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2007 Vol. 37, No. 12
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2007, 37(12): 1-6,124.
doi: 10.13204/j.gyjz200712001
Abstract:
Based on the constitutive models of steel and core recycled aggregate concrete (RAC), the load versus deformation curves of RACFST stub columns, beams and beam- columns were calculated using numerical method, and the calculated results agreed well with the tested results.Finally, based on the results of parametric analysis, simplified formulae for the calculation of bearing capacity of RACFST members were proposed.
Based on the constitutive models of steel and core recycled aggregate concrete (RAC), the load versus deformation curves of RACFST stub columns, beams and beam- columns were calculated using numerical method, and the calculated results agreed well with the tested results.Finally, based on the results of parametric analysis, simplified formulae for the calculation of bearing capacity of RACFST members were proposed.
2007, 37(12): 7-12.
doi: 10.13204/j.gyjz200712002
Abstract:
Based on the constitutivemodels of steel and core recycled aggregate concrete (RAC), the failure modes and the load versus deformation complete curves of recycled aggregate concrete filled steel tubular (RACFST) stub columns, beams and beam- columns were calculated using finite element analysis (FEA) method.The analytical results reveal the rules of stress distribution in steel and RAC cross-section, and the interaction between the steel tube and core RAC under loading procedure.The results in this paper deeply demonstrate the working mechanisms of RACFST members subjected to static loads.
Based on the constitutivemodels of steel and core recycled aggregate concrete (RAC), the failure modes and the load versus deformation complete curves of recycled aggregate concrete filled steel tubular (RACFST) stub columns, beams and beam- columns were calculated using finite element analysis (FEA) method.The analytical results reveal the rules of stress distribution in steel and RAC cross-section, and the interaction between the steel tube and core RAC under loading procedure.The results in this paper deeply demonstrate the working mechanisms of RACFST members subjected to static loads.
2007, 37(12): 13-17.
doi: 10.13204/j.gyjz200712003
Abstract:
Concrete- filled thin-walled square steel tubes are becoming more and more attractive to be used in engineering practice, for reasons of saving construction time and costs.However, local buckling is more likely to occur for thin-walled tubes, and thus decreases the lateral confinement on the concrete core.In order to improve the performance of such kind of composite columns, the effectiveness of longitudinal stiffeners welded on the steel tubes has been studied in recent years, which demonstrates the fact that the stiffeners can effectively delay the tube local buckling, and improve the serviceability of composite members.This paper discusses the allowed width- to- thickness ratio of the sub- panels and the rigidity requirement of the stiffeners used in stiffened composite stub columns.To evaluate the feasibility of currently available design codes in predicting the load- carrying capacity of the stiffened composite stub columns, the bearing capacities predicted using those design codes are compared with the currently available test results of adequately stiffened stub columns.
Concrete- filled thin-walled square steel tubes are becoming more and more attractive to be used in engineering practice, for reasons of saving construction time and costs.However, local buckling is more likely to occur for thin-walled tubes, and thus decreases the lateral confinement on the concrete core.In order to improve the performance of such kind of composite columns, the effectiveness of longitudinal stiffeners welded on the steel tubes has been studied in recent years, which demonstrates the fact that the stiffeners can effectively delay the tube local buckling, and improve the serviceability of composite members.This paper discusses the allowed width- to- thickness ratio of the sub- panels and the rigidity requirement of the stiffeners used in stiffened composite stub columns.To evaluate the feasibility of currently available design codes in predicting the load- carrying capacity of the stiffened composite stub columns, the bearing capacities predicted using those design codes are compared with the currently available test results of adequately stiffened stub columns.
2007, 37(12): 18-21,60.
doi: 10.13204/j.gyjz200712004
Abstract:
The hollow steel tubes used in concrete filled thin-walled steel tubular structures are often served as formwork for the infill of concrete.The hollow steel tubes suffer the vertical construction loads and self-weight of the structures, as well as the hydrostatic loads of inner wet concrete or other dynamic loads during the construction stage.This paper firstly determined the construction load based on a literature review.Then, a finite element analysis was performed for hollow steel tubes under construction loads.Based on the analysis results of an example, some key issues on the construction safety of concrete-filled thin -walled steel tubular structures were discussed.
