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Earthquake engineering and engineering Vibration 2024年第2期23卷 445-454页

作者： Li Yuchun Shen Chao Liu Wei Li Dong department of hydraulic engineering College of Civil EngineeringTongji UniversityShanghai 200092China

The auto-parametric resonance of a continuous-beam bridge model subjected to a two-point periodic excitation is experimentally and numerically investigated in this study.An auto-parametric resonance experiment of the test model is conducted to observe and measure the auto-parametric resonance of a continuous beam under a two-point excitation on columns.The parametric vibration equation is established for the test model using the finite-element method.The auto-parametric resonance stability of the structure is analyzed by using Newmark's method and the energy-growth exponent method.The effects of the phase difference of the two-point excitation on the stability boundaries of auto-parametric resonance are studied for the test model.Compared with the experiment,the numerical instability predictions of auto-parametric resonance are consistent with the test phenomena,and the numerical stability boundaries of auto-parametric resonance agree with the experimental ones.For a continuous beam bridge,when the ratio of multipoint excitation frequency(applied to the columns)to natural frequency of the continuous girder is approximately equal to 2,the continuous beam may undergo a strong auto-parametric resonance.Combined with the present experiment and analysis,a hypothesis of Volgograd Bridge's serpentine vibration is discussed.

关键词： auto-parametric resonance continuous beam bridge model two-point excitation experimental investigation stability analysis vibration of Volgograd Bridge

Interaction Mechanisms between Natural Debris Flow and Rigid Barrier Deflectors:A New Perspective for Rational Design and Optimal Arrangement

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Computer Modeling in engineering & Sciences 2024年第5期139卷 1679-1699页

作者： Yu Huang Beilei Liu Dianlei Feng Hao Shi department of Geotechnical engineering College of Civil EngineeringTongji UniversityShanghai200092China department of hydraulic engineering College of Civil EngineeringTongji UniversityShanghai200092China

Rigid barrier deflectors can effectively prevent overspilling landslides,and can satisfy disaster prevention requirements.However,the mechanisms of interaction between natural granular flow and rigid barrier deflectors require further investigation.To date,few studies have investigated the impact of deflectors on controlling viscous debris flows for geological disaster prevention.To investigate the effect of rigid barrier deflectors on impact mechanisms,a numerical model using the smoothed particle hydrodynamics(SPH)method with the Herschel–Bulkley model is proposed to simulate the interaction between natural viscous flow and single/dual barriers with and without deflectors.This model was validated using laboratory flume test data from the literature.Then,the model was used to investigate the influence of the deflector angle and multi-barrier arrangements.The optimal configuration of multi-barriers was analyzed with consideration to the barrier height and distance between the barriers,because these metrics have a significant impact on the viscous flow pile-up,run-up,and overflow mechanisms.The investigation considered the energy dissipation process,retention efficiency,and dead-zone formation.Compared with bare barriers with similar geometric characteristics and spatial distribution,rigid barriers with deflectors exhibit superior effectiveness in preventing the overflow and overspilling of viscous debris flow.Recommendations for the rational design of deflectors and the optimal arrangement of multi-barriers are provided to mitigate geological disasters.

关键词： Rigid barrier deflectors deflector angle single-barrier dual-barrier arrangements viscous debris flow over-spilling delta-plus-SPH

Sparse Modal Decomposition Method Addressing Underdetermined Vortex-Induced Vibration Reconstruction Problem for Marine Risers

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China Ocean engineering 2024年第2期38卷 285-296页

作者： DU Zun-feng ZHU Hai-ming YU Jian-xing State Key Laboratory of hydraulic engineering Intelligent Construction and Operation School of Civil EngineeringTianjin UniversityTianjin 300350China

