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Alkylene-functionality in bridged and fused nitrogen-rich poly-cyclic energetic materials:Synthesis,structural diversity and energetic properties
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作者 Man Xu Nanxi Xiang +2 位作者 Ping Yin Qi Lai Siping Pang 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2024年第5期18-46,共29页
From the standpoint of chemical structures,the organic backbones of energetic materials can be classified into aromatic rings,nonaromatic rings,and open chains.Although the category of aromatic energetic compounds exh... From the standpoint of chemical structures,the organic backbones of energetic materials can be classified into aromatic rings,nonaromatic rings,and open chains.Although the category of aromatic energetic compounds exhibits several advantages in the regulation of energetic properties,the nonaromatic heterocycles,assembling nitramino explosophores with simple alkyl bridges,still have prevailed in benchmark materials.The methylene bridge plays a pivotal role in the constructions of the classic nonaromatic heterocycle-based energetic compounds,e.g.,hexahydro-1,3,5-trinitro-1,3,5-triazine(RDX)and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine(HMX),whereas ethylene bridge is the core moiety of state-of-the-art explosive 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane(CL-20).In this context,it is of great interest to employ simple and practical bridges to assemble aromatic and nonaromatic nitrogen-rich heterocycles,thereby expanding the structural diversity of energetic materials,e.g.,bridged and fused nitrogen-rich poly-heterocycles.Furthermore,alkyl-bridged poly-heterocycles highlight the potential for the open chain type of energetic materials.In this review,the development of alkyl bridges in linking nitrogen-rich heterocycles is presented,and the perspective of the newly constructed energetic backbones is summarized for the future design of advanced energetic materials. 展开更多
关键词 Energetic materials Alkyl bridge strategy Nitrogen-rich azoles Fused heterocycles AZoLES
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Deformation monitoring of long-span railway bridges based on SBAS-InSAR technology
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作者 Lv Zhou Xinyi Li +4 位作者 Yuanjin Pan Jun Ma Cheng Wang Anping Shi Yukai Chen 《Geodesy and Geodynamics》 EI CSCD 2024年第2期122-132,共11页
The deformation monitoring of long-span railway bridges is significant to ensure the safety of human life and property.The interferometric synthetic aperture radar(In SAR)technology has the advantage of high accuracy ... The deformation monitoring of long-span railway bridges is significant to ensure the safety of human life and property.The interferometric synthetic aperture radar(In SAR)technology has the advantage of high accuracy in bridge deformation monitoring.This study monitored the deformation of the Ganjiang Super Bridge based on the small baseline subsets(SBAS)In SAR technology and Sentinel-1A data.We analyzed the deformation results combined with bridge structure,temperature,and riverbed sediment scouring.The results are as follows:(1)The Ganjiang Super Bridge area is stable overall,with deformation rates ranging from-15.6 mm/yr to 10.7 mm/yr(2)The settlement of the Ganjiang Super Bridge deck gradually increases from the bridge tower toward the main span,which conforms to the typical deformation pattern of a cable-stayed bridge.(3)The sediment scouring from the riverbed cause the serious settlement on the bridge’s east side compared with that on the west side.(4)The bridge deformation negatively correlates with temperature,with a faster settlement at a higher temperature and a slow rebound trend at a lower temperature.The study findings can provide scientific data support for the health monitoring of long-span railway bridges. 展开更多
关键词 SBAS-InSAR Long-span railway bridge Deformation monitoring bridge structure Time series deformation
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Making bridges between preclinical and clinical insights into age-related cognitive decline
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作者 David VC Brito Clévio Nóbrega 《Neural Regeneration Research》 SCIE CAS 2025年第8期2321-2322,共2页
With people living longer,the societal impact of age-related cognitive decline is becoming more pronounced(Crimmins,2015).Thus,it is increasingly important to comprehend the cognitive shifts linked to aging-whether th... With people living longer,the societal impact of age-related cognitive decline is becoming more pronounced(Crimmins,2015).Thus,it is increasingly important to comprehend the cognitive shifts linked to aging-whether they are physiological or pathological. 展开更多
关键词 bridgES BECoMING INSIGHT
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Auto-parametric resonance of a continuous-beam-bridge model under two-point periodic excitation:an experimental investigation and stability analysis
