Only simplified two-dimensional model and a single failure mode are adopted to calculate the ultimate pullout capacity(UPC)of anchor cables in most previous research.This study focuses on a more comprehensive combinat...Only simplified two-dimensional model and a single failure mode are adopted to calculate the ultimate pullout capacity(UPC)of anchor cables in most previous research.This study focuses on a more comprehensive combination failure mode that consists of bond failure of an anchorage body and failure of an anchored rock mass.The three-dimensional ultimate pullout capacity of the anchor cables is calculated based on the Hoek-Brown failure criterion and variation analysis method.The numerical solution for the curvilinear function in fracture plane is obtained based on the finite difference theory,which more accurately reflects the failure state of the anchor cable,as opposed to that being assumed in advance.The results reveal that relying solely on a single failure mode for UPC calculations has limitations,as changes in parameter values not only directly impact the UPC value but also can alter the failure model and thus the calculation method.展开更多
Ultimate bearing capacity(UBC)is a key subject in geotechnical/foundation engineering as it determines the limit of loads imposed on the foundation.The most reliable means of determining UBC is through experiment,but ...Ultimate bearing capacity(UBC)is a key subject in geotechnical/foundation engineering as it determines the limit of loads imposed on the foundation.The most reliable means of determining UBC is through experiment,but it is costly and time-consuming which has led to the development of various models based on the simplified assumptions.The outcomes of the models are usually validated with the experimental results,but a large gap usually exists between them.Therefore,a model that can give a close prediction of the experimental results is imperative.This study proposes a grasshopper optimization algorithm(GOA)and salp swarm algorithm(SSA)to optimize artificial neural networks(ANNs)using the existing UBC experimental database.The performances of the proposed models are evaluated using various statistical indices.The obtained results are compared with the existing models.The proposed models outperformed the existing models.The proposed hybrid GOA-ANN and SSA-ANN models are then transformed into mathematical forms that can be incorporated into geotechnical/foundation engineering design codes for accurate UBC measurements.展开更多
To date no analytical solution of the pile ultimate lateral capacity for the general c–φ soil has been obtained. In the present study, a new dimensionless embedded ratio was proposed and the analytical solutions of ...To date no analytical solution of the pile ultimate lateral capacity for the general c–φ soil has been obtained. In the present study, a new dimensionless embedded ratio was proposed and the analytical solutions of ultimate lateral capacity and rotation center of rigid pile in c–φ soils were obtained. The results showed that both the dimensionless ultimate lateral capacity and dimensionless rotation center were the univariate functions of the embedded ratio. Also,the ultimate lateral capacity in the c–φ soil was the combination of the ultimate lateral capacity(f;) in the clay, and the ultimate lateral capacity(f;) in the sand. Therefore, the Broms chart for clay, solution for clay(φ=0) put forward by Poulos and Davis, solution for sand(c=0) obtained by Petrasovits and Awad, and Kondner’s ultimate bending moment were all proven to be the special cases of the general solution in the present study. A comparison of the field and laboratory tests in 93 cases showed that the average ratios of the theoretical values to the experimental value ranged from 0.85 to 1.15. Also, the theoretical values displayed a good agreement with the test values.展开更多
Rock masses are commonly used as the underlying layer of important structures such as bridges, dams and transportation constructions. The success of a foundation design for such structures mainly depends on the accura...Rock masses are commonly used as the underlying layer of important structures such as bridges, dams and transportation constructions. The success of a foundation design for such structures mainly depends on the accuracy of estimating the bearing capacity of rock beneath them. Several traditional numerical approaches are proposed for the estimation of the bearing capacity of foundations resting on rock masses to avoid performing elaborate and expensive experimental studies. Despite this fact, there still exists a serious need to develop more robust predictive models. This paper proposes new nonlinear prediction models for the ultimate bearing capacity of shallow foundations resting on non-fractured rock masses using a novel evolutionary computational approach, called linear genetic programming. A comprehensive set of rock socket, centrifuge rock socket, plate load and large-scaled footing load test results is used to develop the models. In order to verify the validity of the models, the sensitivity analysis is conducted and discussed. The results indicate that the proposed models accurately characterize the bearing capacity of shallow foundations. The correlation coefficients between the experimental and predicted bearing capacity values are equal to 0.95 and 0.96 for the best LGP models. Moreover, the derived models reach a notably better prediction performance than the traditional equations.展开更多
In order to improve the safety of drilling operations, this paper presents a new method for forecasting the ultimate bearing capacity of oil field drilling masts. The method is based on a double nonlinear finite eleme...In order to improve the safety of drilling operations, this paper presents a new method for forecasting the ultimate bearing capacity of oil field drilling masts. The method is based on a double nonlinear finite element theory and applies a referential stress method for measuring defects and defacements. The lab mast model was analyzed using the proposed method. The relative error, which was less than 5.0% between the forecast results and the destructive experiment values,verified the correctness of this method. It also forecasts the ultimate bearing capacity for a local drilling mast.展开更多
