86 results on '"Shichun, Zhao"'
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2. Investigating the effectiveness of CFRP strengthening in improving the impact performance of RC members
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Al-Bukhaiti, Khalil, Yanhui, Liu, Shichun, Zhao, and Daguang, Han
- Published
- 2024
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3. Comparative Study on Dynamic Response of Square Section RC-Members and CFRP-Reinforced Members Under Unequal Transverse Impact Loading
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Yanhui, Liu, AL-Bukhaiti, Khalil, Shichun, Zhao, Abas, Hussein, Zaidi, Khaled, Xu, Nan, Aoran, Dong, di Prisco, Marco, Series Editor, Chen, Sheng-Hong, Series Editor, Vayas, Ioannis, Series Editor, Kumar Shukla, Sanjay, Series Editor, Sharma, Anuj, Series Editor, Kumar, Nagesh, Series Editor, Wang, Chien Ming, Series Editor, Kang, Thomas, editor, and Lee, Youngjin, editor
- Published
- 2022
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4. CFRP Strengthened Reinforce Concrete Square Elements Under Unequal Lateral Impact Load
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AL-Bukhaiti, Khalil, Yanhui, Liu, Shichun, Zhao, Abas, Hussein, di Prisco, Marco, Series Editor, Chen, Sheng-Hong, Series Editor, Vayas, Ioannis, Series Editor, Kumar Shukla, Sanjay, Series Editor, Sharma, Anuj, Series Editor, Kumar, Nagesh, Series Editor, Wang, Chien Ming, Series Editor, Pellegrino, Carlo, editor, Faleschini, Flora, editor, Zanini, Mariano Angelo, editor, Matos, José C., editor, Casas, Joan R., editor, and Strauss, Alfred, editor
- Published
- 2022
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5. Failure mechanism and static bearing capacity on circular RC members under asymmetrical lateral impact train collision
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AL-Bukhaiti, Khalil, Yanhui, Liu, Shichun, Zhao, Abas, Hussein, Yu, Yan Xing, Nan, Xu, Daguang, Han, and Lang, Yang
- Published
- 2023
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6. Based on BP Neural Network: Prediction of Interface Bond Strength between CFRP Layers and Reinforced Concrete
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Al-Bukhaiti, Khalil, primary, Yanhui, Liu, additional, Shichun, Zhao, additional, and Daguang, Han, additional
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- 2024
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7. Numerical study on existing RC circular section members under unequal impact collision
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Yanhui, Liu, Al-Bukhaiti, Khalil, Shichun, Zhao, Abas, Hussein, Nan, Xu, Lang, Yang, Yu, Yan Xing, and Daguang, Han
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- 2022
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8. Experimental Study on Existing RC Circular Members Under Unequal Lateral Impact Train Collision
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AL-Bukhaiti, Khalil, Yanhui, Liu, Shichun, Zhao, Abas, Hussein, Nan, Xu, Lang, Yang, Yu, Yan Xing, and Daguang, Han
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- 2022
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9. Blood chemical components analysis of honeysuckle and formulation of xanthan gum/starch-based (PVA-co-AA) hydrogels for controlled release
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Zhenzhong Zang, Shichun Zhao, Ming Yang, Chengqun Yu, Hui Ouyang, Lihua Chen, Weifeng Zhu, Zheng-gen Liao, Abid Naeem, and Yongmei Guan
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Lonicera japonica ,Extracts ,Hydrogels ,Decoction ,UPLC-LTQ-Orbitrap-MS ,Chemistry ,QD1-999 - Abstract
Honeysuckle is a commonly used Chinese medicine for treating intestinal inflammation and other diseases. Compounds that are absorbed into the blood produce pharmacodynamic effects. However, it is still unclear which compounds in honeysuckle are absorbed into the blood. Thus, the purpose of this study was to investigate the composition and in vivo absorption of active components in honeysuckle in male Sprague-Dawley rats, and develop a controlled release hydrogel system. UPLC-LTQ-Orbitrap-MS was used to determine the active ingredients of honeysuckle in vitro and in vivo. A total of 80, out of which 42 components were found to be absorbed into the blood, which includes flavonoids, iridoids, organic acids and other compounds. FTIR analysis confirmed crosslinking between hydrogel content and drug loading, and TGA and DSC analysis indicated a high thermal stability. XRD analysis showed a decrease in crystallinity following crosslinking, and SEM revealed an irregular and hard surface. The maximum swelling and drug release were observed at pH 7.4 as compared to pH 1.2. The identified blood components can be used to determine Q-markers, while the prepared hydrogels can serve as an effective and promising carrier for the controlled release of honeysuckle extracts.
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- 2022
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10. CFRP Strengthened Reinforce Concrete Square Elements Under Unequal Lateral Impact Load
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AL-Bukhaiti, Khalil, primary, Yanhui, Liu, additional, Shichun, Zhao, additional, and Abas, Hussein, additional
- Published
- 2021
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11. An Approximate Formula for Asymmetrical Lateral-Impact Forces: A Residuals Margin and Laplace Transform Approach.
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Al-Bukhaiti, Khalil, Yanhui, Liu, and Shichun, Zhao
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IMPACT (Mechanics) ,REINFORCED concrete testing ,IMPACT loads ,STRUCTURAL engineering ,CONCRETE slabs ,DEAD loads (Mechanics) ,INFANT formulas ,MARINE debris - Abstract
Calculating impact forces in asymmetrical lateral structures has been a complex challenge that spans decades in engineering. Traditional models often fall short due to the inherent complexity of asymmetrical members and the need for significant computational resources or a vast pool of training data. This paper develops an approximate formula for accurately calculating the impact force of asymmetrical lateral-impact members under lateral impact. Existing methods for assessing impact forces have been limited in their application due to the inherent complexity of asymmetrical members and the significant computational resources or extensive training data they often require. Our approach employs the residuals margin method, and Laplace transforms to derive an efficient and accurate formula for impact force calculation. The paper rigorously validates this Formula through experimental testing, demonstrating high precision with an error margin of less than 5%. Further validation against diverse impact data from multiple studies on different materials and loadings under static and dynamic conditions confirmed the Formula's consistency. Despite simplifying assumptions, this research contributes a novel and computationally efficient approach for calculating impact forces. The formula offers engineers a practical tool while advancing a fundamental understanding of asymmetric impact dynamics. Rigid experimentation verified its significant accuracy, establishing the formula as a valuable structural impact analysis and design resource. This research presents an analytical formula for calculating impact forces on structures like buildings, bridges, and vehicles experiencing asymmetrical lateral impacts. Such impacts commonly occur due to falling debris, vehicle collisions, seismic pounding, and derailed train strikes. However, existing design formulas often oversimplify impact mechanics or require complex simulations. The proposed method provides engineers with a simple spreadsheet-compatible equation relating impact force directly to tangible mechanical quantities like momentum. This enables rapid impact load assessments essential for performance-based design against accidental hazards. The formula was validated through laboratory impact tests on reinforced concrete slabs, demonstrating precision within 5% of measured forces. Additional validations against published experimental and simulation data on different construction materials confirmed accuracy. The proposed formula equips structural engineers and safety analysts with a practical impact analysis tool by offering a computationally efficient approach with proven reliability. It facilitates assessing design performance for asymmetrical impact load scenarios, helping improve resilience for critical facilities subjected to hazardous lateral impacts. [ABSTRACT FROM AUTHOR]
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- 2024
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12. Numerical Exploration of Asymmetrical Impact Dynamics: Unveiling Nonlinearities in Collision Problems and Resilience of Reinforced Concrete Structures.
