This article presents an innovative method of bio-mediated soil improvement for increasing the shear strength of loose sand.The improvement is realized by mixing the loose sand with the inoculum of Rhizopus oligosporu...This article presents an innovative method of bio-mediated soil improvement for increasing the shear strength of loose sand.The improvement is realized by mixing the loose sand with the inoculum of Rhizopus oligosporus,a kind of fungus widely used in food industry for making Indonesian tempeh.The objective of this article is to investigate the performance and mechanism of mixing tempeh inoculum as a binding agent of loose sand particles.The inoculum dosage,water content of loose sand,and curing time were examined for identifying the increment of unconfined compressive strength(q_u)of the samples.The results showed that q_u of the treated samples increased when the inoculum dosage was elevated.It shows that 5.24%inoculum could yield 68 kPa of q_u,and 5%water content and 3 d curing time produced the maximum q_u.Moreover,the mechanism of hypha and mycelium in binding the soil particles was clearly observed using a digital microscope and scanning electron microscope.展开更多
Kinked rebar is a special type of steel material,which is installed in beam column nodes and frame beams.It effectively enhances the blast resilience,seismic collapse resistance,and progressive collapse resistance of ...Kinked rebar is a special type of steel material,which is installed in beam column nodes and frame beams.It effectively enhances the blast resilience,seismic collapse resistance,and progressive collapse resistance of reinforced concrete(RC)structures without imposing substantial cost burdens,thereby emerging as a focal point of recent research endeavors.On the basis of explaining the working principle of kinked rebars,this paper reviews the research status of kinked rebars at home and abroad from three core domains:the tensile mechanical properties of kinked rebars,beam column nodes with kinked rebars,and concrete frame structures with kinked rebars.The analysis underscores that the straightening process of kinked rebars does not compromise their ultimate strength but significantly bolsters structural ductility and enhances energy dissipation capabilities.In beam-column joints,the incorporation of kinked rebars facilitates the seamless transfer of plastic hinges,adhering to the design principle of“strong columns and weak beams.”In addition,kinked rebars can greatly improve the resistance of the beam;The seismic resistance,internal explosion resistance,and progressive collapse resistance of reinforced concrete frame structures with kinked rebar have significantly improved.Beyond its primary application,the principle of kinked rebar was extended to other applications of kinked materials such as corrugated steel plates and origami structures,and the stress characteristics of related components and structures were studied.Intriguingly,this paper also proposes the application of kinked rebars in bridge engineering,aiming to address the challenges of localized damage concentration and excessive residual displacement in RC bridge piers.The introduction of kinked rebars in piers is envisioned to mitigate these issues,with the paper outlining its advantages and feasibility,thereby offering valuable insights for future research on kinked reinforcement and seismic design strategies for bridges.展开更多
Using the knowledge obtained from previous courses such as:soil mechanics,structural analysis,steel design,etc.,a team of seven students at California State University,Northridge(CSUN)designed a two-story residential ...Using the knowledge obtained from previous courses such as:soil mechanics,structural analysis,steel design,etc.,a team of seven students at California State University,Northridge(CSUN)designed a two-story residential steel house for their senior design course.The home was chosen to be located in the city of Pacific Palisades,California.The following paper outlines the design of the home ranging from the architectural plans to the beam,column,and foundation design.California is known to be seismically active,therefore,seismic loading played a large factor into the design of the house.Once the design of the house was completed,a cost estimate of the house was prepared using the estimating platform RSMeans.Additionally,a second estimate of the home was also completed with the addition of LEED(Leadership in Energy and Environmental Design)features such as solar panels,LED lighting,and energy star appliances that make the home environmentally friendly and will give the owner a greater return on their investment in the future.展开更多
The present researched topic was conceived from a senior design course for Civil Engineering students at CSUN (California State University), Northridge. In this work, experimental trials were performed and compared to...The present researched topic was conceived from a senior design course for Civil Engineering students at CSUN (California State University), Northridge. In this work, experimental trials were performed and compared to establish theoretical values of the discharge coefficient. The discharge coefficient is a dimensionless number used to characterize the flow and pressure loss behavior of nozzles and orifices in fluid systems. A group of low-income undergraduate students with diverse backgrounds designed multiple 3D printed orifices where each 3D printed orifice had a specific shape. Utilizing the methods of technical problem solving, the undergraduates found experimental discharge coefficient values for the following orifices: borda, short-tubed, and sharp-edged. Implementing ethics of engineering practice and utilizing university resources, this study is a representation of the collaborative work of minorities and females that want to expand their knowledge within their respective discipline of Civil Engineering.展开更多
This paper presents the partial results of a project in progress that aims to improve the teaching and learning of Graphic Geometry modules taught in Engineering and Civil Engineering courses at the Federal University...This paper presents the partial results of a project in progress that aims to improve the teaching and learning of Graphic Geometry modules taught in Engineering and Civil Engineering courses at the Federal University of Pernambuco through the development of education methodologies and content integration of these disciplines using computational technologies. This study covers and analyzes the contents of Tridimensional Graphic Geometry, Technical Drawing 3 and Descriptive Geometry in the BSc course in Civil Engineering, in order to create an integrated assessment model across these disciplines from the use of specific computer graphic softwares. It is proposed to use computer graphic for： （i） concept formation, （ii） completing and/or reviewing the content, （iii） creation of a database with virtual geometric models and their applications in Engineering and for the studies of their representations, geometric properties, etc., providing digital images of everyday forms and objects. In order to begin the diagnosis of the current situation, we gave an open questionnaire to 65 students from the 16 groups of three-dimensional graphical geometry, 20 students from the two courses in Technical Drawing 3 and 35 students from the three Descriptive Geometry classes. The analysis of the data suggests that students better understand the two-dimensional representations of three-dimensional models through their modeling with the computer graphics software used, and the association of abstract concepts with concrete content. From the analysis of the data we can verify that when our students enter the foundation Engineering courses, the main difficulty in the disciplines of drawing is the three-dimensional visualization. The hypothesis is that the student will better understand the two-dimensional representations of three-dimensional models through their modeling with the computer graphic software used and the association of abstract concepts with concrete content.展开更多