When investigating the vortex-induced vibration(VIV)of marine risers,extrapolating the dynamic response on the entire length based on limited sensor measurements is a crucial step in both laboratory experiments and fatigue monitoring of real risers.The problem is conventionally solved using the modal decomposition method,based on the principle that the response can be approximated by a weighted sum of limited vibration modes.However,the method is not valid when the problem is underdetermined,i.e.,the number of unknown mode weights is more than the number of known measurements.This study proposed a sparse modal decomposition method based on the compressed sensing theory and the Compressive Sampling Matching Pursuit(Co Sa MP)algorithm,exploiting the sparsity of VIV in the modal space.In the validation study based on high-order VIV experiment data,the proposed method successfully reconstructed the response using only seven acceleration measurements when the conventional methods failed.A primary advantage of the proposed method is that it offers a completely data-driven approach for the underdetermined VIV reconstruction problem,which is more favorable than existing model-dependent solutions for many practical applications such as riser structural health monitoring.

关键词： motion reconstruction vortex-induced vibration(VIV) marine riser modal decomposition method compressed sensing

Experimental Study on Towing Characteristics of Composite Bucket Wellhead Platform

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China Ocean engineering 2024年第3期38卷 531-542页

作者： ZHANG Pu-yang LIU Ying-fei LE Cong-huan DING Hong-yan BAI Yu State Key Laboratory of hydraulic engineering Intelligent Construction and Operation Tianjin UniversityTianjin 300072China

With the rapid development of large-scale development of marginal oilfields in China,simple wellhead platforms that are simple in structure and easy to install have become an inevitable choice in the process of oilfield development.However,traditional simple wellhead platforms are often discarded after a single use.In pursuit of a more costeffective approach to developing marginal oilfields,this paper proposes a new offshore oil field development facility—an integrated bucket foundation for wellhead platform.To verify the safety of its towing behavior and obtain the dynamic response characteristics of the structure,this paper takes a bucket integrated bucket foundation for wellhead platform with a diameter of 40 m as the research object.By combining physical model tests and numerical simulations,it analyzes the static stability and dynamic response characteristics of the structure during towing,complete with the effects of the draft,wave height,wave period,and towing point height,which produce the dynamic responses of the structure under different influence factors,such as roll angle,pitch angle,heave acceleration and towing force as well as the sensibility to transport variables.The results show that the integrated bucket foundation for wellhead platform is capable of self-floating towing,and its movement is affected by the local environment,which will provide a reference for actual projects.

关键词： composite bucket foundation wellhead platform air flotation towing model test

Time-dependent deviation of bridge pile foundations caused by adjacent large-area surcharge loads in soft soils and its preventive measures

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Frontiers of Structural and Civil engineering 2024年第2期18卷 184-201页

作者： Shuanglong LI Limin WEI Jingtai NIU Zhiping DENG Bangbin WU Wuwen QIAN Feifei HE School of hydraulic engineering Nanchang Institute of TechnologyNanchang 330099China School of Civil engineering Central South UniversityChangsha 410075China

Time-dependent characteristics(TDCs)have been neglected in most previous studies investigating the deviation mechanisms of bridge pile foundations and evaluating the effectiveness of preventive measures.In this study,the stress-strain-time characteristics of soft soils were illustrated by consolidation-creep tests based on a typical engineering case.An extended Koppejan model was developed and then embedded in a finite element(FE)model via a user-material subroutine(UMAT).Based on the validated FE model,the time-dependent deformation mechanism of the pile foundation was revealed,and the preventive effect of applying micropiles and stress-release holes to control the deviation was investigated.The results show that the calculated maximum lateral displacement of the cap differs from the measured one by 6.5%,indicating that the derived extended Koppejan model reproduced the deviation process of the bridge cap-pile foundation with time.The additional load acting on the pile side caused by soil lateral deformation was mainly concentrated within the soft soil layer and increased with the increase in load duration.Compared with t=3 d(where t is surcharge time),the maximum lateral additional pressure acting on Pile 2#increased by approximately 47.0%at t=224 d.For bridge pile foundation deviation in deep soft soils,stress-release holes can provide better prevention compared to micropiles and are therefore recommended.

