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2011 Vol. 41, No. 9
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2011, 41(9): 1-7,62.
doi: 10.13204/j.gyjz201109001
Abstract:
The over-consolidated unified hardening model (UH model) proposed by Yao et al can describe many characteristics of over-consolidated clays well,including stress-strain relationships,stress dilatancy,strain hardening and softening,and stress history dependency. Based on the assumption of elastic-plastic model and solution of a quadratic equation,the computational scheme of UH model in FLAC3D was derived. According to the secondary developing platform,the UH model was developed in FLAC3D with Visual C + + environment. Using that program,numerical simulations of triaxial compression,triaxial extension and plane strain tests were performed,which showed a good agreement with the analytic solution. Compared with the modified Cam-clay model,UH model had several advantages in stress dilatancy,strain softening,loading and unloading features. Finally,the advantage of using constructive models with nonassociated flow rule in FLAC3D was discussed.
The over-consolidated unified hardening model (UH model) proposed by Yao et al can describe many characteristics of over-consolidated clays well,including stress-strain relationships,stress dilatancy,strain hardening and softening,and stress history dependency. Based on the assumption of elastic-plastic model and solution of a quadratic equation,the computational scheme of UH model in FLAC3D was derived. According to the secondary developing platform,the UH model was developed in FLAC3D with Visual C + + environment. Using that program,numerical simulations of triaxial compression,triaxial extension and plane strain tests were performed,which showed a good agreement with the analytic solution. Compared with the modified Cam-clay model,UH model had several advantages in stress dilatancy,strain softening,loading and unloading features. Finally,the advantage of using constructive models with nonassociated flow rule in FLAC3D was discussed.
2011, 41(9): 8-11,48.
doi: 10.13204/j.gyjz201109002
Abstract:
Under the condition of undiminished cyclic loading,the plastic deformation of soil can not be described by using classical elastoplastic models in the reloading process. The UH model can be used to describe many characteristics of clay well, including stress dilatancy, strain hardening and softening, and path dependency behaviour. It can also be used to describe the plastic deformation in the reloading process under the condition of cyclic loading. The UH model was applied under complex stress path condition. The numerical simulation of the bearing capacity of foundation was performed. The p-s curves of the foundation calculated by using the UH model and Camclay model were analyzed. The stress-strain characteristics of nodes at different positions on the surface were analyzed. Based on the results,it was found that the UH model could rationally exhibit the soil behaviors under the complex loading condition.
Under the condition of undiminished cyclic loading,the plastic deformation of soil can not be described by using classical elastoplastic models in the reloading process. The UH model can be used to describe many characteristics of clay well, including stress dilatancy, strain hardening and softening, and path dependency behaviour. It can also be used to describe the plastic deformation in the reloading process under the condition of cyclic loading. The UH model was applied under complex stress path condition. The numerical simulation of the bearing capacity of foundation was performed. The p-s curves of the foundation calculated by using the UH model and Camclay model were analyzed. The stress-strain characteristics of nodes at different positions on the surface were analyzed. Based on the results,it was found that the UH model could rationally exhibit the soil behaviors under the complex loading condition.
2011, 41(9): 12-17,104.
doi: 10.13204/j.gyjz201109003
Abstract:
Integrating existing research results,such as compressed,dilatancy,and strength,the influence produced by particle breaking on stress-strain characteristic of rockfill was analyzed. Based on the deformation and strength characteristics of rockfill,a new hardening parameters H was introduced,and corresponding yield function was derived,then a elastic-plastic constitutive model was proposed which could consider the impact of rockfill particle breaking. Based on the transformation stress method on SMP criterion and referring to triaxial test results of rockfill,it was validated the feasibility of three-dimensional constitutive model considering crushing. Finally,the stress-strain relationship of rockfill was simulated by using three-dimensional constitutive model considering crushing for rockfill under different stress states.
Integrating existing research results,such as compressed,dilatancy,and strength,the influence produced by particle breaking on stress-strain characteristic of rockfill was analyzed. Based on the deformation and strength characteristics of rockfill,a new hardening parameters H was introduced,and corresponding yield function was derived,then a elastic-plastic constitutive model was proposed which could consider the impact of rockfill particle breaking. Based on the transformation stress method on SMP criterion and referring to triaxial test results of rockfill,it was validated the feasibility of three-dimensional constitutive model considering crushing. Finally,the stress-strain relationship of rockfill was simulated by using three-dimensional constitutive model considering crushing for rockfill under different stress states.
2011, 41(9): 18-23,140.
doi: 10.13204/j.gyjz201109004
Abstract:
Based on researching the features of the modified Cam-clay model and UH model,the mechanism of model describing the behaviors of the over-consolidated (OC) clays is revealed. For the OC clays,the curves predicted by the modified Cam-clay model have abrupt changing points,so the model cannot model continue and gradual changing process well. For the heavy OC clays,the predicted peak strength is rather higher than test data under the drained condition. The model cannot describe the stress-strain relationships in true-triaxial test. The parameters in UH model are the same as those in the modified Cam-clay model. The model using the transformed stress method based on SMP criterion can rationally model many characteristics of the OC clays well,including shear dilatancy,strain hardening and softening,and stress path dependence behavior.
