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2012 Vol. 42, No. 4
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2012, 42(4): 1-4.
doi: 10.13204/j.gyjz201204001
Abstract:
Based on the test results of the basic performance of the recycled aggregate in Sichuan Province,the free water cement ratio method for mix design was adopted,and the value of W /C was suggested to be 0. 4. The experimental formula of conversion strength for different recycled aggregate replacement ratio was proved according to 90 sets of experimental data. The results by formula agreed well with those of the tests,which provided strength index for the use of recycled aggregate concrete and estimate of early strength of structure in this region.
Based on the test results of the basic performance of the recycled aggregate in Sichuan Province,the free water cement ratio method for mix design was adopted,and the value of W /C was suggested to be 0. 4. The experimental formula of conversion strength for different recycled aggregate replacement ratio was proved according to 90 sets of experimental data. The results by formula agreed well with those of the tests,which provided strength index for the use of recycled aggregate concrete and estimate of early strength of structure in this region.
2012, 42(4): 5-9,14.
doi: 10.13204/j.gyjz201204002
Abstract:
In consideration of the increasing waste concrete (WC) and its harm,there is a pressing need of rational development and scientific use of it. In view of the multi-route source and the diversified quality of recycled aggregate (RA) as well as its impact on the quality of recycled aggregate concretes (RAC),four kinds of waste concretes of different sources,such as old house demolition,high-strength pile foundation,municipal administration and scientific research,which are of the most typical representative,are selected and fragmented into four kinds of recycled aggregates,then four replacement ratios of 25%,50%,75% and 100% respectively are chosen after purification and crosstie of the four recycled aggregates,which are configured into four recycled aggregate concretes by referring to the correlative standards and the cubic comprehensive strength and the prism comprehensive strength are tested according to the standard test. The aim of the above experiment is to make sure and discuss the impact on cubic comprehensive strength and prism comprehensive strength of recycled aggregate concrete of different RA sources. The result indicated that the effects of replacement ratio of recycled aggregate have a great impact on the cubic comprehensive strength and the prism comprehensive strength while the impact from recycled aggregate of different sources is not distinct. What' s more,it is pointed out that the mineral admixture is another important factor that influences the prism comprehensive strength.
In consideration of the increasing waste concrete (WC) and its harm,there is a pressing need of rational development and scientific use of it. In view of the multi-route source and the diversified quality of recycled aggregate (RA) as well as its impact on the quality of recycled aggregate concretes (RAC),four kinds of waste concretes of different sources,such as old house demolition,high-strength pile foundation,municipal administration and scientific research,which are of the most typical representative,are selected and fragmented into four kinds of recycled aggregates,then four replacement ratios of 25%,50%,75% and 100% respectively are chosen after purification and crosstie of the four recycled aggregates,which are configured into four recycled aggregate concretes by referring to the correlative standards and the cubic comprehensive strength and the prism comprehensive strength are tested according to the standard test. The aim of the above experiment is to make sure and discuss the impact on cubic comprehensive strength and prism comprehensive strength of recycled aggregate concrete of different RA sources. The result indicated that the effects of replacement ratio of recycled aggregate have a great impact on the cubic comprehensive strength and the prism comprehensive strength while the impact from recycled aggregate of different sources is not distinct. What' s more,it is pointed out that the mineral admixture is another important factor that influences the prism comprehensive strength.
2012, 42(4): 10-14.
doi: 10.13204/j.gyjz201204003
Abstract:
According to the strain value along the anchor length based on the pull out test of the recycled aggregate concrete, it was calculated the bond stress and summarized the rule of the bond stress along the anchor length. The changing principal of the chemical joint strength,the mechanical linking strength and the friction force along with the pulling force was discussed. The load transfer unit and load transfer mode theory was firstly proposed. And the theoretical model of the bond stress along the anchor length was given, whose results agreed with the experimental results. Finally,it was defined the asymmetry coefficient of bond stress and analyzed the influence of factors on the distribution of bond stress at ultimate state.
According to the strain value along the anchor length based on the pull out test of the recycled aggregate concrete, it was calculated the bond stress and summarized the rule of the bond stress along the anchor length. The changing principal of the chemical joint strength,the mechanical linking strength and the friction force along with the pulling force was discussed. The load transfer unit and load transfer mode theory was firstly proposed. And the theoretical model of the bond stress along the anchor length was given, whose results agreed with the experimental results. Finally,it was defined the asymmetry coefficient of bond stress and analyzed the influence of factors on the distribution of bond stress at ultimate state.
2012, 42(4): 15-20.
doi: 10.13204/j.gyjz201204004
Abstract:
The strength of recycled concrete was studied whose recycled coarse aggregate was preprocessed by DSP grout. At the same time,the strength of recycled concrete added DSP grout as part of the concrete directly in the mixing process was also studied,but also with a comparison of the basic recycled concrete. The results show that for the cube compressive strength and prism compressive strength,the strength of recycled concrete improved by DSP grout is the highest,respectively,increased by 25. 6% (or 26. 7% ) as compared to the prism compressive strength of the basic recycled concrete. And for DSP grout pretreatment recycled aggregate concrete,7 d cube compressive strength is higher than the basic recycled concrete,28 d cube compressive strength is lower than the basic recycled concrete, 28d prism compressive strength is high and low. In addition,the failure mechanism of the recycled concrete is analyzed.