关键词： bridge pile foundation surcharge load soft soil time-dependent deformation interaction mechanism preventive measure

Particle Discontinuous Deformation Analysis of Static and Dynamic Crack Propagation in Brittle Material

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Computer Modeling in engineering & Sciences 2024年第5期139卷 2215-2236页

作者： Zediao Chen Feng Liu State Key Laboratory of hydraulic engineering Intelligent Construction and Operation Tianjin UniversityTianjin300072China

Crack propagation in brittle material is not only crucial for structural safety evaluation,but also has a wideranging impact on material design,damage assessment,resource extraction,and scientific research.A thorough investigation into the behavior of crack propagation contributes to a better understanding and control of the properties of brittle materials,thereby enhancing the reliability and safety of both materials and structures.As an implicit discrete elementmethod,the Discontinuous Deformation Analysis(DDA)has gained significant attention for its developments and applications in recent years.Among these developments,the particle DDA equipped with the bonded particle model is a powerful tool for predicting the whole process of material from continuity to failure.The primary objective of this research is to develop and utilize the particle DDAtomodel and understand the complex behavior of cracks in brittle materials under both static and dynamic loadings.The particle DDA is applied to several classical crack propagation problems,including the crack branching,compact tensile test,Kalthoff impact experiment,and tensile test of a rectangular plate with a hole.The evolutions of cracks under various stress or geometrical conditions are carefully investigated.The simulated results are compared with the experiments and other numerical results.It is found that the crack propagation patterns,including crack branching and the formation of secondary cracks,can be well reproduced.The results show that the particle DDA is a qualified method for crack propagation problems,providing valuable insights into the fracture mechanism of brittle materials.

关键词： Discontinuous deformation analysis particle DDA crack propagation crack branching brittle materials

Preface for the Special Issue on“Safety and Intelligent Maintenance of Offshore Structures”

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China Ocean engineering 2024年第2期38卷 181-182页

作者： XU Wan-hai State Key Laboratory of hydraulic engineering Intelligent Construction and Operation Tianjin UniversityTianjin 300072China

The ocean serves as a vital carrier for human resource development and economic growth and contains rich mineral resources such as oil,natural gas,polymetallic nodules,cobalt-rich ferromanganese crusts,polymetallic sulfides,and rare earth ore.Moreover,the ocean has wealthy reserves of wind,wave,tidal,and solar energy,making it an essential strategic space for sustainable future development.However,offshore structures are complex.

关键词： ocean offshore tidal

Comparisons of Wave Force Model Effects on the Structural Responses and Fatigue Loads of a Semi-Submersible Floating Wind Turbine

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Journal of Ocean University of China 2024年第1期23卷 69-79页

作者： HAN Yanqing LE Conghuan ZHANG Puyang XU Shengnan State Key Laboratory of hydraulic engineering Simulation and Safety Tianjin UniversityTianjin 300072China School of hydraulic engineering Ludong UniversityYantai 264025China School of Civil engineering Tianjin UniversityTianjin 300072China Shandong Marine Aerospace Equipment Technological Innovation Center Yantai 264004China

The selection of wave force models will significantly impact the structural responses of floating wind turbines.In this study,comparisons of wave force model effects on the structural responses and fatigue loads of a semi-submersible floating wind turbine(SFWT)were conducted.Simulations were performed by employing the Morison equation(ME)with linear or second-order wave kinematics and potential flow theory(PFT)with first-or second-order wave forces.A comparison of regular waves,irregular waves,and coupled wind/waves analyses with the experimental data showed that many of the simulation results and experimental data are relatively consistent.However,notable discrepancies are found in the response amplitude operators for platform heave,tower base bending moment,and tension in mooring lines.PFT models give more satisfactory results of heave but more significant discrepan-cies in tower base bending moment than the ME models.In irregular wave analyses,low-frequency resonances were captured by PFT models with second-order difference-frequency terms,and high-frequency resonances were captured by the ME models or PFT models with second-order sum-frequency terms.These force models capture the response frequencies but do not reasonably predict the response amplitudes.The coupled wind/waves analyses showed more satisfactory results than the wave-only analyses.However,an important detail to note is that this satisfactory result is based on the overprediction of wind-induced responses.