This research focuses on the application of three soft computing techniques including Minimax Probability Machine Regression(MPMR),Particle Swarm Optimization based Artificial Neural Network(ANN-PSO)and Particle Swarm...This research focuses on the application of three soft computing techniques including Minimax Probability Machine Regression(MPMR),Particle Swarm Optimization based Artificial Neural Network(ANN-PSO)and Particle Swarm Optimization based Adaptive Network Fuzzy Inference System(ANFIS-PSO)to study the shallow foundation reliability based on settlement criteria.Soil is a heterogeneous medium and the involvement of its attributes for geotechnical behaviour in soil-foundation system makes the prediction of settlement of shallow a complex engineering problem.This study explores the feasibility of soft computing techniques against the deterministic approach.The settlement of shallow foundation depends on the parametersγ(unit weight),e0(void ratio)and CC(compression index).These soil parameters are taken as input variables while the settlement of shallow foundation as output.To assess the performance of models,different performance indices i.e.RMSE,VAF,R^2,Bias Factor,MAPE,LMI,U(95),RSR,NS,RPD,etc.were used.From the analysis of results,it was found that MPMR model outperformed PSO-ANFIS and PSO-ANN.Therefore,MPMR can be used as a reliable soft computing technique for non-linear problems for settlement of shallow foundations on soils.展开更多
A new model to simulate spatially correlated earthquake ground motions is developed. In the model, the main factors that characterize three distinct effects of spatial variability, namely, the incoherency effect, the ...A new model to simulate spatially correlated earthquake ground motions is developed. In the model, the main factors that characterize three distinct effects of spatial variability, namely, the incoherency effect, the wave-passage effect and the site-response effect, are taken into account, and corresponding terms/parameters are incorporated into the well known model of uniform ground motions. Some of these terms/parameters can be determined by the root operation, and others can be calculated directly. The proposed model is first verified theoretically, and examples of ground motion simulations are provided as a further illustration. It is proven that the ensemble expected value and the ensemble auto-/cross-spectral density functions of the simulated ground motions are identical to the target spectral density functions. The proposed model can also be used to simulate other correlated stochastic processes, such as wave and wind loads.展开更多
The focus of this study is to critically review the physiochemical and engineering properties of the fly ash and its applications in various fields.The utilization of fly ash has become a widespread area,but the amoun...The focus of this study is to critically review the physiochemical and engineering properties of the fly ash and its applications in various fields.The utilization of fly ash has become a widespread area,but the amount of utilization is still a serious issue.It has many beneficial qualities(such as pozzolanic property,fineness,spherical shape,lightweight,etc.),which enhance its properties and make it suitable for its utilization as a new construction material.For the bulk utilization of fly ash,it should be employed in the areas independent of any other parameters.So that,the disposal problem can be reduced significantly.The knowledge of its physiochemical characteristic helps in the judgment of appropriate fly ash for any particular type of work.Fly ash can be utilized in other areas such as asphalt concrete,geopolymer concrete,ground improvement,agricultural sector,roller compacted concrete,brick,etc.that will reduce the existing ashes,and also the disposal problem can be solved appreciably.The implementation of fly ash must be avoided below the natural ground water level and below 4°C temperature conditions.展开更多
Reliability-based design (RBD) is being adopted by geotechnical design codes worldwide, and it is therefore necessary that rock engineering practice evolves to embrace RBD. This paper examines the Hoek-Brown (H-B) str...Reliability-based design (RBD) is being adopted by geotechnical design codes worldwide, and it is therefore necessary that rock engineering practice evolves to embrace RBD. This paper examines the Hoek-Brown (H-B) strength criterion within the RBD framework, and presents three distinct analyses using a Bayesian approach. Firstly, a compilation of intact compressive strength test data for six rock types is used to examine uncertainty and variability in the estimated H-B parameters m and σc, and corresponding predicted axial strength. The results suggest that within- and between-rock type variabilities are so large that these parameters need to be determined from rock testing campaigns, rather than reference values being used. The second analysis uses an extensive set of compressive and tensile (both direct and indirect) strength data for a granodiorite, together with a new Bayesian regression model, to develop joint probability distributions of m and σc suitable for use in RBD. This analysis also shows how compressive and indirect tensile strength data may be robustly used to fit an H-B criterion. The third analysis uses the granodiorite data to investigate the important matter of developing characteristic strength criteria. Using definitions from Eurocode 7, a formal Bayesian interpretation of characteristic strength is proposed and used to analyse strength data to generate a characteristic criterion. These criteria are presented in terms of characteristic parameters mk and σck, the values of which are shown to depend on the testing regime used to obtain the strength data. The paper confirms that careful use of appropriate Bayesian statistical analysis allows the H-B criterion to be brought within the framework of RBD. It also reveals that testing guidelines such as the International Society for Rock Mechanics and Rock Engineering (ISRM) suggested methods will require modification in order to support RBD. Importantly, the need to fully understand the implications of uncertainty in nonlinear strength criteria is identified.展开更多
The deep cement mixing(DCM)is used to improve the capacity and reduce the settlement of the soft ground by forming cemented clay columns.The investigation on the mechanical behaviour of the DCM samples is limited to e...The deep cement mixing(DCM)is used to improve the capacity and reduce the settlement of the soft ground by forming cemented clay columns.The investigation on the mechanical behaviour of the DCM samples is limited to either laboratory-prepared samples or in-situ samples under unconfined compression.In this study,a series of drained and undrained triaxial shearing tests was performed on the in-situ cored DCM samples with high cement content to assess their mechanical behaviours.It is found that the drainage condition affects significantly the stiffness,peak and residual strengths of the DCM samples,which is mainly due to the state of excess pore water pressure at different strain levels,i.e.being positive before the peak deviatoric stress and negative after the peak deviatoric stress,in the undrained tests.The slope of the failure envelope changes obviously with the confining pressures,being steeper at lower stress levels and flatter at higher stress levels.The strength parameters,effective cohesion and friction angle obtained from lower stress levels(c′0 andφ′0)are 400 kPa and 58°,respectively,which are deemed to be true for design in most DCM applications where the in-situ stress levels are normally at lower values of 50-200 kPa.Additionally,the computed tomography(CT)scanning system was adopted to visualize the internal structures of DCM samples.It is found that the clay pockets existing inside the DCM samples due to uneven mixing affect markedly their stress-strain behaviour,which is one of the main reasons for the high variability of the DCM samples.展开更多