The strength of recycled concrete was studied whose recycled coarse aggregate was preprocessed by DSP grout. At the same time,the strength of recycled concrete added DSP grout as part of the concrete directly in the mixing process was also studied,but also with a comparison of the basic recycled concrete. The results show that for the cube compressive strength and prism compressive strength,the strength of recycled concrete improved by DSP grout is the highest,respectively,increased by 25. 6% (or 26. 7% ) as compared to the prism compressive strength of the basic recycled concrete. And for DSP grout pretreatment recycled aggregate concrete,7 d cube compressive strength is higher than the basic recycled concrete,28 d cube compressive strength is lower than the basic recycled concrete, 28d prism compressive strength is high and low. In addition,the failure mechanism of the recycled concrete is analyzed.
2012, 42(4): 21-24,117.
doi: 10.13204/j.gyjz201204005
Abstract:
In this paper,seismic behavior of 4 members,two of them made of recycled aggregate concrete and the other made of RC,is studied under low frequency reversed moment,shear and torsion. The failure features,the hysteresis loops and the ductility under seismic loads are comparatively investigated. The test and analyses show that the seismic behavior of members including the ductility with recycled concrete is slightly lower than that of members with conventional concrete and both of them can meet the requirements of the code for seismic design of buildings.
In this paper,seismic behavior of 4 members,two of them made of recycled aggregate concrete and the other made of RC,is studied under low frequency reversed moment,shear and torsion. The failure features,the hysteresis loops and the ductility under seismic loads are comparatively investigated. The test and analyses show that the seismic behavior of members including the ductility with recycled concrete is slightly lower than that of members with conventional concrete and both of them can meet the requirements of the code for seismic design of buildings.
2012, 42(4): 25-30.
doi: 10.13204/j.gyjz201204006
Abstract:
Based on bending performance experiment of three groups beams with fifteen test components,whose recycled coarse aggregate replacement rate were different,it was the article analyzed the effect of recycled aggregate replacement ratio on RAC beams meeting the linear plane assumption,deflection,crack width and limit carrying capacity. Meantime the applicability of recycled concrete beams bending limit carrying capacity byCode for Design of Concrete Structures(GB 500102002) was discussed. The research indicated that under the same loads,the appearance of crack on the recycled concrete beams was previous while the width of crack was larger on recycled concrete beams and recycled concrete beams degraded rapidly in stiffness as well. The average strain measured on cross-section could meet the requirement of the plane section assumption. The computational results of recycled concrete beams bending limit carrying capacity by Code for Design of Concrete Structures were feasible,but the formula of GB 500102002 was not comprehensive. It was introduced a kind of suggested formula and adjustment coefficient,which could help to solve related calculation problem and was proved to be effective.
Based on bending performance experiment of three groups beams with fifteen test components,whose recycled coarse aggregate replacement rate were different,it was the article analyzed the effect of recycled aggregate replacement ratio on RAC beams meeting the linear plane assumption,deflection,crack width and limit carrying capacity. Meantime the applicability of recycled concrete beams bending limit carrying capacity byCode for Design of Concrete Structures(GB 500102002) was discussed. The research indicated that under the same loads,the appearance of crack on the recycled concrete beams was previous while the width of crack was larger on recycled concrete beams and recycled concrete beams degraded rapidly in stiffness as well. The average strain measured on cross-section could meet the requirement of the plane section assumption. The computational results of recycled concrete beams bending limit carrying capacity by Code for Design of Concrete Structures were feasible,but the formula of GB 500102002 was not comprehensive. It was introduced a kind of suggested formula and adjustment coefficient,which could help to solve related calculation problem and was proved to be effective.
2012, 42(4): 31-36.
doi: 10.13204/j.gyjz201204007
Abstract:
In this paper,the compression behaviors of 12 concrete columns with different replacement percentages of recycled coarse aggregate and 500 MPa grade reinforcement were experimentally investigated. Failure modes, component lateral deflection curve,concrete strain,steel strain and other features of recycled concrete columns were analyzed. The bearing capacity of experiment was compared with code for design of concrete structures. The results show that the failure process and mode,cross-lateral deflection curves,concrete strain,steel strain of the recycled concrete column and ordinary concrete are not different significantly,and the replacement rate has little effect on the bearing capacity of column. The compression bearing capacity calculated by code for Design of Concrete Structures (GB 500102010) is in good agreement with the experimental results. 500 MPa grade reinforcement in recycled concrete columns work with better performance,and its tensile and compressive strength can be fully realized. In the compression bearing capacity calculations, tensile and compressive strength design values of 500 MPa grade reinforcement in GB 500102010 values have provided a greater safety margin.
In this paper,the compression behaviors of 12 concrete columns with different replacement percentages of recycled coarse aggregate and 500 MPa grade reinforcement were experimentally investigated. Failure modes, component lateral deflection curve,concrete strain,steel strain and other features of recycled concrete columns were analyzed. The bearing capacity of experiment was compared with code for design of concrete structures. The results show that the failure process and mode,cross-lateral deflection curves,concrete strain,steel strain of the recycled concrete column and ordinary concrete are not different significantly,and the replacement rate has little effect on the bearing capacity of column. The compression bearing capacity calculated by code for Design of Concrete Structures (GB 500102010) is in good agreement with the experimental results. 500 MPa grade reinforcement in recycled concrete columns work with better performance,and its tensile and compressive strength can be fully realized. In the compression bearing capacity calculations, tensile and compressive strength design values of 500 MPa grade reinforcement in GB 500102010 values have provided a greater safety margin.
