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Dispersion effect of nano-structure pyrolytic carbon on mechanical,electrical,and microstructural characteristics of cement mortar composite

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International Journal of Smart and Nano Materials 2024年第3期15卷 534-578页

作者： N.K.Karthikeyan S.Elavenil School of civil engineering Vellore Institute of TechnologyChennaiIndia

In material science,converting waste into nanomaterials by green technologies highlights the interest in producing sus-tainable carbon nanomaterial(SCN).This study first-ever uti-lized tyre-char as a Nano-Structure Pyrolytic Carbon(NSPC)to develop electrically conductive *** other car-bon nanomaterials,the efficiency of NSPC particle as an SCN in developing electrically conductive composites was investi-gated in terms of dispersion,mechanical,water absorption,electrical resistivity,and *** results of sedi-mentation and zeta potential(-19 mV)showed the excellent dispersion of NSPC particle in water with the combined effect of superplasticizer and *** compressive(40.37%)and flexural strength(10.76%)than that of plain cement mortar composite(CMC)is achieved with 2 wt.%and 1.5 wt.%of NSPC particle,*** water absorption rate and volume of permeable voids were reduced,exhibiting less *** percolation zone of AC and DC resis-tivity of NSPC composite ranges between 1 and 2 wt.%,and the established percolation threshold is at 2 wt.%.XRD analysis showed C-S-H formation consistently increased with curing age,and HR-SEM with EDAX analysis exhibits the dense micro-structure and well-distributed NSPC particle at the *** experimental outcomes significantly enhanced the relia-bility and provided a framework for tailoring NSPC particle as SCN for developing electrically conductive composite.

关键词： Sustainable nanomaterial dispersion mechanical properties electrical resistivity microstructure analysis

Direct scaling of residual displacements for bilinear and pinching oscillators

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Earthquake engineering and engineering Vibration 2024年第1期23卷 129-149页

作者： Mohammad Saifullah Vinay K.Gupta Department of civil engineering Indian Institute of Technology KanpurKanpur 208016India

The estimation of residual displacements in a structure due to an anticipated earthquake event has increasingly become an important component of performance-based earthquake engineering because controlling these displacements plays an important role in ensuring cost-feasible or cost-effective repairs in a damaged structure after the *** attempt is made in this study to obtain statistical estimates of constant-ductility residual displacement spectra for bilinear and pinching oscillators with 5%initial damping,directly in terms of easily available seismological,site,and model *** of the available models for the bilinear and pinching oscillators are useful when design spectra for a seismic hazard at a site are not *** statistical estimates of a residual displacement spectrum are proposed in terms of earthquake magnitude,epicentral distance,site geology parameter,and three model parameters for a given set of ductility demand and a hysteretic energy capacity coefficient in the case of bilinear and pinching models,as well as for a given set of pinching parameters for displacement and strength at the breakpoint in the case of pinching model *** proposed scaling model is applicable to horizontal ground motions in the western *** earthquake magnitudes less than 7 or epicentral distances greater than 20 km.

关键词： residual displacement spectrum bilinear hysteresis model pinching hysteresis model nonlinear analysis scaling model

Prediction of bearing capacity of pile foundation using deep learning approaches

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Frontiers of Structural and civil engineering 2024年第6期18卷 870-886页

作者： Manish KUMAR Divesh Ranjan KUMAR Jitendra KHATTI Pijush SAMUI Kamaldeep Singh GROVER Department of civil engineering SRM Institute of Science and Technology Tiruchirappalli CampusTrichy 621105India Department of civil engineering National Institute of Technology PatnaBihar 800005India Department of civil engineering Faculty of EngineeringThammasat School of EngineeringThammasat UniversityBangkok10200Thailand Department of civil engineering Rajasthan Technical UniversityKota 324010India

