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Journal of Wuhan University of Technology(Materials Science) 2024年第3期39卷 570-586页

作者：张辉邬忠虎 SONG Huailei WANG Wentao TANG Motian CUI Hengtao college of civil engineering Guizhou UniversityGuiyang 550025China

To study the damage and failure of shale with different fracture inclination angles under uniaxial compression loading,in this work,RFPA2D-Thermal,a two-dimensional real failure process analysis software,was used for numerical *** simulation results show that quartz in shale mainly affects the tensile and compressive strength of shale by increasing rock *** coupling of temperature and pressure will cause lateral and volume destruction of shale,which enables the shale body to be more easily *** inclination is the key factor affecting shale damage *** failure mode of shale with low-and high-angle fractures is mainly shear failure,and the compressive strength does not vary with crack *** damage mode of obliquely intersecting fractured shale is slip damage along the fracture face,the compressive strength decreases and then increases with the fracture inclination,and a minimum value *** acoustic emission simulation results of the damage process effectively reflect the accumulated internal damage and macroscopic crack appearance until fracture instability when the prefabricated fractured shale is subjected to uniaxial compressive *** crack inclinations of 0°and 120℃ corresponds to the most complex"N"shape damage *** crack inclinations of 30°and 60°,and the damage mode is an inverted"λ"shape.

关键词： shale temperature and pressure numerical simulation fracture dip angle fractal dimension

Seismic response of a mid-story isolated structure considering SSI in mountainous areas under long-period earthquakes

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Earthquake engineering and engineering Vibration 2024年第1期23卷 151-161页

作者： Wan Feng Qin Shengwu Liu Dewen Zhao Tiange Zheng Yanping Shan Hang Li Zhiang Peng Fusong Xu Jingran Lei Min college of Construction engineering Jilin UniversityChangchun 130015China college of civil engineering Southwest Forestry UniversityKunming 650024China college of civil engineering Southwest Jiaotong UniversityChengdu 610031China

At present,there is not much research on mid-story isolated structures in mountainous *** this study,a model of a mid-story isolated structure considering soil-structure interaction(SSI)in mountainous areas is established along with a model that does not consider *** long-period earthquake waves and two ordinary earthquake waves are selected as inputs for the dynamic time history analysis of the *** results show that the seismic response of a mid-story isolated structure considering SSI in mountainous areas can be amplified when compared with a structure that does not consider *** structure response under long-period earthquakes is larger than that of ordinary *** structure response under far-field harmonic-like earthquakes is larger than that of near-fault pulse-type *** structure response under near-fault pulse-type earthquakes is larger than that of far-field non-harmonic *** subjected to long-period earthquakes,the displacement of the isolated bearings exceeded the limit value,which led to instability and overturning of the *** structure with dampers in the isolated story could adequately control the nonlinear response of the structure,effectively reduce the displacement of the isolated bearings,and provide a convenient,efficient and economic method not only for new construction but also to retrofit existing structures.

关键词： SSI in mountainous areas long-period earthquakes mid-story isolated structure structural dynamic analysis

Simplified design of nonlinear damper parameters and seismic responses for long-span cable-stayed bridges with nonlinear viscous dampers

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Frontiers of Structural and civil engineering 2024年第7期18卷 1103-1116页

作者： Huihui LI Lifeng LI Rui HU Meng YE college of civil and Transportation engineering Shenzhen UniversityShenzhen 518060China Guangdong Provincial Key Laboratory of Durability for Marine civil engineering Shenzhen UniversityShenzhen 518060China college of civil engineering Hunan UniversityChangsha 410082China

Viscous dampers are widely used as passive energy dissipation devices for long-span cable-stayed bridges for mitigation of seismic load-induced ***,complicated finite element(FE)modeling,together with repetitive and computationally intensive nonlinear time-history analyses(NTHAs)are generally required in conventional design *** streamline the preliminary design process,this paper developed a simplified longitudinal double degree of freedom model(DDFM)for single and symmetric twin-tower cable-stayed *** on the proposed simplified longitudinal DDFM,the analytical equations for the relevant mass-and stiffness-related parameters and longitudinal natural frequencies of the structure were derived by using analytical and energy *** of the relationship between the nonlinear viscous damper parameters and the equivalent damping ratio was achieved through the equivalent linearization ***,the analytical equations of longitudinal seismic responses for long-span cable-stayed bridges with nonlinear viscous dampers were *** on the developed simplified DDFM and suggested analytical equations,this paper proposed a simplified calculation framework to achieve a simplified design method of nonlinear viscous damper ***,the effectiveness and applicability of the developed simplified longitudinal DDFM and the proposed calculation framework were further validated through numerical analysis of a practical cable-stayed ***,the results indicated the following.1)For the obtained fundamental period and longitudinal stiffness,the differences between results of the simplified longitudinal DDFM and numerical analysis were only 2.05%and 1.5%,respectively.2)Relative calculation errors of the longitudinal girder-end displacement and bending moment of the bottom tower section of the bridge obtained from the simplified longitudinal DDFM were limited to less than 25%.3)The equivalent damping ratio of nonline

