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2020 fib Symposium: Concrete structures for Resilient Society

作者： Wang, Xian Qiu, Song Chen, Tao Gu, Xianglin Zhang, Yueran China Communication Construction Corporation Third Harbor Engineering Corporation Limited Shanghai200032 China Key Laboratory of Performance Evolution and Control for Engineering Structures Ministry of Education Tongji University Shanghai200092 China

ISBN: (纸本)9782940643042

Grouted connections (GCs) are widely used to connect superstructures and driven piles in offshore wind turbine structures. In this paper, the vibration mode analyses of an example 5 MW offshore monopile wind turbine structure were carried out. It was found that about 8% error would be induced to the fundamental frequency when neglecting the local stiffness of GCs. These identified the vital role of GCs to the offshore wind structures. Moreover, the earlier fatigue bending test of downscaled GCs in air condition shows that local degradation would not influence the entirety bending capacity of the specimen. However, the GCs resist fatigue loading in marine splash zones and even submerged environments. Thus, this paper designed six GC segment specimens, which were tested under fatigue loading in both the air and water ingression conditions. The results of the air condition show that wide racks and grout material exfoliation were found in specimens with higher loading ranges. The specimens in the water ingression condition showed that the water had entered into the micro cracks of the grout material, which severely degraded the fatigue behavior of the GC specimens. Even in lower loading ranges, specimens W-1 and W-2 only endured 0.264 million and 64 thousand load cycles before the displacement of the top clamp reached -10 mm. Compared with two specimens tested in the air, with a total displacement of less than -0.7 mm after two million load cycles, the severe deteriorating effect of water ingression on the fatigue behavior of GCs was apparent. © Proceedings of the fib Symposium 2020: Concrete structures for Resilient Society. All rights reserved.

关键词： Offshore wind turbines

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Compression-bending behavior of grouted connections considering axial load ratio

Compression-bending behavior of grouted connections consider...

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2020 fib Symposium: Concrete structures for Resilient Society

作者： Fang, Qi Chen, Tao Zhang, Chihai Key Laboratory of Performance Evolution and Control for Engineering Structures of Ministry of Education Tongji University Shanghai200092 China Department of Structural Engineering Tongji University Shanghai200092 China University Corporation for Polar Research Beijing100875 China

ISBN: (纸本)9782940643042

The connection between the support structure and the pile in wind turbines is achieved by the grouted connections. In recent years, the wind turbine has developed rapidly, and the power of wind turbines is getting larger and larger, which puts forward higher requirements on the force performance of the grouted connections. Under the action of complex loads, the grouted connection is subjected to the combined action of axial force and bending moment, but the existing researches and specifications only analyze the performance under the action of individual bending moments or axial loading. Therefore, it is necessary to study and analyze the mechanical properties of the grouted connection under the combined action of axial force and bending moment. In this paper, under the condition of compression-bending force and the axial load ratio as the variable, the finite element analysis method is used to analyze the following cases: the stress state of the grouted connections was analyzed. And the contact pressure of the steel pipe and the grout are compared. Through analysis, a deeper understanding of the axial-flexural behaviour of the grouted connections with shear keys can better guide the design work. © Proceedings of the fib Symposium 2020: Concrete structures for Resilient Society. All rights reserved.

关键词： Finite element method

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Experiment and Analysis of the Flexural Properties of Carbon Fiber Textile Reinforced Concrete (Ctrc) Sheets with Consideration to the Effects of Short Ar-Glass Fibers

SSRN

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SSRN 2021年

作者： Zhang, Qin Yang, Qiaochu Gu, Xianglin Dai, Huanhuan Jiang, Yong College of Civil and Transportation Engineering Hohai University Nanjing210024 China Key Laboratory of Performance Evolution and Control for Engineering Structures of Ministry of Education Tongji University 1239 Siping Rd Shanghai200092 China