The creep characteristics of rock under high crustal stress are of important influence on the long‐term stability of deep rock engineering.To study the creep characteristics and engineering application of sandstone u...The creep characteristics of rock under high crustal stress are of important influence on the long‐term stability of deep rock engineering.To study the creep characteristics and engineering application of sandstone under high crustal stress,this study constructed nonlinear creep damage(NCD)constitutive mode based on the triaxial graded loading‒unloading creep test of sandstone in the Yuezhishan Tunnel.A numerical NCD constitutive model and a breakable lining(BL)model were developed based on FLAC3D and then applied to the stability analysis of the Yuezhishan Tunnel.Based on the creep test results of sandstone,a power function of creep rate and stress level was constructed,by which the long‐term strength was solved.The results show that the long‐term strength of the red sandstone based on the related function of the steady‐state creep rate and stress level is close to the measured stress value in engineering.The NCD model considering damage factors reflects the instantaneous and viscoelastic plasticity deformation characteristics of the red sandstone.The numerical NCD constitutive model and the BL model can reflect surrounding rock deformation characteristics and lining failure characteristics in practical engineering.The research results provide theoretical references for long‐term stability analysis of rock engineering and the deformation control of surrounding rock under high crustal stress.展开更多
At present,the methods of analyzing the stability of slope under earthquake are not accurate and reasonable because of some limitations. Based on the real dynamic tensile-shear failure mechanism of slope,the paper pro...At present,the methods of analyzing the stability of slope under earthquake are not accurate and reasonable because of some limitations. Based on the real dynamic tensile-shear failure mechanism of slope,the paper proposes dynamic analysis of strength reduction FEM (finite element method) and takes the reduction of shear strength parameters and tensile strength parameters into consideration. And it comprehensively takes the transfixion of the failure surface,the non-convergence of calculation and mutation of displacement as the criterion of dynamic instability and failure of the slope. The strength reduction factor under limit state is regarded as the dynamic safety factor of the slope under earthquake effect and its advantages are introduced. Finally,the method is applied in the seismic design of anchors supporting and anti-slide pile supporting of the slope. Calculation examples show that the application of dynamic analysis of strength reduction is feasible in the seismic design of slope engineering,which can consider dynamic interaction of supporting structure and rock-soil mass. Owing to its preciseness and great advantages,it is a new method in the seismic design of slope supporting.展开更多
Soft computing(SC)refers to the ability of a digital computer or robot to perform functions that are normally associated with intelligent individuals,such as reasoning and problem-solving.An example of this would be a...Soft computing(SC)refers to the ability of a digital computer or robot to perform functions that are normally associated with intelligent individuals,such as reasoning and problem-solving.An example of this would be a project aimed at creating systems capable of reasoning,discovering meaning,generalising,or learning from past experience.Science and engineering problems that are both non-linear and complex can be solved using these methodologies.It has been proven that these algorithms can be used to solve numerous real-world problems.The techniques outlined can be used to increase the accuracy of existing models/equations,or they can be used to propose a newmodel that can address the problem.展开更多
In deep-earth engineering,the high earth temperature can significantly affect the rock's mechanical properties,especially when the rock is cooled during the construction process.Accordingly,whether the cooling spe...In deep-earth engineering,the high earth temperature can significantly affect the rock's mechanical properties,especially when the rock is cooled during the construction process.Accordingly,whether the cooling speed affects the mechanical and physical properties of rocks is worth to be investigated.The present study explored the influence of the cooling rate on the physical and chemical properties of granite heated at 25–800°C.The mechanical and physical properties involved in this study included uniaxial compression strength,peak strain,modulus,P-wave velocity,mass and volume,the change of which could reflect the sensitivity of granite to the cooling rate.Acoustic emission(AE)monitoring,microscopic observation,and X-ray diffraction(XRD)are used to analyze the underlying damage mechanism.It is found that more AE signals and large-scale cracks are accounted for based on the b-value method when the specimens are cooled by water.Furthermore,the microscopic observation by polarized light microscopy indicates that the density,opening degree,and connectivity of the cracks under water cooling mode are higher than that under natural cooling mode.In addition,the XRD illustrates that there is no obvious change in mineral content and diffraction angle at different temperatures,which confirms that the change of mechanical properties is not related to the chemical properties.The present conclusion can provide a perspective to assess the damage caused by different cooling methods to hot rocks.展开更多
Building Information Models (BIM) have revealed themselves as a good tool to support construction actions, due to their ability to store all the information in one digital model and to promote collaboration between al...Building Information Models (BIM) have revealed themselves as a good tool to support construction actions, due to their ability to store all the information in one digital model and to promote collaboration between all participants in a project. Teaching Civil Engineering requires a permanent updating of knowledge concerning procedures and technologies used in the construction industry. In this sense, the school should seek to adapt its curriculum to include innovative issues to support new technologies. So, in an educational context, the aim of the present work is to disseminate knowledge concerning the benefits provided when implementing BIM in several aspects within the construction activity. In a Civil Engineering school some topics of BIM application were developed by students within MSc researches. The text describes in detail some of the main topics, showing distinct use of BIM: Generation and use of a 4D/BIM model to support construction planning;coordination of construction project based on BIM methodology;conflict analysis based in an architectural 3D/BIM model. Several study cases were modelled and analyzed, confronting the BIM use with the traditional way when performing the same tasks, and consequently recommendations were carried out. This work contributed to demonstrate the advantages of employing BIM for building tasks purposes when compared with the traditional process, and in a didactic context the main objective is to add competitive skills in the training of future civil engineers.展开更多
