coarse plain aggregates including coarse recycled aggregates and studying the most important mechanical properties of concrete. This research was carried out using fresh concrete properties such as workability tests and hardened concrete properties such as compressive strength, splitting, and flexural tensile strength examined at the durations of 7, 14, and 28 days. The research includes the investigation of the three main properties of concrete. After conducting the tests, the results have shown that the main property of recycled concrete is lower strength than that of conventional concrete, but it can be said that it is within the limits that can be used for construction. The results also showed that compared to normal aggregates, development in the recycled aggregate percentage rates reduces the operational workability of concrete. The research proved that the maximum decrease in compressive, flexural, and tensile strength, density and the slump were 19.4, 18.3, 19.6, 19.5, and 25.0% respectively compared to the control concrete samples. © The Author(s) 2024.

关键词： Tensile strength

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Deciphering decision-making mechanisms for the susceptibility of different slope geohazards:A case study on a SMOTE-RF-SHAP hybrid model

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Journal of Rock Mechanics and Geotechnical engineering 2025年第3期17卷 1612-1630页

作者： Junhao Huang Haijia Wen Jiwei Hu Bo Liu Xinzhi Zhou Mingyong Liao School of Civil Engineering Key Laboratory of New Technology for Construction of Cities in Mountain Area of the Ministry of EducationChongqing UniversityChongqing400045China State Key Laboratory of Hydroscience and Engineering Department of Hydraulic EngineeringTsinghua UniversityBeijingChina

Different slope geohazards have different causal *** study aims to propose a method to investigate the decision-making mechanisms for the susceptibility of different slope *** study includes a geospatial dataset consisting of 1203 historical slope geohazard units,including slope creeps,shallow slides,rockfalls and debris flows,and 584 non-geohazard units,and 22 initial condition *** a 7:3 ratio,the data were randomly divided into a test set and a training set,and an ensemble SMOTE-RF-SHAP model was *** performance and generalization ability of the model were evaluated by confusion matrix and the receiver operating characteristic(ROC)for the four types of *** decision-making mechanism of different geohazards was then identified and investigated using the Shapley additive explanations(SHAP)*** results show that the hybrid optimization improves the overall accuracy of the model from 0.486 to 0.831,with significant improvements in the prediction accuracy for all four types of slope geohazards,as well as reductions in misclassification and omission ***,this study reveals that the main influencing factors and spatiotemporal distribution of different slope geohazards exhibit high similarity,while the impacts of individual factors and different factor values on different slope geohazards demonstrate significant *** example,prolonged continuous rainfall can erode rock masses and lead to slope creep,increased rainfall may trigger shallow mountain landslides,and sudden surface runoff can even cause debris *** findings have important practical implications for slope geohazards risk management.

关键词： Random forest Machine learning SMOTE Slope geohazards

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Bridge Crack Segmentation Method Based on Parallel Attention Mechanism and Multi-Scale Features Fusion

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Computers, Materials & Continua 2023年第3期74卷 6485-6503页

作者： Jianwei Yuan Xinli Song Huaijian Pu Zhixiong Zheng Ziyang Niu College of Civil Engineering Changsha University of Science and TechnologyChangsha410114China College of Computer&Communication Engineering Changsha University of Science and TechnologyChangsha410114China China Construction Fifth Engineering Bureau Co. Ltd.Changsha410004China

Regular inspection of bridge cracks is crucial to bridge maintenance and *** traditional manual crack detection methods are timeconsuming,dangerous and *** the same time,for the existing mainstream vision-based automatic crack detection algorithms,it is challenging to detect fine cracks and balance the detection accuracy and ***,this paper proposes a new bridge crack segmentationmethod based on parallel attention mechanism and multi-scale features fusion on top of the DeeplabV3+network ***,the improved lightweight MobileNetv2 network and dilated separable convolution are integrated into the original DeeplabV3+network to improve the original backbone network Xception and atrous spatial pyramid pooling(ASPP)module,respectively,dramatically reducing the number of parameters in the network and accelerates the training and prediction speed of the ***,we introduce the parallel attention mechanism into the encoding and decoding *** attention to the crack regions can be enhanced from the aspects of both channel and spatial parts and significantly suppress the interference of various ***,we further improve the detection performance of the model for fine cracks by introducing a multi-scale features fusion *** research results are validated on the self-made *** experiments show that our method is more accurate than other *** intersection of union(IoU)and F1-score(F1)are increased to 77.96%and 87.57%,*** addition,the number of parameters is only 4.10M,which is much smaller than the original network;also,the frames per second(FPS)is increased to 15 frames/*** results prove that the proposed method fits well the requirements of rapid and accurate detection of bridge cracks and is superior to other methods.

关键词： Crack detection DeeplabV3+ parallel attention mechanism feature fusion

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Finite Element Simulation of Temperature Variations in Concrete Bridge Girders

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Fluid Dynamics & Materials Processing 2023年第6期19卷 1551-1572页

作者： Hongzhi Liu Shasha Wu Yongjun Zhang Tongxu Hu Shandong Urban Construction Vocational College Jinan250103China School of Civil Engineering Qingdao University of TechnologyQingdao266033China

The internal temperature of cast-in-place concrete bridges undergoes strong variations during the construction as a result of environmental *** order to determine precisely such variations,the present study relies on the finite element method,used to model the bridge box girder section and simulate the internal temperature distribution during *** numerical results display good agreement with measured temperature *** is shown that when the external temperature is higher,and the internal and external temperature difference is relatively small,the deviation of the fitting line from existing specifications(Chinese specification,American specification,New Zealand specification)is relatively large and vice versa.

关键词： Concrete temperature gradient FE model simulation AASHTO and Chinese temperature norm temperature formula exponential monitoring

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