The hollow steel tubes used in concrete filled thin-walled steel tubular structures are often served as formwork for the infill of concrete.The hollow steel tubes suffer the vertical construction loads and self-weight of the structures, as well as the hydrostatic loads of inner wet concrete or other dynamic loads during the construction stage.This paper firstly determined the construction load based on a literature review.Then, a finite element analysis was performed for hollow steel tubes under construction loads.Based on the analysis results of an example, some key issues on the construction safety of concrete-filled thin -walled steel tubular structures were discussed.
BEHAVIOR OF CONCRETE-FILLED DOUBLE SKIN STEEL TUBULAR COLUMNS SUBJECTED TO LONG-TERM SUSTAINED LOADS
2007, 37(12): 22-27.
doi: 10.13204/j.gyjz200712005
Abstract:
Based on the creep and shrinkage models of the concrete under sustained loads proposed in ACI 209 (1992), calculations of the deformation and load- bearing capacity of concrete- filled double skin steel tubular (CFDST) columns are presented in this paper.Influences of several parameters, such as loading age, sustained time, nominal steel ratio, sustained load level, steel strength, inner steel thickness, concrete strength, hollow ratio, slenderness ratio and load eccentricity on the deformation of the columns are analyzed.Formulas to calculate the ultimate bearing capacity of the CFDST columns with long- term sustained loading effects are presented.
Based on the creep and shrinkage models of the concrete under sustained loads proposed in ACI 209 (1992), calculations of the deformation and load- bearing capacity of concrete- filled double skin steel tubular (CFDST) columns are presented in this paper.Influences of several parameters, such as loading age, sustained time, nominal steel ratio, sustained load level, steel strength, inner steel thickness, concrete strength, hollow ratio, slenderness ratio and load eccentricity on the deformation of the columns are analyzed.Formulas to calculate the ultimate bearing capacity of the CFDST columns with long- term sustained loading effects are presented.
2007, 37(12): 28-30,53.
doi: 10.13204/j.gyjz200712006
Abstract:
The 9 multibarrel tube- confined concrete column specimens with square hollow section in the outer and circular hollow section in the inner (SHS in the outer and CHS in the inner) were prepared, of which 6 concrete- filled square steel tubular specimens reinforced by inner circular steel tube and 3 concrete- filled double skin square steel tube specimens.The results show that the circular hollow section has a reinforced effect on concrete- filled square steel tubular specimens reinforced by inner circular steel tube.With the diameter of inner steel tube increased, the ultimate capacity of concretefilled double skin square steel tube columns is reduced soon.
The 9 multibarrel tube- confined concrete column specimens with square hollow section in the outer and circular hollow section in the inner (SHS in the outer and CHS in the inner) were prepared, of which 6 concrete- filled square steel tubular specimens reinforced by inner circular steel tube and 3 concrete- filled double skin square steel tube specimens.The results show that the circular hollow section has a reinforced effect on concrete- filled square steel tubular specimens reinforced by inner circular steel tube.With the diameter of inner steel tube increased, the ultimate capacity of concretefilled double skin square steel tube columns is reduced soon.
2007, 37(12): 31-34,118.
doi: 10.13204/j.gyjz200712007
Abstract:
It is presented that the preliminary test results of three reinforced concrete shear walls framed with concretefilled steel tubular (CFST) columns, steel reinforced concrete columns and reinforced concrete columns, respectively.Test results indicate that shear walls framed with CFST columns have better cyclic behavior.Finite element analysis is performed on the tested shear walls, which shows the calculated load- deflection curves agree well with those of tests.
It is presented that the preliminary test results of three reinforced concrete shear walls framed with concretefilled steel tubular (CFST) columns, steel reinforced concrete columns and reinforced concrete columns, respectively.Test results indicate that shear walls framed with CFST columns have better cyclic behavior.Finite element analysis is performed on the tested shear walls, which shows the calculated load- deflection curves agree well with those of tests.
2007, 37(12): 35-38.
doi: 10.13204/j.gyjz200712008
Abstract:
Using the finite element analysis software ABAQUS, analysis model was established to analyze the thermal field of concrete- filled steel tubes (CFST) in the cement hydration stage.The calculated results agree well with the experimental results.The effects of the sectional size, steel ratio and ambient temperature on the thermal field of CFST section were analyzed.