A new automatic rotary compactor and its abilities in compacting stone mastic asphalt （SMA） are presented. Following an overview of the rotary compactor and the compaction procedure, it is demonstrated that the rota...A new automatic rotary compactor and its abilities in compacting stone mastic asphalt （SMA） are presented. Following an overview of the rotary compactor and the compaction procedure, it is demonstrated that the rotary compactor is able to produce uniform slabs with the desired thickness of 65 mm all over around. Furthermore, 132 cored samples from the rotary compactor had been compacted uniformly with approximately 4% optimum air void content. In addition, performance tests results indicate that the rotary compactor produces asphalt mixturures with the requirements of resilient modulus, Marshall stability and flow. A weight factor was introduced for each fraction of aggregates in the degradation analysis to compensate the crushing effect of aggregates during mixing and compacting.展开更多
A new scour countermeasure using solidified slurry for offshore foundation has been proposed recently.Fluidized solidified slurry is pumped to seabed area around foundation for scour protection or pumped into the deve...A new scour countermeasure using solidified slurry for offshore foundation has been proposed recently.Fluidized solidified slurry is pumped to seabed area around foundation for scour protection or pumped into the developed scour holes for scour repair as the fluidized material solidifies gradually.In the pumping operation and solidification,the engineering behaviors of solidified slurry require to be considered synthetically for the reliable application in scour repair and protection of ocean engineering such as the pumpability related flow value,flow diffusion behavior related rheological property,anti-scour performance related retention rate in solidification and bearing capacity related strength property after solidification.In this study,a series of laboratory tests are conducted to investigate the effects of mix proportion(initial water content and binder content)on the flow value,rheological properties,density,retention rate of solidified slurry and unconfined compressive strength(UCS).The results reveal that the flow value increases with the water content and decreases with the binder amount.All the solidified slurry exhibits Bingham plastic behavior when the shear rate is larger than 5 s^(-1).The Bingham model has been employed to fit the rheology test results,and empirical formulas for obtaining the density,yield stress and viscosity are established,providing scientific support for the numerical assessment of flow and diffusion of solidified slurry.Retention rate of solidified slurry decreases with the water flow velocity and flow value,which means the pumpability of solidified slurry is contrary to anti-scour performance.The unconfined compressive strength after solidification reduces as the water content increases and binder content decreases.A design and application procedure of solidified soil for scour repair and protection is also proposed for engineering reference.展开更多
This Special Issue of the Journal of Rock Mechanics and GeotechnicalEngineering （JRMGE） contains 13 papers prepared by internationalexperts on various general topics in geomechanics, rockmechanics and geotechnical e...This Special Issue of the Journal of Rock Mechanics and GeotechnicalEngineering （JRMGE） contains 13 papers prepared by internationalexperts on various general topics in geomechanics, rockmechanics and geotechnical engineering. It represents a usefulmix of theoretical developments, testing and practical applications.We present in the following brief details in the papers, alphabeticallyin accordance with the last name of the first author.Barla presents a review of tunneling techniques with emphasison the full-face method combining full-face excavation and facereinforcement by means of fiber-glass elements with a yieldcontrolsupport. This method has been used successfully in difficultgeologic conditions, and for a wide spectrum of ground situations.The validation of the method with respect to the Saint Martin LaPorte access adit along the LyoneTurin Base tunnel experiencingseverely squeezing conditions during excavation is also includedin the paper. The numerical modeling with consideration of therock mass time-dependent behavior showed a satisfactory agreementwith monitoring results.展开更多
Silica materials are located in various regions of Libya in large quantities and different mining conditions, so the purpose of this study is silica materials in the south-west of the Libyan region Edree in terms of q...Silica materials are located in various regions of Libya in large quantities and different mining conditions, so the purpose of this study is silica materials in the south-west of the Libyan region Edree in terms of quality and the possibility of using in various engineering industries, particularly construction. The results show that the sands of silica presented in Edree area are of a high degree of purity, as the percentage of silicon （SIO2） reached 99.5%, the percentage of impurities was negligible and represented in some chemical elements in different proportions, such as calcium 0.224%, sodium 0.004%, iron 0.0006%, zinc 0.0003%, boron 0.0003%, potassium 0.0001%, manganese 0.0001% and magnesium 0.0001%, making these materials very suitable in the manufacture of all types of glass, crystal and semi-crystalline high-quality without needing any important treatment, as well as its suitability as a refinement in manufacture of templates metal castings in addition to the possibility of use in the manufacture of cement, building materials and as a filler in paint and brick making and sand and concrete elements can also be used in electronic industries. A geological material of silica present in the form of a sequence of layers of clay and thin layers of sand stone and a large stock of high-quality near the surface, making mining operations of the type of surface and reduces the cost of extraction.展开更多
Many timber producing countries generate more than 2 million m3 of sawdust annually. In developing countries, sawdust is often disposed of by open dumping, open burning, or dumping in landfills. This poses huge enviro...Many timber producing countries generate more than 2 million m3 of sawdust annually. In developing countries, sawdust is often disposed of by open dumping, open burning, or dumping in landfills. This poses huge environmental challenges related to air pollution, greenhouse gas emissions, and destruction of plant and aquatic life. Findings from this review article reveal that sawdust can be used to make sawdust construction composites with good modulus of elasticity, water absorption and strength characteristics that satisfy international specifications. These composites include particleboards, sawdust concrete blocks or bricks and sawdust concrete. The article concludes that partially replacing 5% to 17% of sand with sawdust, or replacing cement with sawdust ash in proportions of 5% to 15% in concrete mixes can produce structural concrete with compressive strengths greater than 20 MPa. Partially replacing 10% to 30% of sand used in the manufacture blocks and bricks with sawdust can also produce sawdust bricks and blocks with compressive strengths greater than 3 MPa. Sawdust composites are also attractive for their low thermal conductivity, high sound absorption and good sound insulation characteristics. These findings indicate that increased utilisation of sawdust composites in construction will mitigate against potential sawdust environmental pollution, conserve energy and reduce disposal costs.展开更多
基金the research funding provided by Ikatan Alumni Teknik Sipil(IATS)UnparUniversitas Katolik Parahyangan.
