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Field Load Test Based SHM System Safety Standard Determination for Rigid Frame Bridge

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Structural Durability & Health Monitoring 2024年第3期18卷 361-376页

作者： Xilong Zheng Qiong Wang Di Guan school of civil and Architectural engineering Harbin UniversityHarbin150076China

The deteriorated continuous rigid frame bridge is strengthened by external prestressing. Static loading tests wereconducted before and after the bridge rehabilitation to verify the effectiveness of the rehabilitation process. Thestiffness of the repaired bridge is improved, and the maximum deflection of the load test is reduced from 37.9 to27.6 mm. A bridge health monitoring system is installed after the bridge is reinforced. To achieve an easy assessmentof the bridge’s safety status by directly using transferred data, a real-time safety warning system is createdbased on a five-level safety standard. The threshold for each safety level will be determined by theoretical calculationsand the outcomes of static loading tests. The highest risk threshold will be set at the ultimate limit statevalue. The remaining levels, namely middle risk, low risk, and very low risk, will be determined usingreduction coefficients of 0.95, 0.9, and 0.8, respectively.

关键词： Continuous rigid frame bridge rehabilitation long-term monitoring field load test safety standard determination

Spatiotemporal variations of sand hydraulic conductivity by microbial application methods

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Journal of Rock Mechanics and Geotechnical engineering 2024年第1期16卷 268-278页

作者： Viroon Kamchoom Thiti Khattiwong Treesukon Treebupachatsakul Suraparb Keawsawasvong Anthony Kwan Leung Excellent Centre for Green and Sustainable Infrastructure Department of Civil EngineeringSchool of EngineeringKing Mongkut’s Institute of Technology Ladkrabang(KMITL)Bangkok10520Thailand Department of Biomedical engineering School of EngineeringKing Mongkut’s Institute of Technology Ladkrabang(KMITL)Bangkok10520Thailand Department of civil engineering Thammasat School of EngineeringThammasat UniversityPrathumthani10200Thailand Department of civil and Environmental engineering The Hong Kong University of Science and Technology(HKUST)Hong KongChina

The spatiotemporal distributions of microbes in soil by different methods could affect the efficacy of the microbes to reduce the soil hydraulic *** this study,the specimens of bio-mediated sands were prepared using three different methods,***,mixing,and pouring a given microbial so-lution onto compacted sand *** hydraulic conductivity was measured by constant-head tests,while any soil microstructural changes due to addition of the microbes were observed by scan-ning electron microscope(SEM)and mercury intrusion porosimetry(MIP)*** amount of dextran concentration produced by microbes in each type of specimen was quantified by a *** show that dextran production increased exponentially after 5-7 d of microbial settling with the supply of culture *** injection and mixing methods resulted in a similar amount and uniform dis-tribution of dextran in the *** pouring method,however,produced a nonuniform distri-bution,with a higher concentration near the specimen *** the supply of culture medium discontinued,the dextran content near the surface produced by the pouring method decreased dramatically due to high competition for nutrients with foreign *** dextran concentration was negatively and correlated with hydraulic conductivity of bio-mediated soils exponentially,due to the clogging of large soil pores by *** hydraulic conductivity of the injection and mixing cases did not change significantly when the supply of culture medium was absent.

关键词： Bio-mediated soil Dextran Hydraulic conductivity Leuconostoc mesenteroides Microbial application Microstructure

Theoretical Analysis on Deflection and Bearing Capacity of Prestressed Bamboo-Steel Composite Beams

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Journal of Renewable Materials 2024年第1期12卷 149-166页

作者： Qifeng Shan Ming Mao Yushun Li school of civil engineering Zhejiang Industry Polytechnic CollegeShaoxing312000China school of civil&Environmental engineering and Geography Science Ningbo UniversityNingbo315211China College of civil engineering and Architecture Qingdao Agricultural UniversityQingdao266109China

A theoretical analysis of upward deflection and midspan deflection of prestressed bamboo-steel composite beams is presented in this *** deflection analysis considers the influences of interface slippage and shear ***,the calculation model for flexural capacity is proposed considering the two stages of *** theoretical results are verified with 8 specimens considering different prestressed load levels,load schemes,and prestress *** results indicate that the proposed theoretical analysis provides a feasible prediction of the deflection and bearing capacity of bamboo-steel composite *** deflection analysis,the method considering the slippage and shear deformation provides better *** theoretical method for bearing capacity matches well with the test results,and the relative errors in the serviceability limit state and ultimate limit state are 4.95%and 5.85%,respectively,which meet the accuracy requirements of the engineered application.