Using the finite element analysis software ABAQUS, analysis model was established to analyze the thermal field of concrete- filled steel tubes (CFST) in the cement hydration stage.The calculated results agree well with the experimental results.The effects of the sectional size, steel ratio and ambient temperature on the thermal field of CFST section were analyzed.
2007, 37(12): 39-42,136.
doi: 10.13204/j.gyjz200712009
Abstract:
Temperature field calculation is an important step in fire engineering design or fire safety research.ABAQUS software is used in this paper to calculate the temperature distribution of planar concrete- filled steel tubular frames exposed to the ISO-834 standard fire.For simplification, one- story and one span frames with reinforced concrete slabs are selected in the modeling.The calculation method was verified by four types of test results.
Temperature field calculation is an important step in fire engineering design or fire safety research.ABAQUS software is used in this paper to calculate the temperature distribution of planar concrete- filled steel tubular frames exposed to the ISO-834 standard fire.For simplification, one- story and one span frames with reinforced concrete slabs are selected in the modeling.The calculation method was verified by four types of test results.
2007, 37(12): 43-46.
doi: 10.13204/j.gyjz200712010
Abstract:
State- o-f the- art of renovation and reuse of existing industrial buildings in China and overseas is studied.For sustainable development of our city and society, the strategy of renovation and reuse of ex isting industrial buildings, especially those in Expo.2010 Park is put forward as: upgrade of performance, betterment of structure, preservation of culture and sustainable usage.By which sustainable development of the city and building industry can be ensured.
State- o-f the- art of renovation and reuse of existing industrial buildings in China and overseas is studied.For sustainable development of our city and society, the strategy of renovation and reuse of ex isting industrial buildings, especially those in Expo.2010 Park is put forward as: upgrade of performance, betterment of structure, preservation of culture and sustainable usage.By which sustainable development of the city and building industry can be ensured.
2007, 37(12): 47-49,57.
doi: 10.13204/j.gyjz200712011
Abstract:
A typical six- floor residential building was taken as an example to analyze its energy- saving potentiality after the energy- saving measures have been adopted.It is proved that energy- saving residential buildings can be used widely, and the energy can be not only saved enormously, but also the better economy can be achieved.
A typical six- floor residential building was taken as an example to analyze its energy- saving potentiality after the energy- saving measures have been adopted.It is proved that energy- saving residential buildings can be used widely, and the energy can be not only saved enormously, but also the better economy can be achieved.
2007, 37(12): 50-53.
doi: 10.13204/j.gyjz200712012
Abstract:
The development and research on ecological and energy- efficient straw- bale buildings are very important for the construction of efficient society and new socialistic rural areas in China.Based on actuality of straw- bale buildings, a systemic review is made about characteristics of straw- bale, structural system of straw-bale buildings, fire proof, water proof and relevant safeguard.According to actual situation, the prospect and problems existing in the development of straw- bale buildings are also discussed.
The development and research on ecological and energy- efficient straw- bale buildings are very important for the construction of efficient society and new socialistic rural areas in China.Based on actuality of straw- bale buildings, a systemic review is made about characteristics of straw- bale, structural system of straw-bale buildings, fire proof, water proof and relevant safeguard.According to actual situation, the prospect and problems existing in the development of straw- bale buildings are also discussed.
2007, 37(12): 54-57.
doi: 10.13204/j.gyjz200712013
Abstract:
Application of a reflector panel in daylighting is given, according to the situation where there is almost no consideration on daylighting in the market of architecture design in our country now.Principle of reflector panel and a specific case simulated by software are presented, a method of design and analysis using reflector panel in architecture design phase is given and the method is learned easily by architects.
Application of a reflector panel in daylighting is given, according to the situation where there is almost no consideration on daylighting in the market of architecture design in our country now.Principle of reflector panel and a specific case simulated by software are presented, a method of design and analysis using reflector panel in architecture design phase is given and the method is learned easily by architects.
2007, 37(12): 58-60.
doi: 10.13204/j.gyjz200712014
Abstract:
The energy- saving of house enclosure is an important part of house energy- saving, the roof is an indispensable part of energy- saving.According to the native characteristic of the houses of villages and small towns in Hubei.It is proposed that the strengthening of roof structure energy- saving, design of changing flat roof into slope one, and energy- saving measures suitable for roof afforestation.