Jack-up platforms of the Ocean engineering structures always withstand the vertical gravity loads which are applied to the seabed by spudcan, so it is important to determine the bearing capacity and the penetration de...Jack-up platforms of the Ocean engineering structures always withstand the vertical gravity loads which are applied to the seabed by spudcan, so it is important to determine the bearing capacity and the penetration depth of the spudcan for its geometry. In fact, it is up to the deformation law and the failure modes of soil surrounding the spudcan which can calculate the ultimate bearing capacity of the spudcan foundation on the soil seabed. By using the finite element analysis software Abaqus, the deformation law of soil around the spudcan is analyzed in detail, and the failure modes of soil surrounding the spudcan foundation are achieved. At the same time, based on the limit equilibrium theory, by use of static permissible slip-line field, the ultimate bearing capacity of the spudcan foundation is analyzed and the lower limit solution is derived theoretically, and the effect of the spudcan angle on the ultimate bearing capacity is investigated. The numerical results are compared with those obtained by the theoretical formulas deduced in this paper. On the basis of the lower limit solutions in this paper, the effect of the spudcan angle on the ultimate bearing capacity is revealed, and a practical bearing capacity formula is given to take the effect of the spudcan angle into consideration.展开更多
In this paper, using incremental equilibrium equation, the authors have studiedthe effeet of ultimate bearing capacity of every component on structuralstability, and discussed the stability analysis method for space c...In this paper, using incremental equilibrium equation, the authors have studiedthe effeet of ultimate bearing capacity of every component on structuralstability, and discussed the stability analysis method for space compositestructures. With the help of the test results for the concrete filled ateel tubeskeleton of the long-spen RC arch bridse, it is proved that the proposed methodis accurate and reliable.展开更多
Based on the theory of limit analysis, the Finite Difference Method (FDM) is established for evaluating the ultimate bearing capacity of subsoils to bear the unburied pipelines. The analytical results of bearing capac...Based on the theory of limit analysis, the Finite Difference Method (FDM) is established for evaluating the ultimate bearing capacity of subsoils to bear the unburied pipelines. The analytical results of bearing capacity of the ideal clay is given. The approach to bearing capacity evaluation of cohesionless subsoils without surcharge is suggested. The results from this method are consistent with those obtained from model tests.展开更多
Based on Hencky's total strain theory of plasticity,ultimate bending capacity of steel pipes can be determined analytically assuming an elastic-linear strain hardening material,the simplified analytical solution is p...Based on Hencky's total strain theory of plasticity,ultimate bending capacity of steel pipes can be determined analytically assuming an elastic-linear strain hardening material,the simplified analytical solution is proposed as well.Good agreement is observed when ultimate bending capacities obtained from analytical solutions are compared with experimental results from full-size tests of steel pipes.Parametric study conducted as part of this paper indicates that the strain hardening effect has significant influence on the ultimate bending capacity of steel pipes.It is shown that pipe considering strain hardening yields higher bending capacity than that of pipe assumed as elastic-perfectly plastic material.Thus,the ignorance of strain hardening effect,as commonly assumed in current codes,may underestimate the ultimate bending capacity of steel pipes.The solutions proposed in this paper are applicable in the design of offshore/onshore steel pipes,supports of offshore platforms and other tubular structural steel members.展开更多
To predict the tensile capacity of adhesive anchors, a multilayered feed-forward neural network trained with the back-propagation algorithm is constructed. The ANN model have 5 inputs, including the compressive streng...To predict the tensile capacity of adhesive anchors, a multilayered feed-forward neural network trained with the back-propagation algorithm is constructed. The ANN model have 5 inputs, including the compressive strength of concrete, tensile strength of concrete, anchor diameter, hole diameter, embedment of anchors, and ultimate load. The predictions obtained from the trained ANN show a good agreement with the experiments. Meanwhile, the predicted ultimate tensile capacity of anchors is close to the one calculated from the strength formula of the combined cone-bond failure model.展开更多
A set of generalized solutions are proposed for estimating ultimate load capacity of pipeline with arbitrary corrosion shapes subjected to combined internal pressure, axial force and bending moment. Isotropic and anis...A set of generalized solutions are proposed for estimating ultimate load capacity of pipeline with arbitrary corrosion shapes subjected to combined internal pressure, axial force and bending moment. Isotropic and anisotropic material characteristics in longitudinal and circumferential direction of pipeline are also considered in the proposed equations. Simplified numerical method is used to solve the generalized expressions. The comparisons of numerical results based generalized solutions and full-scale experimental results are carried out. The predicted results agree reasonably well with the experiment results. Meanwhile, the effects of corrosion shapes and locations on the ultimate load capacity are studied.展开更多