Based on researching the features of the modified Cam-clay model and UH model,the mechanism of model describing the behaviors of the over-consolidated (OC) clays is revealed. For the OC clays,the curves predicted by the modified Cam-clay model have abrupt changing points,so the model cannot model continue and gradual changing process well. For the heavy OC clays,the predicted peak strength is rather higher than test data under the drained condition. The model cannot describe the stress-strain relationships in true-triaxial test. The parameters in UH model are the same as those in the modified Cam-clay model. The model using the transformed stress method based on SMP criterion can rationally model many characteristics of the OC clays well,including shear dilatancy,strain hardening and softening,and stress path dependence behavior.
2011, 41(9): 24-29.
doi: 10.13204/j.gyjz201109005
Abstract:
The Mohr-Coulomb model, the modified Cam-clay model UH model were used to model the stress-strain relationships under the triaxial compression, extension and compression with decreasing principal stress conditions.The result predicted by the Mohr-Coulomb model, as a perfect elasto-plastic model, was elastic stress-strain relationship when stress point was in yield surface and is elasto-plastic stress-strain relationship with the constant stress and infinite increasing deformation when stress point was on yield surface under the triaxial compression condition. The modified Cam-clay model could be used to predict the behavior of the normally consolidated clay in the triaxial test well, but it over-estimated the strength of clay under the extension condition. The UH model for the normally consolidated clay and over-consolidated clay had the same parameters as those in the modified Cam-clay model. For the normally consolidated clay, the UH model was the same as the modified Cam-clay model. By applying the transformed stress method based on SMP criterion, the UH model could describe the property of clay in threedimension stress space.
The Mohr-Coulomb model, the modified Cam-clay model UH model were used to model the stress-strain relationships under the triaxial compression, extension and compression with decreasing principal stress conditions.The result predicted by the Mohr-Coulomb model, as a perfect elasto-plastic model, was elastic stress-strain relationship when stress point was in yield surface and is elasto-plastic stress-strain relationship with the constant stress and infinite increasing deformation when stress point was on yield surface under the triaxial compression condition. The modified Cam-clay model could be used to predict the behavior of the normally consolidated clay in the triaxial test well, but it over-estimated the strength of clay under the extension condition. The UH model for the normally consolidated clay and over-consolidated clay had the same parameters as those in the modified Cam-clay model. For the normally consolidated clay, the UH model was the same as the modified Cam-clay model. By applying the transformed stress method based on SMP criterion, the UH model could describe the property of clay in threedimension stress space.
2011, 41(9): 30-34,55.
doi: 10.13204/j.gyjz201109006
Abstract:
Based on the critical state theory, a constitutive model was proposed for structural loose sand. The structural parameter was used to revise the yield function, thereby predicting the plastic deformation of loose sand more appropriately. Another parameter was used to adjust the hardening parameter and dilatancy equation, thus giving a better description of contraction behavior for loose sand. The introduction of the parameters emphasized the dependency on both density and effective principal stress of sand. Linear isotropic consolidation and critical state lines were applied in void ratio versus the power of effective mean stress space, and more accurately reflected the stressstrain behavior of sand. A comparison between model simulations and experimental results showed the validity of the proposed model.
Based on the critical state theory, a constitutive model was proposed for structural loose sand. The structural parameter was used to revise the yield function, thereby predicting the plastic deformation of loose sand more appropriately. Another parameter was used to adjust the hardening parameter and dilatancy equation, thus giving a better description of contraction behavior for loose sand. The introduction of the parameters emphasized the dependency on both density and effective principal stress of sand. Linear isotropic consolidation and critical state lines were applied in void ratio versus the power of effective mean stress space, and more accurately reflected the stressstrain behavior of sand. A comparison between model simulations and experimental results showed the validity of the proposed model.
2011, 41(9): 35-37,112.
doi: 10.13204/j.gyjz201109007
Abstract:
Asymptotic State(AS) model for normally consolidated clay was extended to asymptotic state model for K0 consolidated clays. The formulation of partially coupled parameter was deduced under triaxial compression condition.A function of partially coupled parameter associated with Lodes angle was proposed. Modified Cam-clay (MCC) model and AS model for K0 consolidated clay were applied to predict stress-strain relationship under triaxial compression and extension conditions. The comparison between predicted results showed that AS model for K0 consolidated clay was more reasonable in describing constitutive relations.
Asymptotic State(AS) model for normally consolidated clay was extended to asymptotic state model for K0 consolidated clays. The formulation of partially coupled parameter was deduced under triaxial compression condition.A function of partially coupled parameter associated with Lodes angle was proposed. Modified Cam-clay (MCC) model and AS model for K0 consolidated clay were applied to predict stress-strain relationship under triaxial compression and extension conditions. The comparison between predicted results showed that AS model for K0 consolidated clay was more reasonable in describing constitutive relations.