The accurate prediction of bearing capacity is crucial in ensuring the structural integrity and safety of pile *** research compares the Deep Neural Networks(DNN),Convolutional Neural Networks(CNN),Recurrent Neural Networks(RNN),Long Short-Term Memory(LSTM),and Bidirectional LSTM(BiLSTM)algorithms utilizing a data set of 257 dynamic pile load tests for the first ***,this research illustrates the multicollinearity effect on DNN,CNN,RNN,LSTM,and BiLSTM models’performance and accuracy for the first time.A comprehensive comparative analysis is conducted,employing various statistical performance parameters,rank analysis,and error matrix to evaluate the performance of these *** performance is further validated using external validation,and visual interpretation is provided using the regression error characteristics(REC)curve and Taylor *** from the comparative analysis reveal that the DNN(Coefficient of determination(R^(2))_(training(TR))=0.97,root mean squared error(RMSE)_(TR)=0.0413;R^(2)_(testing(TS))=0.9,RMSE_(TS)=0.08)followed by BiLSTM(R^(2)_(TR)=0.91,RMSE_(TR)=0.782;R^(2)_(TS)=0.89,RMSE_(TS)=0.0862)model demonstrates the highest performance *** is noted that the BiLSTM model is better than LSTM because the BiLSTM model,which increases the amount of information for the network,is a sequence processing model made up of two LSTMs,one of which takes the input in a forward manner,and the other in a backward *** prediction of pile-bearing capacity is strongly influenced by ram weight(having a considerable multicollinearity level),and the effect of the considerable multicollinearity level has been determined for the model based on the recurrent neural network *** this study,the recurrent neural network model has the least performance and accuracy in predicting the pile-bearing capacity.

关键词： deep learning algorithms high-strain dynamic pile test bearing capacity of the pile

Selection of digital fabrication technique in the construction industry--A multi-criteria decision-making approach

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Frontiers of Structural and civil engineering 2024年第7期18卷 977-997页

作者： M.P.SALAIMANIMAGUDAM J.JAYAPRAKASH Department of Structural and Geotechnical engineering School of Civil EngineeringVellore Institute of TechnologyVellore 632014India

Digital fabrication techniques,in recent decades,have provided the basis of a sustainable revolution in the construction ***,selecting the digital fabrication method in terms of manufacturability and functionality requirements is a complex *** paper presents alternatives and criteria for selection of digital fabrication techniques by adopting the multi-criteria decision-making *** alternatives considered in the study are concrete three-dimensional(3D)printing,shotcrete,smart dynamic casting,material intrusion,mesh molding,injection concrete 3D printing,and thin forming *** criteria include formwork utilization,reinforcement incorporation,geometrical complexity,material enhancement,assembly complexity,surface finish,and build *** demonstrates different multi-criteria decision-making techniques,with both subjective and objective weighting *** given ranking is based on the current condition of digital fabrication in the construction *** study reveals that in the selection of digital fabrication techniques,the criteria including reinforcement incorporation,build area,and geometrical complexity play a pivotal role,collectively accounting for nearly 70% of the overall *** the evaluated techniques,concrete 3D printing emerged as the best performer,however the shotcrete and mesh molding techniques in the second and third positions.

关键词： digital fabrication multicriteria decision-making concrete 3D printing

Bibliographic survey and comprehensive review on mechanical and durability properties of microorganism based self-healing concrete

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Frontiers of Structural and civil engineering 2024年第9期18卷 1445-1465页

作者： Md Marghoobul HAQUE Kunal M.SHELOTE Namrata SINGH Supratic GUPTA Department of civil engineering Indian Institute of Technology DelhiNew Delhi 110016India

Concrete is the most widely utilized material for construction purposes,second only to water,in the ever-increasing need for construction *** is a brittle material and possesses a high risk of crack formation and consequent ***,which allows chemicals to enter and can cause concrete structures to lose their physico-mechanical and durability *** and rehabilitating concrete structures involves high costs and leads to various repair methods including coating,adhesives,polymers,supplementary cementitious materials(SCMs),and *** of the latest technologies is the use of microorganisms in *** added microorganisms lead to calcite precipitation and thereby heal the cracks *** study presents a comprehensive literature survey on bacteria-included concrete,before which a bibliographic survey is performed using VOSViewer *** addition to regular bacterial concrete,this study focuses on also using SCMs and fibers in bacterial concrete.A detailed literature review with data representation for various mechanical properties including compressive strength(CS),split tensile strength(SS),and flexure strength(FS),along with durability properties including carbonation,water absorption,resistance against chloride ion penetration,gas permeation,and resistance against cyclic freeze-and-thaw is presented.A study on the use of X-ray computed tomography(XCT)in bacterial concrete is highlighted,and the scope for future research,along with identification of the research gap,is presented.

