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2011 Vol. 41, No. 6
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2011, 41(6): 1-8.
doi: 10.13204/j.gyjz201106001
Abstract:
This thesis is to obtain the basic form of the strength and stability capacity correlation equations of the concrete filled steel tubular structures under complex stress through the theoretical derivation.It is used the previous CFST equivalent truss model which had been obtained when establishing static equilibrium equations to do mechanical analysis under complex stress.It can be calculated the internal forces of each equivalent truss rod and then determined their yield failure pattern to get yield equation.It is also used the previous balance equation to do computings to offset the internal forces of steel and concrete, in order to obtain the bearing and stability capacity correlation equations.
This thesis is to obtain the basic form of the strength and stability capacity correlation equations of the concrete filled steel tubular structures under complex stress through the theoretical derivation.It is used the previous CFST equivalent truss model which had been obtained when establishing static equilibrium equations to do mechanical analysis under complex stress.It can be calculated the internal forces of each equivalent truss rod and then determined their yield failure pattern to get yield equation.It is also used the previous balance equation to do computings to offset the internal forces of steel and concrete, in order to obtain the bearing and stability capacity correlation equations.
2011, 41(6): 9-14.
doi: 10.13204/j.gyjz201106002
Abstract:
This thesis is to obtain the basic form of the strength and stability capacity correlation equations of the concrete-filled steel tubular structures under complex stress through the theoretical derivation.It should be considered the role of the impact of hoop between the steel and concrete, analyzed and summarized the working performace and loading capacity of concrete-filled steel tubular structures subject to respective axial compression, bending, shear and torsion.It will be introducted a hoop influence coefficient to adjust the various ultimate bearing capacity of items, so as to get a practical calculation formula for the compression, flexural bearing capacity which can be in good agreement with experiment and finite element values.This practical formula considering the role of the impact of hoop will replace the correlating equation to adjust the carrying capacity to finalize the expression of the strength and stability capacity correlation equations of the concrete-filled steel tubular structures under complex stress.
This thesis is to obtain the basic form of the strength and stability capacity correlation equations of the concrete-filled steel tubular structures under complex stress through the theoretical derivation.It should be considered the role of the impact of hoop between the steel and concrete, analyzed and summarized the working performace and loading capacity of concrete-filled steel tubular structures subject to respective axial compression, bending, shear and torsion.It will be introducted a hoop influence coefficient to adjust the various ultimate bearing capacity of items, so as to get a practical calculation formula for the compression, flexural bearing capacity which can be in good agreement with experiment and finite element values.This practical formula considering the role of the impact of hoop will replace the correlating equation to adjust the carrying capacity to finalize the expression of the strength and stability capacity correlation equations of the concrete-filled steel tubular structures under complex stress.
2011, 41(6): 15-19.
doi: 10.13204/j.gyjz201106003
Abstract:
A newly developed reinforced concrete(RC)beam to concrete-filled-steel-tube(CFST)column joint without welding in construction field is introduced in this paper.The seismic experiment is conducted on the joint, and the hysteretic curve of the specimen under cyclic loading on column top is obtained.According to the test results, this joint shows good ductility and the ability of energy dissipation, and it can be used to replace the joints with welded reinforcement on the outer annular plate.Moreover, the test is also simulated with FEM, and the results agree well with the skeleton curves obtained from the test.Parametric analysis is conducted on this joint, with the consideration of different design of beam, column and steel bracket, and the failure mode is discussed.
A newly developed reinforced concrete(RC)beam to concrete-filled-steel-tube(CFST)column joint without welding in construction field is introduced in this paper.The seismic experiment is conducted on the joint, and the hysteretic curve of the specimen under cyclic loading on column top is obtained.According to the test results, this joint shows good ductility and the ability of energy dissipation, and it can be used to replace the joints with welded reinforcement on the outer annular plate.Moreover, the test is also simulated with FEM, and the results agree well with the skeleton curves obtained from the test.Parametric analysis is conducted on this joint, with the consideration of different design of beam, column and steel bracket, and the failure mode is discussed.
2011, 41(6): 20-24,8.
doi: 10.13204/j.gyjz201106004
Abstract:
By means of analyzing the mechanical characteristics and failure model of RC beam to CFST column joint without welding, a three-stage skeleton curve model is presented.In the elastic stage, the initial stiffness is evaluated by solving the stiffness matrix.In the perfect plastic stage and strength degradation stage, the ultimate strength and the degradation stiffness of the joint can be obtained with the limit equilibrium method.In order to verify the theoretical model presented above, finite element analysis results are compared with the theoretical results.It is suggested that the three-stage skeleton curve model can be used to depict the mechanical behavior of this new type of joint.
By means of analyzing the mechanical characteristics and failure model of RC beam to CFST column joint without welding, a three-stage skeleton curve model is presented.In the elastic stage, the initial stiffness is evaluated by solving the stiffness matrix.In the perfect plastic stage and strength degradation stage, the ultimate strength and the degradation stiffness of the joint can be obtained with the limit equilibrium method.In order to verify the theoretical model presented above, finite element analysis results are compared with the theoretical results.It is suggested that the three-stage skeleton curve model can be used to depict the mechanical behavior of this new type of joint.