2011, 41(9): 38-42.
doi: 10.13204/j.gyjz201109008
Abstract:
Besides large compressibility, low permeability, and long deformation time, soft soil sometimes has some overconsolidation characteristics, which increases the difficulty to estimate and calculate the ground settlement. The unified hardening model (UH model) can describe many characteristics of clays well, including stress-strain relationships, stress dilatancy, strain hardening and softening, and path dependency behavior. The parameters in the model as are the same as those in the Cam-clay model. By using the the UH model, numerical simulation of triaxial tests was performed, while the FEM results and unit predicted results using UH model were compared. Threedimensional finite element analysis of deformation of an embankment on soft clay was carried out combining with an actual project. The changes in excess pore pressure, ground settlement and lateral displacement were analyzed and compared with the measured data.
Besides large compressibility, low permeability, and long deformation time, soft soil sometimes has some overconsolidation characteristics, which increases the difficulty to estimate and calculate the ground settlement. The unified hardening model (UH model) can describe many characteristics of clays well, including stress-strain relationships, stress dilatancy, strain hardening and softening, and path dependency behavior. The parameters in the model as are the same as those in the Cam-clay model. By using the the UH model, numerical simulation of triaxial tests was performed, while the FEM results and unit predicted results using UH model were compared. Threedimensional finite element analysis of deformation of an embankment on soft clay was carried out combining with an actual project. The changes in excess pore pressure, ground settlement and lateral displacement were analyzed and compared with the measured data.
2011, 41(9): 43-47.
doi: 10.13204/j.gyjz201109009
Abstract:
Sunken cave, which is warm in winter and cool in summer, is Chinese earth construction. Cave is the most convenient and cheapest living pattern for people on Loess Plateau. It is particularly important to inherit and develop sunken cave nowadays when low carbon is highly promoted. So it is meaningful to study the deformation analysis of structure of sunken cave. In this paper, finite element method was adopted to analyze the deformation of structure of sunken cave and explained that the UH model was more suitable in the analysis. At last, the deformation characteristics was draw, and the weakest part of sunken caves was found out.
Sunken cave, which is warm in winter and cool in summer, is Chinese earth construction. Cave is the most convenient and cheapest living pattern for people on Loess Plateau. It is particularly important to inherit and develop sunken cave nowadays when low carbon is highly promoted. So it is meaningful to study the deformation analysis of structure of sunken cave. In this paper, finite element method was adopted to analyze the deformation of structure of sunken cave and explained that the UH model was more suitable in the analysis. At last, the deformation characteristics was draw, and the weakest part of sunken caves was found out.
2011, 41(9): 49-52,66.
doi: 10.13204/j.gyjz201109010
Abstract:
Based on the analysis of the structure effect of an architecture and the structural contribution to the architecture development, this paper discussed the relationship between architectural design and the structure using. Eventually, it prospected the new ideas of the comprehensive design of architecture and structure.
Based on the analysis of the structure effect of an architecture and the structural contribution to the architecture development, this paper discussed the relationship between architectural design and the structure using. Eventually, it prospected the new ideas of the comprehensive design of architecture and structure.
2011, 41(9): 53-55.
doi: 10.13204/j.gyjz201109011
Abstract:
Along with the development of the era, a shopping mall is developing gradually into a comprehensive form of land-use. Combined with shopping, entertainment, catering industry, and recreation, this commercial complex goes into our urban life and plays more important role. The commerical area that the project of Kunming Shuncheng Wangfujing Shopping Center contains commerce, entertainment industry , realty business, and hospitality industry.How to carry out architecture planning and commical layout need abundant experienced and advanced market insight for the desiguers. The paper introduced the architecture planning and commical layout of that project.
Along with the development of the era, a shopping mall is developing gradually into a comprehensive form of land-use. Combined with shopping, entertainment, catering industry, and recreation, this commercial complex goes into our urban life and plays more important role. The commerical area that the project of Kunming Shuncheng Wangfujing Shopping Center contains commerce, entertainment industry , realty business, and hospitality industry.How to carry out architecture planning and commical layout need abundant experienced and advanced market insight for the desiguers. The paper introduced the architecture planning and commical layout of that project.
2011, 41(9): 56-58,99.
doi: 10.13204/j.gyjz201109012
Abstract:
The paper was introduced the architecture design and construction of the Jiayou Square at Nanmen in Yin chuan, and analyzed and discussed the expression of urban envir on ment and urban culture in commerical building.
The paper was introduced the architecture design and construction of the Jiayou Square at Nanmen in Yin chuan, and analyzed and discussed the expression of urban envir on ment and urban culture in commerical building.
2011, 41(9): 59-62.
doi: 10.13204/j.gyjz201109013
Abstract:
The flat-shell element was constructed by the combination of plane stress element and thin plate bending element,it could be effectively used to analyze shear lag effect of short pier shear wall in the elastic stage proved by the low cyclic loading test. Test and finite element analysis showed that the normal stress distribution in the flange plate section was not even in the elastic stage,shear lag effect was obvious,normal stress concentration was easy to appear in the juncture of web and flange plate,normal stress distribution in the flange plate section was changed to more uneven and the maximum normal stress position was changed with the cyclic loading because of stress redistribution in the plastic stage. So,the flange plate section must keep space for stress redistribution to guarantee that the most part of the flange plate section can fully display the bearing capacity with the development of plastic deformation.