文摘This article presents an innovative method of bio-mediated soil improvement for increasing the shear strength of loose sand.The improvement is realized by mixing the loose sand with the inoculum of Rhizopus oligosporus,a kind of fungus widely used in food industry for making Indonesian tempeh.The objective of this article is to investigate the performance and mechanism of mixing tempeh inoculum as a binding agent of loose sand particles.The inoculum dosage,water content of loose sand,and curing time were examined for identifying the increment of unconfined compressive strength(q_u)of the samples.The results showed that q_u of the treated samples increased when the inoculum dosage was elevated.It shows that 5.24%inoculum could yield 68 kPa of q_u,and 5%water content and 3 d curing time produced the maximum q_u.Moreover,the mechanism of hypha and mycelium in binding the soil particles was clearly observed using a digital microscope and scanning electron microscope.
基金supported by the Zhejiang Provincial Natural Science Foundation of China under Grant No.LTGG23E080001Zhejiang Engineering Research Center of Intelligent Urban Infrastructure under Grant No.IUI2022-ZD-01.
文摘Kinked rebar is a special type of steel material,which is installed in beam column nodes and frame beams.It effectively enhances the blast resilience,seismic collapse resistance,and progressive collapse resistance of reinforced concrete(RC)structures without imposing substantial cost burdens,thereby emerging as a focal point of recent research endeavors.On the basis of explaining the working principle of kinked rebars,this paper reviews the research status of kinked rebars at home and abroad from three core domains:the tensile mechanical properties of kinked rebars,beam column nodes with kinked rebars,and concrete frame structures with kinked rebars.The analysis underscores that the straightening process of kinked rebars does not compromise their ultimate strength but significantly bolsters structural ductility and enhances energy dissipation capabilities.In beam-column joints,the incorporation of kinked rebars facilitates the seamless transfer of plastic hinges,adhering to the design principle of“strong columns and weak beams.”In addition,kinked rebars can greatly improve the resistance of the beam;The seismic resistance,internal explosion resistance,and progressive collapse resistance of reinforced concrete frame structures with kinked rebar have significantly improved.Beyond its primary application,the principle of kinked rebar was extended to other applications of kinked materials such as corrugated steel plates and origami structures,and the stress characteristics of related components and structures were studied.Intriguingly,this paper also proposes the application of kinked rebars in bridge engineering,aiming to address the challenges of localized damage concentration and excessive residual displacement in RC bridge piers.The introduction of kinked rebars in piers is envisioned to mitigate these issues,with the paper outlining its advantages and feasibility,thereby offering valuable insights for future research on kinked reinforcement and seismic design strategies for bridges.
文摘Using the knowledge obtained from previous courses such as:soil mechanics,structural analysis,steel design,etc.,a team of seven students at California State University,Northridge(CSUN)designed a two-story residential steel house for their senior design course.The home was chosen to be located in the city of Pacific Palisades,California.The following paper outlines the design of the home ranging from the architectural plans to the beam,column,and foundation design.California is known to be seismically active,therefore,seismic loading played a large factor into the design of the house.Once the design of the house was completed,a cost estimate of the house was prepared using the estimating platform RSMeans.Additionally,a second estimate of the home was also completed with the addition of LEED(Leadership in Energy and Environmental Design)features such as solar panels,LED lighting,and energy star appliances that make the home environmentally friendly and will give the owner a greater return on their investment in the future.
文摘The present researched topic was conceived from a senior design course for Civil Engineering students at CSUN (California State University), Northridge. In this work, experimental trials were performed and compared to establish theoretical values of the discharge coefficient. The discharge coefficient is a dimensionless number used to characterize the flow and pressure loss behavior of nozzles and orifices in fluid systems. A group of low-income undergraduate students with diverse backgrounds designed multiple 3D printed orifices where each 3D printed orifice had a specific shape. Utilizing the methods of technical problem solving, the undergraduates found experimental discharge coefficient values for the following orifices: borda, short-tubed, and sharp-edged. Implementing ethics of engineering practice and utilizing university resources, this study is a representation of the collaborative work of minorities and females that want to expand their knowledge within their respective discipline of Civil Engineering.
文摘This paper presents the partial results of a project in progress that aims to improve the teaching and learning of Graphic Geometry modules taught in Engineering and Civil Engineering courses at the Federal University of Pernambuco through the development of education methodologies and content integration of these disciplines using computational technologies. This study covers and analyzes the contents of Tridimensional Graphic Geometry, Technical Drawing 3 and Descriptive Geometry in the BSc course in Civil Engineering, in order to create an integrated assessment model across these disciplines from the use of specific computer graphic softwares. It is proposed to use computer graphic for： （i） concept formation, （ii） completing and/or reviewing the content, （iii） creation of a database with virtual geometric models and their applications in Engineering and for the studies of their representations, geometric properties, etc., providing digital images of everyday forms and objects. In order to begin the diagnosis of the current situation, we gave an open questionnaire to 65 students from the 16 groups of three-dimensional graphical geometry, 20 students from the two courses in Technical Drawing 3 and 35 students from the three Descriptive Geometry classes. The analysis of the data suggests that students better understand the two-dimensional representations of three-dimensional models through their modeling with the computer graphics software used, and the association of abstract concepts with concrete content. From the analysis of the data we can verify that when our students enter the foundation Engineering courses, the main difficulty in the disciplines of drawing is the three-dimensional visualization. The hypothesis is that the student will better understand the two-dimensional representations of three-dimensional models through their modeling with the computer graphic software used and the association of abstract concepts with concrete content.