关键词： bacterial concrete bibliographic survey biomineralization carbonation fibers

Machine learning-enhanced Monte Carlo and subset simulations for advanced risk assessment in transportation infrastructure

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Journal of Mountain Science 2024年第2期21卷 690-717页

作者： Furquan AHMAD Pijush SAMUI S.S.MISHRA Department of civil engineering National Institute of TechnologyPatna 800006India

The maintenance of safety and dependability in rail and road embankments is of utmost importance in order to facilitate the smooth operation of transportation *** study introduces a comprehensive methodology for soil slope stability evaluation,employing Monte Carlo Simulation(MCS)and Subset Simulation(SS)with the"UPSS 3.0 Add-in"in *** on an 11.693-meter embankment with a soil slope(inclination ratio of 2H:1V),the investigation considers earthquake coefficients(kh)and pore water pressure ratios(ru)following Indian zoning *** chance of slope failure showed a considerable increase as the Coefficient of Variation(COV),seismic coefficients(kh),and pore water pressure ratios(ru)experienced an *** SS approach showed exceptional efficacy in calculating odds of failure that are notably *** computational modeling,the study optimized the worst-case scenario using ANFIS-GA,ANFIS-GWO,ANFIS-PSO,and ANFIS-BBO *** ANFIS-PSO model exhibits exceptional accuracy(training R2=0.9011,RMSE=0.0549;testing R2=0.8968,RMSE=0.0615),emerging as the most *** study highlights the significance of conducting thorough risk assessments and offers practical insights into evaluating and improving the stability of soil slopes in transportation *** findings contribute to the enhancement of safety and reliability in real-world situations.

关键词： Monte Carlo Simulation Subset Simulation Machine Learning Seismic coefficient

Temporal and spatial compliance behaviour of pedestrians under the influence of time pressure at signalized intersections:A pedestrian simulator study

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Journal of Traffic and Transportation engineering(English Edition) 2024年第1期11卷 55-68页

作者： Apurwa Dhoke Pushpa Choudhary Department of civil engineering Indian Institute of Technology RoorkeeRoorkee 247667India

Pedestrian safety is at high stakes due to the non-compliance practices of pedestrians at signalized ***,when pedestrians are hurrying,they deliberately engage in such unsafe ***,the purpose of this study was to understand how time pressure(i.e.,feeling of hurry or saving time)affected pedestrians'decisions to follow traffic rules at signalized *** achieve the study objectives,a pedestrian simulator setup was used to collect the crossing behaviour of forty participants at a four-legged signalized ***-compliance,one of the riskiest pedestrian behaviours,was examined with respect to three different forms,comprising dangerous temporal non-compliance(D-TNC),non-dangerous temporal non-compliance(ND-TNC),and spatial non-compliance(SNC)behaviour under two distinct conditions:baseline(i.e.,no time pressure)and time pressure *** effects of demographics,usual walking features,and time pressure on D-TNC and ND-TNC were investigated using a multinomial regression model,while SNC behaviour was investigated using a binary regression *** was interesting to note that the majority of the factors related to pedestrians’usual walking behaviour had an impact on all kinds of non-compliance ***,the results also showcased that time pressure had a contrasting impact on D-TNC and ND-TNC behaviour whereas SNC behaviour increased under time ***,the varying impacts of D-TNC,ND-TNC,and SNC were also reflected in the occurrence of the crashes,which were probably triggered by discrepancies in the influence of time pressure on non-compliance *** findings highlight the need for technical solutions,educational outreach,and efficient enforcement practices to reduce pedestrians'non-compliant behaviour.