The flat-shell element was constructed by the combination of plane stress element and thin plate bending element,it could be effectively used to analyze shear lag effect of short pier shear wall in the elastic stage proved by the low cyclic loading test. Test and finite element analysis showed that the normal stress distribution in the flange plate section was not even in the elastic stage,shear lag effect was obvious,normal stress concentration was easy to appear in the juncture of web and flange plate,normal stress distribution in the flange plate section was changed to more uneven and the maximum normal stress position was changed with the cyclic loading because of stress redistribution in the plastic stage. So,the flange plate section must keep space for stress redistribution to guarantee that the most part of the flange plate section can fully display the bearing capacity with the development of plastic deformation.
2011, 41(9): 63-66.
doi: 10.13204/j.gyjz201109014
Abstract:
The reasearch on shear behavior of stone masonry joint is a key factor to understand the seismic behaviorof stone masonry structures. Twelve stone masonry specimens constructed by paving mortar were tested under shearand compression load to investigate the shear behavior of mortar joint. The main influence parameters were mortar strength in mortar joint and vertical compressive stress under morar joint. The failure process, shear strength and deformation of stone masonry mortar joint in mortar joint analyzed. Test results indicated that the failure process of stone masonry constructed by paving mortar mainly contains elastic－plastic deformation and frictional sliding phases, and that the shear strength of mortar joint is improved with increasing the mortar strength and vertical compressive stress. Finally, by means of a regression analysis, a formula was proposed to calculate the shear strength of stone masonry joints. The calculated results by proposed formula were in good agreement with the test results.
The reasearch on shear behavior of stone masonry joint is a key factor to understand the seismic behaviorof stone masonry structures. Twelve stone masonry specimens constructed by paving mortar were tested under shearand compression load to investigate the shear behavior of mortar joint. The main influence parameters were mortar strength in mortar joint and vertical compressive stress under morar joint. The failure process, shear strength and deformation of stone masonry mortar joint in mortar joint analyzed. Test results indicated that the failure process of stone masonry constructed by paving mortar mainly contains elastic－plastic deformation and frictional sliding phases, and that the shear strength of mortar joint is improved with increasing the mortar strength and vertical compressive stress. Finally, by means of a regression analysis, a formula was proposed to calculate the shear strength of stone masonry joints. The calculated results by proposed formula were in good agreement with the test results.
2011, 41(9): 67-72,89.
doi: 10.13204/j.gyjz201109015
Abstract:
Steel fiber concrete waffle composite slab system includes material composite and structure typecomposite, which has good mechanical and thermal insulation properties. Nonlinear finite element analysis for themechanical properties of the whole process on the composite structure system was presented, and by changing thefiber content the parameter were discussed. The functions of steel fibers were considered mainly through modificationof the constitutive relationship of concrete and elastic modulus and other parameters, without consideration of the bondand slip between steel fiber and concrete in the finite element analysis model to simplify calculation. The analysis results showed that the structural deformation and crack resistance could be improved significantly even adding less steel fiber in concrete. The stress of different positions in different steel fiber content were basically the same before the formation of upper plastic hinge line, but after the formation of plastic hinges line, the influence of steel fiber content on stress distribution was larger because of the influence of redistribution of internal forces. In addition, the steel fiber volume fraction on the developing and distribution of the cracks had little effect. Because steel fiber can increase the tensile strength of concrete, which had a certain impact on the distribution of structural cracks.
Steel fiber concrete waffle composite slab system includes material composite and structure typecomposite, which has good mechanical and thermal insulation properties. Nonlinear finite element analysis for themechanical properties of the whole process on the composite structure system was presented, and by changing thefiber content the parameter were discussed. The functions of steel fibers were considered mainly through modificationof the constitutive relationship of concrete and elastic modulus and other parameters, without consideration of the bondand slip between steel fiber and concrete in the finite element analysis model to simplify calculation. The analysis results showed that the structural deformation and crack resistance could be improved significantly even adding less steel fiber in concrete. The stress of different positions in different steel fiber content were basically the same before the formation of upper plastic hinge line, but after the formation of plastic hinges line, the influence of steel fiber content on stress distribution was larger because of the influence of redistribution of internal forces. In addition, the steel fiber volume fraction on the developing and distribution of the cracks had little effect. Because steel fiber can increase the tensile strength of concrete, which had a certain impact on the distribution of structural cracks.
2011, 41(9): 73-75.
doi: 10.13204/j.gyjz201109016
Abstract:
Simulation of the blasting demolition of RC frames was carried out with the dynamic finite element software of ANSYS/LS-DYNA. The calculated result of simulation was very close to the real condition, which meant that using proper numerical model and parameters could simulate such complex problem as the collapse of RC frames, the quantitative analysis and optimization of the real blasting project.