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作者 Li Yuchun Shen Chao +1 位作者 Liu Wei Li Dong 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2024年第2期445-454,共10页
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 ... 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. 展开更多
关键词 auto-parametric resonance continuous beam bridge model two-point excitation experimental investigation stability analysis vibration of Volgograd bridge
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Dynamic Response Impact of Vehicle Braking on Simply Supported Beam Bridges with Corrugated Steel Webs Based on Vehicle-Bridge Coupled Vibration Analysis
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作者 Yan Wang Siwen Li Na Wei 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第6期3467-3493,共27页
A novel approach for analyzing coupled vibrations between vehicles and bridges is presented,taking into account spatiotemporal effects and mechanical phenomena resulting fromvehicle braking.Efficient modeling and solu... A novel approach for analyzing coupled vibrations between vehicles and bridges is presented,taking into account spatiotemporal effects and mechanical phenomena resulting fromvehicle braking.Efficient modeling and solution of bridge vibrations induced by vehicle deceleration are realized using this method.The method’s validity and reliability are substantiated through numerical examples.A simply supported beam bridge with a corrugated steel web is taken as an example and the effects of parameters such as the initial vehicle speed,braking acceleration,braking location,and road surface roughness on the mid-span displacement and impact factor of the bridge are analyzed.The results show that vehicle braking significantly amplifies mid-span displacement and impact factor responses in comparison to uniform vehicular motion across the bridge.Notably,the influence of wheelto-bridge friction forces is of particular significance and cannot be overlooked.When the vehicle initiates braking near the middle of the span,both the mid-span displacement and impact factor of the bridge exhibit substantial increases,further escalating with higher braking acceleration.Under favorable road surface conditions,the midspan displacement and the impact factor during vehicle braking may exceed the design values stipulated by codes.It is important to note that road surface roughness exerts a more pronounced effect on the impact factor of the bridge in comparison to the effects of vehicle braking. 展开更多
关键词 Corrugated steel web girder bridges simply supported beam bridges vehicle-bridge coupled vibration BRAKING impact factor
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Bridge Bidding via Deep Reinforcement Learning and Belief Monte Carlo Search
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作者 Zizhang Qiu Shouguang Wang +1 位作者 Dan You MengChu Zhou 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2024年第10期2111-2122,共12页
Contract Bridge,a four-player imperfect information game,comprises two phases:bidding and playing.While computer programs excel at playing,bidding presents a challenging aspect due to the need for information exchange... Contract Bridge,a four-player imperfect information game,comprises two phases:bidding and playing.While computer programs excel at playing,bidding presents a challenging aspect due to the need for information exchange with partners and interference with communication of opponents.In this work,we introduce a Bridge bidding agent that combines supervised learning,deep reinforcement learning via self-play,and a test-time search approach.Our experiments demonstrate that our agent outperforms WBridge5,a highly regarded computer Bridge software that has won multiple world championships,by a performance of 0.98 IMPs(international match points)per deal over 10000 deals,with a much cost-effective approach.The performance significantly surpasses previous state-of-the-art(0.85 IMPs per deal).Note 0.1 IMPs per deal is a significant improvement in Bridge bidding. 展开更多
关键词 Contract bridge reinforcement learning SEARCH
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Recent Construction Technology Innovations and Practices for Large-Span Arch Bridges in China
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作者 Jielian Zheng 《Engineering》 SCIE EI CAS CSCD 2024年第10期110-129,共20页
Arch bridges provide significant technical and economic benefits under suitable conditions.In particular,concrete-filled steel tubular(CFST)arch bridges and steel-reinforced concrete(SRC)arch bridges are two types of ... Arch bridges provide significant technical and economic benefits under suitable conditions.In particular,concrete-filled steel tubular(CFST)arch bridges and steel-reinforced concrete(SRC)arch bridges are two types of arch bridges that have gained great economic competitiveness and span growth potential due to advancements in construction technology,engineering materials,and construction equipment over the past 30 years.Under the leadership of the author,two record-breaking arch bridges—that is,the Pingnan Third Bridge(a CFST arch bridge),with a span of 560 m,and the Tian’e