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Numerical analysis of tunnel segments strengthened by steel-concrete composites

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Underground Space 2022年第6期7卷 1115-1124页

作者： Jiao-Long Zhang Xian Liu Tian-Yu Ren Yi-Ming Shi Yong Yuan Department of Geotechnical Engineering College of Civil EngineeringTongji UniversityShanghai 200092China China Railway Design Corporation Tianjin 3000142China

In order to study the feasibility of strengthening of segmental tunnel linings by using steel-concrete composites(SCC),a three-dimensional(3D)finite element(FE)model is proposed in this paper.The nonlinear mechanical behavior of concrete is described by a plastic-damage model.The nonlinearity,resulting from the interface of the SCC and reinforced concrete(RC)segments,is simulated with the help of a system of springs.The analysis results are compared with those obtained from a full-scale test of a tunnel segment.Their agreement validates the usefulness of the 3D FE model.Numerical re-analysis of the test shows that the interfacial connectors govern both the strengthening effect of SCC and the failure pattern of the strengthened segments.Thus,the force-transmitting capacity of the interfacial connectors should be concerned in design activities.As regards the circular segments,the interfacial connectors refer to both the shearing and the stripping connectors.The composite effect of the SCC and RC segments increases with the increasing number of these connectors.The latter,therefore,results in the increases of the bearing capacities and stiffnesses of the strengthened segments.Those increases become insignificant as the number of these connectors is sufficient to ensure a perfect composite effect of the SCC and RC segments.In addition,the numerical simulations show that using high-performance steel shell(HPS)or/and ultra-high-performance concrete(UHPC)is an effective way to increase the strengthening effect of SCCs.

关键词： Nonlinear analysis concrete structures Composite structures Shield tunnels Full-scale test

Repair ＆ Strengthening of Reinforced concrete structures Using Composite Materials

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Repair ＆ Strengthening of Reinforced Concrete Structures Us...

Effect of types of reinforcement on plastic hinge rotation parameters of RC beams under pushover and cyclic loading

第十三届国际复合材料会议

作者： EdFyfe JinsongWang ZYSong SBSim L＆M Specialist Construction Ltd L＆M Specialist Construction Ltd L＆M Specialist Construction Ltd L＆M Specialist Construction Ltd

＜正＞concrete is the most popular man-made material seen in our everyday life, be buildings, roads, and bridges. Like everything else, maintenance and repair are required from time to time to keep this man-made material in a serviceable condition. In many cases, the existing structures may even need to be strengthened to cater for changing requirements. In a developed country, all this could take up a significant share of the annual construction budget, up to 45% in some cases, and therefore deserve some special attentions.

关键词： repair strengthening concrete structures

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Earthquake Engineering and Engineering Vibration 2015年第3期14卷 503-516页

作者： V.V.S.Surya Kumar Dadi Pankaj Agarwal Department of Civil Engineering Institute of Technology Guru Ghasidas Vishwavidyalaya Bilaspur (C.G.) India Assistant Professor Department of Earthquake Engineering Indian Institute of Technology Roorkee

Experimental evaluation of reinforced concrete beam specimens with different characteristics of reinforcement subjected to pushover and cyclic loading is presented.Plastic hinge rotation parameters are determined based on the idealization of pushover and hysteresis curves of reinforced concrete beam specimens constructed in two percentage of reinforcement(0.471%and 0.71%) with different ductile characteristics.The experimental test results provide a clear demarcation of the effect of types of loading and the types of reinforcement on the nonlinear performance characteristics of beam specimens.These results are helpful to update the nonlinear modeling parameters of beam components for the specific type of reinforcement used in the construction of a structure.The updated non-linear modeling parameters of beam components in lumped plasticity model are compared with the values of ASCE/SEI 41-06(2007) used for the performance based design of structures.