关键词： floating wind turbine wave force model potential flow theory Morison equation second-order wave forces

Experimental,Numerical,and Analytical Studies on the Bending of Mechanically Lined Pipe

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China Ocean engineering 2024年第2期38卷 221-232页

作者： WEI Wen-bin YUAN Lin ZHOU Jia-sheng LIU Zheng State Key Laboratory of hydraulic engineering Simulation and Safety Tianjin UniversityTianjin 300072China School of Civil engineering Tianjin UniversityTianjin 300072China School of Mechanical engineering Tianjin UniversityTianjin 300072China

Mechanically lined pipe(MLP)is often used for offshore oil and gas transport because of its low cost and corrosion resistance.During installation and operation,the pipe may undergo severe bending deformation,which causes the liner to separate from the outer pipe and buckles,affecting the stability of the whole line.In this paper,the buckling response of MLP subjected to bending is investigated to clarify its bending characteristics by employing both experiments,numerical simulation,as theoretical methods.Two types of MLPs were manufactured with GB 45 carbon steel(SLP)and Al 6061(ALP)used as the outer pipe material,respectively.The hydraulic expansion and bending experiments of small-scale MLPs are conducted.In addition to the ovalized shape of the cross-section for the SLP specimens,the copper liner was found to wrinkle on the compressive side.In contrast,the liner of ALP remains intact without developing any wrinkling and collapse mode.In addition,a dedicated numerical framework and theoretical models were also established.It was found both the manufacturing and bending responses of the MLP can be well reproduced,and the predicted maximum moment and critical curvatures are in good agreement with the experimental results.

关键词： lined pipe bending nonlinear ring theory buckling plasticity

Experimental and numerical study regarding H-steel all-bolted connection steel frame with composite wall boards

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Earthquake engineering and engineering Vibration 2024年第2期23卷 427-443页

作者： Fan Min Guo Hongchao Li Shen Wang Zhenshan Wang Huaqiang School of Civil engineering and Architecture Xi’an University of TechnologyXi’an 710048China State Key Laboratory Base of Eco-hydraulic engineering in Arid Area Xi’an University of TechnologyXi’an 710048China

H-steel all-bolted connection steel frame structures with heat preservation and decoration composite wall boards were investigated and the seismic performances of three scaled specimens were studied.The failure modes,hysteresis curves,bearing capacity,ductility,energy dissipation capacity,stiffness degradation and strain distribution were discussed.The calculation method of structural theoretical internal force was presented.The results showed that the overall structural seismic performance was better,and the structural ductility met the demands of elastic-plastic inter-story drift angle for seismic design.The H-steel weak-axis connection structure obtained better energy dissipation capacity,and its bearing capacity and stiffness were slightly different from the strong-axis connection.The heat preservation and decoration performance of composite wallboard and the all-bolted connection of the steel frame realized prefabrication during the whole construction period.The plastic hinge of the steel beam can be moved outwards because of the L-angles,which effectively avoids stress concentration in joint areas and expands the plastic hinge range.The errors between the theoretical structural capacity calculated by the plastic analysis method and the test results were within 2.44%.In addition,structural failure mechanisms and bearing capacities were verified by the finite element(FE)analysis,and the effects of the main parameters on the structures were investigated.The FE verification results were the same as in the test.The research results provide theoretical support and technical guidance for the application of thermal insulation and decorative composite wall panels in H-shaped steel all-bolted steel frames.

关键词： composite wall boards all-bolted steel frame H-steel low-cyclic loading failure modes