基金financially supported by High-end Foreign Expert program(G20190022002)Science and Technology Research Program of Chongqing Municipal Education Commission(Grant No.KJZDK201900102)Chongqing Construction Science and Technology Plan Project(2019-0045),that are gratefully acknowledged。
文摘This research focuses on the application of three soft computing techniques including Minimax Probability Machine Regression(MPMR),Particle Swarm Optimization based Artificial Neural Network(ANN-PSO)and Particle Swarm Optimization based Adaptive Network Fuzzy Inference System(ANFIS-PSO)to study the shallow foundation reliability based on settlement criteria.Soil is a heterogeneous medium and the involvement of its attributes for geotechnical behaviour in soil-foundation system makes the prediction of settlement of shallow a complex engineering problem.This study explores the feasibility of soft computing techniques against the deterministic approach.The settlement of shallow foundation depends on the parametersγ(unit weight),e0(void ratio)and CC(compression index).These soil parameters are taken as input variables while the settlement of shallow foundation as output.To assess the performance of models,different performance indices i.e.RMSE,VAF,R^2,Bias Factor,MAPE,LMI,U(95),RSR,NS,RPD,etc.were used.From the analysis of results,it was found that MPMR model outperformed PSO-ANFIS and PSO-ANN.Therefore,MPMR can be used as a reliable soft computing technique for non-linear problems for settlement of shallow foundations on soils.
基金National Natural Science Foundation of China Under Grant No.90815020 and No.50639010
文摘A new model to simulate spatially correlated earthquake ground motions is developed. In the model, the main factors that characterize three distinct effects of spatial variability, namely, the incoherency effect, the wave-passage effect and the site-response effect, are taken into account, and corresponding terms/parameters are incorporated into the well known model of uniform ground motions. Some of these terms/parameters can be determined by the root operation, and others can be calculated directly. The proposed model is first verified theoretically, and examples of ground motion simulations are provided as a further illustration. It is proven that the ensemble expected value and the ensemble auto-/cross-spectral density functions of the simulated ground motions are identical to the target spectral density functions. The proposed model can also be used to simulate other correlated stochastic processes, such as wave and wind loads.
基金Science and Engineering Research Board(ECR/2015/000580).
文摘The focus of this study is to critically review the physiochemical and engineering properties of the fly ash and its applications in various fields.The utilization of fly ash has become a widespread area,but the amount of utilization is still a serious issue.It has many beneficial qualities(such as pozzolanic property,fineness,spherical shape,lightweight,etc.),which enhance its properties and make it suitable for its utilization as a new construction material.For the bulk utilization of fly ash,it should be employed in the areas independent of any other parameters.So that,the disposal problem can be reduced significantly.The knowledge of its physiochemical characteristic helps in the judgment of appropriate fly ash for any particular type of work.Fly ash can be utilized in other areas such as asphalt concrete,geopolymer concrete,ground improvement,agricultural sector,roller compacted concrete,brick,etc.that will reduce the existing ashes,and also the disposal problem can be solved appreciably.The implementation of fly ash must be avoided below the natural ground water level and below 4°C temperature conditions.
文摘Reliability-based design (RBD) is being adopted by geotechnical design codes worldwide, and it is therefore necessary that rock engineering practice evolves to embrace RBD. This paper examines the Hoek-Brown (H-B) strength criterion within the RBD framework, and presents three distinct analyses using a Bayesian approach. Firstly, a compilation of intact compressive strength test data for six rock types is used to examine uncertainty and variability in the estimated H-B parameters m and σc, and corresponding predicted axial strength. The results suggest that within- and between-rock type variabilities are so large that these parameters need to be determined from rock testing campaigns, rather than reference values being used. The second analysis uses an extensive set of compressive and tensile (both direct and indirect) strength data for a granodiorite, together with a new Bayesian regression model, to develop joint probability distributions of m and σc suitable for use in RBD. This analysis also shows how compressive and indirect tensile strength data may be robustly used to fit an H-B criterion. The third analysis uses the granodiorite data to investigate the important matter of developing characteristic strength criteria. Using definitions from Eurocode 7, a formal Bayesian interpretation of characteristic strength is proposed and used to analyse strength data to generate a characteristic criterion. These criteria are presented in terms of characteristic parameters mk and σck, the values of which are shown to depend on the testing regime used to obtain the strength data. The paper confirms that careful use of appropriate Bayesian statistical analysis allows the H-B criterion to be brought within the framework of RBD. It also reveals that testing guidelines such as the International Society for Rock Mechanics and Rock Engineering (ISRM) suggested methods will require modification in order to support RBD. Importantly, the need to fully understand the implications of uncertainty in nonlinear strength criteria is identified.
基金funded by the Environment and Conservation Fund(Grant Nos.2020-170 and 2021-156)the National Natural Science Foundation of China(Grant No.42102327).