2011, 41(6): 25-29.
doi: 10.13204/j.gyjz201106005
Abstract:
The axial compression tests on six CFST columns reinforced by GFRP and one contrast specimen of CFST column are done in this article, to research the mechanical behavior of this composite member.Experimental results indicate that, the confinement with filament wound reinforced steel tube can greatly enhance the bearing capacity of composite columns.The carrying capacity of the GFRP strengthened CFST column with 90 and 45 fiber orientation can be raised by 40.9% and 27.3% as compared with CFST column.The mechanical performance of composite columns is also discussed in this paper, and the formula of ultimate bearing capacity and simplified model of stress-strain relation of the composite column have been proposed, whose results are in good agreement with the test results.
The axial compression tests on six CFST columns reinforced by GFRP and one contrast specimen of CFST column are done in this article, to research the mechanical behavior of this composite member.Experimental results indicate that, the confinement with filament wound reinforced steel tube can greatly enhance the bearing capacity of composite columns.The carrying capacity of the GFRP strengthened CFST column with 90 and 45 fiber orientation can be raised by 40.9% and 27.3% as compared with CFST column.The mechanical performance of composite columns is also discussed in this paper, and the formula of ultimate bearing capacity and simplified model of stress-strain relation of the composite column have been proposed, whose results are in good agreement with the test results.
2011, 41(6): 30-35.
doi: 10.13204/j.gyjz201106006
Abstract:
Considering the need of practical project design, a framework of simplified assessing method is proposed based on the calculation model and simulation techniques.The potential of structural collapse of single level frame is utilized to represent the potential of whole non-sway structural model and this simplification assumption is verified with simplified mechanical and finite element methods.Based on the principle of energy conservation, pseudo-static analysis method is also verified in evaluating the peak structural dynamic response when considering the slab membrane action.Finally the potential of the structural progressive collapse of CFST structure with joint is analyzed, in which no welding is necessary in construction field.The influence of concrete strength, reinforcement ratio of beam and the bracket length are also investigated.
Considering the need of practical project design, a framework of simplified assessing method is proposed based on the calculation model and simulation techniques.The potential of structural collapse of single level frame is utilized to represent the potential of whole non-sway structural model and this simplification assumption is verified with simplified mechanical and finite element methods.Based on the principle of energy conservation, pseudo-static analysis method is also verified in evaluating the peak structural dynamic response when considering the slab membrane action.Finally the potential of the structural progressive collapse of CFST structure with joint is analyzed, in which no welding is necessary in construction field.The influence of concrete strength, reinforcement ratio of beam and the bracket length are also investigated.
2011, 41(6): 36-42.
doi: 10.13204/j.gyjz201106007
Abstract:
Non-linear finite element method is used to simulate the behaviors of H-CFST columns with different hollow ratio under different fire load ratio, which have the same steel tube size.Results show that when the term fire load ratio is relatively larger, fire resistance time of CFST firstly increases then decreases as hollow ratio increases.While fire load ratio is relatively smaller, fire resistance time of columns linear decreases as hollow ratio increases.When the hollow filled with water, the fire resistance time is almost the same under lager fire load ratio, but it can be obviously improved under small fire load ratio.Based on this conclusion and according to Chinese code, furthermore, a method of calculating the thickness of fireproof paint of H-CFST columns is given.
Non-linear finite element method is used to simulate the behaviors of H-CFST columns with different hollow ratio under different fire load ratio, which have the same steel tube size.Results show that when the term fire load ratio is relatively larger, fire resistance time of CFST firstly increases then decreases as hollow ratio increases.While fire load ratio is relatively smaller, fire resistance time of columns linear decreases as hollow ratio increases.When the hollow filled with water, the fire resistance time is almost the same under lager fire load ratio, but it can be obviously improved under small fire load ratio.Based on this conclusion and according to Chinese code, furthermore, a method of calculating the thickness of fireproof paint of H-CFST columns is given.
2011, 41(6): 43-46,66.
doi: 10.13204/j.gyjz201106008
Abstract:
In the practical construction of a concrete-filled steel tube(CFST)column, the effect of the creep on the CFST performance can not be ignored, which caused by the stratified construction as well as the using of expansive agent to remedy the shrinkage of the concrete.Based on the simulation the stratified construction, a series of experiments were conducted to study effect of the expansive agent dosage on the ultimate bearing capacity of CFST columns and the creep deformation in the longitudinal direction.Also the corresponding properties of the regeneration aggregate concrete filled steel tube(RACFST)have been studied.It has been found that the ultimate bearing capacity of the CFST column can be increased greatly when using more expansive agent, as well as the creep deformation.And the time-interval between two dead-loads also makes a large influence on the creep performance of the CFST column, when the time-interval increases, the amplitude of the creep deformation gets a remarkable decreasing.In contrast, it is a greater influence on the deformation of the RACFST column than the CFST one, and a smaller influence on the ultimate bearing capacity.