关键词： cable-stayed bridges viscous dampers simplified analytical model equivalent damping ratio seismic mitigation

Experimental and numerical study on dynamic mechanical behaviors of shale under true triaxial compression at high strain rate

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International Journal of Mining Science and Technology 2024年第2期34卷 149-165页

作者： Xiaoping Zhou Linyuan Han Jing Bi Yundong Shou School of civil engineering Wuhan UniversityWuhan 430072China college of civil engineering Guizhou UniversityGuiyang 550025China

High-energy gas fracturing of shale is a novel,high efficacy and eco-friendly mining technique,which is a typical dynamic perturbing *** effectively extract shale gas,it is important to understand the dynamic mechanical properties of *** experiments on shale subjected to true triaxial compression at different strain rates are first conducted in this *** dynamic stress-strain curves,peak strain,peak stress and failure modes of shale are *** results of the study indicate that the intermediate principal stress and the minor principal stress have the significant influence on the dynamic mechanical behaviors,although this effect decreases as the strain rate *** characteristics of compression-shear failure primarily occur in shale subjected to triaxial compression at high strain rates,which distinguishes it from the fragmentation characteristics observed in shale under dynamic uniaxial ***,a numerical three-dimensional Split Hopkinson Pressure Bar(3D-SHPB),which is established by coupling PFC3D and FLAC3D methods,is validated to replicate the laboratory characteristics of *** dynamic mechanical characteristics of shale subjected to different confining stresses are systematically investigated by the coupling PFC3D and FLAC3D *** numerical results are in good agreement with the experimental data.

关键词： Dynamic behaviors True triaxial compression High strain rates Dynamic failure mechanism PFC3D-FLAC3D coupled method

An ultra-thin bolt tension sensor and online monitoring system:For application in hydropower plant unit

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Frontiers of Structural and civil engineering 2024年第9期18卷 1388-1400页

作者： Shaoquan ZHANG Yanke TAN Hanbin GE Qilin ZHANG Department of civil engineering Meijo UniversityNagoya 4688502Japan college of civil engineering Tongji UniversityShanghai 200092China

The condition of bolted connections significantly affects the structural ***,conventional bolt tension sensors fail to provide precise measurements due to their bulky size or inadequate *** study employs the piezoresistive effect of crystalline silicon material to fabricate an ultrathin *** sensor exhibits a linear relationship between pressure and voltage,an exceptional stability at varying temperatures,and a superior resistance to corrosion,making it adaptable and user-friendly for applications of high-strength bolt tension monitoring.A monitoring system,incorporating the proposed sensor,has also been *** system provides real-time display of bolt tension and enables the assessment of sensor and structural conditions,including bolt loosening or component *** efficacy of the proposed sensor and monitoring system was validated through a project carried out at the Xiluodu Hydropower *** to the results,the sensor and online monitoring system effectively gauged and proficiently conveyed and stored bolt tension *** addition,correlations were created between bolt tensions and essential unit parameters,such as water head,active power,and pressures at vital points,facilitating anomaly detection and early warning.

关键词： ultra-thin sensor high-strength bolt tension online monitoring system anomaly alarm hydro-generator units

Parametric investigation on the novel and cost-effective nano fly ash impregnated geopolymer system for sustainable construction

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Frontiers of Structural and civil engineering 2024年第2期18卷 170-183页

作者： R.MOHANA S.M.Leela BHARATHI Department of civil engineering Mepco Schlenk Engineering CollegeSivakasi 626123India

The hazardous environmental effects of greenhouse gas emissions and climate change demand alternative sources for cementitious materials in the construction *** development of geopolymer structures provides a way of producing 100%cement-free *** this research work,a novel and simple way of deriving nano particles from waste fly ash particles is *** effect of adding the synthesized nano fly ash particles as a filler medium in geopolymer mortars was investigated by considering strength and durability *** optimization was done by using regression analysis on the geopolymer mortar and the impact of adding nano fly ash particles was studied by varying different percentages of addition ranging from 0 to 7.5%by weight of binder *** the results,it was observed that 1%nano fly ash acted not only as a filler but also as nano-sized precursors of the polymerization process,resulting in denser geopolymer *** can explain the extraordinary gain in strength of 72.11 MPa as well as the denser core with negligible level of chloride ion penetration,making the material suitable for the development of structures susceptible to marine environment.