Simulation of the blasting demolition of RC frames was carried out with the dynamic finite element software of ANSYS/LS-DYNA. The calculated result of simulation was very close to the real condition, which meant that using proper numerical model and parameters could simulate such complex problem as the collapse of RC frames, the quantitative analysis and optimization of the real blasting project.
2011, 41(9): 76-80.
doi: 10.13204/j.gyjz201109017
Abstract:
In order to examine the effect of the rubber powder in the same volume replacing the sand in differentproportions(replacement rate) and the degree of rubber powder's fineness (fineness modulus) on concrete strength, it was used the double-factor repeating test method, that was, just to consider the replacement rate and the finenessmodulus, other test conditions to be maintained invariable basically. The analysis of variance shows that the amount of rubber powder has great influence on concrete's 7d and 28 d compressive and tensile strength, the fineness of rubber powder has great influence on concrete's 7d and 28 d tensile strength, its influence on the 7d compressive strength is significant, while it is not evident on 28d compressive strength, these two factors interaction has great influence on concrete's 7d and 28d compressive strength, its influence on 7d tensile strength is significant, while 28d is not remarkable. Regression analysis shows that the amount of rubber powder and the fineness have linear relationship with concrete's 7d and 28d compressive strength, so does concrete's 7d tensile strength, but they don't have linear relationship with concrete's 28d tensile strength.
In order to examine the effect of the rubber powder in the same volume replacing the sand in differentproportions(replacement rate) and the degree of rubber powder's fineness (fineness modulus) on concrete strength, it was used the double-factor repeating test method, that was, just to consider the replacement rate and the finenessmodulus, other test conditions to be maintained invariable basically. The analysis of variance shows that the amount of rubber powder has great influence on concrete's 7d and 28 d compressive and tensile strength, the fineness of rubber powder has great influence on concrete's 7d and 28 d tensile strength, its influence on the 7d compressive strength is significant, while it is not evident on 28d compressive strength, these two factors interaction has great influence on concrete's 7d and 28d compressive strength, its influence on 7d tensile strength is significant, while 28d is not remarkable. Regression analysis shows that the amount of rubber powder and the fineness have linear relationship with concrete's 7d and 28d compressive strength, so does concrete's 7d tensile strength, but they don't have linear relationship with concrete's 28d tensile strength.
2011, 41(9): 81-84,107.
doi: 10.13204/j.gyjz201109018
Abstract:
The ratio of hematite tailings from western Hubei Province, as the main material in preparation of nonburned and non-autoclaved bricks, to standard building sands were studied in this paper. In addition, the effects of forming water contents, forming pressures and mixture contents on compressive strength were also investigated. The results showed that the non-burned and non-autoclaved brick with compressive strength at 15.9MPa could be prepared in the optimum condition of 78% hematite tailing, 10% the standard building sand, 10% cement, 2% gypsum, 15% molding water, 20 MPa molding pressure, and 0.01% triethanolamine. The strength of product meeted the standard of JC /T422-2007 and this technology could promote the comprehensive utilization of the hematite tailings from western Hubei Province.
The ratio of hematite tailings from western Hubei Province, as the main material in preparation of nonburned and non-autoclaved bricks, to standard building sands were studied in this paper. In addition, the effects of forming water contents, forming pressures and mixture contents on compressive strength were also investigated. The results showed that the non-burned and non-autoclaved brick with compressive strength at 15.9MPa could be prepared in the optimum condition of 78% hematite tailing, 10% the standard building sand, 10% cement, 2% gypsum, 15% molding water, 20 MPa molding pressure, and 0.01% triethanolamine. The strength of product meeted the standard of JC /T422-2007 and this technology could promote the comprehensive utilization of the hematite tailings from western Hubei Province.
2011, 41(9): 85-89.
doi: 10.13204/j.gyjz201109019
Abstract:
As constructing large bridge rise pile cap concrete integral erection in deep water, the stress caused from different temperature in the stage of concrete curing is harmful to its durability. The analysis of material ingredient influence on heat of hydration and thermal stress was done. Taking the main pile cap whose blocking partition dimension was about 51. 35m48.1m for example, the calculated parameters were determined. And a simulation analysis of thermal stress variation during the concrete hardening was introduced. The comparison between calculated results and the monitoring value was made. It was that the first 5 d were the period for surface crack to produce easily during which controlling measures could act well. Rational concrete design was available means of controlling mass concrete thermal crack by retarding and reducing heat of hydration.
As constructing large bridge rise pile cap concrete integral erection in deep water, the stress caused from different temperature in the stage of concrete curing is harmful to its durability. The analysis of material ingredient influence on heat of hydration and thermal stress was done. Taking the main pile cap whose blocking partition dimension was about 51. 35m48.1m for example, the calculated parameters were determined. And a simulation analysis of thermal stress variation during the concrete hardening was introduced. The comparison between calculated results and the monitoring value was made. It was that the first 5 d were the period for surface crack to produce easily during which controlling measures could act well. Rational concrete design was available means of controlling mass concrete thermal crack by retarding and reducing heat of hydration.