Longtan Bridge(an SRC arch bridge),with a span of 600 m—have been built in the past five years,embodying great technological breakthroughs in the construction of these two types of arch bridges.This paper takes these two arch bridges as examples to systematically summarize the latest technological innovations and practices in the construction of CFST arch bridges and SRC arch bridges in China.The technological innovations of CFST arch bridges include cable-stayed fastening-hanging cantilevered assembly methods,new in-tube concrete materials,in-tube concrete pouring techniques,a novel thrust abutment foundation for nonrocky terrain,and measures to reduce the quantity of temporary facilities.The technological innovations of SRC arch bridges involve arch skeleton stiffness selection,the development of encasing concrete materials,encasing concrete pouring,arch rib stress mitigation,and longitudinal reinforcement optimization.To conclude,future research focuses and development directions for these two types of arch bridges are proposed. 展开更多
关键词 Concrete-filled steel tubular arch bridges Steel-reinforced concrete arch bridges Cable-stayed fastening-hanging cantilevered assembly Non-rocky thrust abutment foundation Stiff skeleton Encasing concrete pouring Longitudinal reinforcement optimization
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A Rapid Crack Detection Technique Based on Attention for Intelligent M&O of Cross-Sea Bridge
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作者 ZHOU Yong-chuan LI Guang-jun +2 位作者 WEI Wei WANG Ya-meng JING Qiang 《China Ocean Engineering》 SCIE EI CSCD 2024年第5期866-876,共11页
Rapid and accurate segmentation of structural cracks is essential for ensuring the quality and safety of engineering projects.In practice,however,this task faces the challenge of finding a balance between detection ac... Rapid and accurate segmentation of structural cracks is essential for ensuring the quality and safety of engineering projects.In practice,however,this task faces the challenge of finding a balance between detection accuracy and efficiency.To alleviate this problem,a lightweight and efficient real-time crack segmentation framework was developed.Specifically,in the network model system based on an encoding-decoding structure,the encoding network is equipped with packet convolution and attention mechanisms to capture features of different visual scales in layers,and in the decoding process,we also introduce a fusion module based on spatial attention to effectively aggregate these hierarchical features.Codecs are connected by pyramid pooling model(PPM)filtering.The results show that the crack segmentation accuracy and real-time operation capability larger than 76%and 15 fps,respectively,are validated by three publicly available datasets.These wide-ranging results highlight the potential of the model for the intelligent O&M for cross-sea bridge. 展开更多
关键词 bridge defect detection crack detection lightweight design
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Influence of pier height on the safety of trains running on high-speed railway bridges during earthquakes
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作者 NIE Yu-tao GUO Wei +8 位作者 JIANG Li-zhong YU Zhi-wu ZENG Chen WANG Yang HE Xu-en REN Shao-xun HUANG Ren-qiang LIANG Guang-yue LI Chang-qing 《Journal of Central South University》 SCIE EI CAS CSCD 2024年第6期2102-2115,共14页
Sudden earthquakes pose a threat to the running safety of trains on high-speed railway bridges,and the stiffness of piers is one of the factors affecting the dynamic response of train-track-bridge system.In this paper... Sudden earthquakes pose a threat to the running safety of trains on high-speed railway bridges,and the stiffness of piers is one of the factors affecting the dynamic response of train-track-bridge system.In this paper,a experiment of a train running on a high-speed railway bridge is performed based on a dynamic experiment system,and the corresponding numerical model is established.The reliability of the numerical model is verified by experiments.Then,the experiment and numerical data are analyzed to reveal the pier height effects on the running safety of trains on bridges.The results show that when the pier height changes,the frequency of the bridge below the 30 m pier height changes greater;the increase of pier height causes the transverse fundamental frequency of the bridge close to that of the train,and the shaking angle and lateral displacement of the train are the largest for bridge with 50 m pier,which increases the risk of derailment;with the pier height increases from 8 m to 50 m,the derailment coefficient obtained by numerical simulations increases by 75% on average,and the spectral intensity obtained by experiments increases by 120% on average,two indicators exhibit logarithmic variation. 展开更多
关键词 pier height high-speed railway bridge running safety numerical model
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Seismic fragility analysis of three-tower cable-stayed bridges with different connection configurations
