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2013 Vol. 43, No. 11
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2013, 43(11): 1-6.
doi: 10.13204/j.gyjz201311001
Abstract:
Crush value index is a key parameter for measurement of coarse aggregate strength performance. In this paper eight groups of crush value indexes were tested for the recycled aggregate made of waste concrete gathered from three different removed construction plants. Through the experiment research and combined with comparison of research results of domestic and foreign scholars,the results show that the crush value index of recycled aggregate is2 ~ 2. 5times greater than that of nature aggregate. Meanwhile the crush value index of saturated face dry state is increased by 7. 22% ~ 18. 20% as compared with that in air dried condition. Based on which twenty-six groups of compression strength tests were carried out to research the regularity for change in compressive strength of aggregate from can different source and different replacement rate. The testing result is presented that the recycled aggregate has larger variability,which makes test results differ greatly or be poles apart. For the exploration of relation between aggregate strength and recycled concrete compression strength,the twelve groups of specimens were comparatively analysed in air dried and saturated face dry condition. The least square fitting and result analysis show that the compression strength of RAC may not always be decreased with increase in crush value index and decrease in strength of the aggregate.
Crush value index is a key parameter for measurement of coarse aggregate strength performance. In this paper eight groups of crush value indexes were tested for the recycled aggregate made of waste concrete gathered from three different removed construction plants. Through the experiment research and combined with comparison of research results of domestic and foreign scholars,the results show that the crush value index of recycled aggregate is2 ~ 2. 5times greater than that of nature aggregate. Meanwhile the crush value index of saturated face dry state is increased by 7. 22% ~ 18. 20% as compared with that in air dried condition. Based on which twenty-six groups of compression strength tests were carried out to research the regularity for change in compressive strength of aggregate from can different source and different replacement rate. The testing result is presented that the recycled aggregate has larger variability,which makes test results differ greatly or be poles apart. For the exploration of relation between aggregate strength and recycled concrete compression strength,the twelve groups of specimens were comparatively analysed in air dried and saturated face dry condition. The least square fitting and result analysis show that the compression strength of RAC may not always be decreased with increase in crush value index and decrease in strength of the aggregate.
2013, 43(11): 7-11.
doi: 10.13204/j.gyjz201311002
Abstract:
With the transformation of China's urbanization and accelerated pace of urban agglomeration,increasing construction waste has brought the conflict between the development of a city and its environmental degradation. The use of recycled aggregate( RA) can mitigate to a certain extent the pollution on the environment. Because the source of RA can cause poor stability in its quality,large dispersion and other shortcomings. By three different sources and different service life of the waste concrete for a total of 112 groups of coarse aggregate performance tests and 12 sets of fine aggregate performance tests,comparative analysis of the differences of indicators between recycled aggregate and natural aggregate was done,and a crushing value performance test was also made to analyse the effect of brick particles content on the behavior of recycled coarse aggregate. Which provided a reference for the research on properties of recycled aggregate and the local grading standards suitable for local conditions.
With the transformation of China's urbanization and accelerated pace of urban agglomeration,increasing construction waste has brought the conflict between the development of a city and its environmental degradation. The use of recycled aggregate( RA) can mitigate to a certain extent the pollution on the environment. Because the source of RA can cause poor stability in its quality,large dispersion and other shortcomings. By three different sources and different service life of the waste concrete for a total of 112 groups of coarse aggregate performance tests and 12 sets of fine aggregate performance tests,comparative analysis of the differences of indicators between recycled aggregate and natural aggregate was done,and a crushing value performance test was also made to analyse the effect of brick particles content on the behavior of recycled coarse aggregate. Which provided a reference for the research on properties of recycled aggregate and the local grading standards suitable for local conditions.
2013, 43(11): 12-15.
doi: 10.13204/j.gyjz201311003
Abstract:
For enhanced performance of recycled aggregate concrete,researches are mainly on single fiber recycled aggregate concrete,which are rarely involved in hybrid renewable fiber on performance enhancement. Based on recycled steel fiber and nylon fiber from waste tires in the stripping,through 27 groups of 81 specimens,it was studied the basic mechanical properties and investigated the effect of recycled fiber on the basic mechanical properties of recycled aggregate concrete. Through the test it was analyzed the effect of different content of the recycled hybrid fiber to replace rate,tensile compressive strength and deformation performance of the recycled aggregate concrete with different replacement rate,the results show that the recycled steel fiber can effectively enhance the splitting tensile strength, flexural strength, ductility and crack resistance of the recycled aggregate concrete with all replacement rates. But for the compressive strength decreased slightly. The content optimization of the recycled steel fiber needs further study.
For enhanced performance of recycled aggregate concrete,researches are mainly on single fiber recycled aggregate concrete,which are rarely involved in hybrid renewable fiber on performance enhancement. Based on recycled steel fiber and nylon fiber from waste tires in the stripping,through 27 groups of 81 specimens,it was studied the basic mechanical properties and investigated the effect of recycled fiber on the basic mechanical properties of recycled aggregate concrete. Through the test it was analyzed the effect of different content of the recycled hybrid fiber to replace rate,tensile compressive strength and deformation performance of the recycled aggregate concrete with different replacement rate,the results show that the recycled steel fiber can effectively enhance the splitting tensile strength, flexural strength, ductility and crack resistance of the recycled aggregate concrete with all replacement rates. But for the compressive strength decreased slightly. The content optimization of the recycled steel fiber needs further study.
2013, 43(11): 16-20.
doi: 10.13204/j.gyjz201311004
Abstract:
In order to research the bond mechanism between high strength steel bar and recycled coarse aggregate concrete( RCAC),15 high strength steel bar RCAC cube specimens whose length of side was 150 mm were designed to launch the push-out test with recycled coarse aggregate replacement ratio and embedment length of high strength steel bar being the changing parameters. Characteristic point parameters on curves of loading-end and free-end were obtained,and computational formula of each feature point bond strength was gained by regression. The influence of each changing parameter on bond strength was analyzed,and practical bond strength calculation formulas were adopted to calculate contrastively. The result shows that the main failure mode between high strength steel bar and RCAC is splitting failure. The bond stength at each characteristic point is decreased with an increase in the replacement ratio of RCA. The interface bonding strength between steel bar and RCAC is increased with the increasing of embedment length.