In the practical construction of a concrete-filled steel tube(CFST)column, the effect of the creep on the CFST performance can not be ignored, which caused by the stratified construction as well as the using of expansive agent to remedy the shrinkage of the concrete.Based on the simulation the stratified construction, a series of experiments were conducted to study effect of the expansive agent dosage on the ultimate bearing capacity of CFST columns and the creep deformation in the longitudinal direction.Also the corresponding properties of the regeneration aggregate concrete filled steel tube(RACFST)have been studied.It has been found that the ultimate bearing capacity of the CFST column can be increased greatly when using more expansive agent, as well as the creep deformation.And the time-interval between two dead-loads also makes a large influence on the creep performance of the CFST column, when the time-interval increases, the amplitude of the creep deformation gets a remarkable decreasing.In contrast, it is a greater influence on the deformation of the RACFST column than the CFST one, and a smaller influence on the ultimate bearing capacity.
2011, 41(6): 47-49,53.
doi: 10.13204/j.gyjz201106009
Abstract:
Adaptive reuse has become a main model of industrial heritage buildings conservation.The paper discusses the deep background of the model formation, which may be a reference for other heritage buildings.Redevelopment of urban land proposes the actual demand of industrial sites renewal.The availability of adaptive reuse is also proposed by industrial buildings based on the historical change from buildings and structures to heritage as well as the standpoint of protecting historical witness.Concept of sustainable development and environmental requirements for energy saving and emission reduction give preference to the adaptive-reuse model while the characteristics of industrial heritage buildings can ensure the successful implementation.
Adaptive reuse has become a main model of industrial heritage buildings conservation.The paper discusses the deep background of the model formation, which may be a reference for other heritage buildings.Redevelopment of urban land proposes the actual demand of industrial sites renewal.The availability of adaptive reuse is also proposed by industrial buildings based on the historical change from buildings and structures to heritage as well as the standpoint of protecting historical witness.Concept of sustainable development and environmental requirements for energy saving and emission reduction give preference to the adaptive-reuse model while the characteristics of industrial heritage buildings can ensure the successful implementation.
2011, 41(6): 50-53.
doi: 10.13204/j.gyjz201106010
Abstract:
With the expansion of city scale and further development of the city, the traditional development model of industry - districts is less and less appropriate to the industrial zone development in the urban area, and is unable to meet the requirements of modern city environment. To build a urban industry including the urban functions and urban life, a model of Industrial community planning is established, which provides a option to promote the industry in the urban area.
With the expansion of city scale and further development of the city, the traditional development model of industry - districts is less and less appropriate to the industrial zone development in the urban area, and is unable to meet the requirements of modern city environment. To build a urban industry including the urban functions and urban life, a model of Industrial community planning is established, which provides a option to promote the industry in the urban area.
2011, 41(6): 54-56,123.
doi: 10.13204/j.gyjz201106011
Abstract:
Longbeicun parking lot is built for L4 subway in Beijing, and it is responsible for 20 subway trains' parking, overhaul and scouring.It is located in the the three mountains and five gardens scenic spot, and to the north of the Summer Palace.According to the environment characteristics of the site, archaized architecture design techniques are adopted for the architectural layout, architectural modeling, colors and other details including building elevation and eaves, to harmonize the large-scale steel structure workshop to the scenic spot.
Longbeicun parking lot is built for L4 subway in Beijing, and it is responsible for 20 subway trains' parking, overhaul and scouring.It is located in the the three mountains and five gardens scenic spot, and to the north of the Summer Palace.According to the environment characteristics of the site, archaized architecture design techniques are adopted for the architectural layout, architectural modeling, colors and other details including building elevation and eaves, to harmonize the large-scale steel structure workshop to the scenic spot.
2011, 41(6): 57-61.
doi: 10.13204/j.gyjz201106012
Abstract:
In order to create a better environment for the 2010 Guangzhou asian games.The city of Guangzhou launched a comprehensive treatment on the city's environment, including the transformation of the in-city villages and a series of urban renewal projects.During the implementation process, conflicts often existed, such as the unbalance between the public welfare and commercial value, the demolition problem, slow progress on construction, insufficient funding for future construction, the physical limitation of achieving the planned objects, etc.Taking the conservation scheme of Huangpu historic and ancient village for example, it is proposed reform of old city reconstruction based on people's livelihood-oriented, which may be helpful to the promotion of similar projects.
In order to create a better environment for the 2010 Guangzhou asian games.The city of Guangzhou launched a comprehensive treatment on the city's environment, including the transformation of the in-city villages and a series of urban renewal projects.During the implementation process, conflicts often existed, such as the unbalance between the public welfare and commercial value, the demolition problem, slow progress on construction, insufficient funding for future construction, the physical limitation of achieving the planned objects, etc.Taking the conservation scheme of Huangpu historic and ancient village for example, it is proposed reform of old city reconstruction based on people's livelihood-oriented, which may be helpful to the promotion of similar projects.