- Author
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Khalil, AL-Bukhaiti, Yanhui Liu, Shichun Zhao, and Daguang Han
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REINFORCED concrete ,ELASTIC rods & wires ,IMPACT (Mechanics) ,DEFORMATIONS (Mechanics) ,FINITE element method - Abstract
This study provides a comprehensive analysis of collision and impact problems' numerical solutions, focusing on geometric, contact, and material nonlinearities, all essential in solving large deformation problems during a collision. The initial discussion revolves around the stress and strain of large deformation during a collision, followed by explanations of the fundamental finite element solution method for addressing such issues. The hourglass mode's control methods, such as single-point reduced integration and contact-collision algorithms are detailed and implemented within the finite element framework. The paper further investigates the dynamic response and failure modes of Reinforced Concrete (RC) members under asymmetrical impact using a 3D discrete model in ABAQUS that treats steel bars and concrete connections as bond slips. The model's validity was confirmed through comparisons with the node-sharing algorithm and system energy relations. Experimental parameters were varied, including the rigid hammer's mass and initial velocity, concrete strength, and longitudinal and stirrup reinforcement ratios. Findings indicated that increased hammer mass and velocity escalated RC member damage, while increased reinforcement ratios improved impact resistance. Contrarily, increased concrete strength did not significantly reduce lateral displacement when considering strain rate effects. The study also explores material nonlinearity, examining different materials' responses to collision-induced forces and stresses, demonstrated through an elastic rod impact case study. The paper proposes a damage criterion based on the residual axial load-bearing capacity for assessing damage under the asymmetrical impact, showing a correlation between damage degree hammer mass and initial velocity. The results, validated through comparison with theoretical and analytical solutions, verify the ABAQUS program's accuracy and reliability in analyzing impact problems, offering valuable insights into collision and impact problems' nonlinearities and practical strategies for enhancing RC structures' resilience under dynamic stress. [ABSTRACT FROM AUTHOR]
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- 2024
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13. Elastoplastic Analysis of Circular Steel Tube of CFT Stub Columns under Axial Compression
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Hua Zhao, Rui Han, Weiguang Yuan, Shichun Zhao, and Yuping Sun
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CFT ,cold-formed circular steel tube ,stub column ,biaxial stress state ,local buckling ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
Composite action between the components of the concrete-filled steel tube (CFT) is complex and it is difficult to accurately obtain the experimental relationship between the steel tube and the core concrete of CFT columns. The triaxially stressed core concrete has been studied by hydrostatic test in past research, while little research has been focused on the mechanical behavior of steel tube of CFT columns. It is difficult to obtain the experimental constitutive relationship of the steel tube of CFT columns to reflect the real-time influence of biaxial stress state and local buckling of steel plate on the steel tube. To clarify the mechanical behavior of the steel tube of CFT columns, this paper proposed an elastoplastic analytical method considering biaxial stress state and local buckling of steel tube to obtain the stress–strain curve of the steel tube. This method applied the Hook’s law and the plasticity theory to interpret the information conveyed by the measured vertical and hoop strain histories of the steel tube. To verify its effectiveness, 11 circular concrete-filled steel tube stub columns were fabricated and tested under axial compression. Superposition results of the axial load–strain of steel tube and core concrete were compared against the experimental curves. The widely used Sakino–Sun model of the confined concrete was adopted to calculate the axial load–strain curve of the core concrete. Satisfactory agreements between the calculated and experimental results confirmed the rationality of the proposed method in tracing the constitutive relation of the biaxially stressed steel tube even after the occurrence of the local buckling. The obtained stress–strain relationship is critical for establishment of mathematical constitutive model and finite element model of steel tube.
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- 2022
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14. Design Calculation for Concrete-Filled Steel Tube under Soft Lateral Impact
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Xiangjie Kang, Yanhui Liu, and Shichun Zhao
- Subjects
lateral impact ,CFST ,inertia effect ,design calculation ,error estimation ,Building construction ,TH1-9745 - Abstract
In recent decades, the rapid development of transportation construction has increased the possibility of concrete-filled steel tubes (CFSTs) subjected to soft lateral impact. Some kinds of deviation may still exist between the soft impact process and its design prediction due to frequent safety accidents. To improve the prediction accuracy, this paper contrasted the current soft impact design with the experimental impact processes of CFSTs. The current design is represented by the method and route in Eurocode-1 Actions on structures, which belongs to the one-step type. Extra parameters were added to the one-step method to describe the inertia effect of CFST. According to the experiments and predictions, the soft impact process contains two stages, which are the initial peak stage (IPS) and the stable stage (SS). The current one-step method is consistent with SS but incorrect in IPS and its accuracy is related to the proportion of IPS and SS. An empirical formula, based on the weight of IPS, is summarized to evaluate the overall error of the one-step method in the soft impact design of CFST. This error is due to the unreasonable assumption of the inertial effect in IPS. For the demands of an accurate design in IPS, a new technical route is proposed, consisting of two steps: qualitative analysis and two-stage calculation. The qualitative analysis achieved an approximate quantitative division of IPS and SS, and provided the design loads for the two-stage calculation. The two-stage calculation supplemented the prediction of the inertia effect in IPS and independently estimated the resistances and responses of CFST in the two stages. The above qualitative analysis and two-stage calculation constituted the two-step method and its accuracy and applicability are generally better than that of the one-step design.