2012, 42(4): 37-43.
doi: 10.13204/j.gyjz201204008
Abstract:
From experimental study on seismic behavior of five recycled concrete hollow block walls under low-cyclic loading,research their failure mode,energy dissipation capacity,deformation performance etc in different height- width ratio,axial compression ratio and concrete constructional columns. The test results showed that the recycled concrete hollow block walls have better seismic performance,at the same time,check calculation of the results according to related current national code,and can be used in practical engineering.
From experimental study on seismic behavior of five recycled concrete hollow block walls under low-cyclic loading,research their failure mode,energy dissipation capacity,deformation performance etc in different height- width ratio,axial compression ratio and concrete constructional columns. The test results showed that the recycled concrete hollow block walls have better seismic performance,at the same time,check calculation of the results according to related current national code,and can be used in practical engineering.
2012, 42(4): 44-47,102.
doi: 10.13204/j.gyjz201204009
Abstract:
Having the specific engineering examples as a background,starting from architectural properties of nursery buildings,through one-dimensional steady heat transfer theory of architectural maintenance structure and other knowledge,combined with architectural structures and construction cost,various forms of energy-saving roofs were calculated. Which were also analyzed and compared. For the finally determined energy-saving roof scheme,it was done the investment recovery analysis. According to the results calculated by dynamic and static methods,it was fully validated the energy-saving superiorities of flat inversion type roof.
Having the specific engineering examples as a background,starting from architectural properties of nursery buildings,through one-dimensional steady heat transfer theory of architectural maintenance structure and other knowledge,combined with architectural structures and construction cost,various forms of energy-saving roofs were calculated. Which were also analyzed and compared. For the finally determined energy-saving roof scheme,it was done the investment recovery analysis. According to the results calculated by dynamic and static methods,it was fully validated the energy-saving superiorities of flat inversion type roof.
2012, 42(4): 48-50,55.
doi: 10.13204/j.gyjz201204010
Abstract:
It was analyzed the sea grass residential buildings in Jiaodong. According to the field research and the existing residential buildings,it was exploited the general and simple ecological value,paractical significance and sustainability of traditional residential buildings,which may provide a theoretical basis and practice for the design of new residential buildings with ecological value.
It was analyzed the sea grass residential buildings in Jiaodong. According to the field research and the existing residential buildings,it was exploited the general and simple ecological value,paractical significance and sustainability of traditional residential buildings,which may provide a theoretical basis and practice for the design of new residential buildings with ecological value.
2012, 42(4): 51-55.
doi: 10.13204/j.gyjz201204011
Abstract:
In view of the horizontal and vertical connections of a new concrete superimposed wall panel,the bearing capacity and the deformation performance of the wall panel may be affected since the area of effective section at the connections is smaller than the wall panel. Cyclic loading tests for two superimposed wall panels which have the horizontal connections with dowel bar and the vertical connections with embedded column and horizontal bars are carried out respectively. The characteristics of failure,ductility,stiffness and energy dissipation are analyzed for each panel,and the comparisons with conventional reinforced concrete wall panel are also presented. The results show that the influence of the horizontal and vertical connections on the bearing capacity is small,but the horizontal connections may reduce the overall deformation performance.
In view of the horizontal and vertical connections of a new concrete superimposed wall panel,the bearing capacity and the deformation performance of the wall panel may be affected since the area of effective section at the connections is smaller than the wall panel. Cyclic loading tests for two superimposed wall panels which have the horizontal connections with dowel bar and the vertical connections with embedded column and horizontal bars are carried out respectively. The characteristics of failure,ductility,stiffness and energy dissipation are analyzed for each panel,and the comparisons with conventional reinforced concrete wall panel are also presented. The results show that the influence of the horizontal and vertical connections on the bearing capacity is small,but the horizontal connections may reduce the overall deformation performance.
2012, 42(4): 56-59.
doi: 10.13204/j.gyjz201204012
Abstract:
Overall bending moment has played an important role in the performance of high grid structure with phosphogypsum as the wall under lateral loads,but the shear forces. Utilizing structural analysis program PKPM,and using the floors as parameter,it is conducted the performance analysis of structure under the horizontal and vertical loads. The results show that overall bending moment has a great impact on the overturning moment of the bottom columns,the axial force increases by a linear relationship,but small impact on the overturning shear force. Deformation of the bottom is curved and that of the upper part is shear. Rectangular frame columns bear the axial force and shear force,that is respectively increased by about 2% and 15% as compared with L-shaped frame column when the sectional area of side frame columns is equal. Rectangular frame columns bear the axial force and shear force,that is respectively increased by about 9% and 18% as compared with L-shaped frame column when the moment of inertia of side frame columns is equal.