The effects of fiber content levels and fiber lengths on the mechanical properties of fine-grained concrete reinforced with short AR-glass fibers were investigated in this study. In addition, four-point bending tests were carried out in order to analyze the flexural behaviors of carbon textile reinforced concrete (CTRC) sheets. In this study’s experiments, 19 serial specimens were tested, with consideration given to the fiber lengths, mass content levels of the fibers, and the reinforcing ratio of carbon textiles. The results indicated that the mechanical properties of the fine concrete with short fibers increased with the increases in the lengths and content levels of the fibers. Also, it was determined that the comprehensive mechanical properties were the best when the glass fiber mass content ranged between 5% and 8%. Furthermore, this study’s bending tests of the CTRC revealed that the bending strength and deformability were significantly improved with increases in the fiber content and the reinforcing ratio of carbon textiles. By utilizing short fibers, the cracking load of the CTRC sheets had been improved by 80.35%. The maximum improvement of the ultimate bending load was more than 6 times compared with the specimens without carbon fiber textiles and short fibers. Finally, a trilinear model was proposed to predict the flexural behaviors of the CTRC specimens reinforced with AR-glass fibers . It was determined that the predicted data agreed well with the experimental data. © 2021, The Authors. All rights reserved.

关键词： Bending strength

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Flexural behavior and stiffness calculation of steel-prestressed concrete composite girders under negative moment

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structures 2025年 79卷

作者： Fei Peng Weichen Xue Lili Bai College of Civil Engineering Hunan University Changsha 410082 China Department of Structural Engineering Tongji University Shanghai 200092 China Key Laboratory of Performance Evolution and Control for Engineering Structures of the Ministry of Education Tongji University Shanghai 200092 China

This paper aims to investigate the flexural behavior of steel-prestressed concrete composite girders under negative moments and to develop a reliable approach for calculating their flexural stiffness. Experimental tests were conducted on four steel-prestressed composite girders and one non-prestressed composite girder until failure. The test results indicate that post-tensioning the concrete slab effectively delays crack initiation and enhances the post-cracking stiffness of the composite girders. When the shear connection degree exceeds 1.0, further reducing the shear connector spacing has a negligible impact on the hogging moment capacity but improves the girders' flexural stiffness. The flexural stiffness predictions for cracked sections in current design guidelines were found to be conservative at low service load levels but unconservative at higher service load levels. To address this, a design equation for the effective flexural stiffness of prestressed composite beams is proposed, considering the slip effect at the steel-concrete interface and the tension-stiffening effect in the prestressed concrete slab. Finally, a database of 14 steel-prestressed concrete composite girders was compiled to validate the accuracy of the proposed equation.

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Automated detection of complex construction scenes using a lightweight transformer-based method

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Automation in Construction 2025年 177卷

作者： Hongru Xiao Bin Yang Yujie Lu Wenshuo Chen Songning Lai Biaoli Gao College of Civil Engineering Tongji University Shanghai China Key Laboratory of Performance Evolution and Control for Engineering Structures of Ministry of Education Tongji University Shanghai 200092 China Hong Kong University of Science and Technology (Guangzhou) Guangzhou China

Accurate and real-time object detection in complex construction scenes from multiple viewpoints plays a crucial role in effective project management. However, this task remains limited by boundary information sharing and scene sensitivity inherent in deep features. To investigate the deep features in construction scenes and analyze method performance, SODA and VisDrone datasets, mean Average Precision (mAP) series metrics, visual inspection, Grad-CAM, and ablation studies are utilized. This paper proposes a lightweight Transformer-based detection framework named Complex Construction Scenes Transformer (CCS-TR), which integrates with a Scale-Isolate Fusion Attention (SIFA) mechanism and an Instructive Contrastive Learning (ICL) strategy. Evaluation results demonstrate that CCS-TR achieves a 5.1 %–8.8 % improvement in detection accuracy while maintaining lower computational costs, making it suitable for real-time on-site detection. Future work will address detection in interacting complex scenes and develop multi-modal collaboration strategies for extreme lighting.