2011, 41(6): 62-66.
doi: 10.13204/j.gyjz201106013
Abstract:
In accordance with the conditions of a project, it is compared the mechanical properties of BFRP reinforced mortise-tenon joint of different construction methods, and explored the seismic performance of the said joint, including hysteretic skeleton curve, strength and stiffness degradation rules, ultimate strength and maximum stiffness.The results show that hysteretic curve graph of BFRP reinforced mortise-tenon of different construction methods is obviously different, the ultimate strength and maximum rigidity of the mortise-tenon joint also have a greater difference.
In accordance with the conditions of a project, it is compared the mechanical properties of BFRP reinforced mortise-tenon joint of different construction methods, and explored the seismic performance of the said joint, including hysteretic skeleton curve, strength and stiffness degradation rules, ultimate strength and maximum stiffness.The results show that hysteretic curve graph of BFRP reinforced mortise-tenon of different construction methods is obviously different, the ultimate strength and maximum rigidity of the mortise-tenon joint also have a greater difference.
2011, 41(6): 67-70.
doi: 10.13204/j.gyjz201106014
Abstract:
Three reinforced concrete frame beam-column interior spatial joints experiments are conducted under low level cyclic loadings.The aseismic character of the beam-column spatial joints is studied including failure mode, hysterisis curve, stiffness degradation, energy dissipation and displacement ductility.The experiment result shows that the column-hinge damage mechanism had happened.The aseismic character of bearing capactity, displacement ductility had decreased and the torsion effect had also existed under the oblique direction earthquake effect.The aseismic designing method should consider the oblique direction earthquake effect.
Three reinforced concrete frame beam-column interior spatial joints experiments are conducted under low level cyclic loadings.The aseismic character of the beam-column spatial joints is studied including failure mode, hysterisis curve, stiffness degradation, energy dissipation and displacement ductility.The experiment result shows that the column-hinge damage mechanism had happened.The aseismic character of bearing capactity, displacement ductility had decreased and the torsion effect had also existed under the oblique direction earthquake effect.The aseismic designing method should consider the oblique direction earthquake effect.
2011, 41(6): 71-74.
doi: 10.13204/j.gyjz201106015
Abstract:
In order to investigate the flexural behavior of concrete beam reinforced with 400 MPa fine grain high steel bars, the static bending tests on four rectangle cross-section concrete beams were made.Mechanical characteristics, flexural capacity of normal section, crack and deflection were analyzed according to present code.The results show that the flexural behavior of concrete beam reinforced with 400 MPa fine grain high steel bars is similar to normal concrete beam, the average concrete strain of different height keeps plane;flexural capacity and crack spacing could still be calculated by the current code for their values are close to the tested values.The current code was not suit able for calculating crack width;deflection value calculated by current code was a little smaller than the test value, so the stiffness-calculating formula was proposed to multiply 0.85 for adjustment;under the state of serviceability, crack width and deflection meet the requirements of the current code.
In order to investigate the flexural behavior of concrete beam reinforced with 400 MPa fine grain high steel bars, the static bending tests on four rectangle cross-section concrete beams were made.Mechanical characteristics, flexural capacity of normal section, crack and deflection were analyzed according to present code.The results show that the flexural behavior of concrete beam reinforced with 400 MPa fine grain high steel bars is similar to normal concrete beam, the average concrete strain of different height keeps plane;flexural capacity and crack spacing could still be calculated by the current code for their values are close to the tested values.The current code was not suit able for calculating crack width;deflection value calculated by current code was a little smaller than the test value, so the stiffness-calculating formula was proposed to multiply 0.85 for adjustment;under the state of serviceability, crack width and deflection meet the requirements of the current code.
2011, 41(6): 75-78.
doi: 10.13204/j.gyjz201106016
Abstract:
Based on the test results of static loading experiment of composite slabs made of fiber-reinforced gypsum panel and reinforced concrete, the calculation model is set up to analyze the behavior of the composite slabs by using the finite element analysis program ADINA.The analytical results indicate that the FEM model is appropriate for this case and the results computed by FEM are coincident with the testing ones.This paper also inquires into the fiber-reinforced gypsum panel's contribution to the bearing capacity of the composite slabs.
Based on the test results of static loading experiment of composite slabs made of fiber-reinforced gypsum panel and reinforced concrete, the calculation model is set up to analyze the behavior of the composite slabs by using the finite element analysis program ADINA.The analytical results indicate that the FEM model is appropriate for this case and the results computed by FEM are coincident with the testing ones.This paper also inquires into the fiber-reinforced gypsum panel's contribution to the bearing capacity of the composite slabs.
2011, 41(6): 79-83.
doi: 10.13204/j.gyjz201106017
Abstract:
The detailed formations of precast floor slab connectors have significant effect on its shear capacity, but there is no such specific provision on it at present.The effects of detailed formations on the shear strength, stiffness and deformation capacity of hairpin connectors(HPC) are studied, through numerical simulation analysis of it under in-plane shear force.The imbedded depth(d), slug length(h), steel plate thickness(t)and its stickout(s)are taken as parameters.On the basis of analysis, the recommendations on formation details of HPC are proposed for design and construction.