Overall bending moment has played an important role in the performance of high grid structure with phosphogypsum as the wall under lateral loads,but the shear forces. Utilizing structural analysis program PKPM,and using the floors as parameter,it is conducted the performance analysis of structure under the horizontal and vertical loads. The results show that overall bending moment has a great impact on the overturning moment of the bottom columns,the axial force increases by a linear relationship,but small impact on the overturning shear force. Deformation of the bottom is curved and that of the upper part is shear. Rectangular frame columns bear the axial force and shear force,that is respectively increased by about 2% and 15% as compared with L-shaped frame column when the sectional area of side frame columns is equal. Rectangular frame columns bear the axial force and shear force,that is respectively increased by about 9% and 18% as compared with L-shaped frame column when the moment of inertia of side frame columns is equal.
2012, 42(4): 60-64.
doi: 10.13204/j.gyjz201204013
Abstract:
Based on the traditional mechanical model of thin-walled straight beam,it is conducted a systematic analysis and research on the pre-twisted thin-walled beam finite element numerical model. Firstly,based on the geometric deformation differential relationship,it is deduced the pre-twisted thin-walled beam Saint-Venant warping strain. According to traditional thin-walled straight beam finite element mechanical model,it is also established its finite element stiffness matrix considering the Saint-Venant warping deformations. Finally,by calculating the pre- twisted elliptical section beam example,and contrasting three-dimensional solid finite element using ANSYS,the comparative analysis results show that pre-twisted thin-walled beam element stiffness matrix considering Saint-Venant warping deformation has a good accuracy.
Based on the traditional mechanical model of thin-walled straight beam,it is conducted a systematic analysis and research on the pre-twisted thin-walled beam finite element numerical model. Firstly,based on the geometric deformation differential relationship,it is deduced the pre-twisted thin-walled beam Saint-Venant warping strain. According to traditional thin-walled straight beam finite element mechanical model,it is also established its finite element stiffness matrix considering the Saint-Venant warping deformations. Finally,by calculating the pre- twisted elliptical section beam example,and contrasting three-dimensional solid finite element using ANSYS,the comparative analysis results show that pre-twisted thin-walled beam element stiffness matrix considering Saint-Venant warping deformation has a good accuracy.
2012, 42(4): 65-68.
doi: 10.13204/j.gyjz201204014
Abstract:
In this paper,the true response of a prestressed conrete beam for shrinkage and creep effects have been tested. The results of data analysis illustrate that the strain of concrete consistent with the previous data of shrinkage and creep. As compared to the total strain of 201 d,the proportion of concrete strain in 100 d was close to 75%. As compared to the predicting models of JTG D622004 code,ACI 209R-1992 and China Academy of Building Research(1986), the early test results approximated to the model of ACI 209R-1992,whose changes in late period approximated to the model of JTG D622004 code. Revised test results coincided to those of the predicting models.
In this paper,the true response of a prestressed conrete beam for shrinkage and creep effects have been tested. The results of data analysis illustrate that the strain of concrete consistent with the previous data of shrinkage and creep. As compared to the total strain of 201 d,the proportion of concrete strain in 100 d was close to 75%. As compared to the predicting models of JTG D622004 code,ACI 209R-1992 and China Academy of Building Research(1986), the early test results approximated to the model of ACI 209R-1992,whose changes in late period approximated to the model of JTG D622004 code. Revised test results coincided to those of the predicting models.
2012, 42(4): 69-72.
doi: 10.13204/j.gyjz201204015
Abstract:
In order to reveal the failure mechanism and bearing capacity of extended service reinforced concrete pole strengthened with carbon fiber reinforced polymer (CFRP),4 reinforced concrete poles were designed for bending test,including three reinforced concrete poles strengthened by CFRP and one common reinforced concrete pole. According to the test,the whole failure process,failure pattern,the complete loading-displacement curve and the ultimate bearing capacity were obtained. Experimental results showed that the failure progress of CFRP strengthening reinforced concrete pole was very rapid and no premonition,CFRP fracture was the final failure pattern of specimens. The concrete pole bearing capacity was improved apparently by CFRP strengthening technology. With the layer of CFRP increasing,the bearing capacity was improved,but the improvement was not linear.
In order to reveal the failure mechanism and bearing capacity of extended service reinforced concrete pole strengthened with carbon fiber reinforced polymer (CFRP),4 reinforced concrete poles were designed for bending test,including three reinforced concrete poles strengthened by CFRP and one common reinforced concrete pole. According to the test,the whole failure process,failure pattern,the complete loading-displacement curve and the ultimate bearing capacity were obtained. Experimental results showed that the failure progress of CFRP strengthening reinforced concrete pole was very rapid and no premonition,CFRP fracture was the final failure pattern of specimens. The concrete pole bearing capacity was improved apparently by CFRP strengthening technology. With the layer of CFRP increasing,the bearing capacity was improved,but the improvement was not linear.
2012, 42(4): 73-77.
doi: 10.13204/j.gyjz201204016
Abstract:
The experimental study on flexural capacity of strengthened RC beams about C13,which were detached from the damaged building of Wenchuan earthquake was carried out,then loading to the same damage. There were 22 RC test beams adopting 8 kinds of strengthened methods by composite CFRP sheets under monotonic loading,it was investigated strength,stiffness,ductility,crack and strain changes of the beams. Results showed that: 1) The ultimate bearing capacity of reinforcement compound solutions of automatic glue pouring,replacement concrete after picked slot,implanting steels and pasting CFRP was much higher than direct pasting CFRP; cracking load and ductility was improved evidently. 2) The maximum stress of CFRP on which reinforcement compound solutions was bigger than direct pasting,the high-strength effect of CFRP was used very well,interoperability between new and old concrete was strong,which could play a good role in high-strength CFRP. 3) For the beam strengthened with the compound technology,raising the amount of CFRP could further improve the stress of steel, and effectively improve the cracking load and limit load of beam.