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作者 Chen Chen Liu Jinlong +1 位作者 Lin Junqi Li Suchao 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2024年第4期1009-1027,共19页
Seismic fragility analysis of three-tower cable-stayed bridges with three different structural systems,including rigid system(RS),floating system(FS),and passive energy dissipation system(PEDS),is conducted to study t... Seismic fragility analysis of three-tower cable-stayed bridges with three different structural systems,including rigid system(RS),floating system(FS),and passive energy dissipation system(PEDS),is conducted to study the effects of connection configurations on seismic responses and fragilities.Finite element models of bridges are established using OpenSees.A new ground motion screening method based on the statistical characteristic of the predominant period is proposed to avoid irregular behavior in the selection process of ground motions,and incremental dynamic analysis(IDA)is performed to develop components and systems fragility curves.The effects of damper failure on calculated results for PEDS are examined in terms of seismic response and fragility analysis.The results show that the bridge tower is the most affected component by different structural systems.For RS,the fragility of the middle tower is significantly higher than other components,and the bridge failure starts from the middle tower,exhibiting a characteristic of local failure.For FS and PEDS,the fragility of the edge tower is higher than the middle tower.The system fragility of RS is higher than FS and PEDS.Taking the failure of dampers into account is necessary to obtain reliable seismic capacity of cable-stayed bridges. 展开更多
关键词 seismic fragility cable-stayed bridge connection configuration viscous damper comparison analysis
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Field survey and analysis on near-fault severely damaged high-speed railway bridge in 2022 M6.9 Menyuan earthquake
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作者 Lin Xuchuan Liu Fuxiang Shan Wenchen 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2024年第4期1043-1055,共13页
The 2022 M6.9 Menyuan earthquake caused severe damage to a high-speed railway bridge,which was designed for high-speed trains running at speeds of above 250 km/h and is located right next to the fault.Bridges of this ... The 2022 M6.9 Menyuan earthquake caused severe damage to a high-speed railway bridge,which was designed for high-speed trains running at speeds of above 250 km/h and is located right next to the fault.Bridges of this type have been widely used for rapidly constructing the high-speed railway network,but few bridges have been tested by near-fault devastating earthquakes.The potential severe impact of the earthquake on the high-speed railway is not only the safety of the infrastructure,trains and passengers,but also economic loss due to interrupted railway use.Therefore,a field survey was carried out immediately after the earthquake to collect time-sensitive data.The damage to the bridge was carefully investigated,and quantitative analyses were conducted to better understand the mechanism of the bridge failure.It was found that seismic action perpendicular to the bridge’s longitudinal direction caused severe damage to the girders and rails,while none of the piers showed obvious deformation or cracking.The maximum values of transverse displacement,out-of-plane rotation and twisting angle of girders reached 212.6 cm,3.1 degrees and 19.9 degrees,respectively,causing severe damage to the bearing supports and anti-seismic retaining blocks.These observations provide a basis for improving the seismic design of high-speed railway bridges located in near-fault areas. 展开更多
关键词 Menyuan earthquake field survey high-speed railway bridge near fault seismic damage
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Bridge Condition Assessment by Visual Inspection-Croatian Experience
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作者 Goran Puž 《Journal of Civil Engineering and Architecture》 2024年第10期504-514,共11页
Most decisions relating to bridge maintenance are founded on assessments that are based on visual inspections conducted by specially trained engineers,using procedures and aids defined in the management system.Visual ... Most decisions relating to bridge maintenance are founded on assessments that are based on visual inspections conducted by specially trained engineers,using procedures and aids defined in the management system.Visual inspection is the main tool for bridge condition assessment,and is therefore of crucial significance for planning periodic maintenance activities.Paper shall present the study aimed at harmonizing bridge assessment activities,which was conducted in early 2012 in company Hrvatske ceste-Croatian National Road Authority.Small RC bridges were chosen for this study,since visual inspection is usually only tool utilized for their assessment.Ratings obtained by inspection were analyzed using methods of mathematical statistics.The results point to weaknesses in the current assessment system,while the study itself constitutes a good basis for further improvement of management aids,manuals and procedures for bridge inspection. 展开更多