The energy- saving of house enclosure is an important part of house energy- saving, the roof is an indispensable part of energy- saving.According to the native characteristic of the houses of villages and small towns in Hubei.It is proposed that the strengthening of roof structure energy- saving, design of changing flat roof into slope one, and energy- saving measures suitable for roof afforestation.
2007, 37(12): 61-66.
doi: 10.13204/j.gyjz200712015
Abstract:
The stiffness degradation model of SRC frame is determined based on the experimental data of a SRC frame. Combined it with the stiffness degradation rule in different deformation phases of RC core wall, and RC frame, it is advised that a / three- stage seismic design0 process be adopted in frame- core wall structure design through response spectrum analysis design means based on stiffness degradation.And the realization step of the means is introduced, whose applicability in / dual system0 is tested by a calculation illustration.In the end, some rules of the inner force redistribution in frame- core wall structure under earthquake load are introduced, and the possible failure mode of frame column is discussed.
The stiffness degradation model of SRC frame is determined based on the experimental data of a SRC frame. Combined it with the stiffness degradation rule in different deformation phases of RC core wall, and RC frame, it is advised that a / three- stage seismic design0 process be adopted in frame- core wall structure design through response spectrum analysis design means based on stiffness degradation.And the realization step of the means is introduced, whose applicability in / dual system0 is tested by a calculation illustration.In the end, some rules of the inner force redistribution in frame- core wall structure under earthquake load are introduced, and the possible failure mode of frame column is discussed.
2007, 37(12): 67-70.
doi: 10.13204/j.gyjz200712016
Abstract:
Based on the experiments of 4 specimens of the endplate bolted SC beam and RC column joints under low cyclic loadings, hysteretic curves of the joints are obtained and the characteristics of restoring force are discussed.Uniform formula for calculating the skeleton curve is deduced.In terms of the test results, failure pattern, strain law, ductility, rigidity degeneration and energy dissipation are studied.From the results, it can be concluded that the ductility and the energy dissipation are diminished with the decrease of stud connector.
Based on the experiments of 4 specimens of the endplate bolted SC beam and RC column joints under low cyclic loadings, hysteretic curves of the joints are obtained and the characteristics of restoring force are discussed.Uniform formula for calculating the skeleton curve is deduced.In terms of the test results, failure pattern, strain law, ductility, rigidity degeneration and energy dissipation are studied.From the results, it can be concluded that the ductility and the energy dissipation are diminished with the decrease of stud connector.
2007, 37(12): 71-75.
doi: 10.13204/j.gyjz200712017
Abstract:
Precise prediction for the hysteretic behaviors of reinforced concrete (RC) column under seismic load is important to assess the aseismic performance of RC structures.Due to the overturning moment in the earthquakes, besides being subjected to seismic lateral forces, RC columns also experience variable axial loads.Therefore the influence of variable axial forces must be taken into account when to study the hysteretic behaviors of RC columns under cyclic loads.A numerical analysis model based on a fiber model program has been validated firstly through the rational hysteretic simulations of two RC columns under various patterns of axial loads, Then a frame column has been simulated under various patterns of variable axial loads by numerical method.The analytical results indicate that the variety of axial loads has considerable effect on the hysteretic behaviors of RC columns.Because of the randomness of axial loads and to facilitate carrying on experimental researches and analyzing earthquake- resistant behaviors of RC structures, a equivalent fixed axial load method is put forward to determine the seismic behaviors of RC columns in structures under earthquake.
Precise prediction for the hysteretic behaviors of reinforced concrete (RC) column under seismic load is important to assess the aseismic performance of RC structures.Due to the overturning moment in the earthquakes, besides being subjected to seismic lateral forces, RC columns also experience variable axial loads.Therefore the influence of variable axial forces must be taken into account when to study the hysteretic behaviors of RC columns under cyclic loads.A numerical analysis model based on a fiber model program has been validated firstly through the rational hysteretic simulations of two RC columns under various patterns of axial loads, Then a frame column has been simulated under various patterns of variable axial loads by numerical method.The analytical results indicate that the variety of axial loads has considerable effect on the hysteretic behaviors of RC columns.Because of the randomness of axial loads and to facilitate carrying on experimental researches and analyzing earthquake- resistant behaviors of RC structures, a equivalent fixed axial load method is put forward to determine the seismic behaviors of RC columns in structures under earthquake.