This paper is devoted to improve the containment capacity of the Hesgoula south dumping site.The general geology of the dumping site was obtained through geological surveys.Physico-mechanical properties of silty clay ...This paper is devoted to improve the containment capacity of the Hesgoula south dumping site.The general geology of the dumping site was obtained through geological surveys.Physico-mechanical properties of silty clay and bedrock layers that have a large impact on the stability of the dump were measured by direct shear tests and triaxial tests in laboratory.Then ultimate bearing capacity of the substrate were analyzed and calculated.This paper proposed three capacity expansion and increase plans and used GeoStudio software for comparison.Through computation of the stability of the dump site slope after capacity expansion and increase for each plan,the capacity expansion plan was determined.The capacity expansion and increase plan will solve the problem of the current insufficient containment capacity of the Hesgoula south dumping site,which is of great significance for saving mine transportation costs,improving work efficiency,and reducing grassland occupation.展开更多
The paper presents conclusions related to the design of shallow foundations,at the site where the Substation at Kashari,in Tirana is foreseen to be constructed.The project includes buildings with small to medium struc...The paper presents conclusions related to the design of shallow foundations,at the site where the Substation at Kashari,in Tirana is foreseen to be constructed.The project includes buildings with small to medium structures with 1-3 stories.The geological survey works include 6 boreholes of a depth 20.0 m,90 SPT(Standard Penetration Tests)tests,and laboratory works include 13 direct shear tests,27 unconfined and compressive strength tests,7 CU(consolidated undrained)tests and 9 UU(unconsolidated undrained)tests,etc.The foundation design must fulfill both,bearing and settlement criteria,but in this case the settlements of foundations are not possible to be calculated,since the laboratory works do not include any consolidation test.So,the local bearing capacity is expected to control the design in terms of bearing capacity and settlements.The local bearing capacity of shallow square foundations is evaluated by using Terzaghi’s formula,based on reduced shear strength parameters of soils below the bottom of foundations.The results are compared with the bearing capacity values calculated by using Burland and Burbdige(1984)method,based on the data of SPT tests.This method is used for checking the settlement(serviceability)criterion in the foundation design,when the direct settlement calculation is missing.The paper presents some conclusions related to local bearing capacity foundation-based design.展开更多
Due to the long construction life,improper design methods,brittle material properties and poor construction techniques,most existing masonry structures do not perform well during earthquakes.The retrofitting method us...Due to the long construction life,improper design methods,brittle material properties and poor construction techniques,most existing masonry structures do not perform well during earthquakes.The retrofitting method using an external steel-meshed mortar layer is widely used to retrofit existing masonry buildings.Assessing the seismic performance of masonry walls reinforced by an external steel-meshed mortar layer reasonably and effectively is a difficult subject in the research field of masonry structures.Based on the combined finite-discrete elements method,the numerical models of retrofitted brick walls with four different masonry mortar strengths by an external mortar layer are established.The shear strength of mortar and the contact between the retrofitted mortar layer and the brick blocks are discussed in detail.The failure patterns and load-displacement curves of the retrofitted brick walls were obtained by applying low cycle reciprocating loads to the numerical model,and the bearing capacity and the failure mechanism of the retrofitted walls were obtained by comparing the failure patterns,ultimate bearing capacity,deformability and other aspects with the tests.This study provides a basis for improving the seismic strengthening design method of masonry structures and helps to better assess the seismic performance of masonry structures after retrofitting.展开更多
The behaviour of square concrete-filled steel tube columns under concentrical loading was studied. More than one hundred specimens were tested to investigate the effects of thickness of steel tube on the load carrying...The behaviour of square concrete-filled steel tube columns under concentrical loading was studied. More than one hundred specimens were tested to investigate the effects of thickness of steel tube on the load carrying capacity of the concrete-filled tubular columns (CFTs). The effect of the grade of concrete and content of expansive agent were also investigated. The effect of these parameters on the confinement of the concrete core was studied as well. From the experimental study it was found that for both CFTs with different strength grade concrete core, the ultimate load carrying capacity increases with the increase in percentage of expansive agent up to 20% but it again decreases at 25% of expansive agent content. It was also shown that the failure mode of CFTs depends on the strength grade of concrete core.展开更多
The details of a research study of galvanized steel tube under web crippling were presented. A total of 48 galvanized steel square hollow sections with different boundary conditions, loading conditions, bearing length...The details of a research study of galvanized steel tube under web crippling were presented. A total of 48 galvanized steel square hollow sections with different boundary conditions, loading conditions, bearing lengths and web slenderness were tested. The experimental scheme, failure modes, load-displacement curves and strain intensity distribution curves were also presented. The investigation was focused on the effects of loading condition, bearing length and slenderness on web crippling ultimate capacity, initial compressive stiffness and ductility of galvanized steel tube. The results show that web crippling ultimate capacity increases linearly with the increase of the bearing length under EOF and IOF loading condition. In the end-flange and ITF loading conditions, strain intensity of the centerline of web reaches the peak and decreases progressively from central web to flanges. Finite element models were developed to numerically simulate the tests in terms of failure modes and ultimate capacity. Web crippling strength of galvanized steel tube increases linearly with the increase of the ratio of the bearing length to web thickness and decrease of web slenderness. The effect of ratio of galvanized layer thickness to web thickness on web crippling strength is small. Based on the results of the parametric study, a number of calculation formulas proposed in this work can be successfully employed as a design rule for predicting web crippling ultimate capacity of galvanized steel tube under four loading and boundary conditions.展开更多