关键词 Visual inspection concrete bridges bridge management bridge rating
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Experimental Investigation of Wave-Current Loads on a Bridge Shuttle-Shaped Cap–Pile Foundation
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作者 Chenkai Hong Zhongda Lyu +2 位作者 Fei Wang Zhuo Zhao Lei Wang 《Fluid Dynamics & Materials Processing》 EI 2024年第7期1565-1592,共28页
To scrutinize the characteristics of wave-current loads on a bridge shuttle-shaped cap–pile foundation,a 1:125 test model was considered in a laboratory flume.The inline,transverse and vertical wave–current forces a... To scrutinize the characteristics of wave-current loads on a bridge shuttle-shaped cap–pile foundation,a 1:125 test model was considered in a laboratory flume.The inline,transverse and vertical wave–current forces acting on the shuttle-shaped cap-pile group model were measured considering both random waves and a combination of random waves with a current.The experimental results have shown that the wave-current forces can be well correlated with the wave height,the wavelength,the current velocity,the incident direction and the water level in the marine environment.An increase in the current velocity can lead to a sharp increase in the inline and transverse wave-current forces,while the vertical wave-current force decreases.Moreover,the wave-current forces are particularly strong when a combination of high tide,strong wave and strong current is considered. 展开更多
关键词 Shuttle-shaped cap-pile foundation wave-current force wave flume experiment sea-crossing bridge
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Understanding Bridging Sites and Accelerating Quantum Efficiency for Photocatalytic CO_(2) Reduction
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作者 Kangwang Wang Zhuofeng Hu +8 位作者 Peifeng Yu Alina M.Balu Kuan Li Longfu Li Lingyong Zeng Chao Zhang Rafael Luque Kai Yan Huixia Luo 《Nano-Micro Letters》 SCIE EI CAS CSCD 2024年第1期68-84,共17页
We report a novel double-shelled nanoboxes photocatalyst architecture with tailored interfaces that accelerate quantum efficiency for photocatalytic CO_(2) reduction reaction(CO_(2)RR)via Mo–S bridging bonds sites in... We report a novel double-shelled nanoboxes photocatalyst architecture with tailored interfaces that accelerate quantum efficiency for photocatalytic CO_(2) reduction reaction(CO_(2)RR)via Mo–S bridging bonds sites in S_(v)–In_(2)S_(3)@2H–MoTe_(2).The X-ray absorption near-edge structure shows that the formation of S_(v)–In_(2)S_(3)@2H–MoTe_(2) adjusts the coordination environment via interface engineering and forms Mo–S polarized sites at the interface.The interfacial dynamics and catalytic behavior are clearly revealed by ultrafast femtosecond transient absorption,time-resolved,and in situ diffuse reflectance–Infrared Fourier transform spectroscopy.A tunable electronic structure through steric interaction of Mo–S bridging bonds induces a 1.7-fold enhancement in S_(v)–In_(2)S_(3)@2H–MoTe_(2)(5)photogenerated carrier concentration relative to pristine S_(v)–In_(2)S_(3).Benefiting from lower carrier transport activation energy,an internal quantum efficiency of 94.01%at 380 nm was used for photocatalytic CO_(2)RR.This study proposes a new strategy to design photocatalyst through bridging sites to adjust the selectivity of photocatalytic CO_(2)RR. 展开更多
关键词 Quantum efficiency Electronic structure Steric interaction bridging sites Co_(2)reduction
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Experimental study on seismic reinforcement of bridge foundation on silty clay landslide with inclined interlayer
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作者 Lei Da Xiao Hanmo +3 位作者 Ran Jianhua Luo Bin Jiang Guanlu Xue Tianlang 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2024年第1期193-207,共15页
A shaking table test for a bridge foundation reinforced by anti-slide piles on a silty clay landslide model with an inclined interlayer was performed.The deformation characteristics of the bridge foundation piles and ... A shaking table test for a bridge foundation reinforced by anti-slide piles on a silty clay landslide model with an inclined interlayer was performed.The deformation characteristics of the bridge foundation piles and anti-slide piles were analyzed in different loading conditions.The dynamic response law of a silty clay landslide with an inclined interlayer was summarized.The spacing between the rear anti-slide piles and bridge foundation should be reasonably controlled according to the seismic fortification requirements,to avoid the two peaks in the forced deformation of the bridge foundation piles.The“blocking effect”of the bridge foundation piles reduced the deformation of the forward anti-slide piles.The stress-strain response of silty clay was intensified as the vibration wave field appeared on the slope.Since the vibration intensified,the thrust distribution of the landslide underwent a process of shifting from triangle to inverted trapezoid,the difference in the acceleration response between the bearing platform and silty clay landslide tended to decrease,and the spectrum amplitude near the natural vibration frequency increased.The rear anti-slide piles were able to slow down the shear deformation of the soil in front of the piles and avoid excessive acceleration response of the bridge foundation piles. 展开更多