2011, 41(9): 90-93.
doi: 10.13204/j.gyjz201109020
Abstract:
The experiment of microstructure SEM and compressive strength of HPC after exposure to hightemperatures was performed and the relationship between microstructure and mechanical properties of HPC was investigated. The results show that the variation of microstructure in concrete is in conformity with the change in mechanical properties. With the temperature increased, concrete aggregates change from compact to loose, the microcrack is increased and interconnected in quantity and width, and the mechanical properties are decreased accordingly. The vapor pressure of inner-concrete is decreased due to interconnected pores after polypropylene fiber melted, which can alleviate the damage of high temperature to concrete.
The experiment of microstructure SEM and compressive strength of HPC after exposure to hightemperatures was performed and the relationship between microstructure and mechanical properties of HPC was investigated. The results show that the variation of microstructure in concrete is in conformity with the change in mechanical properties. With the temperature increased, concrete aggregates change from compact to loose, the microcrack is increased and interconnected in quantity and width, and the mechanical properties are decreased accordingly. The vapor pressure of inner-concrete is decreased due to interconnected pores after polypropylene fiber melted, which can alleviate the damage of high temperature to concrete.
2011, 41(9): 94-99.
doi: 10.13204/j.gyjz201109021
Abstract:
According to three sites measurement to axial force of vertical strut of superhigh or large-span form strut system, the influences on internal force of vertical strut by different pouring methods of concrete and structure type of floor system were analyzed. The results showed that pouring method and floor system had significant effect on high or large-span form strut axial force. Compared to manual pouring, pumping had not only horizontal impact force but also vertical impact force. Compared to flat roof, the axial force of vertical strut in sloping roof form strut system was more uneven and the maximal difference reached about 2 times. According to the measured results, the present formula should be revised and corresponding research methods were put forward. In the end, the finite element simulation was done by ABAQUS.
According to three sites measurement to axial force of vertical strut of superhigh or large-span form strut system, the influences on internal force of vertical strut by different pouring methods of concrete and structure type of floor system were analyzed. The results showed that pouring method and floor system had significant effect on high or large-span form strut axial force. Compared to manual pouring, pumping had not only horizontal impact force but also vertical impact force. Compared to flat roof, the axial force of vertical strut in sloping roof form strut system was more uneven and the maximal difference reached about 2 times. According to the measured results, the present formula should be revised and corresponding research methods were put forward. In the end, the finite element simulation was done by ABAQUS.
2011, 41(9): 100-104.
doi: 10.13204/j.gyjz201109022
Abstract:
Two-way steel-concrete composite floors system have been applied to large-span structure system gradually. Compared with reinforced concrete floors system, it has advantages of good integrality, ductility, reducing structure height, lowering self-weight and shortening erection time. According to the design and construction difficulties, it was presented that application scope, size selection, calculation method, joint design, crack control, and construction method of this composite floor system. Combined with practical work, design and construction technology of two-way steel concrete composite system were expounded in detail. The economic and technical indexes of that floor system were compared with others.
Two-way steel-concrete composite floors system have been applied to large-span structure system gradually. Compared with reinforced concrete floors system, it has advantages of good integrality, ductility, reducing structure height, lowering self-weight and shortening erection time. According to the design and construction difficulties, it was presented that application scope, size selection, calculation method, joint design, crack control, and construction method of this composite floor system. Combined with practical work, design and construction technology of two-way steel concrete composite system were expounded in detail. The economic and technical indexes of that floor system were compared with others.
2011, 41(9): 105-107.
doi: 10.13204/j.gyjz201109023
Abstract:
Large-diameter super-long punching piles and post grouting technology were adopted in the construction of Henan TV tower. According to difficulty and design parameters, construction technology and scheme were introduced, and construction quality ensuring measures were put forward. The results showed that the construction quality control of piles bottom post grouing of bored piles was solved, supporting course at piles end and the soil layers around the piles were improved, the synthetic bearing capacity of piles was greatly improved and piles foundation settlement was controlled effectively.
Large-diameter super-long punching piles and post grouting technology were adopted in the construction of Henan TV tower. According to difficulty and design parameters, construction technology and scheme were introduced, and construction quality ensuring measures were put forward. The results showed that the construction quality control of piles bottom post grouing of bored piles was solved, supporting course at piles end and the soil layers around the piles were improved, the synthetic bearing capacity of piles was greatly improved and piles foundation settlement was controlled effectively.