2007, 37(12): 76-80,99.
doi: 10.13204/j.gyjz200712018
Abstract:
Performance based seismic design is being applied in super tall buildings and complicated high- rise structures. But the quantified definition of performance levels for different type of structures is lacking so far.Based on analyses of relevant data, this paper established the interstory displacement calculating method and quantified performance levels of high- rise structures with strengthened stories considering the mechanical property of this kind of structures, which provide reference on structural performance levels for performance based seismic design of high-rise structures with strengthened stories.
Performance based seismic design is being applied in super tall buildings and complicated high- rise structures. But the quantified definition of performance levels for different type of structures is lacking so far.Based on analyses of relevant data, this paper established the interstory displacement calculating method and quantified performance levels of high- rise structures with strengthened stories considering the mechanical property of this kind of structures, which provide reference on structural performance levels for performance based seismic design of high-rise structures with strengthened stories.
2007, 37(12): 81-83.
doi: 10.13204/j.gyjz200712019
Abstract:
The D- P criterion is adopted as a constitutive relation of a foundation.The quadrangle element and beam element are also used.The effect of the distance away from buildings, the depth, the height and overburden in working-out section area is studied using FEM.The simplified stiffness matrix method considering the second matrix is used to calculate deformation, location and sequence of plastic hinges.The result shows that the working-out section area affects the frame structure greatly in a certain distance.When shear stress of column increases, the sequence of plastic hinge changes.The ductility of the structures changes into poor one.The result also shows the strip foundation is advantageous over the independence foundation.At last, some structure measures are suggested to protect the frame buildings.
The D- P criterion is adopted as a constitutive relation of a foundation.The quadrangle element and beam element are also used.The effect of the distance away from buildings, the depth, the height and overburden in working-out section area is studied using FEM.The simplified stiffness matrix method considering the second matrix is used to calculate deformation, location and sequence of plastic hinges.The result shows that the working-out section area affects the frame structure greatly in a certain distance.When shear stress of column increases, the sequence of plastic hinge changes.The ductility of the structures changes into poor one.The result also shows the strip foundation is advantageous over the independence foundation.At last, some structure measures are suggested to protect the frame buildings.
2007, 37(12): 84-87,95.
doi: 10.13204/j.gyjz200712020
Abstract:
In order to cancel the noise in TDR signal and retain the faint reflectometry signal made by deformation of rock and soil, it is proposed to use method integrated filtering and noise canceling based on wavelet transform with characteristic of TDR signal.One engineering case showed that useful signal implicated can be visualized highlightly by using this method. The method is more clearly and more useful than other method which only using some kinds of detail signals acquired by simple wavelet transform.
In order to cancel the noise in TDR signal and retain the faint reflectometry signal made by deformation of rock and soil, it is proposed to use method integrated filtering and noise canceling based on wavelet transform with characteristic of TDR signal.One engineering case showed that useful signal implicated can be visualized highlightly by using this method. The method is more clearly and more useful than other method which only using some kinds of detail signals acquired by simple wavelet transform.
2007, 37(12): 88-92.
doi: 10.13204/j.gyjz200712021
Abstract:
The finite element method is used to analyze, in a three dimensional way, the deformation property of pile group of a composite foundation under the action of a horizontal load in different soil layers conditions.Comparing the property of ax ial strain under different conditions, such as different material properties of soil layers, pile length, pile diameter and mattress thickness.It.s obtained the variation law for the position in the pile of the composite foundation where fracture would most probably occur along with the change of different soil layer condition.
The finite element method is used to analyze, in a three dimensional way, the deformation property of pile group of a composite foundation under the action of a horizontal load in different soil layers conditions.Comparing the property of ax ial strain under different conditions, such as different material properties of soil layers, pile length, pile diameter and mattress thickness.It.s obtained the variation law for the position in the pile of the composite foundation where fracture would most probably occur along with the change of different soil layer condition.