In order to study the web-crippling behavior of aluminum hollow sectionsubjected to concentrated load, sixteen aluminum hollow tubes with different loadingconditions, bearing length and web slenderness ratios were tes...In order to study the web-crippling behavior of aluminum hollow sectionsubjected to concentrated load, sixteen aluminum hollow tubes with different loadingconditions, bearing length and web slenderness ratios were tested. This paper alsodiscussed a method to improve the web crippling strength of the aluminum hollowsections by infilling the mortar as composite section, and four aluminum compositesections were tested. The literature has reported lots of web crippling tests, but there isfew reports on web crippling behavior of aluminum composite sections. Interior-Ground(IG) and End-Ground (EG) loading conditions were adopted, with the specimens placedon the ground to simulate the load of floor joists. Specimens were also placed on abearing plate with end (ETF) or interior (ITF) bearing load. The influence of supportingconditions, loading positions, bearing length and web slenderness ratios on web cripplingultimate bearing capacity and ductility of aluminum hollow sections was studied. Theenhancements of infilling mortar were also evaluated. The results obtained from theexperiments show that infilling the mortar in aluminum hollow tubes is an effectivemethod for enhancing the ultimate capacity of the web, especially for specimens underInterior-Ground (IG) condition. Based on the results of parameter research, this paperproposes a series of design formulas for well predicting web crippling ultimate capacityof aluminum hollow and composite tubes under four different loading and boundaryconditions.展开更多
A model of debris flow risk zoning is carried out with momentum analysis of debris flow. This model zones the debris flow inundation fan with density and velocity calculated by numerical simulation. The risk classific...A model of debris flow risk zoning is carried out with momentum analysis of debris flow. This model zones the debris flow inundation fan with density and velocity calculated by numerical simulation. The risk classification standard is determined according to the ultimate bearing capacities of different structures under impacting. And the ultimate bearing capacities are tested by impact failure experiment of destruction. Two structures typical in Chinese mountain towns, reinforced concrete frame construction and brickwork with concrete, are chosen in the experiment. The model makes debris flow risk zoning quantitative and the results comparable widely. The results differ much from that of other methods especially in the identification of medium and low risk zones.展开更多
An experimental investigation was conducted on the flexural behavior of FRP-PVC confined concrete circular tubular members.A total of six specimens were prepared and tested under flexural loading.The main parameters v...An experimental investigation was conducted on the flexural behavior of FRP-PVC confined concrete circular tubular members.A total of six specimens were prepared and tested under flexural loading.The main parameters varied in the tests were the layer of FRP and the strengthening approach of BFRP and CFRP.The failure modes,ultimate bending capacity and stress-strain relation curves were investigated in details.Furthermore,the relation model of moment(M)-curvature(φ)was studied,and on the basis of M-φ relation model,a simplified formula was presented to compute the ultimate bending moment capacity.The results show that the external confinement of concrete specimens by FRP-PVC tubes results in enhancing the ultimate bending strength and ultimate deformation,and the ultimate bending capacity increased with the FRP layers.Simultaneously,the reinforcement effect in CFRP is better than that in BFRP.The ultimate bending moment capacity values predicted by the presented formula agree well with the experimental results,which imply that the presented formula is applicable and efficient for prediction of the ultimate bending moment capacity as well.展开更多
This work experimentally investigates the effects of shear stud characteristics on the interface slippage of steel-concrete composite push-out specimens. ABAQUS is used to establish a detailed 3D finite element(FE) mo...This work experimentally investigates the effects of shear stud characteristics on the interface slippage of steel-concrete composite push-out specimens. ABAQUS is used to establish a detailed 3D finite element(FE) model and analyze the behavior of push-out specimens. The modeling results are in good agreement with the experimental results. Based on parametrical analysis using the validated FE approaches, the effects of important design parameters, such as the diameter, number, length to diameter ratio, and yield strength of studs, concrete strength and steel transverse reinforcement ratio, on the load-slip relationship at the interface of composite beams are discussed. In addition, a simplified approach to model studs is developed using virtual springs with an equivalent stiffness. This approach is demonstrated to be able to predict the load-displacement response and ultimate bearing capacity of steel-concrete composite beams. The predicted results show satisfactory agreement with experimental results from the literature.展开更多
基金supported by the Natural Science Foundation of Hunan Province(2023JJ40078)the Scientific Research Project of Hunan Provincial Education Department(No.22C0573)+2 种基金the National Natural Science Foundation of China(51478477,51878668)Guizhou Provincial Department of Transportation Foundation(2017-122058)Foundation of Guizhou Provincial Science and Technology Department([2018]2815).