In order to research the bond mechanism between high strength steel bar and recycled coarse aggregate concrete( RCAC),15 high strength steel bar RCAC cube specimens whose length of side was 150 mm were designed to launch the push-out test with recycled coarse aggregate replacement ratio and embedment length of high strength steel bar being the changing parameters. Characteristic point parameters on curves of loading-end and free-end were obtained,and computational formula of each feature point bond strength was gained by regression. The influence of each changing parameter on bond strength was analyzed,and practical bond strength calculation formulas were adopted to calculate contrastively. The result shows that the main failure mode between high strength steel bar and RCAC is splitting failure. The bond stength at each characteristic point is decreased with an increase in the replacement ratio of RCA. The interface bonding strength between steel bar and RCAC is increased with the increasing of embedment length.
2013, 43(11): 21-25.
doi: 10.13204/j.gyjz201311005
Abstract:
Four recycled concrete column models with different proportions were designed and created based on the following recycled concrete frame model. Meanwhile,cyclic loading tests for them were carried out. It was compared the failure pattern,hysteretic behavior,stiffness degradation and ductility of 4 columns with different proportions through the experiment,the silica fume and recycled hybrid fiber effect on seismic behavior of ordinary recycled concrete columns was studied. The result was shown: compared with ordinary recycled concrete columns,cracking load,yield load and the corresponding displacement were increased slightly with incorporation of a single silica fume.But,the ultimate load and displacement were slightly lower. The indexes of seismic performance of ordinary recycled concrete columns could be effectively improved by adding appropriate recycled hybrid fiber.
Four recycled concrete column models with different proportions were designed and created based on the following recycled concrete frame model. Meanwhile,cyclic loading tests for them were carried out. It was compared the failure pattern,hysteretic behavior,stiffness degradation and ductility of 4 columns with different proportions through the experiment,the silica fume and recycled hybrid fiber effect on seismic behavior of ordinary recycled concrete columns was studied. The result was shown: compared with ordinary recycled concrete columns,cracking load,yield load and the corresponding displacement were increased slightly with incorporation of a single silica fume.But,the ultimate load and displacement were slightly lower. The indexes of seismic performance of ordinary recycled concrete columns could be effectively improved by adding appropriate recycled hybrid fiber.
2013, 43(11): 26-29,25.
doi: 10.13204/j.gyjz201311006
Abstract:
Low-cycle loading tests were carried out for 1 common concrete column and 3 recycled concrete columns models. Recycled concrete columns were respectively ordinary regeneration concrete column,regenerated brick granules recycled concrete column,silicon powder and fiber reinforced regenerated brick granule recycled concrete column. Through the experiment comparison,it was analysed the failure modes,the hysteretic performance,degradation of rigidity,ductility,energy dissipation and the load capability of the 4 specimens. Based on which it was studied the seismic performance of the brick granules and silicon powder and fiber reinforced recycled concrete column. Research showed that compared with ordinary concrete column,the seismic resistance of 3 pieces of the regenerated concrete columns was decreased. But regenerated brick grains recycled concrete elastic modulus and ductility were significantly decreased,and silicon powder and fiber could obviously improve their elastic modulus and ductility performance.
Low-cycle loading tests were carried out for 1 common concrete column and 3 recycled concrete columns models. Recycled concrete columns were respectively ordinary regeneration concrete column,regenerated brick granules recycled concrete column,silicon powder and fiber reinforced regenerated brick granule recycled concrete column. Through the experiment comparison,it was analysed the failure modes,the hysteretic performance,degradation of rigidity,ductility,energy dissipation and the load capability of the 4 specimens. Based on which it was studied the seismic performance of the brick granules and silicon powder and fiber reinforced recycled concrete column. Research showed that compared with ordinary concrete column,the seismic resistance of 3 pieces of the regenerated concrete columns was decreased. But regenerated brick grains recycled concrete elastic modulus and ductility were significantly decreased,and silicon powder and fiber could obviously improve their elastic modulus and ductility performance.
2013, 43(11): 30-33,44.
doi: 10.13204/j.gyjz201311007
Abstract:
The test is mainly focused on enhanced recycled aggregate concrete. There are two main factors which enhance the performance of recycled aggregate concrete: silica fume and hybrid fiber. The research on the seismic behavior of frame could be done in such way that according to different replacement rate of recycled aggregate the reinforcing materials with different ratio were added to the main parts of frame. The natural frequency,equivalent stiffness,the damping ratio,the vibration mode,the acceleration response and the displacement response etc were analyzed and discussed. The inter-storey deformation was adopted as the index to evaluate the seismic performance of the RAC frame model. The experimental results show that the following points: reinforced materials can significantly inhibit the damage of the RAC frame structure model,reduce earthquake damage of the frame key parts and make up for the deficiency of the ductility of the recycled aggregate concrete. According to research,reinforced materials have good effect on enhancing the aseismic capacity of recycled aggregate concrete frame structures.
The test is mainly focused on enhanced recycled aggregate concrete. There are two main factors which enhance the performance of recycled aggregate concrete: silica fume and hybrid fiber. The research on the seismic behavior of frame could be done in such way that according to different replacement rate of recycled aggregate the reinforcing materials with different ratio were added to the main parts of frame. The natural frequency,equivalent stiffness,the damping ratio,the vibration mode,the acceleration response and the displacement response etc were analyzed and discussed. The inter-storey deformation was adopted as the index to evaluate the seismic performance of the RAC frame model. The experimental results show that the following points: reinforced materials can significantly inhibit the damage of the RAC frame structure model,reduce earthquake damage of the frame key parts and make up for the deficiency of the ductility of the recycled aggregate concrete. According to research,reinforced materials have good effect on enhancing the aseismic capacity of recycled aggregate concrete frame structures.