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- 2022
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15. Deflection Calculation Based on SDOF Method for Axially Loaded Concrete-Filled Steel Tubular Members Subjected to Lateral Impact
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Luming Wang, Yanhui Liu, Jiahuan Song, Shichun Zhao, Zhe Wang, Yue Zeng, and Xingyu Feng
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Physics ,QC1-999 - Abstract
Axial force has a great influence on the dynamic behavior and the impact resistance of concrete-filled steel tubular (CFST) members. Based on numerical simulation and theoretical analysis, the impact response and deflection calculation method for axially loaded CFST members subjected to lateral impact are investigated in this paper. The nonlinear numerical model of an axially loaded CFST member considering the strain rate effects has been established, and the simulation accuracy has been validated by comparing with existing test results. The contrastive investigation is carried out to illustrate the influence of axial load on the variation pattern of impact force for CFST members under various structural and impact parameters, and its result indicates that the impact force-time histories for CFST members with different axial loads are mainly characterized by rectangular pulse and triangular pulse. Moreover, a simplified calculation method considering the effect of axial force is proposed based on the equivalent single degree of freedom (SDOF) method, devoted to predicting the deflection of axially loaded CFST members subjected to lateral impact. The comparisons with the numerical simulation prove that the deflection calculation method has a reasonable accuracy; thus, the proposed method can be utilized in the damage assessment and anti-impact design for CFST members subjected to lateral impact and axial load.
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- 2020
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16. Energy Absorption Mechanism and Its Influencing Factors for Circular Concrete-Filled Steel Tubular Members Subjected to Lateral Impact
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Luming Wang, Yanhui Liu, Lang Yang, Nan Xu, and Shichun Zhao
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concrete-filled steel tube (CFST) ,lateral impact ,material strain rate ,segmented numerical model ,energy absorption mechanism ,influencing factor ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
The energy absorption characteristic of steel tube material and concrete material is an important indicator to reflect the impact resistance of circular concrete-filled steel tubular (CFST) members. In order to efficiently simulate the material energy absorption of the steel tube and concrete under lateral impact, a nonlinear finite element model considering the material strain rate of the circular CFST member was established and validated based on the drop weight tests. Then, the energy absorption mechanism of circular CFST members subjected to lateral impact was investigated including the revelation of the energy absorption process and the determination of the energy absorption distribution for the steel tube material and concrete material, which are obtained respectively based on the comprehensive analysis of dynamic response and innovative establishment of the segmented numerical model. In addition, the influence of impact momentum on energy absorption process and the effect of impact location on energy absorption distribution are further carried out. The observations of this investigation can provide reference for the anti-impact design and damage reinforcement of circular CFST members subjected to lateral impact.
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- 2021
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17. A Survey of Aesthetic Standards of the Ear
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Lei, Liu, Shichun, Zhao, Zhenzhong, Liu, Qiangwei, Wu, Fangfang, Huang, Zhensheng, Hu, and Bo, Pan
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- 2020
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18. An Application of BP Neural Network to the Prediction of Compressive Strength in Circular Concrete Columns Confined with CFRP
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Khalil AL-Bukhaiti, Yanhui Liu, Shichun Zhao, and Hussein Abas
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Civil and Structural Engineering - Published
- 2023
19. Dynamic response of reinforced concrete sheds against the impact of rock block with different shapes and angles
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Shichun Zhao, Chun Liu, and Nguyen Phuong
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Impact effect ,Materials science ,business.industry ,Block (telecommunications) ,Impact angle ,Particle ,Structural engineering ,business ,Reinforced concrete ,General Environmental Science ,Civil and Structural Engineering - Abstract
This study aimed to quantitatively identify the influence of the block impact angle and block shape on the impact effect of reinforced concrete (RC) sheds. The smooth particle hydrodynamic (SPH) method and finite element method (FEM) were coupled and used to solve the simulation difficulty of large deformation of the sand buffer layer in the RC shed. SPH was used to simulate the sand buffer layer in the impact area that experienced large deformation. Concrete, reinforced, bedrock, block and sand buffer layer in the non-impact area were simulated by FEM. The accuracy of the coupled model was verified by the full-scale test data. Finally, the impact forces and the dynamic responses of the RC shed were analyzed, focusing on the effects of the block impact angle and shape. The numerical results show that the coupled SPH-FEM method is effective for simulating how block impacts the RC shed. The block impact angle and shape can significantly influence the normal and tangential impact forces. The design of the RC shed based on the assumption of blocks as free-falling spherical projectiles can lead to inaccuracy in some impact scenarios, and an appropriate correction was put forward in available empirical calculating formulae to include the effect of the irregular shape and impact angle of the block. The sand buffer layer dissipates a large part of the energy, which accounts for at least 58% of the initial impact energy.
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- 2022
20. Nonlinear Numerical Modeling of the Wire-Ring Net for Flexible Barriers
- Author
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Zhixiang Yu, Chun Liu, Liping Guo, Lei Zhao, and Shichun Zhao
- Subjects
Physics ,QC1-999 - Abstract
To investigate the nonlinear mechanical behavior of the wire-ring net, this paper presents a new numerical model that can collectively consider equivalence between numerical and actual wire rings. Quasi-static tests, including tensile tests on steel wires and one-ring specimens, and puncturing tests on net specimens were conducted. Based on the test results, the axial constitutive curves of steel wires were obtained. The linear correlation equations for the breaking loads of the one-ring specimens and the puncturing strength of wire-ring nets were established, both of which were related to the number of windings. The wire rings were modeled via an equivalent structure with a single winding and a circular cross section. Equivalence between the numerical and actual wire rings in terms of bending and tensile strength, total mass, contact with sliding friction, and rupture behavior were also derived and presented. In particular, the emphasis was on simulating the flattening effect, a phenomenon rarely accounted for in conventional numerical models. All dominant factors were reflected in a model with the material law by the input of material parameters. The proposed mechanical model was calibrated and verified by the data from the tests of the wire-ring net. The calibrated mechanical model is also shown to successfully simulate a full-scale test of a flexible rockfall protection barrier according to the ETAG027 standard.
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- 2019
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21. Quantitative back analysis of in situ tests on guiding flexible barriers for rockfall protection based on 4D energy dissipation
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Liru Luo, Zhixiang Yu, Yuntao Jin, Lijun Zhang, Liping Guo, Xin Qi, and Shichun Zhao
- Subjects
Geotechnical Engineering and Engineering Geology - Published
- 2022
22. Effect of the axial load on the dynamic response of the wrapped CFRP reinforced concrete column under the asymmetrical lateral impact load.