关键词： Bamboo scrimber composite beam prestress deflection bearing capacity

Reinforcing effects of polypropylene on energy absorption and fracturing of cement-based tailings backfill under impact loading

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International Journal of Minerals,Metallurgy and Materials 2024年第4期31卷 650-664页

作者： Jiajian Li Shuai Cao Erol Yilmaz school of civil and resources engineering University of Science and Technology BeijingBeijing 100083China State Key Laboratory of High-Efficient Mining and Safety of Metal Mines of Ministry of Education University of Science and Technology BeijingBeijing 100083China Department of civil engineering Geotechnical DivisionRecep Tayyip Erdogan UniversityFenerRize TR53100Turkey

Polypropylene(PP)fiber-reinforced cement-based tailings backfill(FRCTB)is a green compound material with superior crack resistance and has good prospects for application in underground ***,FRCTB exhibits susceptibility to dynamic events,such as impact ground pressure and blast *** paper investigates the energy and crack distribution behavior of FRCTB under dynamic impact,considering the height/diameter(H/D)*** Hopkinson pressure bar,industrial computed tomography scan,and scanning electron microscopy(SEM)experiments were carried out on six types of *** outcomes confirmed fiber aggregation at the bottom of *** H/D was less than 0.8,the proportion of PP fibers distributed along theθangle direction of80°-90°*** the total energy,all samples presented similar energy absorption,reflectance,and ***,a rise in H/D may cause a rise in the energy absorption rate of FRCTB during the peak phase.A positive correlation existed between the average strain rate and absorbed energy per unit *** increase in H/D resulted in a decreased crack volume fraction of *** the H/D was greater than or equal to 0.7,the maximum crack volume fraction of FRCTB was observed close to the incidence *** cracks were present only in the FRCTB with an H/D ratio of *** with H/D ratios of 0.5 and 0.6 showed similar distributions of weakly and heavily damaged *** fibers can limit the emergence and expansion of cracks by influencing their *** observations revealed considerable differences in the bonding strengths between fibers and the *** that adhered particularly well to the substrate were attracted together with the hydration products adhering to *** results show that FRCTB is promising as a sustainable and green backfill for determining the design properties of mining with backfill.

关键词： cement-based tailings fiber-reinforced backfills fracture energy absorption impact loading

Quasi-static and dynamic compressive behaviour of additively manufactured Menger fractal cube structures

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Defence Technology（防务技术） 2024年第7期37卷 39-49页

作者： Damith Mohotti Dakshitha Weerasinghe Madhusha Bogahawaththa Hongxu Wang Kasun Wijesooriya Paul JHazell school of engineering and Technology UNSWCanberraACT2600Australia school of civil Mining and Environmental EngineeringFaculty of Engineering and Information SciencesUniversity of WollongongWollongongNSWAustralia

This paper presents the first-ever investigation of Menger fractal cubes'quasi-static compression and impact *** cubes with different void ratios were 3D printed using polylactic acid(PLA)with dimensions of 40 mm×40 mm×40 *** different orders of Menger cubes with different void ratios were considered,namely M1 with a void ratio of 0.26,M2 with a void ratio of 0.45,and M3with a void ratio of ***-static Compression tests were conducted using a universal testing machine,while the drop hammer was used to observe the behaviour under impact *** fracture mechanism,energy efficiency and force-time histories were *** the structured nature of the void formation and predictability of the failure modes,the Menger geometry showed some promise compared to other alternatives,such as foams and *** the increasing void ratio,the Menger geometries show force-displacement behaviour similar to hyper-elastic materials such as rubber and *** third-order Menger cubes showed the highest energy absorption efficiency compared to the other two geometries in this *** findings of the present work reveal the possibility of using additively manufactured Menger geometries as an energy-efficient system capable of reducing the transmitting force in applications such as crash barriers.

关键词： Additive manufacturing Fractal geometries Menger cube Energy absorption Quasi-static

Self-templating synthesis of biomass-based porous carbon nanotubes for energy storage and catalytic degradation applications

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Green Energy & Environment 2024年第3期9卷 584-595页

作者： Manman Xu Shiqi Fu Yukai Wen Wei Li Qiongfang Zhuo Haida Zhu Zhikeng Zheng Yuwen Chen Anqi Wang Kai Yan Research Centre for Eco-Environmental engineering School of Environment and Civil EngineeringDongguan University of TechnologyDongguan523808China school of Environmental Science and engineering Sun Yat-sen UniversityGuangzhou510275China

Dwindling energy sources and a worsening environment are huge global problems,and biomass wastes are an under-exploited source of material for both energy and material ***,self-template decoction dregs of Ganoderma lucidum-derived porous carbon nanotubes(ST-DDLGCs)were synthesized via a facile and scalable strategy in response to these ***-DDLGCs exhibited a large surface area(1731.51 m^(2)g^(-1))and high pore volume(0.76 cm^(3)g^(-1)),due to the interlacing tubular structures of precursors and extra-hierarchical porous structures on tube *** the ST-DDLGC/PMS system,the degradation efficiency of capecitabine(CAP)reached~97.3%within 120 ***,ST-DDLGCs displayed high catalytic activity over a wide pH range of 3–9,and strong anti-interference to these typical and ubiquitous anions in wastewater and natural water bodies(i.e.,H_(2)PO_(4)^(-),NO_(3)^(-),Cl^(-) and HCO_(3)^(-)),in which a ^(1)O_(2)-dominated oxidation was identified and non-radical mechanisms were ***,ST-DDLGC-based coin-type symmetrical supercapacitors exhibited outstanding electrochemical performance,with specific capacitances of up to 328.1 F g^(-1)at 0.5 A g^(-1),and cycling stability of up to 98.6%after 10,000 cycles at a current density of 2 A g^(-1).The superior properties of ST-DDLGCs could be attributed to the unique porous tubular structure,which facilitated mass transfer and presented numerous active *** results highlight ST-DDLGCs as a potential candidate for constructing inexpensive and advanced environmentally functional materials and energy storage devices.