关键词： Signalized intersection Time pressure Pedestrians Temporal compliance Spatial compliance Pedestrian simulator

Evaluation of red soil-bentonite mixtures for compacted clay liners

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Journal of Rock Mechanics and Geotechnical engineering 2024年第2期16卷 697-710页

作者： A.S.Devapriya T.Thyagaraj Department of civil engineering Indian Institute of Technology MadrasChennai600036India

Compacted clay liners are an integral part of the waste landfills,which are provided to contain the leachate within the landfills and protect the surrounding ***,locally available natural soils are used for the construction of compacted clay liners if they satisfy the design ***,not all soils in their natural state satisfy all the design criteria for the liner ***,there is a definite need to modify the locally available natural soils by blending with bentonite to meet the required design criteria for the *** view of this,the present study evaluates the suitability of an Indian red soil enhanced with bentonite as a liner *** achieve this,a series of experiments were carried out using locally available red soil and ***,the suitability of the red soil was evaluated as a liner *** experimental results showed that the red soil met all the selection criteria stipulated by the Environmental Protection Agencies(EPAs)for the liners except the hydraulic conductivity ***,the red soil was mixed with bentonite contents of 10%,20%and 30%,and the red soil-bentonite mixtures were evaluated for their suitability for liners in their compacted ***,as the liners in the arid and semi-arid regions are subjected to moisture variations due to seasonal moisture fluctuations and other factors,the red soil-bentonite mixtures were subjected to wetdry cycles,and their suitability was evaluated after wet-dry *** experimental results revealed that all the red soil-bentonite mixtures met the stipulated EPA criteria for the liners in the as-compacted ***,the red soil-bentonite mixtures with 20%and 30%bentonite contents only satisfied the hydraulic conductivity requirement even after wet-dry *** experimental findings were supplemented with the microstructural insights captured through digital camera images,scanning electron microscopy(SEM),and mercury intrusion porosimetry(M

关键词： Compacted clay lines Hydraulic conductivity Wet-dry cycles Microstructure

Boulder-induced form roughness and skin shear stresses in a gravel-bed stream

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Journal of Mountain Science 2024年第1期21卷 346-360页

作者： DAS Ratul DATTA Akash civil engineering Department National Institute of Technology AgartalaAgartala-799046India

Boulder spacing in mountain rivers and near-wake flow zones within the boulder array is very useful for fish habitat and growth of aquatic *** present study aims to investigate how the boulder array and spacing influence the near-bed flow structures in a gravel-bed *** are staggered over a gravel-bed stream with three different inter-boulder spacing namely(a)large(b)medium and(c)small *** acoustic Doppler velocimeter was used for flow measurements in a rectangular channel and the results were compared with those acquired from numerical *** time-averaged velocity profiles at the near-wake flow zones of boulders experience maximum flow retardation which is an outcome of the boulder-induced form *** ratio of velocity differences associated to form and skin roughness and its positive magnitude reveals the dominance of form roughness closest to the *** roughness computed is 1.75 to 2 times higher than the skin roughness at the near-wake flow *** particular,the collective immobile boulders placed at different inter-boulder spacings developed high and low bed shear stresses closest to the *** low bed shear stresses characterised by a secondary peak developed at the trough location of the boulders is attributed to the skin shear ***,the spatial averaging of time-averaged flow quantities gives additional impetus to present an improved illustration of fluid shear *** formation of form-induced shear stress is estimated to be 17%to 23%of doubleaveraged Reynolds shear stress and partially compensates for the damping of time-averaged Reynolds shear stress in the interfacial *** quadrant analysis of spatial velocity fluctuations depicts that the form-induced shear stresses are dominant in the interfacial sub-layer and have no significance above the gravel-bed surface.

关键词： Array of boulders Near wake flow zones Velocity distributions Skin roughness Form induced shear stresses