- Author
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AL-Bukhaiti, Khalil, Yanhui, Liu, Shichun, Zhao, Abas, Hussein, Daguang, Han, Nan, Xu, Lang, Yang, and Xing Yu, Yan
- Subjects
AXIAL loads ,LATERAL loads ,CONCRETE columns ,DYNAMIC loads ,REINFORCED concrete ,IMPACT loads ,COMPOSITE columns ,TRANSVERSE reinforcements - Abstract
This study investigated the impact of axial load on the dynamic response of reinforced concrete (RC) members to asymmetrical lateral impact loads. A series of asymmetrical-span impact tests were conducted on circular and square RC members with and without Carbon Fiber Reinforced Polymers (CFRP) while varying the axial compression ratios. The impact process was simulated using ABAQUS software, and the time history curves of deflection and impact were measured. The study found that specific impact loads caused bending and shearing failures. The axial compression ratio ranged from 0.05 to 0.13 when the impact curve reached its maximum deflection before the component's impact resistance decreased. Analysis of the impact point and inclined crack location revealed that axial load affects the maximum local concrete. The speed of inclined crack penetration and inclined cracks take longer to form, with weaker resistance to damage to local concrete when the axial compression ratio is between 0.05 and 0.13. When the axial compression ratio is greater than 0.13, inclined cracks form sooner with more brittle and severe damage to the impact point's concrete. The study also identified key parameters affecting the dynamic response of RC members, including impact height, CFRP layer thickness, axial force, and impact location. Thicker CFRP layers in RC can improve impact resistance, especially when the impact location is farther from the center. However, there is a limit to the impact of axial force on this resistance. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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- View/download PDF
23. A coupled SPH-DEM-FEM model for fluid-particle-structure interaction and a case study of Wenjia gully debris flow impact estimation
- Author
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Shichun Zhao, Chun Liu, and Zhixiang Yu
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021110 strategic, defence & security studies ,0211 other engineering and technologies ,Landslide ,02 engineering and technology ,Mechanics ,Geotechnical Engineering and Engineering Geology ,Debris ,Discrete element method ,Finite element method ,Debris flow ,Particle ,Penalty method ,Impact ,Geology ,021101 geological & geomatics engineering - Abstract
Debris flows are rapid gravity-driven unsteady flows of highly concentrated mixtures of water and solid particle material, destroying numerous mountain building structures and traffic facilities. The investigation of debris flows is thus of significance to hazard prevention and mitigation. This paper aims to provide a numerical model capable of reproducing debris flow impact estimation by accounting for the complicated fluid-particle-structure interaction (FPSI) using a coupled smoothed particles hydrodynamics (SPH), discrete element method (DEM), and finite element method (FEM) approach. The fluid phase is represented by SPH. The solid phase consists of physical particle(s) and is represented by the DEM, and the deformable structure is represented by the FEM. The interaction forces among the fluid, solid particles, and structure are computed using the penalty function method. The proposed model is capable of simultaneously simulating a fluid-particle interaction (FPI), particle-structure interaction (PSI), and fluid-structure interaction (FSI), with good agreement between the complicated hybrid numerical and experimental results. Finally, a Wenjia gully debris flow is carried out to demonstrate the capability of the coupled model in simulating the FPSI as an application of debris flow impact simulations. When compared with the actual situation, the propagation of the debris flow and destruction of the structures were predicted accurately. Additionally, the Wenjia gully debris flow was treated, and the treatment measure was analyzed from the impact evolution (e.g., interception by dams, impact force, and destruction of dams). The developed method will contribute to a better understanding of the FPSI and is a promising tool for hazard analysis and mitigation.
- Published
- 2021
24. Dynamic simulation of CFRP‐shear strengthening on existing square RC members under unequal lateral impact loading
- Author
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Al‐Bukhaiti, Khalil, primary, Yanhui, Liu, additional, Shichun, Zhao, additional, and Abas, Hussein, additional
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- 2022
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25. Experimental and numerical study on unequal lateral impact behavior of Circular RC and CFRPRC components
- Author
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Yanhui Liu, Al-Bukhaiti Khalil, Shichun Zhao, Abas Hussein, Xu Nan, Yang Lang, Yu Yan Xing, and Daguang Han
- Abstract
The dynamic response of Reinforced Concrete (RC) and Carbon Fiber Reinforced Polymers with Reinforced Concrete (CFRPRC) is studied. These tests were performed on RC members covered in one to six layers of CFRP. Once the energy is high, the two components' deflection-time histories are produced. It increases component impact resistance in studies. Component deflection is reduced by carbon fiber reinforced polymer (CFRP). RC members shear while CFRPRC components bend due to significant concrete damage. It fractures more easily when wrapped with CFRP. The model's predictions match the tests adequately. A numerical simulation study looked at the impact force of members under unequal-span lateral collisions. Regardless of impact velocity, lateral impact on an unequal span induces severe shear failure of RC members. However, CFRPRC component bending deformation reflects impact velocity. Increasing the reinforcement ratio of RC members has little effect on the impact resistance of CFRPRC components. To avoid steel fracture, greater reinforcing ratios are used.
- Published
- 2022
26. Experimental and Numerical Study of RC Square Members Under Unequal Lateral Impact Load.
- Author
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Abas, Hussein, Yanhui, Liu, Al-Bukhaiti, Khalil, Shichun, Zhao, and Aoran, Dong
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IMPACT loads ,LATERAL loads ,REINFORCED concrete ,FAILURE mode & effects analysis ,IMPACT testing ,FINITE element method - Abstract
Reinforced concrete members under impact loading stress may be destroyed in a split period. Because of the need to investigate the impact resistance of reinforced concrete members, this issue remains a much-debated topic. This study investigates the response of reinforced concrete (RC) square members under an unequal lateral impact force. The performance of RC members under the effect of impact load is examined using a drop hammer impact test system. The importance of unequal lateral impact load is highlighted and addressed by examining RC members' failure mode and dynamic response characteristics. Four types of RC members are experimentally investigated in detail. A finite element method (FEM) modeling is proposed to predict the impact responses of the RC members. Moreover, the effects of the impact position, height, and hammer mass on the dynamic response characteristics under an impact force are evaluated. The predictions of the proposed numerical model are validated against experimental results, emphasizing impact force history, deflection time history, and failure modes. Results indicate the viability of the FEM model. The findings from the experimental and numerical studies can improve the impact-resistant performance of reinforced concrete members. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