关键词 silty clay landslide inclined interlayer shaking table test anti-slide pile bridge foundation pile
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A discussion about the limitations of the Eurocode’s high-speed load model for railway bridges
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作者 Gonçalo Ferreira Pedro Montenegro +2 位作者 JoséRui Pinto António Abel Henriques Rui Calçada 《Railway Engineering Science》 EI 2024年第2期211-228,共18页
High-speed railway bridges are subjected to normative limitations concerning maximum permissible deck accelerations.For the design of these structures,the European norm EN 1991-2 introduces the high-speed load model(H... High-speed railway bridges are subjected to normative limitations concerning maximum permissible deck accelerations.For the design of these structures,the European norm EN 1991-2 introduces the high-speed load model(HSLM)—a set of point loads intended to include the effects of existing high-speed trains.Yet,the evolution of current trains and the recent development of new load models motivate a discussion regarding the limits of validity of the HSLM.For this study,a large number of randomly generated load models of articulated,conventional,and regular trains are tested and compared with the envelope of HSLM effects.For each type of train,two sets of 100,000 load models are considered:one abiding by the limits of the EN 1991-2 and another considering wider limits.This comparison is achieved using both a bridge-independent metric(train signatures)and dynamic analyses on a case study bridge(the Canelas bridge of the Portuguese Railway Network).For the latter,a methodology to decrease the computational cost of moving loads analysis is introduced.Results show that some theoretical load models constructed within the stipulated limits of the norm can lead to effects not covered by the HSLM.This is especially noted in conventional trains,where there is a relation with larger distances between centres of adjacent vehicle bogies. 展开更多
关键词 High-speed load model Dynamic analysis High-speed railways Train signature Railway bridges Deck acceleration
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Value of Charpy impact test results with sub-and half-size specimens extracted from overage steel bridge members
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作者 Hirohata Mikihito 《China Welding》 CAS 2024年第3期8-13,共6页
For the maintenance of steel bridges,the mechanical properties of steel used in the bridges must be elucidated.When enough dimensions of specimens cannot be extracted from the actual members,miniaturized specimens are... For the maintenance of steel bridges,the mechanical properties of steel used in the bridges must be elucidated.When enough dimensions of specimens cannot be extracted from the actual members,miniaturized specimens are used for evaluation.In the case of the Charpy impact test,sub-and half-size specimens are specified instead of full-size specimens of which the thickness is 10 mm.The value of absorbed energy and energy transient temperature obtained by Charpy impact tests with sub-size and half-size specimens were investigated from the viewpoint of maintenance of bridges in this study.The absorbed energy was not in proportion to the thickness of specimens of steel used in the actual overage bridges.The tendency of energy transient temperature obtained by thin specimens of the overage steel differed from that of the present steel.A method for evaluating the performance against brittle fracture occurrence based on the WES3003 criterion was examined.The results show the significance of evaluation based on the energy transient temperature for reasonable maintenance of bridges. 展开更多
关键词 steel bridge maintenance brittle fracture Charpy impact test overage steel
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Reliability-based life-cycle cost seismic design optimization of coastal bridge piers with nonuniform corrosion using different materials
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作者 Wu Xiangtong Yuan Wenting Guo Anxin 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2024年第1期209-225,共17页