文摘Only simplified two-dimensional model and a single failure mode are adopted to calculate the ultimate pullout capacity(UPC)of anchor cables in most previous research.This study focuses on a more comprehensive combination failure mode that consists of bond failure of an anchorage body and failure of an anchored rock mass.The three-dimensional ultimate pullout capacity of the anchor cables is calculated based on the Hoek-Brown failure criterion and variation analysis method.The numerical solution for the curvilinear function in fracture plane is obtained based on the finite difference theory,which more accurately reflects the failure state of the anchor cable,as opposed to that being assumed in advance.The results reveal that relying solely on a single failure mode for UPC calculations has limitations,as changes in parameter values not only directly impact the UPC value but also can alter the failure model and thus the calculation method.
基金supported by Korea Research Fellowship Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Science and ICT(Grant No.2019H1D3A1A01102993)the Inha University Research Grant(2022).
文摘Ultimate bearing capacity(UBC)is a key subject in geotechnical/foundation engineering as it determines the limit of loads imposed on the foundation.The most reliable means of determining UBC is through experiment,but it is costly and time-consuming which has led to the development of various models based on the simplified assumptions.The outcomes of the models are usually validated with the experimental results,but a large gap usually exists between them.Therefore,a model that can give a close prediction of the experimental results is imperative.This study proposes a grasshopper optimization algorithm(GOA)and salp swarm algorithm(SSA)to optimize artificial neural networks(ANNs)using the existing UBC experimental database.The performances of the proposed models are evaluated using various statistical indices.The obtained results are compared with the existing models.The proposed models outperformed the existing models.The proposed hybrid GOA-ANN and SSA-ANN models are then transformed into mathematical forms that can be incorporated into geotechnical/foundation engineering design codes for accurate UBC measurements.
基金financially supported by the National Natural Science Foundation of China(Grant No.51379132)
文摘To date no analytical solution of the pile ultimate lateral capacity for the general c–φ soil has been obtained. In the present study, a new dimensionless embedded ratio was proposed and the analytical solutions of ultimate lateral capacity and rotation center of rigid pile in c–φ soils were obtained. The results showed that both the dimensionless ultimate lateral capacity and dimensionless rotation center were the univariate functions of the embedded ratio. Also,the ultimate lateral capacity in the c–φ soil was the combination of the ultimate lateral capacity(f;) in the clay, and the ultimate lateral capacity(f;) in the sand. Therefore, the Broms chart for clay, solution for clay(φ=0) put forward by Poulos and Davis, solution for sand(c=0) obtained by Petrasovits and Awad, and Kondner’s ultimate bending moment were all proven to be the special cases of the general solution in the present study. A comparison of the field and laboratory tests in 93 cases showed that the average ratios of the theoretical values to the experimental value ranged from 0.85 to 1.15. Also, the theoretical values displayed a good agreement with the test values.
文摘Rock masses are commonly used as the underlying layer of important structures such as bridges, dams and transportation constructions. The success of a foundation design for such structures mainly depends on the accuracy of estimating the bearing capacity of rock beneath them. Several traditional numerical approaches are proposed for the estimation of the bearing capacity of foundations resting on rock masses to avoid performing elaborate and expensive experimental studies. Despite this fact, there still exists a serious need to develop more robust predictive models. This paper proposes new nonlinear prediction models for the ultimate bearing capacity of shallow foundations resting on non-fractured rock masses using a novel evolutionary computational approach, called linear genetic programming. A comprehensive set of rock socket, centrifuge rock socket, plate load and large-scaled footing load test results is used to develop the models. In order to verify the validity of the models, the sensitivity analysis is conducted and discussed. The results indicate that the proposed models accurately characterize the bearing capacity of shallow foundations. The correlation coefficients between the experimental and predicted bearing capacity values are equal to 0.95 and 0.96 for the best LGP models. Moreover, the derived models reach a notably better prediction performance than the traditional equations.
基金Scientific research and technological development item of China National Petroleum Corporation (Item number: 03B209000)
文摘In order to improve the safety of drilling operations, this paper presents a new method for forecasting the ultimate bearing capacity of oil field drilling masts. The method is based on a double nonlinear finite element theory and applies a referential stress method for measuring defects and defacements. The lab mast model was analyzed using the proposed method. The relative error, which was less than 5.0% between the forecast results and the destructive experiment values,verified the correctness of this method. It also forecasts the ultimate bearing capacity for a local drilling mast.