2013, 43(11): 34-36,53.
doi: 10.13204/j.gyjz201311008
Abstract:
At the present stage,the green building has attracted the attention of the people,and becomes the inevitable direction of building development,but the research of green industrial buildings is still very limited.Compared with the developed countries,developing green industrial buildings will be more urgent owing to the the particular stage of industrialization and the nervous energy and environmental pressures in China, while the development of green industrial buildings is the only way to achieve the strategy of China's manufacturing power.Compared with civil construction,it is analyzed the characteristics of the industrial building and put forward the main point of green industrial buildings development in China.
At the present stage,the green building has attracted the attention of the people,and becomes the inevitable direction of building development,but the research of green industrial buildings is still very limited.Compared with the developed countries,developing green industrial buildings will be more urgent owing to the the particular stage of industrialization and the nervous energy and environmental pressures in China, while the development of green industrial buildings is the only way to achieve the strategy of China's manufacturing power.Compared with civil construction,it is analyzed the characteristics of the industrial building and put forward the main point of green industrial buildings development in China.
2013, 43(11): 37-40.
doi: 10.13204/j.gyjz201311009
Abstract:
This paper presented the design concept of the culture of subway station spatial interface. Regarding the representative subway station spatial interface of the Beijing,Shanghai,and Tianjin as the object of study,the paper analyzed and summarized the design characteristics of the culture of subway station spatial interface of the three cities through field investigation. From the wall facing ,the top facing ,and the bottom facing three major components and site case analysis of the subway station,this paper also explored the design method of the culture of subway station spatial interface,and suggested that the design of the spatial interface of subway station should be clarified in theme to highlight the culture,upgrade connotation and enhance interactivity,and rich form and hierarchies.
This paper presented the design concept of the culture of subway station spatial interface. Regarding the representative subway station spatial interface of the Beijing,Shanghai,and Tianjin as the object of study,the paper analyzed and summarized the design characteristics of the culture of subway station spatial interface of the three cities through field investigation. From the wall facing ,the top facing ,and the bottom facing three major components and site case analysis of the subway station,this paper also explored the design method of the culture of subway station spatial interface,and suggested that the design of the spatial interface of subway station should be clarified in theme to highlight the culture,upgrade connotation and enhance interactivity,and rich form and hierarchies.
2013, 43(11): 41-44.
doi: 10.13204/j.gyjz201311010
Abstract:
A lot of problems,such as aging,weak infrastructure etc exist in many traditional residential blocks. The intensification of conflicts between these problems and its inherent historical and cultural value are more and more serious,It makes living type streets become the chicken ribs. It was explored the elderly-oriented reforming strategies of thechicken ribsblocks by investigating the situation of one residential block in Xuzhou,and being concerned with the outdoor action space of aging populations,also adjusting the spatial configuration of the block according to research data,and leading the virtual community of blocks to benign direction.
A lot of problems,such as aging,weak infrastructure etc exist in many traditional residential blocks. The intensification of conflicts between these problems and its inherent historical and cultural value are more and more serious,It makes living type streets become the chicken ribs. It was explored the elderly-oriented reforming strategies of thechicken ribsblocks by investigating the situation of one residential block in Xuzhou,and being concerned with the outdoor action space of aging populations,also adjusting the spatial configuration of the block according to research data,and leading the virtual community of blocks to benign direction.
2013, 43(11): 45-48.
doi: 10.13204/j.gyjz201311011
Abstract:
HRBF500 rebar is a successfully developed new-type high-strength steel bar in Chinese metallurgical industry. Based on the fatigue life numerical simulation and test results,fatigue damage mechanism of rectangular and T-section RC beams with HRBF500 steel bars was analyzed and investigated. The fatigue damage was defined by using the residual bending rigidity of the beams and the accumulative fatigue damage model was obtained. According to the test results,it can be seen that the growth rates of fatigue damage reduced with increase of the initial stress of the tensile reinforcements,and the expressions for correlation coefficients( the growth rate of fatigue damage) of the model was introduced. The results indicate that,the proposed accumulative fatigue damage model can accurately describe the first and second stages of fatigue damage process of RC beams with HRBF500 bars. The remaining fatigue life can be predicted by the model.
HRBF500 rebar is a successfully developed new-type high-strength steel bar in Chinese metallurgical industry. Based on the fatigue life numerical simulation and test results,fatigue damage mechanism of rectangular and T-section RC beams with HRBF500 steel bars was analyzed and investigated. The fatigue damage was defined by using the residual bending rigidity of the beams and the accumulative fatigue damage model was obtained. According to the test results,it can be seen that the growth rates of fatigue damage reduced with increase of the initial stress of the tensile reinforcements,and the expressions for correlation coefficients( the growth rate of fatigue damage) of the model was introduced. The results indicate that,the proposed accumulative fatigue damage model can accurately describe the first and second stages of fatigue damage process of RC beams with HRBF500 bars. The remaining fatigue life can be predicted by the model.
2013, 43(11): 49-53.
doi: 10.13204/j.gyjz201311012
Abstract:
A comparative test was carried out between a new steel bar truss concrete superimposed two-way slab and a cast-in-situ two-way slab. It was measured that the vertical displacement,steel bar strain and crack propagation of the two slabs. By analyzing the main test phenomenon and result,the conclusion was that superimposed two-way slab stiffness and crack resistance were slightly lower than the overall site casting slab,but cracking propagation and position were almost the same. The joint configuration could realise two-way forcing of the new steel bar truss superimposed slab.
A comparative test was carried out between a new steel bar truss concrete superimposed two-way slab and a cast-in-situ two-way slab. It was measured that the vertical displacement,steel bar strain and crack propagation of the two slabs. By analyzing the main test phenomenon and result,the conclusion was that superimposed two-way slab stiffness and crack resistance were slightly lower than the overall site casting slab,but cracking propagation and position were almost the same. The joint configuration could realise two-way forcing of the new steel bar truss superimposed slab.