27. Dynamic simulation of CFRP‐shear strengthening on existing square RC members under unequal lateral impact loading.
- Author
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Al‐Bukhaiti, Khalil, Yanhui, Liu, Shichun, Zhao, and Abas, Hussein
- Subjects
LATERAL loads ,IMPACT response ,DYNAMIC simulation ,IMPACT loads ,DEAD loads (Mechanics) ,FINITE element method - Abstract
With the plethora of data on how CFRP layers enhance RCs under static loads, research on how the reinforced structural components react to unequal lateral impact loads from a derailed train striking metro station columns or a car accident is lacking. A similar motivation inspired the current study, which sought to create a numerical technique backed by actual testing to evaluate RC members with CFRP in a range of unequal lateral impact scenarios. This paper uses explicit nonlinear finite element techniques to numerically analyze the response of unequal lateral impact‐loaded RC members wrapped in (CFRP) layers. Diverse variables related to CFRP, concrete, steel reinforcement, and impact energy are investigated. This kind of thorough analysis provides unique insights to strengthen RC members against unequal lateral impact loads. The effects of internal forces and deflections, as well as absorbed energy on the impact response of CFRP‐RC components, were investigated and verified by prior experimental results. A parametric sensitivity analysis was conducted after the strain characteristics of steel bars confirmed the finite element model, reinforcement ratio, impact velocity, CFRP properties, and ductility index all influence the member's impact response. This study's results will help advance the field's understanding of CFRP‐RC components analysis and design under unequal lateral impact. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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28. Failure Mechanism Analysis of Circular Cfrp Components Under Unequal Impact Load
- Author
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Yanhui, Liu, primary, Al-Bukhaiti, Khalil, additional, Shichun, Zhao, additional, Abas, Hussein, additional, Nan, Xu, additional, Lang, Yang, additional, Yu, Yan Xing, additional, and Daguang, Han, additional
- Published
- 2022
- Full Text
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29. Consideration of maximum impact force design for a rock shed against dry granular flow
- Author
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Chun Liu, Shichun Zhao, and Zhixiang Yu
- Subjects
Environmental Engineering ,Flow (mathematics) ,021105 building & construction ,0211 other engineering and technologies ,02 engineering and technology ,Mechanics ,Impact ,Discrete element method ,Geology ,Finite element method ,021101 geological & geomatics engineering ,Civil and Structural Engineering - Abstract
This paper focuses on the estimation of the maximum impact force of dry granular flow upon a rock shed using a coupled discrete element method (DEM) and finite element method (FEM). The dry granula...
- Published
- 2020
30. Full-Scale Test and Numerical Simulation of Guided Flexible Protection System under a Blasting Load
- Author
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Qi Xin, Shichun Zhao, Keqin Sun, Hu Xu, and Zhixiang Yu
- Subjects
021110 strategic, defence & security studies ,Environmental Engineering ,Computer simulation ,business.industry ,0211 other engineering and technologies ,02 engineering and technology ,Structural engineering ,Protection system ,Geotechnical Engineering and Engineering Geology ,Earth and Planetary Sciences (miscellaneous) ,Full scale test ,business ,Geology ,021101 geological & geomatics engineering ,Rock blasting - Abstract
Both active and passive flexible protection methods are effective against rockfalls, but they can result in a secondary hazard due to cumulate rocks inside the structure. To solve this problem, guided flexible protection systems are receiving increased attention in the engineering community. In this study, a full-scale test of a guided flexible protection system was carried out, where the bottom of the mesh was anchored under a blasting load, which can be considered as an extreme loading event related to rockfall hazards. The fluid-solid coupling method was employed in a finite element model to simulate the entire process from the blast to the accumulation of rocks at the bottom of the slope. Based on the experimental and numerical results, a two-stage process was revealed, the internal force and the dissipated energy of each component were compared and analyzed, and the load-transferring path within the system was obtained. The internal forces of the support ropes reached their maximum values in the intercept stage. The posts experienced two peak values, the first of which, in the guide stage, was twice that in the intercept stage. The brake rings were the main energy-dissipating components, and the energy dissipation in the intercept stage was much greater than that in the guide stage. Furthermore, the interaction in terms of collision and friction between the rocks, the slope, and the system was not insignificant, particularly in the guide stage, which can account for more than 40 percent of the consumed energy of the rockfall.
- Published
- 2020
31. Nonlinear Numerical Modeling of the Wire-Ring Net for Flexible Barriers
- Author
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Chun Liu, Lei Zhao, Zhixiang Yu, Shichun Zhao, and Liping Guo
- Subjects
geography ,Materials science ,geography.geographical_feature_category ,Article Subject ,Mechanical Engineering ,0211 other engineering and technologies ,Numerical modeling ,020101 civil engineering ,02 engineering and technology ,Mechanics ,Geotechnical Engineering and Engineering Geology ,Condensed Matter Physics ,lcsh:QC1-999 ,Flattening ,0201 civil engineering ,Puncturing ,Nonlinear system ,Rockfall ,Mechanics of Materials ,Electromagnetic coil ,Ultimate tensile strength ,Equivalence (measure theory) ,lcsh:Physics ,021101 geological & geomatics engineering ,Civil and Structural Engineering - Abstract
To investigate the nonlinear mechanical behavior of the wire-ring net, this paper presents a new numerical model that can collectively consider equivalence between numerical and actual wire rings. Quasi-static tests, including tensile tests on steel wires and one-ring specimens, and puncturing tests on net specimens were conducted. Based on the test results, the axial constitutive curves of steel wires were obtained. The linear correlation equations for the breaking loads of the one-ring specimens and the puncturing strength of wire-ring nets were established, both of which were related to the number of windings. The wire rings were modeled via an equivalent structure with a single winding and a circular cross section. Equivalence between the numerical and actual wire rings in terms of bending and tensile strength, total mass, contact with sliding friction, and rupture behavior were also derived and presented. In particular, the emphasis was on simulating the flattening effect, a phenomenon rarely accounted for in conventional numerical models. All dominant factors were reflected in a model with the material law by the input of material parameters. The proposed mechanical model was calibrated and verified by the data from the tests of the wire-ring net. The calibrated mechanical model is also shown to successfully simulate a full-scale test of a flexible rockfall protection barrier according to the ETAG027 standard.
- Published
- 2019
32. Experimental and Numerical Study of RC Square Members Under Unequal Lateral Impact Load
- Author
-
Abas, Hussein, primary, Yanhui, Liu, additional, Al-Bukhaiti, Khalil, additional, Shichun, Zhao, additional, and Aoran, Dong, additional
- Published
- 2021
- Full Text
- View/download PDF
33. Quantifying the impact of a debris avalanche against a flexible barrier by coupled DEM-FEM analyses
- Author
-
Shichun Zhao, Chun Liu, and Zhixiang Yu
- Subjects
021110 strategic, defence & security studies ,0211 other engineering and technologies ,Landslide ,02 engineering and technology ,Mechanics ,Dissipation ,Geotechnical Engineering and Engineering Geology ,Kinetic energy ,Debris ,Discrete element method ,Finite element method ,Energy transformation ,Impact ,Geology ,021101 geological & geomatics engineering - Abstract
Flexible barriers are an effective type of mitigation measure against debris avalanches in valleys and can affect the kinetic energy and mass of debris avalanches. To investigate the complex dynamic interaction between a debris avalanche and a flexible barrier, a modeling framework was developed based on coupled discrete element method (DEM) and finite element method (FEM). The debris avalanche was modeled as an assembly of discrete particles accounting for collision–friction effect, and the flexible barrier was modeled by applying the FEM accounting for connections and contact in a realistic manner. The coupled numerical model was well validated by comparing the numerical results with experimental data reported in the literature. This model was employed to examine the dynamics of debris avalanche–barrier interaction, such as the interaction process, impact force, energy dissipation mechanism, and evolution of the internal forces of the components, as well as the influences of the bulk density and impact height of the debris avalanche and the slope angle of the channel on the coupled impact force. Based on the numerical results, three interaction stages were identified, namely, frontal impact, run-up, and pile-up. During the interaction process, the effects of run-up and dead zone formation need to be accounted to avoid conservative estimates of the impact force. The analyses of the energy transformation showed that 76.2% of the initial total energy was dissipated by interaction friction, and the flexible barriers may mainly focus on the frontal impact energy of the debris avalanche by using an energy design approach. The sensitivities of the bulk density, impact height, and slope angle on the maximum impact force are 1, 0.186, and 2.084, respectively. The parameters with high sensitivity are the main influencing parameters and should be given priority in the design of flexible barriers.