2011, 41(9): 108-112.
doi: 10.13204/j.gyjz201109024
Abstract:
Xingou River Bridge in Jiangyin City is a self-anchored suspended bridge with double cable planes, the main girdes are five consecutive span prestressed concrete stiffening girders. As a self-anchored suspended bridge, the construction sequence is the girder first and then the cable, the main cable is anchored in the constructed main girder that bears the horizontal axial force, and the main suspension cable of suspension bridge bears all the permanent and live loads transmitted by hoisting cables. Because of the strong sensitivity of main cable erection line to the geometry of bridge structure, its erection linear error will cause great changes to the constructed bridge linear and internal stress distribution. Meanwhile, the main cable construction process itself has strong geometrical nonlinearity, the influence of temperature, construction and manufacturing error on main cable erection line is very sensitive, and the quality of the shape will be the decisive factor to the precision and service time of the bridge.Erecting the main suspension cable is a critical sequence in the construction of the bridge. It was introduced the construction technology of the self-anchored suspension bridge with the example of the construction of Xingou River Bridge in Jiangyin City.
Xingou River Bridge in Jiangyin City is a self-anchored suspended bridge with double cable planes, the main girdes are five consecutive span prestressed concrete stiffening girders. As a self-anchored suspended bridge, the construction sequence is the girder first and then the cable, the main cable is anchored in the constructed main girder that bears the horizontal axial force, and the main suspension cable of suspension bridge bears all the permanent and live loads transmitted by hoisting cables. Because of the strong sensitivity of main cable erection line to the geometry of bridge structure, its erection linear error will cause great changes to the constructed bridge linear and internal stress distribution. Meanwhile, the main cable construction process itself has strong geometrical nonlinearity, the influence of temperature, construction and manufacturing error on main cable erection line is very sensitive, and the quality of the shape will be the decisive factor to the precision and service time of the bridge.Erecting the main suspension cable is a critical sequence in the construction of the bridge. It was introduced the construction technology of the self-anchored suspension bridge with the example of the construction of Xingou River Bridge in Jiangyin City.
2011, 41(9): 113-115,143.
doi: 10.13204/j.gyjz201109025
Abstract:
Combined with the characteristics of a project, this paper introduces the key construction technology of pipe-jacking by using modified large-diameter die, also enumerates directly the superiorities, similarities and differences of the modified die as compared to the common one, and also makes an analytical comparison of economic benefit between them.
Combined with the characteristics of a project, this paper introduces the key construction technology of pipe-jacking by using modified large-diameter die, also enumerates directly the superiorities, similarities and differences of the modified die as compared to the common one, and also makes an analytical comparison of economic benefit between them.
2011, 41(9): 116-119.
doi: 10.13204/j.gyjz201109026
Abstract:
The excavation of underground tunnels must be on the premise of the normal usage of ground buildings.Cracking, settlement, incline and other issues of buildings may be caused by excessive ground settlement, which may severely affect the safe usage of buildings. Based on previous studies, the research methods and results of the impact of underground shield tunnel and shallow bored tunnel construction on adjacent buildings were respectively reviewed and summarized, and the further study and research ideas were put forward.
The excavation of underground tunnels must be on the premise of the normal usage of ground buildings.Cracking, settlement, incline and other issues of buildings may be caused by excessive ground settlement, which may severely affect the safe usage of buildings. Based on previous studies, the research methods and results of the impact of underground shield tunnel and shallow bored tunnel construction on adjacent buildings were respectively reviewed and summarized, and the further study and research ideas were put forward.
2011, 41(9): 120-123,75.
doi: 10.13204/j.gyjz201109027
Abstract:
Based on a mid-side connection of a steel frame, this paper analyzed the deformation mechanism of the bolted-welded connection after loading and deduced a theoretical formula that could calculate initial stiffness. In order to verify the rationality of the formula, 15 finite element models were established to calculated the initial stiffness.The results show that the theoretical formula is fit to calculate initial stiffness. Besides, according to Eurocode 3, many connections can not meet the demands of rigid connections stiffness. They belong to semi-rigid connections.
Based on a mid-side connection of a steel frame, this paper analyzed the deformation mechanism of the bolted-welded connection after loading and deduced a theoretical formula that could calculate initial stiffness. In order to verify the rationality of the formula, 15 finite element models were established to calculated the initial stiffness.The results show that the theoretical formula is fit to calculate initial stiffness. Besides, according to Eurocode 3, many connections can not meet the demands of rigid connections stiffness. They belong to semi-rigid connections.
2011, 41(9): 124-126,130.
doi: 10.13204/j.gyjz201109028
Abstract:
Surrounding members(i.e. beams and columns) were assumed to supply simply supported edges for steelplate shear wall in the design of steel plate shear wall, and then the embedded coefficient of 1. 23 was introduced to consider the restriction effect of surrounding members. The effect of rigidities of the surrounding members was not considered in the design process. A finite element analysis was carried out to investigate the elastic buckling of steel plate shear wall under shear and compression load. It was found that the factor , that is ratio of rotational rigidity of the surrounding members and bending rigidity of the steel plate, was a good factor to measure precisely the elastic restraints of surrounding members to the shear wall. Based on computing data from more than 400 models, the equation of shear buckling coefficients was developed for steel plate shear wall with elastic restraint of two sides.