Reinforcement corrosion is the main cause of performance deterioration of reinforced concrete(RC)structures.Limited research has been performed to investigate the life-cycle cost(LCC)of coastal bridge piers with nonun... Reinforcement corrosion is the main cause of performance deterioration of reinforced concrete(RC)structures.Limited research has been performed to investigate the life-cycle cost(LCC)of coastal bridge piers with nonuniform corrosion using different materials.In this study,a reliability-based design optimization(RBDO)procedure is improved for the design of coastal bridge piers using six groups of commonly used materials,i.e.,normal performance concrete(NPC)with black steel(BS)rebar,high strength steel(HSS)rebar,epoxy coated(EC)rebar,and stainless steel(SS)rebar(named NPC-BS,NPC-HSS,NPC-EC,and NPC-SS,respectively),NPC with BS with silane soakage on the pier surface(named NPC-Silane),and high-performance concrete(HPC)with BS rebar(named HPC-BS).First,the RBDO procedure is improved for the design optimization of coastal bridge piers,and a bridge is selected to illustrate the procedure.Then,reliability analysis of the pier designed with each group of materials is carried out to obtain the time-dependent reliability in terms of the ultimate and serviceability performances.Next,the repair time of the pier is predicted based on the time-dependent reliability indices.Finally,the time-dependent LCCs for the pier are obtained for the selection of the optimal design. 展开更多
关键词 reliability-based design optimization(RBDo) life-cycle cost(LCC) nonuniform corrosion coastal bridge pier REPAIR
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Weldability of steel used in an aged bridge
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作者 Hirohata Mikihito 《China Welding》 CAS 2024年第3期33-38,共6页
A series of experiments was performed to investigate the weldability of steel used in an aged bridge.A steel material used in an aged railway bridge constructed in 1912 was extracted for this investigation.The chemica... A series of experiments was performed to investigate the weldability of steel used in an aged bridge.A steel material used in an aged railway bridge constructed in 1912 was extracted for this investigation.The chemical compositions of this steel were suitable for welding.However,the aged steel contained much sulfur.Cruciform welded joints were fabricated with this aged steel.Welding defects or cracks were not observed in the joints.The Vickers hardness test on the welded part did not confirm extreme hardening or softening.After yielding by the static tensile test,the cruciform joints were fractured at the welded parts.One of the specimens was fractured in the middle of the thickness of the aged steel.The Sulfur contained in the aged steel might cause this type of fracture.The results show that there may be a risk of brittle fracture not only from the welded part but also from the base metal.The chemical compositions of aged steel must be analyzed when repair welding is applied to the steel. 展开更多
关键词 aged steel bridge repair welding chemical compositions weld defect brittle fracture
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Random Differential Settlement Effects on Reliability of Existing Bridges
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作者 Zuo-Cai Wang 《Journal of Civil Engineering and Architecture》 2024年第2期60-68,共9页
This paper investigates the impact of differential foundation settlement on the reliability of bridge superstructure based on loads and resistances statistical properties in Missouri State.Maximum deterministic differ... This paper investigates the impact of differential foundation settlement on the reliability of bridge superstructure based on loads and resistances statistical properties in Missouri State.Maximum deterministic differential settlement is often used in current AASHTO LRFD(load and resistance factored design)specification.However,the expected foundation settlement is quite different from the actual settlement due to the soil’s large variability.Therefore,it makes sense to consider settlement as a random variable.In this paper,a lognormal distribution with coefficient of variation of 0.25 of random settlement is considered in reliability analysis based on limited previous studies.Dead and live loads are modeled as random variables with normal and Gumbel Type I distributions,respectively.Considering the regional traffic condition on Missouri roadways,the live load effect on existing bridges based on weight-in-motion data is also investigated.The calibrated resistance statistical properties such as bias and COV(coefficient of variance)are used for reliability analysis.Total 14 existing bridges based on Strength I Limit State are analyzed.Since no differential settlement is considered in the past designed bridges in Missouri,small differential settlement can significantly reduce the reliability indices of the superstructure,depending upon the span length and rigidity of the girder.The analysis results also show that the reliability of existing steel-girder bridges is consistently higher than prestressed concrete and solid slab bridges;the shorter and stiffer the spans,the more significant the settlement’s effect on the reliability of bridge superstructures;As the span length ratio becomes less than 0.75,the girder and solid slab bridges’reliability drops significantly at small settlements. 展开更多
关键词 bridgES SUPERSTRUCTURE LRFD
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