关键词： concrete structures pushover loads cyclic loads hy

Mitigation of the blast load effects on a building structure using newly composite structural configurations

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Defence Technology（防务技术） 2021年第1期17卷 75-84页

作者： Ahmed K.Taha M.S.Zahran Zhengguo Gao School of Transportation Science and Engineering Beihang University(Beijing University of Aeronautics and Astronautics)Beijing100191PR China Department of Civil Engineering Military Technical CollegeEgypt

In this study,a nonlinear three-dimensional hydrocode numerical simulation was carried out using AUTODYN-3D to investigate the effect of blasting of a high explosive material(TNT)against several configurations of the composite structure.Several numerical models were carried out to study the effect of varying the thickness of the walls and the effect of adding an air layer or aluminum foam layer inside two layers of concrete in mitigating the effect of blast waves on the structure walls.The results showed that increasing the thickness of walls has a good effect on mitigating the effect of blast waves.When a layer of air was added,the effect of blast waves was exaggerated,while when a layer of aluminum foam was added the blast wave effects were mitigated with a reasonable percentage.

关键词： concrete structures Blast waves Numerical simulation TNT

Multi-objective optimization design of bridge piers with hybrid heuristic algorithms

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2012年第6期13卷 420-432页

作者： Francisco J. MARTINEZ-MARTIN Fernando GONZALEZ-VIDOSA Antonio HOSPITALER Víctor YEPES Department of Geotechnical Engineering Universitat Politècnica de València 46022 Valencia Spain Department of Construction Engineering ICITECH Universitat Politècnica de València 46022 Valencia Spain

This paper describes one approach to the design of reinforced concrete (RC) bridge piers, using a three-hybrid multi- objective simulated annealing (SA) algorithm with a neighborhood move based on the mutation operator from the genetic algorithms (GAs), namely MOSAMO1, MOSAMO2 and MOSAMO3. The procedure is applied to three objective functions: the economic cost, the reinforcing steel congestion and the embedded CO 2 emissions. Additional results for a random walk and a descent local search multi-objective algorithm are presented. The evaluation of solutions follows the Spanish Code for structural concrete. The methodology was applied to a typical bridge pier of 23.97 m in height. This example involved 110 design variables. Results indicate that algorithm MOSAMO2 outperforms other algorithms regarding the definition of Pareto fronts. Further, the proposed procedure will help structural engineers to enhance their bridge pier designs.

关键词： Bridge piers concrete structures Multi-objective optimization Simulated annealing (SA) Structural design

FINITE ELEMENT MODELLING OF COMPLEX 3D STATIC AND DYNAMIC CRACK PROPAGATION BY EMBEDDING COHESIVE ELEMENTS IN ABAQUS

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Acta Mechanica Solida Sinica 2010年第3期23卷 271-282页

作者： Xiangting Su Zhenjun Yang Guohua Liu College of Civil Engineering and Architecture Zhejiang University Hangzhou 310027 China Department of Engineering the University of Liverpool L69 3GQ UK

This study proposes an algorithm of embedding cohesive elements in Abaqus and develops the computer code to model 3D complex cragk propagation in quasi-brittle materials in a relatively easy and efficient manner. The cohesive elements with softening traction-separation relations and damage initiation and evolution laws are embedded between solid elements in regions of interest in the initial mesh to model potential cracks. The initial mesh can consist of tetrahedrons, wedges, bricks or a mixture of these elements. Neither remeshing nor objective crack propagation criteria are needed. Four examples of concrete specimens, including a wedgesplitting test, a notched beam under torsion, a pull-out test of an anchored cylinder and a notched beam under impact, were modelled and analysed. The simulated crack propagation processes and load-displacement curves agreed well with test results or other numerical simulations for all the examples using initial meshes with reasonable densities. Making use of Abaqus＇s rich pre/post- processing functionalities and powerful standard/explicit solvers, the developed method offers a practical tool for engineering analysts to model complex 3D fracture problems.