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The quality traceability system for prefabricated buildings using blockchain:An integrated framework

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Frontiers of engineering Management 2020年第4期7卷 528-546页

作者： Ziyao ZHANG Zhenmin YUAN Guodong NI Han LIN Yujie LU Institute of Project Management School of Mechanics and Civil EngineeringChina University of Mining and TechnologyXuzhou 221116China School of Information Engineering Jiangsu Key Laboratory of Auditing Information EngineeringNanjing Audit UniversityNanjing 211815China Department of Building Engineering College of Civil EngineeringKey Laboratory of Performance Evolution and Control for Engineering Structures of Ministry of EducationShanghai Institute of Intelligent Science and TechnologyTongji UniversityShanghai 200092China

The quality traceability of precast components has largely affected the widespread adoption of prefabricated *** technology provides an effective solution to change the centralized storage mode of traditional traceability system and its related *** this paper,we propose a framework of quality traceability system for precast components based on blockchain *** system framework adopts a hybrid blockchain architecture and dual storage mode,defines three types of smart contracts,and creates an interactive and efficient source tracing query method,which could effectively achieve the goals of decentralization,openness,and non-tamperability,as well as efficient traceability.

关键词： quality traceability precast components blockchain framework

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Anti-cracking Property of EVA-modified Polypropylene Fiber-reinforced Concrete Under Thermal-cooling Cycling Curing

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Journal of Wuhan University of Technology(Materials Science) 2019年第5期34卷 1109-1118页

作者： LIU Sifeng[[ YANG Siyu KONG Yaning WAN Tingting ZHAO Guorong School of Materials Science and Engineering Tongji UniversityShanghai 201804China Key Laboratory of Advanced Civil Engineering Materials of Ministry of Education Tongji UniversityShanghai 200092China Key Laboratory of Performance Evolution and Control for Engineering Structures of Ministry of Education Tongji UniversityShanghai 200092China

In order to investigate the synergistic effect of re-dispersible powder-ethylene-vinyl acetate copolymer(EVA) and polypropylene fiber on the crack resistance of concrete under thermal fatigue loading, the compressive strength, ultimate tensile strength, ultimate tensile strain and tensile modulus of elasticity were tested. In addition, ultrasonic method and scanning electron microscope analysis were used to explain the microstructure mechanism. The results show that polypropylene fiberreinforced concrete presents a better performance on crack resistance than ordinary concrete, and the synergism of EVA and polypropylene fiber can improve the anti-cracking ability of concrete further.

关键词： anti-cracking property EVA-modified polypropylene fiber-reinforced concrete thermal-cooling cycling curing

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Collapse simulation of damaged reinforced concrete frame structures in earthquakes 20

Collapse simulation of damaged reinforced concrete frame str...

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20th IABSE Congress, New York City 2019: The Evolving Metropolis

作者： Yang, Yang Gu, Xianglin Mr College of Civil Engineering Tongji University Key Laboratory of Performance Evolution and Control for Engineering Structures of Ministry of Education Tongji University Shanghai China College of Civil Engineering Tongji University Key Laboratory of Performance Evolution and Control for Engineering Structures of Ministry of Education Tongji University Shanghai China

ISBN: (纸本)9783857481659

A simulation system based on the discrete element method (DEM) was developed to simulate the collapse behavior of damaged reinforced concrete (RC) frame structures in earthquakes. A frame structure was discretized into beam-column-joint discrete system according to its failure mode. The elements were assumed to be cuboid, and a group of concrete springs and steel bar springs were set between two adjacent elements to represent their interactions. The failure of material was initiated by fracture of springs, and the impact actions among separated components were considered. Using the simulation system, the full-range collapse process of an RC frame, including debris stacking, was visually simulated. The efficiency of the system was verified by comparing the simulated collapse behavior with that observed in a collapse experiment. A new method, in which concrete springs and steel bar springs were cut off in advance to simulate the respective initial imperfection, was proposed to model earthquake-induced damage states of RC frame structures. Then displacement loadings were conducted to form the respective damage states. Finally, a parametric analysis was conducted to investigate the collapse processes of the RC frame with different scenarios of initial damage. The results indicated that the initial damages on columns were of greater influence on collapse patterns than the initial damages on beams, and the residual interstory drifts were nonnegligible in evaluating the structural collapse resistance. © 20th Congress of IABSE, New York City 2019: The Evolving Metropolis - Report. All rights reserved.