2013, 43(11): 54-58,83.
doi: 10.13204/j.gyjz201311013
Abstract:
Strong-motion measurement is the basis of earthquake engineering. A lot of strong-motion datas were obtained by nationwide earthquake observation stations when earthquake occurred in Wenchuan,which provided a good data basis for analysis of strong earthquake records. In this paper,some spectral features of the peak acceleration are based on statistical analysis of strong motion records recorded in Wenchuan earthquake. Theory of earthquake response spectrum is the main method of seismic analysis and an important achievement based on depth research and analysis on acceleration characteristics. The max response of structure under earthquake input is only varying with period in traditional response spectrum during the whole time duration. The relationship between the maximum response and time duration can not be shown in the response spectrum of earthquake. The concept of unsteady response spectrum was proposed based on the moveable spectrum in this paper. Based on the conventional response spectrum,the time factor was taken into account in unsteady response spectrum research. Then the response spectrum could be studied based on time varying. As examples for strong motion records obtained from Wenchuan earthquake,two methods were proposed to research the effect of time duration on response spectrum.
Strong-motion measurement is the basis of earthquake engineering. A lot of strong-motion datas were obtained by nationwide earthquake observation stations when earthquake occurred in Wenchuan,which provided a good data basis for analysis of strong earthquake records. In this paper,some spectral features of the peak acceleration are based on statistical analysis of strong motion records recorded in Wenchuan earthquake. Theory of earthquake response spectrum is the main method of seismic analysis and an important achievement based on depth research and analysis on acceleration characteristics. The max response of structure under earthquake input is only varying with period in traditional response spectrum during the whole time duration. The relationship between the maximum response and time duration can not be shown in the response spectrum of earthquake. The concept of unsteady response spectrum was proposed based on the moveable spectrum in this paper. Based on the conventional response spectrum,the time factor was taken into account in unsteady response spectrum research. Then the response spectrum could be studied based on time varying. As examples for strong motion records obtained from Wenchuan earthquake,two methods were proposed to research the effect of time duration on response spectrum.
2013, 43(11): 59-63,48.
doi: 10.13204/j.gyjz201311014
Abstract:
To study the influence of isolation layer stiffness on the base isolation structure,and find the optimal stiffness of the isolation layer,friction sliding isolation steel plate of 0. 05 friction coefficient was set behind a multilayer simple reinforced concrete frame structure basement,and SAP2000 was used for modeling and analysis. It was compare the isolation situation of first layer pillars bottom made of rigid baseplate or not,and also compare the isolation situation of the structure with different isolation layer stiffness. The results show that the isolation structure having a rigid baseplate can effectively control the basement maximum slippage. The selected structure has the best isolation effect when the isolation layer stiffness is 2 000 kN / m,thus reducing the peak response of the structure in the earthquake,such as vibration period,interlayer displacement,interlayer shear and acceleration response,some damping rate even exceeds 90%.
To study the influence of isolation layer stiffness on the base isolation structure,and find the optimal stiffness of the isolation layer,friction sliding isolation steel plate of 0. 05 friction coefficient was set behind a multilayer simple reinforced concrete frame structure basement,and SAP2000 was used for modeling and analysis. It was compare the isolation situation of first layer pillars bottom made of rigid baseplate or not,and also compare the isolation situation of the structure with different isolation layer stiffness. The results show that the isolation structure having a rigid baseplate can effectively control the basement maximum slippage. The selected structure has the best isolation effect when the isolation layer stiffness is 2 000 kN / m,thus reducing the peak response of the structure in the earthquake,such as vibration period,interlayer displacement,interlayer shear and acceleration response,some damping rate even exceeds 90%.
2013, 43(11): 64-66,11.
doi: 10.13204/j.gyjz201311015
Abstract:
Based on the formula of the crack width in the present code,the nominal tensile stress value corresponding to the limit of crack width was studied. The influences of cross section height,the cover thickness,concrete strength grade,non-prestressed reinforcement ratio,diameters of non-prestressed reinforcement and prestress degree on the normal tensile stress of the given crack width were also discussed. Then the influence coefficients of these parameters on the normal tensile stress values were concluded. The comprehensive influence coefficient on the normal tensile stress was obtained by multiplication of the single influence coefficient of the parmeters. In the end,an example was calculated by using the method of normal tensile stress and the formula of the code. The result shows that the method of normal tensile stress is a simple,convenient and creditable method on the crack control of the prestressed concrete structures.
Based on the formula of the crack width in the present code,the nominal tensile stress value corresponding to the limit of crack width was studied. The influences of cross section height,the cover thickness,concrete strength grade,non-prestressed reinforcement ratio,diameters of non-prestressed reinforcement and prestress degree on the normal tensile stress of the given crack width were also discussed. Then the influence coefficients of these parameters on the normal tensile stress values were concluded. The comprehensive influence coefficient on the normal tensile stress was obtained by multiplication of the single influence coefficient of the parmeters. In the end,an example was calculated by using the method of normal tensile stress and the formula of the code. The result shows that the method of normal tensile stress is a simple,convenient and creditable method on the crack control of the prestressed concrete structures.
STUDY OF INFLUENCE OF SHEAR RING ON FORCE AND DEFORMATION PROPERTIES OF STEEL TUBULAR COMPOSITE PILE
2013, 43(11): 67-72,88.
doi: 10.13204/j.gyjz201311016
Abstract:
To investigate the effects of shear ring on the force and deformation characteristics of steel tubular composite( STC) piles under axial load-moment-lateral load,five specimens with different combinations of shear ring,drilling mud skin and anti-corrosion coating were tested,in which four specimens with shear ring,1D,1. 5D,2D,and 3D( D was the pile diameter) were taken as its spacing. Based on analysis of the test results,the effects of shear ring on STC pile bending stiffness were studied. The results obtained from the tests showed that the bearing capacity for lateral deformation of STC pile was greatly improved by shear ring. Also,the force and deformation of STC pile end were significantly increased,when the spacing of shear ring was more than 2D. That resulted in the strains at cross section of pile tip in the shape of m. Finally,the relation between bending stiffness increment of STC piles and shear ring spacing was formulated,both of which showed a hyperbolic law change.