关键词： Ganoderma lucidum residue Porous carbon nanotubes Self-template method Wastewater treatment Supercapacitor electrode

Review of tribological properties of nanoparticle-based lubricants and their hybrids and composites

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Friction 2024年第4期12卷 569-590页

作者： Ye Zar Ni HTWE Aws.S.AL-JANABI Yasmin WADZER Hussin MAMAT Ku NOORYASMIN school of Materials&Mineral resources engineering Universiti Sains Malaysia(Engineering Campus)Nibong Tebal 14300Malaysia school of Aerospace engineering Universiti Sains Malaysia(Engineering Campus)Nibong Tebal 14300Malaysia Universiti Sains Malaysia

Due to their encouraging results,nanolubricants have been revolutionary in the field of *** degree,to which the new material may improve the tribology,energy savings,and durability,is a crucial consideration for any new additive to a conventional *** results of the earlier research on carbon,metal,metal oxide,and their composites and hybrid nanolubricants as well as their effects on tribology,are summarized in this review *** most popular measuring methodologies,the tribology results for lubricants with an oil base,biodegradable base,and a water base,as well as the reasons that explain these tribological advancements,are all included in this ***,prospects for more study in this area are emphasized.

关键词： nanolubricants tribology carbon metal metal oxide hybrid

Experimental study of the damage characteristics of rocks containing non-penetrating cracks under cyclic loading

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International Journal of Mining Science and Technology 2024年第2期34卷 197-210页

作者： Jun Xu Xiaochun Xiao Lu Ma Sen Luo Jiaxu Jin Baijian Wu school of Mechanics and engineering Liaoning Technical UniversityFuxin 123000China school of civil engineering Liaoning Technical UniversityFuxin 123000China Department of engineering Mechanics Southeast UniversityNanjing 211189China

The damage evolution process of non-penetrating cracks often causes some unexpected engineering *** specimens containing non-penetrating crack(s)are used to study the damage evolution and characteristics under cyclic *** results show that under cyclic loading,the relationship between the number of non-penetrating crack(s)and the characteristic parameters(cyclic number,peak stress,peak strain,failure stress,and failure strain)of the pre-cracked specimens can be represented by a decreasing linear *** damage evolution equation is fitted by calibrating the accumulative plastic strain for each cycle,and the damage constitutive equation is proposed by the concept of effective ***,non-penetrating cracks are more likely to cause uneven stress distribution,damage accumulation,and local failure of *** local failure can change the stress distribution and relieve the inhibition of non-penetrating crack extension and eventually cause a dramatic destruction of the ***,the evolution process caused by non-penetrating cracks can be regarded as one of the important reasons for inducing *** results are expected to improve the understanding of the process of spalling formation and rockburst and can be used to analyze the stability of rocks or rock structures.

关键词： Damage characteristics Constitutive model Fissured rocks Non-penetrating crack Cyclic loading

BDSec:Security Authentication Protocol for BeiDou-Ⅱ civil Navigation Message

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China Communications 2024年第6期21卷 206-218页

作者： Wu Zhijun Zhang Yuan Yang Yiming Wang Peng Yue Meng school of Safety Science and engineering Civil Aviation University of ChinaTianjin 300300China school of Electronic Information and Automation Civil Aviation University of ChinaTianjin 300300China

Due to the lack of authentication mechanism in BeiDou navigation satellite system(BDS),BD-Ⅱ civil navigation message(BDⅡ-CNAV) are vulnerable to spoofing attack and replay *** solve this problem,we present a security authentication protocol,called as BDSec,which is designed by using China’s cryptography Shangyong Mima(SM) series algorithms,such as SM2/4/9 and Zu Chongzhi(ZUC)*** BDSec protocol,both of BDⅡ-CNAV and signature information are encrypted using the SM4 algorithm(Symmetric encryption mechanism).The encrypted result is used as the subject authentication *** protocol applies SM9 algorithm(Identity-based cryptography mechanism) to protect the integrity of the BDⅡ-CNAV,adopts the SM2 algorithm(Public key cryptosystem) to guarantee the confidentiality of the important session information,and uses the ZUC algorithm(Encryption and integrity algorithm) to verify the integrity of the message authentication serial number and initial information and the information in authentication initialization sub-protocol *** results of the SVO logic reasoning and performance analysis show that BDSec protocol meets security requirements for the dual user identity authentication in BDS and can realize the security authentication of BDⅡ-CNAV.

关键词： BDII civil navigation messages(BDIICNAV) BeiDou navigation satellite system(BDS) identity-based cryptography mechanism navigation message authentication protocol(BDSec)