The experimental study on flexural capacity of strengthened RC beams about C13,which were detached from the damaged building of Wenchuan earthquake was carried out,then loading to the same damage. There were 22 RC test beams adopting 8 kinds of strengthened methods by composite CFRP sheets under monotonic loading,it was investigated strength,stiffness,ductility,crack and strain changes of the beams. Results showed that: 1) The ultimate bearing capacity of reinforcement compound solutions of automatic glue pouring,replacement concrete after picked slot,implanting steels and pasting CFRP was much higher than direct pasting CFRP; cracking load and ductility was improved evidently. 2) The maximum stress of CFRP on which reinforcement compound solutions was bigger than direct pasting,the high-strength effect of CFRP was used very well,interoperability between new and old concrete was strong,which could play a good role in high-strength CFRP. 3) For the beam strengthened with the compound technology,raising the amount of CFRP could further improve the stress of steel, and effectively improve the cracking load and limit load of beam.
2012, 42(4): 78-81,98.
doi: 10.13204/j.gyjz201204017
Abstract:
The mechanical behavior of large pre-stressed concrete full containment LNG tank roof was analyzed. According to the existing project,the physical model of large pre-stressed concrete full containment LNG tank is established with finite element method (FEM). The geometry factors implicating the stress and deformation of the roof were considered during the phase of project design,including external tank diameter,curvature radius of the roof and the thickness of roof. By calculating the LNG tanks with different dimensions and contrasting the results,the optimal states of the geometry factors on stress and deformation are obtained,which provides suggestions on designing the large LNG tanks and lays a foundation for China' s independent design of large-size LNG tanks.
The mechanical behavior of large pre-stressed concrete full containment LNG tank roof was analyzed. According to the existing project,the physical model of large pre-stressed concrete full containment LNG tank is established with finite element method (FEM). The geometry factors implicating the stress and deformation of the roof were considered during the phase of project design,including external tank diameter,curvature radius of the roof and the thickness of roof. By calculating the LNG tanks with different dimensions and contrasting the results,the optimal states of the geometry factors on stress and deformation are obtained,which provides suggestions on designing the large LNG tanks and lays a foundation for China' s independent design of large-size LNG tanks.
2012, 42(4): 82-88,106.
doi: 10.13204/j.gyjz201204018
Abstract:
According to the experimental data of reinforced retaining wall,the reasonable shape and location of the rupture face of reinforced retaining wall were selected and considering the effect of the uniform load on the rupture face,it was got the formula of the critical length of rigid dental-strip reinforcements used in retaining wall based on the equilibrium method for wedge sliding. The influence of the height of the vertical reinforcing element and that of the vertical spacing of the horizontal reinforcing element on the critical length of the reinforced retaining wall were analyzed. A more effective way of the material used was discussed.
According to the experimental data of reinforced retaining wall,the reasonable shape and location of the rupture face of reinforced retaining wall were selected and considering the effect of the uniform load on the rupture face,it was got the formula of the critical length of rigid dental-strip reinforcements used in retaining wall based on the equilibrium method for wedge sliding. The influence of the height of the vertical reinforcing element and that of the vertical spacing of the horizontal reinforcing element on the critical length of the reinforced retaining wall were analyzed. A more effective way of the material used was discussed.
2012, 42(4): 89-94.
doi: 10.13204/j.gyjz201204019
Abstract:
Model tests were designed to investigate the bearing capacity properties of composite steel pipe pile foundations in sandy soil. Results indicated that:To a single pile composite foundation,the load was totally carried by ground under the cap before sealing piles. Then,after sealing,the pile started to work and the pile-soil load share ratios were between 73. 5% ～ 92% before reaching ultimate bearing capacity. As vertical load increased continually to the capacity limit,the ratio reduced obviously. To a composite foundation with 8 steel pipe piles was tested,the attenuation gradient of axial load was larger in the middle and lower parts rather than the upper part during axial load transfer. The rates of the corner piles were biggest,then the side piles. The side frictional resistances developed gradually from the top to the bottom and the maximum value reached at the distance of 1. 55 m below the top. At every load step,the resistances of the corner piles were greater than that of side piles. Moreover,the ultimate bearing capacity of the steel pipe pile composite foundation was significantly higher than that of the high-rise cap pile group foundation.
Model tests were designed to investigate the bearing capacity properties of composite steel pipe pile foundations in sandy soil. Results indicated that:To a single pile composite foundation,the load was totally carried by ground under the cap before sealing piles. Then,after sealing,the pile started to work and the pile-soil load share ratios were between 73. 5% ～ 92% before reaching ultimate bearing capacity. As vertical load increased continually to the capacity limit,the ratio reduced obviously. To a composite foundation with 8 steel pipe piles was tested,the attenuation gradient of axial load was larger in the middle and lower parts rather than the upper part during axial load transfer. The rates of the corner piles were biggest,then the side piles. The side frictional resistances developed gradually from the top to the bottom and the maximum value reached at the distance of 1. 55 m below the top. At every load step,the resistances of the corner piles were greater than that of side piles. Moreover,the ultimate bearing capacity of the steel pipe pile composite foundation was significantly higher than that of the high-rise cap pile group foundation.