To investigate the effects of shear ring on the force and deformation characteristics of steel tubular composite( STC) piles under axial load-moment-lateral load,five specimens with different combinations of shear ring,drilling mud skin and anti-corrosion coating were tested,in which four specimens with shear ring,1D,1. 5D,2D,and 3D( D was the pile diameter) were taken as its spacing. Based on analysis of the test results,the effects of shear ring on STC pile bending stiffness were studied. The results obtained from the tests showed that the bearing capacity for lateral deformation of STC pile was greatly improved by shear ring. Also,the force and deformation of STC pile end were significantly increased,when the spacing of shear ring was more than 2D. That resulted in the strains at cross section of pile tip in the shape of m. Finally,the relation between bending stiffness increment of STC piles and shear ring spacing was formulated,both of which showed a hyperbolic law change.
2013, 43(11): 73-76.
doi: 10.13204/j.gyjz201311017
Abstract:
It is very important to master the influence of creep characteristics on artificial frozen soil to the engineering safety under construction of freezing method. For the creep,the integer order calculus constitutive relation of artificial frozen soil needs too many components and has other disadvantages,replaced the serial mode of Burgers model with fractional oder derivative function model,fractional order derivative Burgers creep model was constructed to simulate the steady stage of creep. Connected acceleration element in the fractional order derivative Burgers model,the fractional order derivative acceleration Burger creep model to simulate the acceleration stage of creep was constructed. By comparing the result of fractional order derivative Burgers creep model with trial value,the established creep model preferably reflected each stage of creep process of artificial frozen soil. Fractional order derivative Burgers model for artificial frozen soil was a new method for artificial frozen soil creep calculation.
It is very important to master the influence of creep characteristics on artificial frozen soil to the engineering safety under construction of freezing method. For the creep,the integer order calculus constitutive relation of artificial frozen soil needs too many components and has other disadvantages,replaced the serial mode of Burgers model with fractional oder derivative function model,fractional order derivative Burgers creep model was constructed to simulate the steady stage of creep. Connected acceleration element in the fractional order derivative Burgers model,the fractional order derivative acceleration Burger creep model to simulate the acceleration stage of creep was constructed. By comparing the result of fractional order derivative Burgers creep model with trial value,the established creep model preferably reflected each stage of creep process of artificial frozen soil. Fractional order derivative Burgers model for artificial frozen soil was a new method for artificial frozen soil creep calculation.
2013, 43(11): 77-83.
doi: 10.13204/j.gyjz201311018
Abstract:
According to the site working conditions,the 3D full-scale non-linear finite element methods were used to simulate the deep excavation supported by a composite soil nailed wall with bored piles in soft soil. The modified Cam-clay model was applied as the soil's constitutive relationship during the simulation. The results showed that the retaining effects of bored piles and the anchorage effects of anchors were quite good when they were added in the composite soil nailed wall. In order to bring the bored piles and anchors into full play and decrease the adverse effects on the behaviors of the composite soil nailed wall due to deep excavation,it was suggested that the bored pile spacing and embedded depth should be set from 2 m to 2. 5 m and the embedded depth should be no more than the excavation depth,while the anchor inclination should be controlled within 20. The numerical results agreed well with the field data.
According to the site working conditions,the 3D full-scale non-linear finite element methods were used to simulate the deep excavation supported by a composite soil nailed wall with bored piles in soft soil. The modified Cam-clay model was applied as the soil's constitutive relationship during the simulation. The results showed that the retaining effects of bored piles and the anchorage effects of anchors were quite good when they were added in the composite soil nailed wall. In order to bring the bored piles and anchors into full play and decrease the adverse effects on the behaviors of the composite soil nailed wall due to deep excavation,it was suggested that the bored pile spacing and embedded depth should be set from 2 m to 2. 5 m and the embedded depth should be no more than the excavation depth,while the anchor inclination should be controlled within 20. The numerical results agreed well with the field data.
2013, 43(11): 84-88.
doi: 10.13204/j.gyjz201311019
Abstract:
Considering effects of temperature and shrinkage,the stress field analysis of the basement exterior pilaster wall with and without buttress columns and wall with post-castiag strips was done by the finite element method( ABAQUS). The results showed that the stress induced by temperature and shrinkage actions in a concrete pilaster wall were closely related to the distance between buttress columns instead of the length of section walls. The megabuttress columns that played part of the role of post-casting strips,had a positive impact on the crack control resulted from temperature and shrinkage actions. It was concluded that the results of stress field analysis could not only be successfully applied to engineering examples shown in this paper,but also provide a reference for other projects.
Considering effects of temperature and shrinkage,the stress field analysis of the basement exterior pilaster wall with and without buttress columns and wall with post-castiag strips was done by the finite element method( ABAQUS). The results showed that the stress induced by temperature and shrinkage actions in a concrete pilaster wall were closely related to the distance between buttress columns instead of the length of section walls. The megabuttress columns that played part of the role of post-casting strips,had a positive impact on the crack control resulted from temperature and shrinkage actions. It was concluded that the results of stress field analysis could not only be successfully applied to engineering examples shown in this paper,but also provide a reference for other projects.
2013, 43(11): 89-91,125.
doi: 10.13204/j.gyjz201311020
Abstract:
The coastal concrete structures in the salt spray environment are suffered from chloride ion,which produces greatest risk to the structural durability and safety and leads to the destruction of the structure just within the design reference period. Based on the construction of high-grade highway structures in coast of Jiangsu province,the effect of the content of mineral admixtures on the durability of concrete under the salt spray environment was studied.Coastal environment was simulated by salt spray wet and dry circle. And five concrete specimens with different contents of fly ash and slag were analyzed in the corrosion test. The results show that the mineral admixtures in concrete can effectively fill the concrete pores,reduce porosity and improve the ability of concrete to resist the chloride ions ingress. When the fly ash and slag account for 25% of total cementing materials respectively,the diffusion coefficient of chloride ion of the sample is the smallest,which better performance of resistance to chloride ion erosion.