基金financially supported by the National Natural Science Foundation of China(Grant No.51679224)
文摘Jack-up platforms of the Ocean engineering structures always withstand the vertical gravity loads which are applied to the seabed by spudcan, so it is important to determine the bearing capacity and the penetration depth of the spudcan for its geometry. In fact, it is up to the deformation law and the failure modes of soil surrounding the spudcan which can calculate the ultimate bearing capacity of the spudcan foundation on the soil seabed. By using the finite element analysis software Abaqus, the deformation law of soil around the spudcan is analyzed in detail, and the failure modes of soil surrounding the spudcan foundation are achieved. At the same time, based on the limit equilibrium theory, by use of static permissible slip-line field, the ultimate bearing capacity of the spudcan foundation is analyzed and the lower limit solution is derived theoretically, and the effect of the spudcan angle on the ultimate bearing capacity is investigated. The numerical results are compared with those obtained by the theoretical formulas deduced in this paper. On the basis of the lower limit solutions in this paper, the effect of the spudcan angle on the ultimate bearing capacity is revealed, and a practical bearing capacity formula is given to take the effect of the spudcan angle into consideration.
文摘In this paper, using incremental equilibrium equation, the authors have studiedthe effeet of ultimate bearing capacity of every component on structuralstability, and discussed the stability analysis method for space compositestructures. With the help of the test results for the concrete filled ateel tubeskeleton of the long-spen RC arch bridse, it is proved that the proposed methodis accurate and reliable.
文摘Based on the theory of limit analysis, the Finite Difference Method (FDM) is established for evaluating the ultimate bearing capacity of subsoils to bear the unburied pipelines. The analytical results of bearing capacity of the ideal clay is given. The approach to bearing capacity evaluation of cohesionless subsoils without surcharge is suggested. The results from this method are consistent with those obtained from model tests.
基金financially supported by the National Natural Science Foundation of China(Grant No.51309236)the Opening Fund of State Key Laboratory of Ocean Engineering(Shanghai Jiao Tong University)(Grant No.1314)+2 种基金the Opening Fund of State Key Laboratory of Hydraulic Engineering Simulation and Safety(Tianjin University)(Grant No HESS-1411)the Opening Fund of State Key Laboratory of Coastal and Offshore Engineering(Dalian University of Technology)(Grant No.LP1507)the Science Foundation of China University of Petroleum,Beijing(Grant Nos.2462015YQ0403 and 2462015YQ0408)
文摘Based on Hencky's total strain theory of plasticity,ultimate bending capacity of steel pipes can be determined analytically assuming an elastic-linear strain hardening material,the simplified analytical solution is proposed as well.Good agreement is observed when ultimate bending capacities obtained from analytical solutions are compared with experimental results from full-size tests of steel pipes.Parametric study conducted as part of this paper indicates that the strain hardening effect has significant influence on the ultimate bending capacity of steel pipes.It is shown that pipe considering strain hardening yields higher bending capacity than that of pipe assumed as elastic-perfectly plastic material.Thus,the ignorance of strain hardening effect,as commonly assumed in current codes,may underestimate the ultimate bending capacity of steel pipes.The solutions proposed in this paper are applicable in the design of offshore/onshore steel pipes,supports of offshore platforms and other tubular structural steel members.
基金The National Natural Science Foundationof China (No50578025)
文摘To predict the tensile capacity of adhesive anchors, a multilayered feed-forward neural network trained with the back-propagation algorithm is constructed. The ANN model have 5 inputs, including the compressive strength of concrete, tensile strength of concrete, anchor diameter, hole diameter, embedment of anchors, and ultimate load. The predictions obtained from the trained ANN show a good agreement with the experiments. Meanwhile, the predicted ultimate tensile capacity of anchors is close to the one calculated from the strength formula of the combined cone-bond failure model.
基金financially supported by the National Natural Science Foundation of China(Grant No.51309236)Doctoral Foundation of the Ministry of Education of China(Grant No.20120007120009)+2 种基金the Opening Fund of State Key Laboratory of Ocean Engineering(Shanghai Jiao Tong University,Grant No.1314)the Opening Fund of State Key Laboratory of Hydraulic Engineering Simulation and Safety(Tianjin University,Grant No.HESS-1411)the Science Foundation of China University of Petroleum(Beijing)(Grant No.QD-2010-08)
文摘A set of generalized solutions are proposed for estimating ultimate load capacity of pipeline with arbitrary corrosion shapes subjected to combined internal pressure, axial force and bending moment. Isotropic and anisotropic material characteristics in longitudinal and circumferential direction of pipeline are also considered in the proposed equations. Simplified numerical method is used to solve the generalized expressions. The comparisons of numerical results based generalized solutions and full-scale experimental results are carried out. The predicted results agree reasonably well with the experiment results. Meanwhile, the effects of corrosion shapes and locations on the ultimate load capacity are studied.