- Published
- 2019
34. Numerical simulation study of wind-induced snow drifting on low-sloped gable roofs
- Author
-
Ruizhou Cao, Zhixiang Yu, and Shichun Zhao
- Subjects
General Earth and Planetary Sciences ,Geotechnical Engineering and Engineering Geology - Published
- 2022
35. Studies on flexible rockfall barriers for failure modes, mechanisms and design strategies: a case study of Western China
- Author
-
Hu Xu, Shichun Zhao, L. Zhao, Zhixiang Yu, Yao-Peng Liu, and Siu Lai Chan
- Subjects
021110 strategic, defence & security studies ,geography ,geography.geographical_feature_category ,Computer simulation ,business.industry ,0211 other engineering and technologies ,02 engineering and technology ,Structural engineering ,Dissipation ,Geotechnical Engineering and Engineering Geology ,Durability ,Rockfall ,Buckling ,Deflection (engineering) ,Impact ,business ,Geology ,021101 geological & geomatics engineering ,Rope - Abstract
A field investigation on the actual protective performance of a flexible rockfall barrier along a mountain road in western China is presented in this paper. The total area of the flexible rockfall barrier under investigation was approximately 20,000 m2. Five typical failure modes of the flexible rockfall barrier were revealed, including steel post buckling, connection failure, ring net destruction, steel cable rope breakage and anchorage point failure. In addition, component rusting, which leads to decrease in durability, was noted. Furthermore, failure mechanisms were analysed, and the main factors that were found to induce flexible rockfall barrier failure included the sliding capacity of the cable ropes at the end post support positions, the boundary conditions of the steel posts and the compatibility between the energy dissipating devices and connected cable ropes. From these observations, corresponding design strategies were proposed. In addition, an improved flexible rockfall barrier system was constructed, and its effectiveness was verified by a full-scale impact test using 5000 kJ of impact energy. Finally, the impact deflection, impact force, cable force and energy dissipation of the improved flexible rockfall barrier system were studied in combination with a non-linear numerical simulation which could be a useful tool for design of flexible barrier systems.
- Published
- 2018
36. Dynamic Simulation Study of CFRP Strengthened RC Members under Unequal Trans-lateral Impact Loading Acknowledgment
- Author
-
Al-Bukhaiti, Khalil, Shichun, Zhao, Yanhui, Liu, Abas, Hussein, and Aaron, Dong
- Published
- 2021
- Full Text
- View/download PDF
37. Dynamic Equilibrium of CFRP-RC Square Elements under Unequal Lateral Impact
- Author
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AL-Bukhaiti, Khalil, primary, Yanhui, Liu, additional, Shichun, Zhao, additional, Abas, Hussien, additional, and Aoran, Dong, additional
- Published
- 2021
- Full Text
- View/download PDF
38. Cyclic behavior of concrete-filled square tubular columns with stiffened plastic hinge region
- Author
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Rui Han, Hua Zhao, Yuping Sun, Nengpan Ju, and Shichun Zhao
- Subjects
Mechanics of Materials ,Metals and Alloys ,Building and Construction ,Civil and Structural Engineering - Published
- 2022
39. Deflection Calculation Based on SDOF Method for Axially Loaded Concrete-Filled Steel Tubular Members Subjected to Lateral Impact
- Author
-
Yanhui Liu, Wang Zhe, Jiahuan Song, Luming Wang, Feng Xingyu, Shichun Zhao, and Yue Zeng
- Subjects
Materials science ,Computer simulation ,Article Subject ,business.industry ,Mechanical Engineering ,Physics ,QC1-999 ,020101 civil engineering ,02 engineering and technology ,Structural engineering ,Strain rate ,Geotechnical Engineering and Engineering Geology ,Condensed Matter Physics ,0201 civil engineering ,Nonlinear system ,020303 mechanical engineering & transports ,0203 mechanical engineering ,Mechanics of Materials ,Deflection (engineering) ,Axial load ,Impact ,business ,Single degree of freedom ,Axial symmetry ,Civil and Structural Engineering - Abstract
Axial force has a great influence on the dynamic behavior and the impact resistance of concrete-filled steel tubular (CFST) members. Based on numerical simulation and theoretical analysis, the impact response and deflection calculation method for axially loaded CFST members subjected to lateral impact are investigated in this paper. The nonlinear numerical model of an axially loaded CFST member considering the strain rate effects has been established, and the simulation accuracy has been validated by comparing with existing test results. The contrastive investigation is carried out to illustrate the influence of axial load on the variation pattern of impact force for CFST members under various structural and impact parameters, and its result indicates that the impact force-time histories for CFST members with different axial loads are mainly characterized by rectangular pulse and triangular pulse. Moreover, a simplified calculation method considering the effect of axial force is proposed based on the equivalent single degree of freedom (SDOF) method, devoted to predicting the deflection of axially loaded CFST members subjected to lateral impact. The comparisons with the numerical simulation prove that the deflection calculation method has a reasonable accuracy; thus, the proposed method can be utilized in the damage assessment and anti-impact design for CFST members subjected to lateral impact and axial load.