The detailed formations of precast floor slab connectors have significant effect on its shear capacity, but there is no such specific provision on it at present.The effects of detailed formations on the shear strength, stiffness and deformation capacity of hairpin connectors(HPC) are studied, through numerical simulation analysis of it under in-plane shear force.The imbedded depth(d), slug length(h), steel plate thickness(t)and its stickout(s)are taken as parameters.On the basis of analysis, the recommendations on formation details of HPC are proposed for design and construction.
2011, 41(6): 84-87.
doi: 10.13204/j.gyjz201106018
Abstract:
As the last line of defense for nuclear fuels leak, once the containment of nuclear power plant is destroyed by an earthquake, it will lead to serious consequences which will result in great panic at people's psychology.Based on a domestic containment as the research object, this paper establishes a finite element model of containment by finite element software.And this paper respectively makes the static, modal and spectrum analyseis of the finite element model.The purpose of this paper aims to do research on the dynamic response and the failure law under horizontal earthquakes.It is hoped that this paper may providea a reference for the aseismatic design of containment structures.
As the last line of defense for nuclear fuels leak, once the containment of nuclear power plant is destroyed by an earthquake, it will lead to serious consequences which will result in great panic at people's psychology.Based on a domestic containment as the research object, this paper establishes a finite element model of containment by finite element software.And this paper respectively makes the static, modal and spectrum analyseis of the finite element model.The purpose of this paper aims to do research on the dynamic response and the failure law under horizontal earthquakes.It is hoped that this paper may providea a reference for the aseismatic design of containment structures.
2011, 41(6): 88-91,42.
doi: 10.13204/j.gyjz201106019
Abstract:
Unstable fracture toughness is used to analyze size, boundary effect and crack propagation of concrete.Both size effect, boundary effect formula for unstable fracture toughness and crack propagation formula with real physical meaning and realistic rule are presented.Based on which, formulas for predicting the equivalent strength of unilater interval induced joint are proposed, in which these coupling effects on the equivalent strength are considered.The comparisons of the predictions given by the present model with experimental data prove that the model of the paper is efficient and accurate.
Unstable fracture toughness is used to analyze size, boundary effect and crack propagation of concrete.Both size effect, boundary effect formula for unstable fracture toughness and crack propagation formula with real physical meaning and realistic rule are presented.Based on which, formulas for predicting the equivalent strength of unilater interval induced joint are proposed, in which these coupling effects on the equivalent strength are considered.The comparisons of the predictions given by the present model with experimental data prove that the model of the paper is efficient and accurate.
2011, 41(6): 92-96.
doi: 10.13204/j.gyjz201106020
Abstract:
It is forbidden to use concrete perforated brick(CPB)wall at early ages for its big shringkage and high water content, Nevertheless, there are still many applications in engineering practice due to various reasons.Engineers should recognize their characteristics, then decide how to repair the walls.Experimental investigation is carried out in this study including bricks and walls.Firstly bricks are tested with water content, compressive strength, and etc;then whole walls at diffirent ages are tested with walls' end deformations and instantaneous strains;at last analysis and estimations are done and engineering restrictions are proposed.It is concluded that some early-age CPB bricks have wet inflations, whereas CPB walls have wet inflation and dry shrinkage circulations.Its shinkage rate is about 1.6~2.010-4.Walls' instantaneous strains show a pressure characreristic at beginning and then to tensile, and tend to be stable at last.Relationship between instantaneous strain and time(age)has an exponential decay trend.Results obtained in this study help engineers to control cracks and repair walls, It reflects the basic characteristics of walls at different ages, and thus has relevant engineering significance.
It is forbidden to use concrete perforated brick(CPB)wall at early ages for its big shringkage and high water content, Nevertheless, there are still many applications in engineering practice due to various reasons.Engineers should recognize their characteristics, then decide how to repair the walls.Experimental investigation is carried out in this study including bricks and walls.Firstly bricks are tested with water content, compressive strength, and etc;then whole walls at diffirent ages are tested with walls' end deformations and instantaneous strains;at last analysis and estimations are done and engineering restrictions are proposed.It is concluded that some early-age CPB bricks have wet inflations, whereas CPB walls have wet inflation and dry shrinkage circulations.Its shinkage rate is about 1.6~2.010-4.Walls' instantaneous strains show a pressure characreristic at beginning and then to tensile, and tend to be stable at last.Relationship between instantaneous strain and time(age)has an exponential decay trend.Results obtained in this study help engineers to control cracks and repair walls, It reflects the basic characteristics of walls at different ages, and thus has relevant engineering significance.
2011, 41(6): 97-101,114.
doi: 10.13204/j.gyjz201106021
Abstract:
Based on the large pullout test of double twisted hexagonal wire mesh reinforced coarse-grained red sandstone soil, the development process of mesh reinforcement's anti-pullout force was analyzed.After the deficiencies of ideal plastic material model, hyperbolic model, exponential model were studied when they were used to describe the pullout test's shear stress-displacement curve, the power function model which was fitting to described the mesh reinforcement's interaction relationship with soil was established, then the interface relationship of Geogrid in FLAC3D was modified by Fish Function and a numerical simulation of pullout test was carried out to verify the feasibility of power function mode.