2012, 42(4): 95-98.
doi: 10.13204/j.gyjz201204020
Abstract:
In order to investigate the working mechanism of reinforced pile-supported foundation,field tests in Shenzhen Airport Apron had been performed. The test results of settlement and pore water pressure were analyzed and compared in detail. The results showed that the reinforced pile-supported foundation could reduce the total settlements and differential settlements,the differential settlements were 19 ～ 25 mm. The soil arching effect existed within the embankment. The height of soil arching was about 0. 83 ～ 1. 04 times the pile clear spacing. The average height of soil aching was about 0. 94 times the pile clear spacing. The differential settlement was closely related to soil arching effect,and the differential settlement was the prerequisite to produce soil arching.
In order to investigate the working mechanism of reinforced pile-supported foundation,field tests in Shenzhen Airport Apron had been performed. The test results of settlement and pore water pressure were analyzed and compared in detail. The results showed that the reinforced pile-supported foundation could reduce the total settlements and differential settlements,the differential settlements were 19 ～ 25 mm. The soil arching effect existed within the embankment. The height of soil arching was about 0. 83 ～ 1. 04 times the pile clear spacing. The average height of soil aching was about 0. 94 times the pile clear spacing. The differential settlement was closely related to soil arching effect,and the differential settlement was the prerequisite to produce soil arching.
2012, 42(4): 99-102.
doi: 10.13204/j.gyjz201204021
Abstract:
Taking Zhejiang Taizhou mucky clay as the research object,PAM was added on the basis of cement,lime and fly ash,SEM observations were designed to remolding soil samples of the mucky clay,the mucky clay without PAM,the remolding soil with PAM,in order to study the influence of PAM and inorganic materials on the remolding clay pore structure. And curing agent changes in the silt clay pore structure was studied by computer image processing technique. The results of the study showed that links between the clay particles were strengthened and structural stability was improved by curing agent. Finally,the quantitative analysis was done about the perimeter ( such as image gap and the total area,etc) by MATLAB,it was found that natural porosity ratio of mucky clay was larger,the mucky clay with PAM was smaller. So the mucky clay with PAM and inorganic materials had a better reinforcement effect than the mucky clay with inorganic materials only.
Taking Zhejiang Taizhou mucky clay as the research object,PAM was added on the basis of cement,lime and fly ash,SEM observations were designed to remolding soil samples of the mucky clay,the mucky clay without PAM,the remolding soil with PAM,in order to study the influence of PAM and inorganic materials on the remolding clay pore structure. And curing agent changes in the silt clay pore structure was studied by computer image processing technique. The results of the study showed that links between the clay particles were strengthened and structural stability was improved by curing agent. Finally,the quantitative analysis was done about the perimeter ( such as image gap and the total area,etc) by MATLAB,it was found that natural porosity ratio of mucky clay was larger,the mucky clay with PAM was smaller. So the mucky clay with PAM and inorganic materials had a better reinforcement effect than the mucky clay with inorganic materials only.
2012, 42(4): 103-106.
doi: 10.13204/j.gyjz201204022
Abstract:
It was investigated that the effects of Polyvinyl Alcohol ( PVA) fiber on the workability,mechanical properties and impermeability of concrete. The influences of PVA and Polypropylene ( PP) fiber on the plastic shrinkage crack of mortar were also studied. Results show that PVA fiber has no negative effect on the workability in a certain range,but exerts an adverse effect when the addition is up to 6. 5 kg/cm 3. The PVA fiber in concrete can improve the compressive strength performance,especially the splitting tensile strength of concrete. When PVA and PP fibers are mixed into cement-based materials,crack resistance and impermeability are effectively improved.
It was investigated that the effects of Polyvinyl Alcohol ( PVA) fiber on the workability,mechanical properties and impermeability of concrete. The influences of PVA and Polypropylene ( PP) fiber on the plastic shrinkage crack of mortar were also studied. Results show that PVA fiber has no negative effect on the workability in a certain range,but exerts an adverse effect when the addition is up to 6. 5 kg/cm 3. The PVA fiber in concrete can improve the compressive strength performance,especially the splitting tensile strength of concrete. When PVA and PP fibers are mixed into cement-based materials,crack resistance and impermeability are effectively improved.
2012, 42(4): 107-112.
doi: 10.13204/j.gyjz201204023
Abstract:
Based on the Asian Games engineering pipe-jacking construction,key construction technologies were systematically analyzed and researched from mud balance pipe-jacking of reinforced concrete pipe with large-diameter and long-distance in soft soil,including high precision rectifying deviation,resistance reduction by efficient grouting, pipe-jacking construction,monitoring and measurement,etc. Using infrared tracking and positioning technology,with the help of deviation chart correction method,it was done the correction timely and efficiently,ensuring the direction of the route and elevation of high precision. Using the good performance of bentonite and new polymer,high expansion rate of the grouting material,it was modified grouting technology,thus changing the sliding friction into rolling friction. The frictional resistance and total jacking force were reduced by about 43%,the number of relay was reduced. These difficulties were solved by the construction technologies and control methods finally,obtaining excellent economic and social benefits.