Surrounding members(i.e. beams and columns) were assumed to supply simply supported edges for steelplate shear wall in the design of steel plate shear wall, and then the embedded coefficient of 1. 23 was introduced to consider the restriction effect of surrounding members. The effect of rigidities of the surrounding members was not considered in the design process. A finite element analysis was carried out to investigate the elastic buckling of steel plate shear wall under shear and compression load. It was found that the factor , that is ratio of rotational rigidity of the surrounding members and bending rigidity of the steel plate, was a good factor to measure precisely the elastic restraints of surrounding members to the shear wall. Based on computing data from more than 400 models, the equation of shear buckling coefficients was developed for steel plate shear wall with elastic restraint of two sides.
2011, 41(9): 127-130.
doi: 10.13204/j.gyjz201109029
Abstract:
It was carried out an analysis of fatigue performance of crane girder using FE simulation according to the result of fatigue performance stress testing of crane girder for a steel plant. The result indicate that stress concentration is obvious on the mutation section of the crane girder and fatigue performance is serious. With the advances in production technology, the cranes are increasing the frequency of operation which will make the under-load effect coefficient increase significantly. The value in the existing Code of Design of Steel Structures (GB 500172003) may be is lower than that of the actual situation, leading to insecurity. Therefore, it was recommended that 0.9 should be taken as the value of under-load effect coefficient for the heavy duty work system of crane hook in order to ensure the fatigue security of crane girders.
It was carried out an analysis of fatigue performance of crane girder using FE simulation according to the result of fatigue performance stress testing of crane girder for a steel plant. The result indicate that stress concentration is obvious on the mutation section of the crane girder and fatigue performance is serious. With the advances in production technology, the cranes are increasing the frequency of operation which will make the under-load effect coefficient increase significantly. The value in the existing Code of Design of Steel Structures (GB 500172003) may be is lower than that of the actual situation, leading to insecurity. Therefore, it was recommended that 0.9 should be taken as the value of under-load effect coefficient for the heavy duty work system of crane hook in order to ensure the fatigue security of crane girders.
2011, 41(9): 131-135.
doi: 10.13204/j.gyjz201109030
Abstract:
This paper was aimed to obtain the key impact parameters of prying action, which existed in the tensile region of flange-plate connection under bending moment. It took an analysis of four basic kinds of flange-plate connectionsflexural capacity, which was developed by means of finite element method simulation with finite element program ANSYS. The analysis especially studied the effect factors of prying force in the tensile region of connection.The corresponding parametric analysis was developed. It was proved that the thickness of flange-plate, the ratio of outer and inner diameter of flange-plate and the ratio of diameter of tube to the inner edge of bolts had a greater effect on the prying forces. It was suggested that prying forces should be controlled based on the adjustment of these key impact parameters in practical engineering design.
This paper was aimed to obtain the key impact parameters of prying action, which existed in the tensile region of flange-plate connection under bending moment. It took an analysis of four basic kinds of flange-plate connectionsflexural capacity, which was developed by means of finite element method simulation with finite element program ANSYS. The analysis especially studied the effect factors of prying force in the tensile region of connection.The corresponding parametric analysis was developed. It was proved that the thickness of flange-plate, the ratio of outer and inner diameter of flange-plate and the ratio of diameter of tube to the inner edge of bolts had a greater effect on the prying forces. It was suggested that prying forces should be controlled based on the adjustment of these key impact parameters in practical engineering design.
2011, 41(9): 136-140.
doi: 10.13204/j.gyjz201109031
Abstract:
It was conducted the static nonlinear pushover analysis of a moment frame structure. Through the analysis of the structure basis shearing force-top displacements elastoplasticity change relations, the structure plastic hinges formation course and the destruction mechanism, it was obtained the performance point of the structure. Then it was examined the story displacement of the structure to see whether it satisfied the limit of the story displacement specified by the code GB 500112011, so as to examine and inspect the earthquake resistance ability. Finally the structure failure mechanism was discussed, and the method of improving structure earthquake resistance performance was researched.
It was conducted the static nonlinear pushover analysis of a moment frame structure. Through the analysis of the structure basis shearing force-top displacements elastoplasticity change relations, the structure plastic hinges formation course and the destruction mechanism, it was obtained the performance point of the structure. Then it was examined the story displacement of the structure to see whether it satisfied the limit of the story displacement specified by the code GB 500112011, so as to examine and inspect the earthquake resistance ability. Finally the structure failure mechanism was discussed, and the method of improving structure earthquake resistance performance was researched.
2011, 41(9): 141-143.
doi: 10.13204/j.gyjz201109032
Abstract:
The design of environment, which is involved in many aspects, is the core content of the design of residential area in a city. Just from the angle of the outside space and environment of the residential area, the article analyzed the basic problems in a systemic way, and advances the eight-design principles: nature, safety, health, pleasing to the eye, convenience, humanity, moderation, and harmony.
The design of environment, which is involved in many aspects, is the core content of the design of residential area in a city. Just from the angle of the outside space and environment of the residential area, the article analyzed the basic problems in a systemic way, and advances the eight-design principles: nature, safety, health, pleasing to the eye, convenience, humanity, moderation, and harmony.