Based on the large pullout test of double twisted hexagonal wire mesh reinforced coarse-grained red sandstone soil, the development process of mesh reinforcement's anti-pullout force was analyzed.After the deficiencies of ideal plastic material model, hyperbolic model, exponential model were studied when they were used to describe the pullout test's shear stress-displacement curve, the power function model which was fitting to described the mesh reinforcement's interaction relationship with soil was established, then the interface relationship of Geogrid in FLAC3D was modified by Fish Function and a numerical simulation of pullout test was carried out to verify the feasibility of power function mode.
2011, 41(6): 102-108.
doi: 10.13204/j.gyjz201106022
Abstract:
A simplified analytical method was developed for the axial harmonic response of totally and partially embedded pile groups in homogeneous and layered soil deposits.Based on BDWF model, finite element sub-structure method was used to setup the dynamic model of cap-pile groups which could precisely simulate cap's influence on impedance of pile groups.A comprehensive parameter study was focused the influence of the caps' height and mass density on pile groups dynamic response, and then limitation of rigid cap in practical design was presented.A solution was finally presented for the internal forces distributed on pile heads due to pile-to-pile interaction.The solution of present method was compared with that of traditional simplified method(rigid and massless cap solution) in simulating an in-site experiments of totally embedded pile groups and dynamics response of partially embedded pile groups for offshore fan foundation under harmonic load, it is demonstrated that present one can predict the pile groups dynamics response more reasonable and reliable.
A simplified analytical method was developed for the axial harmonic response of totally and partially embedded pile groups in homogeneous and layered soil deposits.Based on BDWF model, finite element sub-structure method was used to setup the dynamic model of cap-pile groups which could precisely simulate cap's influence on impedance of pile groups.A comprehensive parameter study was focused the influence of the caps' height and mass density on pile groups dynamic response, and then limitation of rigid cap in practical design was presented.A solution was finally presented for the internal forces distributed on pile heads due to pile-to-pile interaction.The solution of present method was compared with that of traditional simplified method(rigid and massless cap solution) in simulating an in-site experiments of totally embedded pile groups and dynamics response of partially embedded pile groups for offshore fan foundation under harmonic load, it is demonstrated that present one can predict the pile groups dynamics response more reasonable and reliable.
2011, 41(6): 109-114.
doi: 10.13204/j.gyjz201106023
Abstract:
Pile-net composite foundation is a new kind of soft soil treatment method developed in recent years.As the remarkable effects in control the residual settlement, and differential settlement, it was used extensively in highway engineering.In this paper, According to the pile type, two experimental section were designed to investigate the bearing mechanism and the settlement characteristics of pile-net composite foundation.Based on the test data, the bearing mechanism of soil arch was also analyzed.
Pile-net composite foundation is a new kind of soft soil treatment method developed in recent years.As the remarkable effects in control the residual settlement, and differential settlement, it was used extensively in highway engineering.In this paper, According to the pile type, two experimental section were designed to investigate the bearing mechanism and the settlement characteristics of pile-net composite foundation.Based on the test data, the bearing mechanism of soil arch was also analyzed.
2011, 41(6): 115-119.
doi: 10.13204/j.gyjz201106024
Abstract:
Before a tunnel excavation, the groundwater in the rock and the surrounding rock stress are in a state of relative balance, because the excavation makes tunnel groundwater drain has a new channel, thus accelerating the water cycle, which destroyed balance of the original supplies-migration-the drainage system;On the other hand, the surrounding rock stress was redistributed and part of structural surface was closed due to pressurization, part of unloading rock mass produced shear slippage, which vandalized the original groundwater seepage condition, thus making tunnel itself become an underground corridor to discharge water in different forms, resulting in bursting water disasters.Monte Carlo method was used to establish 2-d discrete-fracture network, which was input rock mass structure discrete fissure network medium model(DFN), according to the model of the discrete element method in fractured rock mass seepage characteristics, fracture rock cavern excavation mechanical characteristics and seepage stress coupling mechanism of fractured rock mass.Combined with concrete examples, a comparison was done for cases of excavating caverns in fractured rocks with and without consideration of hydraulic coupling.
Before a tunnel excavation, the groundwater in the rock and the surrounding rock stress are in a state of relative balance, because the excavation makes tunnel groundwater drain has a new channel, thus accelerating the water cycle, which destroyed balance of the original supplies-migration-the drainage system;On the other hand, the surrounding rock stress was redistributed and part of structural surface was closed due to pressurization, part of unloading rock mass produced shear slippage, which vandalized the original groundwater seepage condition, thus making tunnel itself become an underground corridor to discharge water in different forms, resulting in bursting water disasters.Monte Carlo method was used to establish 2-d discrete-fracture network, which was input rock mass structure discrete fissure network medium model(DFN), according to the model of the discrete element method in fractured rock mass seepage characteristics, fracture rock cavern excavation mechanical characteristics and seepage stress coupling mechanism of fractured rock mass.Combined with concrete examples, a comparison was done for cases of excavating caverns in fractured rocks with and without consideration of hydraulic coupling.