Based on the Asian Games engineering pipe-jacking construction,key construction technologies were systematically analyzed and researched from mud balance pipe-jacking of reinforced concrete pipe with large-diameter and long-distance in soft soil,including high precision rectifying deviation,resistance reduction by efficient grouting, pipe-jacking construction,monitoring and measurement,etc. Using infrared tracking and positioning technology,with the help of deviation chart correction method,it was done the correction timely and efficiently,ensuring the direction of the route and elevation of high precision. Using the good performance of bentonite and new polymer,high expansion rate of the grouting material,it was modified grouting technology,thus changing the sliding friction into rolling friction. The frictional resistance and total jacking force were reduced by about 43%,the number of relay was reduced. These difficulties were solved by the construction technologies and control methods finally,obtaining excellent economic and social benefits.
2012, 42(4): 113-117.
doi: 10.13204/j.gyjz201204024
Abstract:
Prestressed steel reinforced concrete structure(PSRC) is a composite structure,which has advantage of both prestressed reinforced concrete structure and reinforced concrete structure. In this paper,development of prestressed reinforced concrete structure in China is introduced and research way of prestressed reinforced concrete structure is presented. Then several problems during the study about integral analysis and single member analysis are summarized. The development of tendency of this type of structure is prospected.
Prestressed steel reinforced concrete structure(PSRC) is a composite structure,which has advantage of both prestressed reinforced concrete structure and reinforced concrete structure. In this paper,development of prestressed reinforced concrete structure in China is introduced and research way of prestressed reinforced concrete structure is presented. Then several problems during the study about integral analysis and single member analysis are summarized. The development of tendency of this type of structure is prospected.
2012, 42(4): 118-122,142.
doi: 10.13204/j.gyjz201204025
Abstract:
Cumulated damage theory based on existing earthquake regarding the structure,structural element members and materials is presented. From damage index perspective,it is analyzed comparatively that the merits and demerits of the classical theoretical model. It is provided recommendations for study on further revealing the mechanism of earthquake damage.
Cumulated damage theory based on existing earthquake regarding the structure,structural element members and materials is presented. From damage index perspective,it is analyzed comparatively that the merits and demerits of the classical theoretical model. It is provided recommendations for study on further revealing the mechanism of earthquake damage.
2012, 42(4): 123-130,30.
doi: 10.13204/j.gyjz201204026
Abstract:
Based on the wind-tunnel test of rigid model of Jilin Railway Station,the mean and fluctuating pressure coefficients,the lift coefficients of the roof were presented and discussed with and without the surrounding buildings. Analyses of the characteristics of the local shape coefficient distributions and wind-induced responses were conducted. It was found that negative pressures (suctions) occurred on the railway station roof in general,the values of the lift coefficients of the roof were negative,and high negative pressure coefficients occurred on the eaves,cantilevered roof and the bulge part of the roof on the main station building. Relatively smaller suctions occurred on the platform awnings of the station because of open surrounding configurations there. The surrounding buildings have some shielding effect on the local shape coefficients of the roof,but can not ignore the situation where they are increased in some areas. Wind-induced responses were significant on the corner of platform awnings,cantilevered roof and the bulge part of the roof. The conclusions obtained from this study are expected to be useful in the wind-resistant design of long-span steel roof structures with complex shapes.
Based on the wind-tunnel test of rigid model of Jilin Railway Station,the mean and fluctuating pressure coefficients,the lift coefficients of the roof were presented and discussed with and without the surrounding buildings. Analyses of the characteristics of the local shape coefficient distributions and wind-induced responses were conducted. It was found that negative pressures (suctions) occurred on the railway station roof in general,the values of the lift coefficients of the roof were negative,and high negative pressure coefficients occurred on the eaves,cantilevered roof and the bulge part of the roof on the main station building. Relatively smaller suctions occurred on the platform awnings of the station because of open surrounding configurations there. The surrounding buildings have some shielding effect on the local shape coefficients of the roof,but can not ignore the situation where they are increased in some areas. Wind-induced responses were significant on the corner of platform awnings,cantilevered roof and the bulge part of the roof. The conclusions obtained from this study are expected to be useful in the wind-resistant design of long-span steel roof structures with complex shapes.
2012, 42(4): 131-135.
doi: 10.13204/j.gyjz201204027
Abstract:
Support structure system of air cooled condenser is an important component in a thermal power plant,the security of the structure directly related to the normal operation of the power plant. Spatial steel truss-reinforced concrete pipe column vertical hybrid structure, whose stiffness and mass is badly non-uniform at vertical direction, is used in the traditional 300 MW and 600 MW unit thermal power plants. Compared with the 300 MW and 600MW unit power plants,processing set-up and support structure have changed in 1 000 MW unit power plant,the risk that caused by deterioration of the structure is fearful. Because of the torsional effect and the coupling effect between the modes are obvious in this kind of structure,multidimensional earthquake response analysis,in which torsional components of ground motion is considered,is put forward in this paper to study the force transmission mechanism. Research results show that lateral-torsional coupled seismic design should be considered severely in this kind of vertical hybrid structure.