2007, 37(12): 93-95.
doi: 10.13204/j.gyjz200712022
Abstract:
A nonlinear constraint model is put forward according to a practical foundation horizontal constraint S- u curve. The distribution laws of normal thermal stress and shear stress for a concrete plate along its different cross- sections on a nonlinear constraint foundation are obtained by means of an incremen-t dimensional precise integration method and a relaxed iteration method.The results of a calculation case show that the method mentioned above is more effective and its calculations are more accurate.
A nonlinear constraint model is put forward according to a practical foundation horizontal constraint S- u curve. The distribution laws of normal thermal stress and shear stress for a concrete plate along its different cross- sections on a nonlinear constraint foundation are obtained by means of an incremen-t dimensional precise integration method and a relaxed iteration method.The results of a calculation case show that the method mentioned above is more effective and its calculations are more accurate.
2007, 37(12): 96-99.
doi: 10.13204/j.gyjz200712023
Abstract:
Steel fibers, steel fibers and polypropylene fibers were introduced to reinforce lightweight aggregate concrete (LWAC) of LC30 and LC35.It was studied the effect of steel fiber dosage on the mechanical properties of LWAC.The results indicate compressive strength, flexural strength and toughness of steel fibers lightweight aggregate concrete (SFLWAC) have been increased significantly as compared to reference LWAC.But its apparent density will be increased correspondingly.By fibers mixture, the toughness of LWAC is improved effectively, and both its low apparent density and strength are then maintained.
Steel fibers, steel fibers and polypropylene fibers were introduced to reinforce lightweight aggregate concrete (LWAC) of LC30 and LC35.It was studied the effect of steel fiber dosage on the mechanical properties of LWAC.The results indicate compressive strength, flexural strength and toughness of steel fibers lightweight aggregate concrete (SFLWAC) have been increased significantly as compared to reference LWAC.But its apparent density will be increased correspondingly.By fibers mixture, the toughness of LWAC is improved effectively, and both its low apparent density and strength are then maintained.
2007, 37(12): 100-103.
doi: 10.13204/j.gyjz200712024
Abstract:
The free thermal expansion strain (FTES) is a very important one among deformation components of concrete under high temperature.There are marked differences among these FTESes of concrete with different strength grades when exposed to different raising temperature rates.Based on experimental results, the influence of different raising temperature rates on the FTES of concrete with different strength grades is analyzed in this paper and the corresponding calculation formulas are also given.They can be contributed to rationally establish a constitutive relationship of concrete under high temperature and accurately calculate mechanical behaviors of concrete when exposed to fire.
The free thermal expansion strain (FTES) is a very important one among deformation components of concrete under high temperature.There are marked differences among these FTESes of concrete with different strength grades when exposed to different raising temperature rates.Based on experimental results, the influence of different raising temperature rates on the FTES of concrete with different strength grades is analyzed in this paper and the corresponding calculation formulas are also given.They can be contributed to rationally establish a constitutive relationship of concrete under high temperature and accurately calculate mechanical behaviors of concrete when exposed to fire.
2007, 37(12): 104-108.
doi: 10.13204/j.gyjz200712025
Abstract:
Corrosion rate is an improtant parameter for durability of the reinforcement.Linear polarization device GECOR 6 is used to detect concrete specimens with corroded rebars made in the lab.Corrosion rate, corrosion potential and the electronic circuit resistance are gotten.The regression model is developed according to the data of the test in chloride- induced corrosion of the reinforcement in normal atmosphere.Specially losing weight method is used to calibrate the results linear of polarization and find the error between the calibrated value and the inspected corrosion rate.An empirical formula is given to modify the corrosion rate and get a satisfactory result.
Corrosion rate is an improtant parameter for durability of the reinforcement.Linear polarization device GECOR 6 is used to detect concrete specimens with corroded rebars made in the lab.Corrosion rate, corrosion potential and the electronic circuit resistance are gotten.The regression model is developed according to the data of the test in chloride- induced corrosion of the reinforcement in normal atmosphere.Specially losing weight method is used to calibrate the results linear of polarization and find the error between the calibrated value and the inspected corrosion rate.An empirical formula is given to modify the corrosion rate and get a satisfactory result.