基金The authors gratefully acknowledge the financial support from the National Key Research and Development Plan of China(No.2018YFC0604501)the National Natural Science Foundation of China(51674264)the Yue Qi Distinguished Scholar Project,China University of Mining&Technology,Beijing(No.800015Z1138).
文摘This paper is devoted to improve the containment capacity of the Hesgoula south dumping site.The general geology of the dumping site was obtained through geological surveys.Physico-mechanical properties of silty clay and bedrock layers that have a large impact on the stability of the dump were measured by direct shear tests and triaxial tests in laboratory.Then ultimate bearing capacity of the substrate were analyzed and calculated.This paper proposed three capacity expansion and increase plans and used GeoStudio software for comparison.Through computation of the stability of the dump site slope after capacity expansion and increase for each plan,the capacity expansion plan was determined.The capacity expansion and increase plan will solve the problem of the current insufficient containment capacity of the Hesgoula south dumping site,which is of great significance for saving mine transportation costs,improving work efficiency,and reducing grassland occupation.
文摘The paper presents conclusions related to the design of shallow foundations,at the site where the Substation at Kashari,in Tirana is foreseen to be constructed.The project includes buildings with small to medium structures with 1-3 stories.The geological survey works include 6 boreholes of a depth 20.0 m,90 SPT(Standard Penetration Tests)tests,and laboratory works include 13 direct shear tests,27 unconfined and compressive strength tests,7 CU(consolidated undrained)tests and 9 UU(unconsolidated undrained)tests,etc.The foundation design must fulfill both,bearing and settlement criteria,but in this case the settlements of foundations are not possible to be calculated,since the laboratory works do not include any consolidation test.So,the local bearing capacity is expected to control the design in terms of bearing capacity and settlements.The local bearing capacity of shallow square foundations is evaluated by using Terzaghi’s formula,based on reduced shear strength parameters of soils below the bottom of foundations.The results are compared with the bearing capacity values calculated by using Burland and Burbdige(1984)method,based on the data of SPT tests.This method is used for checking the settlement(serviceability)criterion in the foundation design,when the direct settlement calculation is missing.The paper presents some conclusions related to local bearing capacity foundation-based design.
基金National Key Research and Development Program of China under Grant Nos. 2018YFC1504400 and 2019YFC1509301Natural Science Foundation of China under Grant No. 52078471Scientific Research Fund of Institute of Engineering Mechanics,China Earthquake Administration under Grant No. 19EEEVL0402
文摘Due to the long construction life,improper design methods,brittle material properties and poor construction techniques,most existing masonry structures do not perform well during earthquakes.The retrofitting method using an external steel-meshed mortar layer is widely used to retrofit existing masonry buildings.Assessing the seismic performance of masonry walls reinforced by an external steel-meshed mortar layer reasonably and effectively is a difficult subject in the research field of masonry structures.Based on the combined finite-discrete elements method,the numerical models of retrofitted brick walls with four different masonry mortar strengths by an external mortar layer are established.The shear strength of mortar and the contact between the retrofitted mortar layer and the brick blocks are discussed in detail.The failure patterns and load-displacement curves of the retrofitted brick walls were obtained by applying low cycle reciprocating loads to the numerical model,and the bearing capacity and the failure mechanism of the retrofitted walls were obtained by comparing the failure patterns,ultimate bearing capacity,deformability and other aspects with the tests.This study provides a basis for improving the seismic strengthening design method of masonry structures and helps to better assess the seismic performance of masonry structures after retrofitting.
基金Funded by the National Natural Science Foundation of China (50978162)the Key Laboratory of Advanced Civil Engineering Materials (Tongji University), Ministry of Education(K201002)
文摘The behaviour of square concrete-filled steel tube columns under concentrical loading was studied. More than one hundred specimens were tested to investigate the effects of thickness of steel tube on the load carrying capacity of the concrete-filled tubular columns (CFTs). The effect of the grade of concrete and content of expansive agent were also investigated. The effect of these parameters on the confinement of the concrete core was studied as well. From the experimental study it was found that for both CFTs with different strength grade concrete core, the ultimate load carrying capacity increases with the increase in percentage of expansive agent up to 20% but it again decreases at 25% of expansive agent content. It was also shown that the failure mode of CFTs depends on the strength grade of concrete core.