- Published
- 2020
- Full Text
- View/download PDF
40. A unified model for the seismic analysis of brick masonry structures
- Author
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Hu Xu, Shichun Zhao, Hao Wu, Cristina Gentilini, Zhixiang Yu, Xu, Hu, Gentilini, Cristina, Yu, Zhixiang, Wu, Hao, and Zhao, Shichun
- Subjects
Hysteretic curve ,0211 other engineering and technologies ,Unconfined masonry ,020101 civil engineering ,02 engineering and technology ,Confined masonry ,0201 civil engineering ,Seismic analysis ,medicine ,General Materials Science ,Slipping ,Civil and Structural Engineering ,Shrinkage ,021110 strategic, defence & security studies ,business.industry ,Shear capacity ,Stiffness ,Building and Construction ,Structural engineering ,Numerical models ,Unified Model ,Masonry ,Perforated masonry wall ,Brick masonry ,Stiffne ,Materials Science (all) ,medicine.symptom ,business ,Geology - Abstract
A significant portion of the building stock in seismic regions all over the world is constituted by brick masonry structures that are well known to be prone to damage under seismic excitations. For evaluating the dynamic performance of masonry buildings, efficient numerical models are required. In this paper, considering the typical hysteretic behavior of brick masonry walls, a unified model for the static and dynamic analysis of masonry structures governed by ten key parameters is proposed. The model is able to simulate different kinds of walls such as unconfined unperforated and perforated walls, as well as confined unperforated and perforated walls subjected to horizontal reverse cyclic loadings and vertical compression. The identification procedure of each key parameter, that includes, among the others, lateral strength, loading and unloading stiffness, accumulated damage factor, shrinkage factor, as well as slipping factor, is presented by analyzing over one hundred results collected from literature. In order to validate the proposed approach, four different types of wall specimens were tested under cyclic loads. Furthermore, a two-storey half-scale structure was tested to verify the effectiveness of the presented model in reproducing the deformation response and global hysteretic behavior of the structure.
- Published
- 2018
41. Analysis of Energy Absorption Distribution for Circular Concrete-Filled Steel Tubular Members under Lateral Impact
- Author
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Lang Yang, Yanhui Liu, Shichun Zhao, Luming Wang, and Nan Xu
- Subjects
History ,Materials science ,Distribution (number theory) ,Energy absorption ,Composite material ,Computer Science Applications ,Education - Published
- 2021
42. Adaptive-mesh method using RBF interpolation: A time-marching analysis of steady snow drifting on stepped flat roofs
- Author
-
Mingqian Xue, Fu Zhu, Lei Zhao, Shichun Zhao, and Zhixiang Yu
- Subjects
Phase boundary ,010504 meteorology & atmospheric sciences ,Meteorology ,Computer simulation ,Renewable Energy, Sustainability and the Environment ,020209 energy ,Mechanical Engineering ,Boundary (topology) ,02 engineering and technology ,Mechanics ,Snowpack ,Residual ,Snow ,01 natural sciences ,Physics::Geophysics ,0202 electrical engineering, electronic engineering, information engineering ,Astrophysics::Earth and Planetary Astrophysics ,Geology ,0105 earth and related environmental sciences ,Civil and Structural Engineering ,Interpolation ,Wind tunnel - Abstract
a real snow drifting phenomenon may last from hours to several days, therefore the wind-snow phase boundary is dynamic, and can affect the local flow field when enough changes occur in the snow boundary. To simulate the dynamic process of snow boundary, this paper proposes an adaptive-mesh method using radial basis function (RBF) interpolation, which realizes the change of phase boundary in both two-dimensional and three-dimensional snow drifting. A time-marching method based on steady-state algorithm is used in this paper, which can effectively reduce the huge cost of transient computation. According to the method, the wind duration determined by meteorological data or wind tunnel tests is divided into several stages, and the boundary of snowpack is updated based on the results of the previous stage using RBF interpolation. Meanwhile, based on the relative residual of the average mass transport rate of snow phase, the optimum iteration method is adopted to determine the optimal subsection of duration. By employing the adaptive-mesh method proposed in this paper, the snow redistribution on stepped flat roofs is predicted and the process of dynamic change of three-dimensional snow boundary is revealed in detail. The numerical results are in good consistent with the field measurements and the wind tunnel tests. Finally, the differences between two-dimensional and three-dimensional numerical simulation are compared, showing that three-dimensional calculation can provide certain reference to the prediction of the distribution of snow loads on the typical roofs.
- Published
- 2017
43. Compressive stress-strain model of cold-formed circular hollow section stub columns considering local buckling
- Author
-
Shichun Zhao, Yuping Sun, Chang Yang, and Hua Zhao
- Subjects
Materials science ,Manufacturing process ,business.industry ,Mechanical Engineering ,0211 other engineering and technologies ,020101 civil engineering ,Single parameter ,02 engineering and technology ,Building and Construction ,Structural engineering ,0201 civil engineering ,Stub (electronics) ,Nonlinear system ,Compressive strength ,Buckling ,Residual stress ,021105 building & construction ,business ,Cold forming ,Civil and Structural Engineering - Abstract
A complete stress-strain model for cold-formed circular hollow section (CHS) stub columns under compression is proposed with emphasis placed on the modeling of post-local-buckling behavior. The proposed model comprises two mathematical expressions. One of the two equations is to define the ascending portion of the proposed stress-strain curve and depict the nonlinearity caused by residual stress induced during manufacturing process of cold-formed CHS, while the other is to define the descending portion and trace the post-local-buckling behavior. The proposed stress-strain model is a single parameter model. Only if the generalized outer diameter-to-thickness ratio is given, the compressive stress-strain relationship of a CHS can be completely determined. To calibrate the proposed model and verify its accuracy, test results of forty-eight CHS stub columns under compression are collected. The previous tests cover a wide range of structural factors such as outer diameter-to-thickness ratio and yield strength, particularly including CHS stub columns with yield strength of up to 1180 MPa. Comparisons between the measured results and the calculated ones indicate that the proposed model can not only predict the local buckling strength as well as corresponding strain, but also trace the post-local-buckling behavior up to large strain with high accuracy.
- Published
- 2017
44. Effect of CFRP Shear Strengthening on the Flexural Performance of the RC Specimen under Unequal Impact Loading
- Author
-
Liu, Yanhui, primary, Al-Bukhaiti, Khalil, additional, Abas, Hussein, additional, and Shichun, Zhao, additional
- Published
- 2020
- Full Text
- View/download PDF
45. Comprehensive stress-strain model of square steel tube stub columns under compression
- Author
-
Hua Zhao, Yuping Sun, Takashi Takeuchi, and Shichun Zhao
- Subjects
Engineering ,business.industry ,Manufacturing process ,fungi ,Stress–strain curve ,0211 other engineering and technologies ,020101 civil engineering ,02 engineering and technology ,Structural engineering ,0201 civil engineering ,Stub (electronics) ,Compressive strength ,Buckling ,Residual stress ,021105 building & construction ,Steel tube ,Steel plates ,Composite material ,business ,Civil and Structural Engineering - Abstract
A stress-strain model is proposed to define the relationship between axial compressive stress and strain for square steel tube stub columns, which have been widely used as predominant gravity-sustaining structural components in high-rise buildings and skyscrapers. The proposed model consists of two equations, defining the ascending branch and descending branch of the stress-strain curve, respectively, and has a significant advantage over previous models in that it can trace effects of both the residual stress induced during manufacturing process and the local buckling of steel plate on the compressive stress-strain behavior of square steel tube stub columns. Another feature of the proposed model is that it can be used to the stub columns made of very thin steel plates. In order to calibrate the new stress-strain model and verify its reliability and accuracy, sixty-eight hollow square steel tube stub columns under monotonic axial compression are collected. The previous tests cover a wide range of structural factors such as yield strength and width-to-thickness ratio of steel plates. In particular, the previous tests include stub columns made of steel plate with high yield strength of up to 835 MPa. Comparisons between the experimental results and the calculated ones indicate that the proposed model cannot only predict the local buckling strength and the corresponding strain very well, but also trace the compressive stress-strain behavior of square steel tube stub columns up to large strain with high accuracy.