2007, 37(12): 109-112.
doi: 10.13204/j.gyjz200712026
Abstract:
It was investigated that the effects of the different content micro- fines in manufactured sand on the compressive strength, permeability of chloride ion and resistance to freezing in different strength grade concrete.The result shows that the effects of the micro- fines on low and high strength concrete are not completely the same.To the low strength concrete, the resistance to chloride ion permeating of concrete is improved with the micro-fines content, but the resistance to freezing deduces.Especially when the micro-fines content is higher than 10% (ratio by volume of micro- fines and cement exceeds 1 B31 47), the degradation of manufactured- sand concrete is obvious; but to the high strength concrete, the workability becomes bad when the micro- fines content is higher than 7%.Whereas, to the durability of concrete, such as resistance to chloride ion permeating and resistance to freezing etc., there is no degradation in the high strength manufactured sand concrete when the micro fines content rises from 31 5% to 14%.
It was investigated that the effects of the different content micro- fines in manufactured sand on the compressive strength, permeability of chloride ion and resistance to freezing in different strength grade concrete.The result shows that the effects of the micro- fines on low and high strength concrete are not completely the same.To the low strength concrete, the resistance to chloride ion permeating of concrete is improved with the micro-fines content, but the resistance to freezing deduces.Especially when the micro-fines content is higher than 10% (ratio by volume of micro- fines and cement exceeds 1 B31 47), the degradation of manufactured- sand concrete is obvious; but to the high strength concrete, the workability becomes bad when the micro- fines content is higher than 7%.Whereas, to the durability of concrete, such as resistance to chloride ion permeating and resistance to freezing etc., there is no degradation in the high strength manufactured sand concrete when the micro fines content rises from 31 5% to 14%.
2007, 37(12): 113-118.
doi: 10.13204/j.gyjz200712027
Abstract:
Terrible explosion is the most frequent and destroyable approach in terrible activities nowadays, which is the main reason to structure progressive collapse.At present, as the terrible activities is of high frequency, the progressive collapse of structures attracts more and more attention in engineering field and becomes a hotspot for study.The history of the structure progressive collapse is reviewed, and the definition as well as the reason, the analysis intention and analysis process are nailed down.The methods of progressive alternate load path, local resistance, concept design and simulation are summarized and analyzed, the alternate load path is emphasized.At last, the direction and difficulty of progressive collapse are put forward.
Terrible explosion is the most frequent and destroyable approach in terrible activities nowadays, which is the main reason to structure progressive collapse.At present, as the terrible activities is of high frequency, the progressive collapse of structures attracts more and more attention in engineering field and becomes a hotspot for study.The history of the structure progressive collapse is reviewed, and the definition as well as the reason, the analysis intention and analysis process are nailed down.The methods of progressive alternate load path, local resistance, concept design and simulation are summarized and analyzed, the alternate load path is emphasized.At last, the direction and difficulty of progressive collapse are put forward.
2007, 37(12): 119-121.
doi: 10.13204/j.gyjz200712028
Abstract:
Based on an inclined teaching building rectification in Shanghai, and through site observation and evaluation the authors analyse the reasons of the inclined building and present the scheme of using static blo-t pressing pile and drawing out soil in holes meanwhile reinforcing the foundation of the building, then briefly introduce construction process.By the analysis of local monitoring data, the building would be rectified back while the upside remained in safety so as to achieve anticipated effect.
Based on an inclined teaching building rectification in Shanghai, and through site observation and evaluation the authors analyse the reasons of the inclined building and present the scheme of using static blo-t pressing pile and drawing out soil in holes meanwhile reinforcing the foundation of the building, then briefly introduce construction process.By the analysis of local monitoring data, the building would be rectified back while the upside remained in safety so as to achieve anticipated effect.
2007, 37(12): 122-124.
doi: 10.13204/j.gyjz200712029
Abstract:
In light of characters of soil in collapsible loess region, the rectification construction of the Jingguang Pagoda in Meixian County, Shaanxi Province is simulated by finite element method.With the changes of soil parameter, the influence of injecting water on subsoil is simulated and the characters of soil and structure of the tower during rectification are analyzed.At the same time, the result of calculation is contrasted to that of the test and some suggestions are brought out. As a result, some strengthen measures adopted, the rectification method of / holes drilling and soften0 can ensure the safety of the structure and effect of rectification of masonry pagoda.That is an effective rectification method in collapsible loess region.