基金Projects(51278209,51378077,51478047)supported by the National Natural Science Foundation of ChinaProject(ZQN-PY110)supported by Promotion Program for Young and Middle-aged Teacher in Science and Technology Research of Huaqiao University,China+1 种基金Project(2014FJ-NCET-ZR03)supported by Program for New Century Excellent Talents in Fujian Province University,ChinaProject(JA13005)supported by Incubation Program for Excellent Young Science and Technology Talents in Fujian Province Universities,China
文摘The details of a research study of galvanized steel tube under web crippling were presented. A total of 48 galvanized steel square hollow sections with different boundary conditions, loading conditions, bearing lengths and web slenderness were tested. The experimental scheme, failure modes, load-displacement curves and strain intensity distribution curves were also presented. The investigation was focused on the effects of loading condition, bearing length and slenderness on web crippling ultimate capacity, initial compressive stiffness and ductility of galvanized steel tube. The results show that web crippling ultimate capacity increases linearly with the increase of the bearing length under EOF and IOF loading condition. In the end-flange and ITF loading conditions, strain intensity of the centerline of web reaches the peak and decreases progressively from central web to flanges. Finite element models were developed to numerically simulate the tests in terms of failure modes and ultimate capacity. Web crippling strength of galvanized steel tube increases linearly with the increase of the ratio of the bearing length to web thickness and decrease of web slenderness. The effect of ratio of galvanized layer thickness to web thickness on web crippling strength is small. Based on the results of the parametric study, a number of calculation formulas proposed in this work can be successfully employed as a design rule for predicting web crippling ultimate capacity of galvanized steel tube under four loading and boundary conditions.
基金has been supported by the National NaturalScience Foundation of China (Nos. 51478047 and 51778066)the Natural ScienceFoundation of Hubei Province (No. 2018CFB730)Foundation project of College ofengineering and technology, Yangtze University (No. 2017KY06)。
文摘In order to study the web-crippling behavior of aluminum hollow sectionsubjected to concentrated load, sixteen aluminum hollow tubes with different loadingconditions, bearing length and web slenderness ratios were tested. This paper alsodiscussed a method to improve the web crippling strength of the aluminum hollowsections by infilling the mortar as composite section, and four aluminum compositesections were tested. The literature has reported lots of web crippling tests, but there isfew reports on web crippling behavior of aluminum composite sections. Interior-Ground(IG) and End-Ground (EG) loading conditions were adopted, with the specimens placedon the ground to simulate the load of floor joists. Specimens were also placed on abearing plate with end (ETF) or interior (ITF) bearing load. The influence of supportingconditions, loading positions, bearing length and web slenderness ratios on web cripplingultimate bearing capacity and ductility of aluminum hollow sections was studied. Theenhancements of infilling mortar were also evaluated. The results obtained from theexperiments show that infilling the mortar in aluminum hollow tubes is an effectivemethod for enhancing the ultimate capacity of the web, especially for specimens underInterior-Ground (IG) condition. Based on the results of parameter research, this paperproposes a series of design formulas for well predicting web crippling ultimate capacityof aluminum hollow and composite tubes under four different loading and boundaryconditions.
文摘A model of debris flow risk zoning is carried out with momentum analysis of debris flow. This model zones the debris flow inundation fan with density and velocity calculated by numerical simulation. The risk classification standard is determined according to the ultimate bearing capacities of different structures under impacting. And the ultimate bearing capacities are tested by impact failure experiment of destruction. Two structures typical in Chinese mountain towns, reinforced concrete frame construction and brickwork with concrete, are chosen in the experiment. The model makes debris flow risk zoning quantitative and the results comparable widely. The results differ much from that of other methods especially in the identification of medium and low risk zones.
文摘An experimental investigation was conducted on the flexural behavior of FRP-PVC confined concrete circular tubular members.A total of six specimens were prepared and tested under flexural loading.The main parameters varied in the tests were the layer of FRP and the strengthening approach of BFRP and CFRP.The failure modes,ultimate bending capacity and stress-strain relation curves were investigated in details.Furthermore,the relation model of moment(M)-curvature(φ)was studied,and on the basis of M-φ relation model,a simplified formula was presented to compute the ultimate bending moment capacity.The results show that the external confinement of concrete specimens by FRP-PVC tubes results in enhancing the ultimate bending strength and ultimate deformation,and the ultimate bending capacity increased with the FRP layers.Simultaneously,the reinforcement effect in CFRP is better than that in BFRP.The ultimate bending moment capacity values predicted by the presented formula agree well with the experimental results,which imply that the presented formula is applicable and efficient for prediction of the ultimate bending moment capacity as well.
基金Project(2011BAJ09B02)supported by the National Key Technology R&D Program,ChinaProjects(51578548,51378511,51678576)supported by the National Natural Science Foundation of China
文摘This work experimentally investigates the effects of shear stud characteristics on the interface slippage of steel-concrete composite push-out specimens. ABAQUS is used to establish a detailed 3D finite element(FE) model and analyze the behavior of push-out specimens. The modeling results are in good agreement with the experimental results. Based on parametrical analysis using the validated FE approaches, the effects of important design parameters, such as the diameter, number, length to diameter ratio, and yield strength of studs, concrete strength and steel transverse reinforcement ratio, on the load-slip relationship at the interface of composite beams are discussed. In addition, a simplified approach to model studs is developed using virtual springs with an equivalent stiffness. This approach is demonstrated to be able to predict the load-displacement response and ultimate bearing capacity of steel-concrete composite beams. The predicted results show satisfactory agreement with experimental results from the literature.