关键词： geopolymer nano fly ash chloride ion penetration durability polymerization fillers

Preparation and Reinforcement Adaptability of Jute Fiber Reinforced Magnesium Phosphate Cement Based Composite Materials

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Journal of Wuhan University of Technology(Materials Science) 2024年第4期39卷 999-1009页

作者：刘芯州郭远臣 WANG Rui XIANG Kai WANG Xue YE Qing college of civil engineering Chongqing Three Gorges UniversityChongqing 404100China

To improve the brittleness characteristics of magnesium phosphate cement-based materials(MPC)and to promote its promotion and application in the field of structural reinforcement and repair,this study aimed to increase the toughness of MPC by adding jute fiber,explore the effects of different amounts of jute fiber on the working and mechanical properties of MPC,and prepare jute fiber reinforced magnesium phosphate cement-based materials(JFRMPC)to reinforce damaged *** improvement effect of beam performance before and after reinforcement was compared,and the strengthening and toughening mechanisms of jute fiber on MPC were explored through microscopic *** experimental results show that,as the content of jute fiber(JF)increases,the fluidity and setting time of MPC decrease continuously;When the content of jute fiber is 0.8%,the compressive strength,flexural strength,and bonding strength of MPC at 28 days reach their maximum values,which are increased by 18.0%,20.5%,and 22.6%compared to those of M0,*** beam strengthened with JFRMPC can withstand greater deformation,with a deflection of 2.3 times that of the unreinforced beam at *** strain of the steel bar is greatly reduced,and the initial crack and failure loads of the reinforced beam are increased by 192.1%and 16.1%,respectively,compared to those of the unreinforced *** JF added to the MPC matrix dissipates energy through tensile fracture and debonding pull-out,slowing down stress concentration and inhibiting the free development of cracks in the matrix,enabling JFRMPC to exhibit higher strength and better *** JF does not cause the hydration of MPC to generate new compounds but reduces the amount of hydration products generated.

关键词： magnesium phosphate cement jute fiber reinforcement of damaged beam flexural behavior

A unified stochastic damage model for concrete based on multi-scale energy dissipation analysis

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Science China(Technological Sciences) 2024年第3期67卷 863-877页

作者： GUO ChengGong LI Jie college of civil engineering Tongji UniversityShanghai 200092China State Key Laboratory of Disaster Reduction in civil engineering Shanghai 200092China

This work proposes a unified damage model for concrete within the framework of stochastic damage mechanics. Based on the micro-meso stochastic fracture model(MMSF), the nonlinear energy dissipation process of the microspring from nanoscale to microscale is investigated. In nanoscale, the rate process theory is adopted to describe the crack growth rate;therefore, the corresponding energy dissipation caused by a representative crack propagation can be obtained. The scale gap from nanoscale to microscale is bridged by a crack hierarchy model. Thus, the total energy dissipated by all cracks from the nanoscale to the microscale is gained. It is found that the fracture strain of the microspring can be derived from the above multi-scale energy dissipation analysis. When energy dissipation is regarded as some microdamage to the microspring, the constitutive law of the microspring is no longer linearly elastic, as previously assumed. By changing the expression of the damage evolution law from fracture strain to energy dissipation threshold, the new damage evolution model is derived. The proposed model can not only replicate the original static model but also extend to cases of rate dependence. By deriving the fracture strain under different strain rates, the rate sensitivity of concrete materials can be reflected. The model parameters can be conveniently obtained by identifying them with experimental data. Finally, several numerical examples are presented to verify the proposed model.

关键词： concrete damage model stochastic damage rate dependent energy dissipation

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 ***,the mechanisms of interaction between natural granular flow and rigid barrier deflectors require further *** date,few studies have investigated the impact of deflectors on controlling viscous debris flows for geological disaster *** 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 *** model was validated using laboratory flume test data from the ***,the model was used to investigate the influence of the deflector angle and multi-barrier *** 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 *** investigation considered the energy dissipation process,retention efficiency,and dead-zone *** 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 *** 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

Auto-parametric resonance of a continuous-beam-bridge model under two-point periodic excitation:an experimental investigation and stability analysis

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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 *** 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 *** parametric vibration equation is established for the test model using the finite-element *** auto-parametric resonance stability of the structure is analyzed by using Newmark's method and the energy-growth exponent *** effects of the phase difference of the two-point excitation on the stability boundaries of auto-parametric resonance are studied for the test *** 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 *** 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 *** 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