In light of characters of soil in collapsible loess region, the rectification construction of the Jingguang Pagoda in Meixian County, Shaanxi Province is simulated by finite element method.With the changes of soil parameter, the influence of injecting water on subsoil is simulated and the characters of soil and structure of the tower during rectification are analyzed.At the same time, the result of calculation is contrasted to that of the test and some suggestions are brought out. As a result, some strengthen measures adopted, the rectification method of / holes drilling and soften0 can ensure the safety of the structure and effect of rectification of masonry pagoda.That is an effective rectification method in collapsible loess region.
2007, 37(12): 125-127,133.
doi: 10.13204/j.gyjz200712030
Abstract:
It is proposed that the eigen value and allowable value of the foundation deformation of transmission line tower; it is also described that the calculation methods and cases of the deformed foundations strengthened by compaction grouting.
It is proposed that the eigen value and allowable value of the foundation deformation of transmission line tower; it is also described that the calculation methods and cases of the deformed foundations strengthened by compaction grouting.
2007, 37(12): 128-130,70.
doi: 10.13204/j.gyjz200712031
Abstract:
Most of plates in building floor structures are irregular continous plates.The practical simplified calculation methods for this kind of plate are very useful.However, some simplified calculation method are being used wrongfully.To use wrongfully simplified calculation method can cause a relative error such as 20 percent or much more.Some inner laws of bending moments in the multi-span continous plates are discussed.For the veritable state of a loaded plate, one homologous state can be found, and the bending moments in this homologous state are the safe approximations of bending moments in the veritable state.The accuracy of safe approximations is discussed.The computation method of safe approximations is put forward.It is emphasized that one must note qualitative analysis in mechanical computation.
Most of plates in building floor structures are irregular continous plates.The practical simplified calculation methods for this kind of plate are very useful.However, some simplified calculation method are being used wrongfully.To use wrongfully simplified calculation method can cause a relative error such as 20 percent or much more.Some inner laws of bending moments in the multi-span continous plates are discussed.For the veritable state of a loaded plate, one homologous state can be found, and the bending moments in this homologous state are the safe approximations of bending moments in the veritable state.The accuracy of safe approximations is discussed.The computation method of safe approximations is put forward.It is emphasized that one must note qualitative analysis in mechanical computation.
2007, 37(12): 131-133.
doi: 10.13204/j.gyjz200712032
Abstract:
The project(phase- ? ) in national wel-l off inhabitation area / Fei Cui Yuan0 had past the inspection from a group of experts organized by the Ministry of Construction P.R.China in October, 2005, which was rewarded with four gold medals.All of the hot water used during daily life in the buildings is supplied from solar water heating systems.Some of the systems have been operating for more than one year and appreciated by the inhabitants.The technology applied to the integration of solar system with building is introduced and discussed.The calculating formula for the solar collector area is described.In the meantime, several kinds of solar water heating systems, which can be integrated with building closely, are listed and compared.It will provide a valuable case for widely utilizing the technology of integration of solar system with building in the future.
The project(phase- ? ) in national wel-l off inhabitation area / Fei Cui Yuan0 had past the inspection from a group of experts organized by the Ministry of Construction P.R.China in October, 2005, which was rewarded with four gold medals.All of the hot water used during daily life in the buildings is supplied from solar water heating systems.Some of the systems have been operating for more than one year and appreciated by the inhabitants.The technology applied to the integration of solar system with building is introduced and discussed.The calculating formula for the solar collector area is described.In the meantime, several kinds of solar water heating systems, which can be integrated with building closely, are listed and compared.It will provide a valuable case for widely utilizing the technology of integration of solar system with building in the future.
2007, 37(12): 134-136.
doi: 10.13204/j.gyjz200712033
Abstract:
Based on the investigation and practice of building projects, and discussion on the external wall therma-l insulation facing technique of high rise building.This paper summarizes several common methods and comparison between them.
Based on the investigation and practice of building projects, and discussion on the external wall therma-l insulation facing technique of high rise building.This paper summarizes several common methods and comparison between them.