关键词： finite element method cohesive elements three-dimensional crack propagation discrete crack model concrete structures Abaqus

Defect-Detection Model for Underground Parking Lots Using Image Object-Detection Method

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Computers, Materials & Continua 2021年第3期66卷 2493-2507页

作者： Hyun Kyu Shin Si Woon Lee Goo Pyo Hong Lee Sael Sang Hyo Lee Ha Young Kim Architectural Engineering Hanyang UniversityERICAAnsan15588Korea Department of Artificial Intelligence Ajou UniversitySuwon16499Korea Division of Architecture and Civil Engineering Kangwon National UniversitySamcheok25913Korea Division of Smart Convergence Engineering Hanyang UniversityERICAAnsan15588Korea Graduate School of Information Yonsei UniversitySeoul03722Korea

The demand for defect diagnoses is gradually gaining ground owing to the growing necessity to implement safe inspection methods to ensure the durability and quality of structures.However,conventional manpower-based inspection methods not only incur considerable cost and time,but also cause frequent disputes regarding defects owing to poor inspections.Therefore,the demand for an effective and efficient defect-diagnosis model for concrete structures is imminent,as the reduction in maintenance costs is significant from a long-term perspective.Thus,this paper proposes a deep learning-based image objectidentification method to detect the defects of paint peeling,leakage peeling,and leakage traces that mostly occur in underground parking lots made of concrete structures.The deep learning-based object-detection method can replace conventional visual inspection methods.A faster region-based convolutional neural network(R-CNN)model was used with a training dataset of 6,281 images that utilized a region proposal network to objectively localize the regions of interest and detect the surface defects.The defects were classified according to their type,and the learning of each exclusive model was ensured through test sets obtained from real underground parking lots.As a result,average precision scores of 37.76%,36.42%,and 61.29%were obtained for paint peeling,leakage peeling,and leakage trace defects,respectively.Thus,this study verified the performance of the faster RCNN-based defect-detection algorithm along with its applicability to underground parking lots.

关键词： Faster R-CNN deep learning defect detection concrete structures

Characterization of the Reinforcing Steel Corrosion by Potentialdynamic Scan Approach

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Journal of Wuhan University of Technology(Materials Science) 2012年第3期27卷 418-421页

作者：乔国富刘铁军 School of Civil Engineering Harbin Institute of Technology Shenzhen Graduate School Harbin Institute of Technology

Reinforcement corrosion is the major cause of damage and early failure of reinforced concrete structures worldwide with subsequent enormous costs for maintenance, restoration and replacement. Many methods used today for assessment of reinforcement corrosion are based on electrochemical techniques that determine the free corrosion potential or polarization resistance. Most of these methods always consider the B value in Stern-Geary equation as constant. However, B changes with different condition. In this paper, potentialdynamic method is used to characterize the corrosion of reinforcing steel. The corrosion rate of Q235 carbon steel is measured with concrete environment. B is calculated real-time. By this way, the error of reinforcement corrosion rate is minimized.

关键词： concrete structures reinforcing steel corrosion potentialdynamic scan

Shear assessment of compression flanges of structural concrete T-beams

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Frontiers of Structural and Civil Engineering 2014年第4期8卷 354-361页

作者： Bjorn SCHUTTE Viktor SIGRIST Institute of concrete structures Hamburg University of Technology Hamburg 21073 Germany

In T-beams the force transfer from the web into the flange has to be studied. The general design procedure is based on a strut-and-tie （or a stress field） model which comprises spreading compressive and transverse tensile forces. As is known, strut-and-tie models represent the force flow within a structural member at ultimate. This procedure is sufficient for design purposes and in general, leads to safe results. For the assessment of a structure it may be worthwhile to improve the accuracy. For this purpose both web and flange have to be looked at more in detail. An advanced method for the analysis of webs in shear is the Generalized Stress Field Approach [1]. This approach can be utilized for treating flanges, where the classical assumptions have to be adapted; in particular by considering the strain dependence of the concrete compressive strength and thus, defining a representative strain value. In the present contribution background and details of these aspects are given, and the corresponding calculation procedure is described. Theoretical results are compared with experimental data and show a reasonably good agreement. However, as the number of sufficiently documented tests is very limited no concluding findings are attained.

关键词： concrete structures structural assessment stress field analysis shear