- Published
- 2017
46. CFD-DEM modeling of snowdrifts on stepped flat roofs
- Author
-
Xin Qi, Lei Zhao, Fu Zhu, Shichun Zhao, and Zhixiang Yu
- Subjects
010504 meteorology & atmospheric sciences ,business.industry ,Numerical analysis ,0211 other engineering and technologies ,02 engineering and technology ,Building and Construction ,Mechanics ,Computational fluid dynamics ,Snow ,01 natural sciences ,Discrete element method ,Physics::Geophysics ,Physics::Fluid Dynamics ,Flat roof ,Modeling and Simulation ,business ,Roof ,Geology ,CFD-DEM ,021101 geological & geomatics engineering ,0105 earth and related environmental sciences ,Civil and Structural Engineering ,Wind tunnel - Abstract
Snowdrift formation on roofs should be considered in snowy and windy areas to ensure the safety of buildings. Presently, the prediction of snowdrifts on roofs relies heavily on field measurements, wind tunnel tests and numerical simulations. In this paper, a new snowdrift modeling method by using CFD (Computational Fluid Dynamics) coupled with DEM (Discrete Element Method) is presented, including material parameters and particle size, collision parameters, particle numbers and input modes, boundary conditions of CFD, simulation time and inlet velocity, and coupling calculation process. Not only is the two-way coupling between wind and snow particles which includes the transient changes in snow surface topography, but also the cohesion and collision between snow particles are taken into account. The numerical method is applied to simulate the snowdrift on a typical stepped flat roof. The feasibility of using coupled CFD with DEM to study snowdrift is verified by comparing the simulation results with field measurement results on the snow depth distribution of the lower roof.
- Published
- 2016
47. Full-Scale Impact Test and Numerical Simulation of a New-Type Resilient Rock-Shed Flexible Buffer Structure
- Author
-
Yao-Peng Liu, L. Zhao, Shichun Zhao, Caijin Yang, Liping Guo, and Zhixiang Yu
- Subjects
Article Subject ,0211 other engineering and technologies ,Full scale ,020101 civil engineering ,02 engineering and technology ,0201 civil engineering ,Rockfall ,medicine ,Civil and Structural Engineering ,021110 strategic, defence & security studies ,geography ,geography.geographical_feature_category ,Computer simulation ,business.industry ,Mechanical Engineering ,Stiffness ,Structural engineering ,Dissipation ,Geotechnical Engineering and Engineering Geology ,Condensed Matter Physics ,lcsh:QC1-999 ,Structural load ,Mechanics of Materials ,Cushion ,Impact ,medicine.symptom ,business ,Geology ,lcsh:Physics - Abstract
Rock sheds have been widely used to protect against rockfall. Traditionally, a cushion layer is placed on the top of a rock shed to reduce the impact force and dissipate energy. However, heavy cushion layers lead to high dead loads and increased construction costs. This paper discusses the concept of an impact-resilient flexible buffer structure. On the basis of that concept, it also proposes a buffer structure mainly composed of springs, ring nets, spring rods, and support ropes, which can be used to replace the traditional cushion layer on a shed for rockfall protection. Full-scale impact tests were conducted to study the impact-resilient characteristic of the structure combined with numerical simulation. The dynamic responses of the buffer structure, including force, deformation, and energy dissipation, were analysed in depth. Finally, parametric numerical simulations of 33 models were conducted; the spring stiffness of these models ranged from 300 kN/m to 1500 kN/m; the impact energy ranged from 100 kJ to 2000 kJ. Moreover, simple approaches for estimating the impact force and braking distance of the buffer structure were proposed and verified using measured data obtained from the impact test.
- Published
- 2019
- Full Text
- View/download PDF
48. POST-BUCKLING BEHAVIOUR OF CONCRETE-FILLED CIRCULAR STEEL TUBE STUB COLUMNS UNDER AXIAL COMPRESSION
- Author
-
Shichun Zhao, Chang Yang, Hu Xu, Zhixiang Yu, Hua Zhao, Yuping Sun, and China-Japan Resilient
- Subjects
Materials science ,Buckling ,Axial compression ,Steel tube ,Composite material ,Stub (electronics) - Published
- 2018
49. A BUFFER STRUCTURE COMPOSED OF FLEXIBLE NETS AND SPRING-RODS FOR ROCKFALL PROTECTION
- Author
-
Yaopeng Liu, Hu Xu, Zhixiang Yu, Shichun Zhao, Rui Bai, Chang Yang, and Lei Zhao
- Subjects
geography ,Rockfall ,geography.geographical_feature_category ,Geotechnical engineering ,Spring (mathematics) ,Rod ,Buffer (optical fiber) ,Geology - Published
- 2018
50. Numerical analysis study on seismic behavior of resilient high strength concrete columns reinforced by ultra-high-strength bars
- Author
-
Shichun Zhao, Yuping Sun, and Jiabang Shao
- Subjects
Materials science ,business.industry ,Numerical analysis ,Structural engineering ,business ,High strength concrete - Abstract
To make concrete columns with drift-hardening behavior and small residual deformation, a simple method is proposed. The method is the use of ultra-high-strength (UHS) PC wire strands as longitudinal reinforcements of concrete columns. The effectiveness of the method has been verified by experiments. The purpose of this paper is to present an analytical method for simulating seismic behavior of resilient high-strength concrete columns reinforced by PC strands, based on reliable constitutive laws of the PC strands and the concrete. Five square concrete columns with the cross-section of 250mm × 250mm, the height of 1000 mm, the shear span ratio of 2.0, the axial load ratio of 0.25 and compressive cubic strength of 95 MPa were fabricated and tested. The experimental results were compared with the results predicted by the analytical method. Comparisons indicate that the proposed method can predict the development trend and feature points of the envelop curve of the columns until large deformation. Comparisons also indicate that the calculated flexural capacities by the proposed method show very good agreement with the test results. Utilizing the proposed method and the current design code, which are used to evaluate the ultimate flexure and shear capacities, respectively, can give a reasonable evaluation of the failure mode of concrete columns.
- Published
- 2019
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