The coastal concrete structures in the salt spray environment are suffered from chloride ion,which produces greatest risk to the structural durability and safety and leads to the destruction of the structure just within the design reference period. Based on the construction of high-grade highway structures in coast of Jiangsu province,the effect of the content of mineral admixtures on the durability of concrete under the salt spray environment was studied.Coastal environment was simulated by salt spray wet and dry circle. And five concrete specimens with different contents of fly ash and slag were analyzed in the corrosion test. The results show that the mineral admixtures in concrete can effectively fill the concrete pores,reduce porosity and improve the ability of concrete to resist the chloride ions ingress. When the fly ash and slag account for 25% of total cementing materials respectively,the diffusion coefficient of chloride ion of the sample is the smallest,which better performance of resistance to chloride ion erosion.
2013, 43(11): 92-95.
doi: 10.13204/j.gyjz201311021
Abstract:
Based on a commercial plaza hotel in Yangzhou,it was analyzed in detail the principle of using finite difference method to solve the mass concrete temperature field. Through the establishment of the finite difference method model,it was solved this raft foundation mass concrete temperature field. Meanwhile it was studied the technical measures for thermal control by incorporating WC air-entraining high efficient water reducing agent into mass concrete,using stepped pouring method and respirable structure to mitigate the constraint of the baseplate. The solved results of the mass concrete temperature field were compared with the measured results,they were basically the same.
Based on a commercial plaza hotel in Yangzhou,it was analyzed in detail the principle of using finite difference method to solve the mass concrete temperature field. Through the establishment of the finite difference method model,it was solved this raft foundation mass concrete temperature field. Meanwhile it was studied the technical measures for thermal control by incorporating WC air-entraining high efficient water reducing agent into mass concrete,using stepped pouring method and respirable structure to mitigate the constraint of the baseplate. The solved results of the mass concrete temperature field were compared with the measured results,they were basically the same.
2013, 43(11): 96-98.
doi: 10.13204/j.gyjz201311022
Abstract:
The new and old codes for design of concrete structure were compared in this paper,the results showed that the accounting assumption x 2a'swas not available for the new HRB500 bar in the design of double reinforcement rectangle section RC beam,the compressive reinforcement can not reach design value,so a fixed assumption was raised to fit for HRB500 bar. Meanwhile,b was supplemented under correlative formulas and terms of assumption of plane section. When the aboved assumption and b were applied in the design of double reinforcement rectangle section RC beam,the results and analysis proved that the fixed assumption was more adaptive and created less total steel consumption.
The new and old codes for design of concrete structure were compared in this paper,the results showed that the accounting assumption x 2a'swas not available for the new HRB500 bar in the design of double reinforcement rectangle section RC beam,the compressive reinforcement can not reach design value,so a fixed assumption was raised to fit for HRB500 bar. Meanwhile,b was supplemented under correlative formulas and terms of assumption of plane section. When the aboved assumption and b were applied in the design of double reinforcement rectangle section RC beam,the results and analysis proved that the fixed assumption was more adaptive and created less total steel consumption.
2013, 43(11): 99-103,15.
doi: 10.13204/j.gyjz201311023
Abstract:
To improve the traditional BRB,it was proposed a double-T-shaped core member and angle iron bucklingrestrained brace( DTABRB). Using ANSYS software,finite element model of DTABRB was created. The nonlinear finite element analysis( FEA) is carried out on the model under cyclic loading and hysteresis loop of brace was obtained from FEA. Based on which multi-parameter analysis,considering different gap between the steel core member and the buckling-restrained mechanism,restraining stiffness,the length of connection section and transition section was carried out to study impacts of these parameters on hysteresis loop of DTABRB. Finally,the suggested values of these parameters were given,which provided a reference for the design of the new brace.
To improve the traditional BRB,it was proposed a double-T-shaped core member and angle iron bucklingrestrained brace( DTABRB). Using ANSYS software,finite element model of DTABRB was created. The nonlinear finite element analysis( FEA) is carried out on the model under cyclic loading and hysteresis loop of brace was obtained from FEA. Based on which multi-parameter analysis,considering different gap between the steel core member and the buckling-restrained mechanism,restraining stiffness,the length of connection section and transition section was carried out to study impacts of these parameters on hysteresis loop of DTABRB. Finally,the suggested values of these parameters were given,which provided a reference for the design of the new brace.
2013, 43(11): 104-109,6.
doi: 10.13204/j.gyjz201311024
Abstract:
The finite element software ABAQUS was employed to simulate the steel-concrete composite slab with perfobond strip under one-third loading. Nonlinear property of concrete and steel and nonlinear contact between concrete and steel were considered in this model. The comparisons between test results and calculated results were performed in order to verify the FEM model. Comparisons indicate that the developed FEM model could represent the test exactly. And the causes of the error were discussed. Then the results of parameterized analysis show that the influence of hole distance and perforated rebar on the ultimate flexural capacity of the composite slab is very small;yet the hole distance and perforated rebar can cause considerable changes in the stiffness of the composite slab. At last calculation formulas for the ultimate flexural capacity of the composite slab were proposed and the simplified calculation method of meeting the need of engineering application was obtained after analysis of parameters.
The finite element software ABAQUS was employed to simulate the steel-concrete composite slab with perfobond strip under one-third loading. Nonlinear property of concrete and steel and nonlinear contact between concrete and steel were considered in this model. The comparisons between test results and calculated results were performed in order to verify the FEM model. Comparisons indicate that the developed FEM model could represent the test exactly. And the causes of the error were discussed. Then the results of parameterized analysis show that the influence of hole distance and perforated rebar on the ultimate flexural capacity of the composite slab is very small;yet the hole distance and perforated rebar can cause considerable changes in the stiffness of the composite slab. At last calculation formulas for the ultimate flexural capacity of the composite slab were proposed and the simplified calculation method of meeting the need of engineering application was obtained after analysis of parameters.