文摘The deep cement mixing(DCM)is used to improve the capacity and reduce the settlement of the soft ground by forming cemented clay columns.The investigation on the mechanical behaviour of the DCM samples is limited to either laboratory-prepared samples or in-situ samples under unconfined compression.In this study,a series of drained and undrained triaxial shearing tests was performed on the in-situ cored DCM samples with high cement content to assess their mechanical behaviours.It is found that the drainage condition affects significantly the stiffness,peak and residual strengths of the DCM samples,which is mainly due to the state of excess pore water pressure at different strain levels,i.e.being positive before the peak deviatoric stress and negative after the peak deviatoric stress,in the undrained tests.The slope of the failure envelope changes obviously with the confining pressures,being steeper at lower stress levels and flatter at higher stress levels.The strength parameters,effective cohesion and friction angle obtained from lower stress levels(c′0 andφ′0)are 400 kPa and 58°,respectively,which are deemed to be true for design in most DCM applications where the in-situ stress levels are normally at lower values of 50-200 kPa.Additionally,the computed tomography(CT)scanning system was adopted to visualize the internal structures of DCM samples.It is found that the clay pockets existing inside the DCM samples due to uneven mixing affect markedly their stress-strain behaviour,which is one of the main reasons for the high variability of the DCM samples.
基金National Science and Technology Major Project,Grant/Award Number:2017YFC1503102National Natural Science Foundation of China,Grant/Award Number:51704144。
文摘The creep characteristics of rock under high crustal stress are of important influence on the long‐term stability of deep rock engineering.To study the creep characteristics and engineering application of sandstone under high crustal stress,this study constructed nonlinear creep damage(NCD)constitutive mode based on the triaxial graded loading‒unloading creep test of sandstone in the Yuezhishan Tunnel.A numerical NCD constitutive model and a breakable lining(BL)model were developed based on FLAC3D and then applied to the stability analysis of the Yuezhishan Tunnel.Based on the creep test results of sandstone,a power function of creep rate and stress level was constructed,by which the long‐term strength was solved.The results show that the long‐term strength of the red sandstone based on the related function of the steady‐state creep rate and stress level is close to the measured stress value in engineering.The NCD model considering damage factors reflects the instantaneous and viscoelastic plasticity deformation characteristics of the red sandstone.The numerical NCD constitutive model and the BL model can reflect surrounding rock deformation characteristics and lining failure characteristics in practical engineering.The research results provide theoretical references for long‐term stability analysis of rock engineering and the deformation control of surrounding rock under high crustal stress.
基金Financial Support by Special Research fund of State Key Laboratory of Geohazard Prevention and Geoenvironment Protection (Chengdu University of Technology) (GZ2009-14)Special Research fund of Minis-try of Education Key Laboratory of Urban Security and Disaster Engineering
文摘At present,the methods of analyzing the stability of slope under earthquake are not accurate and reasonable because of some limitations. Based on the real dynamic tensile-shear failure mechanism of slope,the paper proposes dynamic analysis of strength reduction FEM (finite element method) and takes the reduction of shear strength parameters and tensile strength parameters into consideration. And it comprehensively takes the transfixion of the failure surface,the non-convergence of calculation and mutation of displacement as the criterion of dynamic instability and failure of the slope. The strength reduction factor under limit state is regarded as the dynamic safety factor of the slope under earthquake effect and its advantages are introduced. Finally,the method is applied in the seismic design of anchors supporting and anti-slide pile supporting of the slope. Calculation examples show that the application of dynamic analysis of strength reduction is feasible in the seismic design of slope engineering,which can consider dynamic interaction of supporting structure and rock-soil mass. Owing to its preciseness and great advantages,it is a new method in the seismic design of slope supporting.
文摘Soft computing(SC)refers to the ability of a digital computer or robot to perform functions that are normally associated with intelligent individuals,such as reasoning and problem-solving.An example of this would be a project aimed at creating systems capable of reasoning,discovering meaning,generalising,or learning from past experience.Science and engineering problems that are both non-linear and complex can be solved using these methodologies.It has been proven that these algorithms can be used to solve numerous real-world problems.The techniques outlined can be used to increase the accuracy of existing models/equations,or they can be used to propose a newmodel that can address the problem.
基金The National Natural Science Foundation of China,Grant/Award Number:41702326the Innovative Experts,Long-term Program of Jiangxi Province,Grant/Award Number:jxsq2018106049+1 种基金the Natural Science Foundation of Jiangxi Province,Grant/Award Number:20202ACB214006the Supported by Program of Qingjiang Excellent Young Talents,Jiangxi University of Science and Technology。
文摘In deep-earth engineering,the high earth temperature can significantly affect the rock's mechanical properties,especially when the rock is cooled during the construction process.Accordingly,whether the cooling speed affects the mechanical and physical properties of rocks is worth to be investigated.The present study explored the influence of the cooling rate on the physical and chemical properties of granite heated at 25–800°C.The mechanical and physical properties involved in this study included uniaxial compression strength,peak strain,modulus,P-wave velocity,mass and volume,the change of which could reflect the sensitivity of granite to the cooling rate.Acoustic emission(AE)monitoring,microscopic observation,and X-ray diffraction(XRD)are used to analyze the underlying damage mechanism.It is found that more AE signals and large-scale cracks are accounted for based on the b-value method when the specimens are cooled by water.Furthermore,the microscopic observation by polarized light microscopy indicates that the density,opening degree,and connectivity of the cracks under water cooling mode are higher than that under natural cooling mode.In addition,the XRD illustrates that there is no obvious change in mineral content and diffraction angle at different temperatures,which confirms that the change of mechanical properties is not related to the chemical properties.The present conclusion can provide a perspective to assess the damage caused by different cooling methods to hot rocks.
文摘Building Information Models (BIM) have revealed themselves as a good tool to support construction actions, due to their ability to store all the information in one digital model and to promote collaboration between all participants in a project. Teaching Civil Engineering requires a permanent updating of knowledge concerning procedures and technologies used in the construction industry. In this sense, the school should seek to adapt its curriculum to include innovative issues to support new technologies. So, in an educational context, the aim of the present work is to disseminate knowledge concerning the benefits provided when implementing BIM in several aspects within the construction activity. In a Civil Engineering school some topics of BIM application were developed by students within MSc researches. The text describes in detail some of the main topics, showing distinct use of BIM: Generation and use of a 4D/BIM model to support construction planning;coordination of construction project based on BIM methodology;conflict analysis based in an architectural 3D/BIM model. Several study cases were modelled and analyzed, confronting the BIM use with the traditional way when performing the same tasks, and consequently recommendations were carried out. This work contributed to demonstrate the advantages of employing BIM for building tasks purposes when compared with the traditional process, and in a didactic context the main objective is to add competitive skills in the training of future civil engineers.