2011, 41(6): 120-123.
doi: 10.13204/j.gyjz201106025
Abstract:
With mass fraction of 3% sodium chloride and 5% sodium sulfate mixed solution as aggressive medium, by adopting slow freeze-thaw method, freeze-thaw tests of freeze-thaw cycles of being 100, 200 and 300 were carried out on concrete specimens.The cubic compressive strength was 54.7MPa.The mass loss, compressive strength, relative dynamic modulus, strain and stress were tested.The results show that with the increase in freeze-thaw cycles, increased erosion of concrete specimen surface and the apparent quality and relative dynamic modulus did not change significantly when both of compressive strength and elastic modulus decreased a lot.Compressive strength and elastic modulus decreased by 26% and 35.1% after 300 freeze-thaw cycles.
With mass fraction of 3% sodium chloride and 5% sodium sulfate mixed solution as aggressive medium, by adopting slow freeze-thaw method, freeze-thaw tests of freeze-thaw cycles of being 100, 200 and 300 were carried out on concrete specimens.The cubic compressive strength was 54.7MPa.The mass loss, compressive strength, relative dynamic modulus, strain and stress were tested.The results show that with the increase in freeze-thaw cycles, increased erosion of concrete specimen surface and the apparent quality and relative dynamic modulus did not change significantly when both of compressive strength and elastic modulus decreased a lot.Compressive strength and elastic modulus decreased by 26% and 35.1% after 300 freeze-thaw cycles.
2011, 41(6): 124-127.
doi: 10.13204/j.gyjz201106026
Abstract:
The autogenous shrinkage of concrete containing various amounts of mineral admixtures, namely fly ash, limestone powder and ground blast furnace slag was investigated under the condition of various water binder ratios.The test results indicate that autogenous shrinkage of concrete nearly reduces in proportion to adding percentage of fly ash and limestone powder, while considerably decreases at initial hydrating period for the concrete containing ground granular blast-furnace slag.The autogenous shrinkage of concrete containing ground granular blast-furnace slag increases obviously with the age, especially in the case of high adding percentage of ground granular blast-furnace slag.
The autogenous shrinkage of concrete containing various amounts of mineral admixtures, namely fly ash, limestone powder and ground blast furnace slag was investigated under the condition of various water binder ratios.The test results indicate that autogenous shrinkage of concrete nearly reduces in proportion to adding percentage of fly ash and limestone powder, while considerably decreases at initial hydrating period for the concrete containing ground granular blast-furnace slag.The autogenous shrinkage of concrete containing ground granular blast-furnace slag increases obviously with the age, especially in the case of high adding percentage of ground granular blast-furnace slag.
2011, 41(6): 128-130.
doi: 10.13204/j.gyjz201106027
Abstract:
Concretes of C30 and C50 were prepared with different content of ferromanganese slag, to test their tendencies of compressive strength.The drying shrinkage of concrete containing ferromanganese slag and ordinary concrete were tested and compared.The results showed that the dosage of feromanganese slag in C30 and C50 concrete could be up to 40% and 20% respectively. The drying shrinkage rate of concrete prepared with ferromanganese slag was smaller than ordinary concrete.
Concretes of C30 and C50 were prepared with different content of ferromanganese slag, to test their tendencies of compressive strength.The drying shrinkage of concrete containing ferromanganese slag and ordinary concrete were tested and compared.The results showed that the dosage of feromanganese slag in C30 and C50 concrete could be up to 40% and 20% respectively. The drying shrinkage rate of concrete prepared with ferromanganese slag was smaller than ordinary concrete.
2011, 41(6): 131-134.
doi: 10.13204/j.gyjz201106028
Abstract:
A comprehensive seismic evaluation for a middle school teaching building in Shanghai was made.The building, completed in 1983, was designed with an earthquake fortification intensity of 6-degree, which cannot meet the demand for the current code.To insure the safety of the structure, initial data were investigated, on-site test was performed, and then seismic performance evaluation was made.According to the evaluation, it was put forward corresponding reinforcement measures, and the structure achieved the seismic fortification criteria.Which not only significantly enhanced the structural integrity and load-carrying capacity, but also improved the safety of the structure.
A comprehensive seismic evaluation for a middle school teaching building in Shanghai was made.The building, completed in 1983, was designed with an earthquake fortification intensity of 6-degree, which cannot meet the demand for the current code.To insure the safety of the structure, initial data were investigated, on-site test was performed, and then seismic performance evaluation was made.According to the evaluation, it was put forward corresponding reinforcement measures, and the structure achieved the seismic fortification criteria.Which not only significantly enhanced the structural integrity and load-carrying capacity, but also improved the safety of the structure.