2013, 43(11): 110-116.
doi: 10.13204/j.gyjz201311025
Abstract:
The vertical modal frequency of long-span hangar roof distributes densely and its vertical seismic response is very significant. Analysis of vertical seismic response control method of long-span hangar roof was carried out.Combining with the dynamic characteristics of long-span hangar,damping method by setting tuned mass damper was proposed. Corresponding calculation analysis was carried out and damping effect of the roof joint vertical seismic response was studied under time domain and frequency domain. Furthermore,multiple tuned mass damper( MTMD)was put forward for shock absorbing of long-span hangar. Damping effect of structure with MTMD of different parameters combination was compared under frequency domain. Results show that the spectrum characteristics of earthquake waves have significant influence on the damping effect. The reasonable damping method should be determined combining with the structure dynamic characteristics and ground characteristics.
The vertical modal frequency of long-span hangar roof distributes densely and its vertical seismic response is very significant. Analysis of vertical seismic response control method of long-span hangar roof was carried out.Combining with the dynamic characteristics of long-span hangar,damping method by setting tuned mass damper was proposed. Corresponding calculation analysis was carried out and damping effect of the roof joint vertical seismic response was studied under time domain and frequency domain. Furthermore,multiple tuned mass damper( MTMD)was put forward for shock absorbing of long-span hangar. Damping effect of structure with MTMD of different parameters combination was compared under frequency domain. Results show that the spectrum characteristics of earthquake waves have significant influence on the damping effect. The reasonable damping method should be determined combining with the structure dynamic characteristics and ground characteristics.
2013, 43(11): 117-120,147.
doi: 10.13204/j.gyjz201311026
Abstract:
Five groups of FE models for two-story of cold-formed thin-walled steel housing were built by combining with the practical projects. The large finite element software ANSYS,it was used to analysed 5 groups of structure models,and also study the openning and retaining wall effects on the natural frequency of the whole structure. The 8degrees seismic waves were input to analyse time history,and the transient displacement curve was got,elastic angular displacement between the layers under the action of 8 degrees common earthquake was calculated. Research showed that the openning reduced the whole lateral stiffness of the structure,the cold-formed thin-walled steel frame without wallboard could not meet the first level fortification goal under the effect of 8 degrees common earthquake.Wallboard had a good skin effect to the whole structure,which could effectively improve the integral rigidity and control displacement of structure. OSB board as wallboard had a good seismic behavior,which provided the reference for the design of rural cold-formed thin-walled steel building structure.
Five groups of FE models for two-story of cold-formed thin-walled steel housing were built by combining with the practical projects. The large finite element software ANSYS,it was used to analysed 5 groups of structure models,and also study the openning and retaining wall effects on the natural frequency of the whole structure. The 8degrees seismic waves were input to analyse time history,and the transient displacement curve was got,elastic angular displacement between the layers under the action of 8 degrees common earthquake was calculated. Research showed that the openning reduced the whole lateral stiffness of the structure,the cold-formed thin-walled steel frame without wallboard could not meet the first level fortification goal under the effect of 8 degrees common earthquake.Wallboard had a good skin effect to the whole structure,which could effectively improve the integral rigidity and control displacement of structure. OSB board as wallboard had a good seismic behavior,which provided the reference for the design of rural cold-formed thin-walled steel building structure.
2013, 43(11): 121-125.
doi: 10.13204/j.gyjz201311027
Abstract:
Based on the finite element model of cable for cable-stayed bridge,it was analyzed the influence of three environmental factors including damper,beam vibration and temperature upon the cable's vibration fundamental frequency when considering engineering parameters of cable. The results show that when the damper's installation position is fixed,the influence of the damper upon the long cable's fundamental frequency is greater than the influence upon the short cable's. When the cable's length and the damper's position are fixed,the influence of the damper upon the fundamental frequency of the cable which has large section diameter is less than the one has small section diameter. The fundamental frequency of the cable has dynamic fluctuations because of the cable-stayed bridge's beam vibration caused by the vehicle load. To make the fundamental frequency more accurate,the time with a few vehicles may be selected when measuring the cable force. Temperature variation also has influence upon the fundamental frequency of the cable. Namely,the higher of the cable's temperature,the smaller of the fundamental frequency; the lower of the cable's temperature,the bigger of the fundamental frequency.
Based on the finite element model of cable for cable-stayed bridge,it was analyzed the influence of three environmental factors including damper,beam vibration and temperature upon the cable's vibration fundamental frequency when considering engineering parameters of cable. The results show that when the damper's installation position is fixed,the influence of the damper upon the long cable's fundamental frequency is greater than the influence upon the short cable's. When the cable's length and the damper's position are fixed,the influence of the damper upon the fundamental frequency of the cable which has large section diameter is less than the one has small section diameter. The fundamental frequency of the cable has dynamic fluctuations because of the cable-stayed bridge's beam vibration caused by the vehicle load. To make the fundamental frequency more accurate,the time with a few vehicles may be selected when measuring the cable force. Temperature variation also has influence upon the fundamental frequency of the cable. Namely,the higher of the cable's temperature,the smaller of the fundamental frequency; the lower of the cable's temperature,the bigger of the fundamental frequency.
2013, 43(11): 126-130.
doi: 10.13204/j.gyjz201311028
Abstract:
To investigate the lateral resistance behavior of steel plate-brick masonry composite frames,two composite frames were tested and simulated in finite element method. The failure mechanism under lateral load was abtained and development rule of steel plate's and masonry's stress and strain in control sections was analyzed. Meanwhile,masonry's influence on bearing capacity and stiffness of the composite frame was discussed,based on which simplified calculation of lateral stiffness of steel plate-brick masonry composite frames was proposed.
To investigate the lateral resistance behavior of steel plate-brick masonry composite frames,two composite frames were tested and simulated in finite element method. The failure mechanism under lateral load was abtained and development rule of steel plate's and masonry's stress and strain in control sections was analyzed. Meanwhile,masonry's influence on bearing capacity and stiffness of the composite frame was discussed,based on which simplified calculation of lateral stiffness of steel plate-brick masonry composite frames was proposed.