关键词： Finite difference method

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Progressive collapse mechanism of three-dimensional self-centering precast concrete frame with infill walls and slabs

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engineering Failure Analysis 2025年 179卷

作者： Haoran Wang Shuang Li Feng Lin School of Civil Engineering Shenyang Jianzhu University Shenyang 110168 China Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of Industry and Information Technology Harbin Institute of Technology Harbin 150090 China Department of Structural Engineering Tongji University Shanghai 200092 China Key Laboratory of Performance Evolution and Control for Engineering Structures of Ministry of Education Shanghai 200092 China

In this study, the effects of infill walls and slabs on the progressive collapse resistance of three-dimension (3D) self-centering precast concrete (PC) frame under corner column failure, middle column failure and internal column failure scenarios were numerically investigated. Based on the verified numerical modeling methods, the failure modes and collapse mechanism of twelve 3D self-centering PC frames were analyzed. The results indicated that the number of spans connected to the failure column will directly influence the progressive collapse resisting-capacity of 3D self-centering PC frames. Compared with slabs, infill walls improved the progressive collapse resistance of 3D self-centering PC frame more obviously. For failure span with small aspect ratio, the presence of infill walls and slabs did not alter the failure mode of the structure. With the aspect ratio of the failure span increased, for 3D self-centering infilled PC frame, the stronger constraint of surrounding frame enhanced the overall stiffness of the infill walls, resulting in a change in the failure mode of the frame. When the slab was arranged, since the larger stiffness of the slabs improved the shear capacity of the beam section, the main concrete damage were still concentrated at the beam ends. A simplified calculation method considering the resistance contribution of structural and non-structural members was proposed to predict the vertical resistance of 3D self-centering PC frame structures under different failure column scenarios in the compressive arch action (CAA) stage.

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Modified spherical cavity-expansion model for projectile penetration into concrete targets

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Acta Mechanica Sinica 2019年第3期35卷 518-534页

作者： Y.Peng H.Wu Q.Fang X.Z.Kong College of Liberal Arts and Sciences National University of Defense TechnologyChangsha 410073China Key Laboratory of Performance Evolution and Control for Engineering Structures Tongji UniversityShanghai 200092China Research Institute of Structural Engineering and Disaster Reduction College of Civil EngineeringTongji UniversityShanghai 200092China State Key Laboratory for Disaster Prevention and Mitigation of Explosion and Impact PLA Amy Engineering UniversityNanjing 210007China

A modified spherical cavity-expansion model is developed in this paper.(1) We introduce a piecewise hyperbolic yield criterion suitable for pressure less than fc/3 to describe the mechanical behavior in the elastic region for the elastic-plastic response and modify the crack occurrence condition for the elastic-cracked-plastic response.(2) The hyperbolic yield criterion and a piecewise equation of state (EOS) are adopted for a better description of the plastic behavior of concrete material. Then, the modified model is validated by several projectile penetration tests in both the normal strength concrete (NSC) and ultra-high performance cement-based composite (UHPCC) targets. Finally, the hydrostatic pressure of the targets under rigid ogive-nosed projectile penetrations is found to be nearly within (0, 1.6 GPa), which usually exceeds the range that the shear strength-pressure test data covered. The influence of yield criterion on depth of penetration is discussed and it is recommended that the pressure should arrive at least 400 MPa in the related triaxial compression tests.

关键词： Dynamic cavity-expansion model Projectile Penetration Concrete Depth of penetration

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