2011, 41(6): 135-138,134.
doi: 10.13204/j.gyjz201106029
Abstract:
According to the on-site inspection data and the operational version provided by the principal, the structural security and the anti-seismic appraisal of the building with adding 1 steel structure extra-floor were done, identification results showed that the building had not special fortification, local inter-story displacement angle exceeded the limited value and beam-column overreinforced, it was proposed that riders should be added between local columns, expanding section of partial columns of the first layer, so as to meet the requirements of the current seismic and relevant specifications.As a lifeline project of this sort of building with adding steel structure extra-floors, it was also discussed the related issues in process of the aseismic appraisal and reinforcement design, which provided references for similar projects or further discussion.
According to the on-site inspection data and the operational version provided by the principal, the structural security and the anti-seismic appraisal of the building with adding 1 steel structure extra-floor were done, identification results showed that the building had not special fortification, local inter-story displacement angle exceeded the limited value and beam-column overreinforced, it was proposed that riders should be added between local columns, expanding section of partial columns of the first layer, so as to meet the requirements of the current seismic and relevant specifications.As a lifeline project of this sort of building with adding steel structure extra-floors, it was also discussed the related issues in process of the aseismic appraisal and reinforcement design, which provided references for similar projects or further discussion.
2011, 41(6): 139-141,145.
doi: 10.13204/j.gyjz201106030
Abstract:
Because of the lack of technical and safety knowledge, some enterprises used corrosive media in their industrial plants, where anticorrosive designs were not cosidered, and caused serious damages to the structures.There were different degrees of damage to the concrete and steel bars of some beams and slabs in a plant, which was appraised as a hydrochloric acid corrosion accident of concrete structure.According to the results of inspection, partial replacement of concrete and replacing reinforcement of the component were used for the corroded components;anticorrosive treatment was also used for the remaining components without damage.
Because of the lack of technical and safety knowledge, some enterprises used corrosive media in their industrial plants, where anticorrosive designs were not cosidered, and caused serious damages to the structures.There were different degrees of damage to the concrete and steel bars of some beams and slabs in a plant, which was appraised as a hydrochloric acid corrosion accident of concrete structure.According to the results of inspection, partial replacement of concrete and replacing reinforcement of the component were used for the corroded components;anticorrosive treatment was also used for the remaining components without damage.
2011, 41(6): 142-145.
doi: 10.13204/j.gyjz201106031
Abstract:
More serious cracking occurred at the simply supported end of large-span simply supported notched beam for a 8-story building after completion of its main structure in Shenzhen, Through cracks census of the damaged structure and ultrasonic testing of crack depth, it was found that the cracks could be divedes into several types, which were complecated and deeper, most of them were pass through ones, thus resulting in serious influence on the bearing capacity of the members.Based on analyzing the cause of the cracks and their influencing degree on the structural safety, the measures such as support treatment, enlargement of section and bonding steel plate etc were taken, by which excellent economic and social benefits had been got.
More serious cracking occurred at the simply supported end of large-span simply supported notched beam for a 8-story building after completion of its main structure in Shenzhen, Through cracks census of the damaged structure and ultrasonic testing of crack depth, it was found that the cracks could be divedes into several types, which were complecated and deeper, most of them were pass through ones, thus resulting in serious influence on the bearing capacity of the members.Based on analyzing the cause of the cracks and their influencing degree on the structural safety, the measures such as support treatment, enlargement of section and bonding steel plate etc were taken, by which excellent economic and social benefits had been got.
2011, 41(6): 146-149,108.
doi: 10.13204/j.gyjz201106032
Abstract:
Combining with the practice of deep excavation support project of the pump station of Guangyuan Road in Shanghai, it was carried out the monitorings and controls of the excavation deformation and surrounding environment during the deep excavation.According to the theory of time-space dependent effect the construction was done by layers and zonation, which shortened the interval without support.The reliability and effectiveness of the theory of time-space dependent effect during the deep excavation are verified by the monitoring results.
Combining with the practice of deep excavation support project of the pump station of Guangyuan Road in Shanghai, it was carried out the monitorings and controls of the excavation deformation and surrounding environment during the deep excavation.According to the theory of time-space dependent effect the construction was done by layers and zonation, which shortened the interval without support.The reliability and effectiveness of the theory of time-space dependent effect during the deep excavation are verified by the monitoring results.
2011, 41(6): 150-153,119.
doi: 10.13204/j.gyjz201106033
Abstract:
Starting from the overall style of south of Anhui and the aspect of history and culture, and taking the carved doors and windows of Dijitang in the Xid Village of Huizhou for example, it is to explained the evolution of doors and windows and the construction features in ancient houses.Furthermore, analyzing the mood and space environment of those carved doors and windows to show the local corditions and customs, as well as art characteristics in Huizhou.
Starting from the overall style of south of Anhui and the aspect of history and culture, and taking the carved doors and windows of Dijitang in the Xid Village of Huizhou for example, it is to explained the evolution of doors and windows and the construction features in ancient houses.Furthermore, analyzing the mood and space environment of those carved doors and windows to show the local corditions and customs, as well as art characteristics in Huizhou.