2013, 43(11): 131-135.
doi: 10.13204/j.gyjz201311029
Abstract:
The blasting vibration effect in the subway excavation process of a multistory masonry building strengthened by shotcrete was analyzed using representative volume element model. Finite element models for both the original structure and the strengthened one were established,and time-history analysis was performed. The effect of shotcrete strengthening on masonry walls was analysed from the structural period,structural stiffness,top lateral displacement and stress level. The result shows that the structural stiffness is effectively enhanced and integrity of the structure is improved. Since the major portion of shear force of the blasting vibration effect in the strengthened wall is resisted by the strengthening concrete layer,the stresses in the masonry wall are reduced and the structural failure is avoided.
The blasting vibration effect in the subway excavation process of a multistory masonry building strengthened by shotcrete was analyzed using representative volume element model. Finite element models for both the original structure and the strengthened one were established,and time-history analysis was performed. The effect of shotcrete strengthening on masonry walls was analysed from the structural period,structural stiffness,top lateral displacement and stress level. The result shows that the structural stiffness is effectively enhanced and integrity of the structure is improved. Since the major portion of shear force of the blasting vibration effect in the strengthened wall is resisted by the strengthening concrete layer,the stresses in the masonry wall are reduced and the structural failure is avoided.
2013, 43(11): 136-139.
doi: 10.13204/j.gyjz201311030
Abstract:
A field inspection was done for the diagonal cracks on the short columns of R. C frame for a street building in Rizhao city. The structure concrete strength was detected by rebounding methed and drilled concrete samples. A transverse frame was taken as the structure calculation unit,temperature deformation of the garage floor was attached to the horizontal frame,then the structure internal force was analyzed by SAP2000 under the case of taking account of lateral restraint influence of backfill,and the case without this consideration. In the end,the reason of the cracks on the R. C colunms had been found out. The retrofitting measures were put forward for damaged R. C columns,which can provide a basis for appraisal and strengthening of similar projects.
A field inspection was done for the diagonal cracks on the short columns of R. C frame for a street building in Rizhao city. The structure concrete strength was detected by rebounding methed and drilled concrete samples. A transverse frame was taken as the structure calculation unit,temperature deformation of the garage floor was attached to the horizontal frame,then the structure internal force was analyzed by SAP2000 under the case of taking account of lateral restraint influence of backfill,and the case without this consideration. In the end,the reason of the cracks on the R. C colunms had been found out. The retrofitting measures were put forward for damaged R. C columns,which can provide a basis for appraisal and strengthening of similar projects.
2013, 43(11): 140-142,139.
doi: 10.13204/j.gyjz201311031
Abstract:
In order to improve the life and bearing capacity of the original brick column,it was changed brick bent into composite masonry bent by using encasing reinforced concrete. Utilizing the underpinning technique and combined with the supporting role of the original wall,it was ultimately achieved the goal of dismantling the original wall and incorporated the use space of the building.
In order to improve the life and bearing capacity of the original brick column,it was changed brick bent into composite masonry bent by using encasing reinforced concrete. Utilizing the underpinning technique and combined with the supporting role of the original wall,it was ultimately achieved the goal of dismantling the original wall and incorporated the use space of the building.
2013, 43(11): 143-147.
doi: 10.13204/j.gyjz201311032
Abstract:
The design of flow lines is the key to Lab concept design. Which is also the key to whether or not a lab meets the project's needs. According to the characteristics of the project and designed requirements,the flow lines of all the biological safety labs were determined,including staff flow,goods flow,animal flow and these three flows were also separated to be clean flow and waste flow.
The design of flow lines is the key to Lab concept design. Which is also the key to whether or not a lab meets the project's needs. According to the characteristics of the project and designed requirements,the flow lines of all the biological safety labs were determined,including staff flow,goods flow,animal flow and these three flows were also separated to be clean flow and waste flow.
2013, 43(11): 148-152.
doi: 10.13204/j.gyjz201311033
Abstract:
By means of analysing selection of the location of connected aisles from shield tunnels of a project in soft soil stratum,reinforcing the stratum by freezing method and excavating,etc,and carrying out the numerical simulation calculation,the main measures of controlling the construction risks from the connected aisle during design and construction were summarized. From which good effect was got in construction. It is of some guiding significance to the design and construction of similar projects in the soft soil strata in the future.
By means of analysing selection of the location of connected aisles from shield tunnels of a project in soft soil stratum,reinforcing the stratum by freezing method and excavating,etc,and carrying out the numerical simulation calculation,the main measures of controlling the construction risks from the connected aisle during design and construction were summarized. From which good effect was got in construction. It is of some guiding significance to the design and construction of similar projects in the soft soil strata in the future.
2013, 43(11): 153-155.
doi: 10.13204/j.gyjz201311034
Abstract:
With the development of the city,many old plants which are superior in location had stepped down from the stage of city. The old plants would be transformed into those having other functions. It was studied the skin renewal of old plants. The new buildings had different requirements in respect of function,technology and culture.Hence the skin renewal of old plants was divided into 4 modes: retention,fusion,coverage and reset of the skin. It was explored different types of architecture and their different design techniques adapting to different modes,hoping that the study could provide design reference for reforming old plants.
With the development of the city,many old plants which are superior in location had stepped down from the stage of city. The old plants would be transformed into those having other functions. It was studied the skin renewal of old plants. The new buildings had different requirements in respect of function,technology and culture.Hence the skin renewal of old plants was divided into 4 modes: retention,fusion,coverage and reset of the skin. It was explored different types of architecture and their different design techniques adapting to different modes,hoping that the study could provide design reference for reforming old plants.
2013, 43(11): 156-158.
doi: 10.13204/j.gyjz201311035
Abstract:
This research takes the external form of multi-unit housing built in recent years in Changchun as the objects,confirms the richness of form contents,and pays more attention to the assimilation of form character and style as well as to the lock of regional cultural characteristics. Treating this assimilation objectively and rationally is the basis of seeking residential building culture diversified development and creating the urban landscape with regional characteristics in the future.
This research takes the external form of multi-unit housing built in recent years in Changchun as the objects,confirms the richness of form contents,and pays more attention to the assimilation of form character and style as well as to the lock of regional cultural characteristics. Treating this assimilation objectively and rationally is the basis of seeking residential building culture diversified development and creating the urban landscape with regional characteristics in the future.