基金the Ministry of Higher Education for funding this research
文摘A new automatic rotary compactor and its abilities in compacting stone mastic asphalt （SMA） are presented. Following an overview of the rotary compactor and the compaction procedure, it is demonstrated that the rotary compactor is able to produce uniform slabs with the desired thickness of 65 mm all over around. Furthermore, 132 cored samples from the rotary compactor had been compacted uniformly with approximately 4% optimum air void content. In addition, performance tests results indicate that the rotary compactor produces asphalt mixturures with the requirements of resilient modulus, Marshall stability and flow. A weight factor was introduced for each fraction of aggregates in the degradation analysis to compensate the crushing effect of aggregates during mixing and compacting.
基金financially supported by the Science and Technology Commission Foundation of Shanghai(Grant Nos.22DZ1208903,20DZ2251900)the National Natural Science Foundation of China(Grant No.51679134)。
文摘A new scour countermeasure using solidified slurry for offshore foundation has been proposed recently.Fluidized solidified slurry is pumped to seabed area around foundation for scour protection or pumped into the developed scour holes for scour repair as the fluidized material solidifies gradually.In the pumping operation and solidification,the engineering behaviors of solidified slurry require to be considered synthetically for the reliable application in scour repair and protection of ocean engineering such as the pumpability related flow value,flow diffusion behavior related rheological property,anti-scour performance related retention rate in solidification and bearing capacity related strength property after solidification.In this study,a series of laboratory tests are conducted to investigate the effects of mix proportion(initial water content and binder content)on the flow value,rheological properties,density,retention rate of solidified slurry and unconfined compressive strength(UCS).The results reveal that the flow value increases with the water content and decreases with the binder amount.All the solidified slurry exhibits Bingham plastic behavior when the shear rate is larger than 5 s^(-1).The Bingham model has been employed to fit the rheology test results,and empirical formulas for obtaining the density,yield stress and viscosity are established,providing scientific support for the numerical assessment of flow and diffusion of solidified slurry.Retention rate of solidified slurry decreases with the water flow velocity and flow value,which means the pumpability of solidified slurry is contrary to anti-scour performance.The unconfined compressive strength after solidification reduces as the water content increases and binder content decreases.A design and application procedure of solidified soil for scour repair and protection is also proposed for engineering reference.
文摘This Special Issue of the Journal of Rock Mechanics and GeotechnicalEngineering （JRMGE） contains 13 papers prepared by internationalexperts on various general topics in geomechanics, rockmechanics and geotechnical engineering. It represents a usefulmix of theoretical developments, testing and practical applications.We present in the following brief details in the papers, alphabeticallyin accordance with the last name of the first author.Barla presents a review of tunneling techniques with emphasison the full-face method combining full-face excavation and facereinforcement by means of fiber-glass elements with a yieldcontrolsupport. This method has been used successfully in difficultgeologic conditions, and for a wide spectrum of ground situations.The validation of the method with respect to the Saint Martin LaPorte access adit along the LyoneTurin Base tunnel experiencingseverely squeezing conditions during excavation is also includedin the paper. The numerical modeling with consideration of therock mass time-dependent behavior showed a satisfactory agreementwith monitoring results.
文摘Silica materials are located in various regions of Libya in large quantities and different mining conditions, so the purpose of this study is silica materials in the south-west of the Libyan region Edree in terms of quality and the possibility of using in various engineering industries, particularly construction. The results show that the sands of silica presented in Edree area are of a high degree of purity, as the percentage of silicon （SIO2） reached 99.5%, the percentage of impurities was negligible and represented in some chemical elements in different proportions, such as calcium 0.224%, sodium 0.004%, iron 0.0006%, zinc 0.0003%, boron 0.0003%, potassium 0.0001%, manganese 0.0001% and magnesium 0.0001%, making these materials very suitable in the manufacture of all types of glass, crystal and semi-crystalline high-quality without needing any important treatment, as well as its suitability as a refinement in manufacture of templates metal castings in addition to the possibility of use in the manufacture of cement, building materials and as a filler in paint and brick making and sand and concrete elements can also be used in electronic industries. A geological material of silica present in the form of a sequence of layers of clay and thin layers of sand stone and a large stock of high-quality near the surface, making mining operations of the type of surface and reduces the cost of extraction.
文摘Many timber producing countries generate more than 2 million m3 of sawdust annually. In developing countries, sawdust is often disposed of by open dumping, open burning, or dumping in landfills. This poses huge environmental challenges related to air pollution, greenhouse gas emissions, and destruction of plant and aquatic life. Findings from this review article reveal that sawdust can be used to make sawdust construction composites with good modulus of elasticity, water absorption and strength characteristics that satisfy international specifications. These composites include particleboards, sawdust concrete blocks or bricks and sawdust concrete. The article concludes that partially replacing 5% to 17% of sand with sawdust, or replacing cement with sawdust ash in proportions of 5% to 15% in concrete mixes can produce structural concrete with compressive strengths greater than 20 MPa. Partially replacing 10% to 30% of sand used in the manufacture blocks and bricks with sawdust can also produce sawdust bricks and blocks with compressive strengths greater than 3 MPa. Sawdust composites are also attractive for their low thermal conductivity, high sound absorption and good sound insulation characteristics. These findings indicate that increased utilisation of sawdust composites in construction will mitigate against potential sawdust environmental pollution, conserve energy and reduce disposal costs.