Support structure system of air cooled condenser is an important component in a thermal power plant,the security of the structure directly related to the normal operation of the power plant. Spatial steel truss-reinforced concrete pipe column vertical hybrid structure, whose stiffness and mass is badly non-uniform at vertical direction, is used in the traditional 300 MW and 600 MW unit thermal power plants. Compared with the 300 MW and 600MW unit power plants,processing set-up and support structure have changed in 1 000 MW unit power plant,the risk that caused by deterioration of the structure is fearful. Because of the torsional effect and the coupling effect between the modes are obvious in this kind of structure,multidimensional earthquake response analysis,in which torsional components of ground motion is considered,is put forward in this paper to study the force transmission mechanism. Research results show that lateral-torsional coupled seismic design should be considered severely in this kind of vertical hybrid structure.
2012, 42(4): 136-142.
doi: 10.13204/j.gyjz201204028
Abstract:
Lateral displacement of the top flange of purlins is prevented by self-drilled screw connections between roof sheet and purlin. Such connected cold-formed Z-shaped cross section purlins,with no anti-sag bars,was analyzed for stress and deformation under the suction effect of wind,using the theory of thin-walled bars. The results are found to be in excellent agreement with results of ANSYS shell element calculations and the method in EC3. Further analysis revealed that the horizontal notional load at the bottom flange introduced in EC3' s approach,consists of two parts:1) one is to replace the torque generated by load not passing through the shear center,2)the other is to offset the horizontal moment caused by the simplified calculation of stress around parallel axis.
Lateral displacement of the top flange of purlins is prevented by self-drilled screw connections between roof sheet and purlin. Such connected cold-formed Z-shaped cross section purlins,with no anti-sag bars,was analyzed for stress and deformation under the suction effect of wind,using the theory of thin-walled bars. The results are found to be in excellent agreement with results of ANSYS shell element calculations and the method in EC3. Further analysis revealed that the horizontal notional load at the bottom flange introduced in EC3' s approach,consists of two parts:1) one is to replace the torque generated by load not passing through the shear center,2)the other is to offset the horizontal moment caused by the simplified calculation of stress around parallel axis.
2012, 42(4): 143-146,64.
doi: 10.13204/j.gyjz201204029
Abstract:
In order to meet the using demands, one and a half stories were added on the original office building of a police station in Guilin. Treatment methods were used to reinforce and reconstruct the building on the basis of preserving the original structures,such as strengthening foundation,setting foundation outrigger,adding pilaster, increasing section etc. Meanwhile,it is more convenient and faster to set ledger beam in the original slope roof for leveling to ensure a certain distance between beam bottom and the original roof under construction,to avoid the additional load of the beam to the original roof directly,and it is also done the analysis and check of the foundation bearing capacity and settlement. Through a series of effective reinforcement measures,after the transformation all indexes of the building meet the current specification requirements,now it has been used for two years,the using effect is good.
In order to meet the using demands, one and a half stories were added on the original office building of a police station in Guilin. Treatment methods were used to reinforce and reconstruct the building on the basis of preserving the original structures,such as strengthening foundation,setting foundation outrigger,adding pilaster, increasing section etc. Meanwhile,it is more convenient and faster to set ledger beam in the original slope roof for leveling to ensure a certain distance between beam bottom and the original roof under construction,to avoid the additional load of the beam to the original roof directly,and it is also done the analysis and check of the foundation bearing capacity and settlement. Through a series of effective reinforcement measures,after the transformation all indexes of the building meet the current specification requirements,now it has been used for two years,the using effect is good.
2012, 42(4): 147-149,112.
doi: 10.13204/j.gyjz201204030
Abstract:
It is presented that the project of Wanda Plaza of Finance Street in Fuzhou and its design concept. Wanda Plaza of Finance Street in Fuzhou positioned as a high-end leisure and business complex with simple,modern design style for the tone of the atmosphere,displays the spirit of Wanda' s unique corporate culture.
It is presented that the project of Wanda Plaza of Finance Street in Fuzhou and its design concept. Wanda Plaza of Finance Street in Fuzhou positioned as a high-end leisure and business complex with simple,modern design style for the tone of the atmosphere,displays the spirit of Wanda' s unique corporate culture.
2012, 42(4): 150-152,157.
doi: 10.13204/j.gyjz201204031
Abstract:
Gallery,as an architectural type and symbol has extensive application in the practice of China modern architecture. It is summarized four related design approaches and proposed a regional architectural design concept of Gallery,which are demonstrated by relevant project examples.
Gallery,as an architectural type and symbol has extensive application in the practice of China modern architecture. It is summarized four related design approaches and proposed a regional architectural design concept of Gallery,which are demonstrated by relevant project examples.
2012, 42(4): 153-157.
doi: 10.13204/j.gyjz201204032
Abstract:
This design of subway space' s information point layout is taken design as the core problem,by using environmental psychology and behavior psychology as the main theoretical basis,and combining the Xi' an metro' s logo-oriented design in practical application of project. In the mastery of subway integral space environment feature, the model and questionnaire are used on basis of sampling to evaluate and analyze area,node,use of population human scale and wayfinding behavior habit comprehensively. Whose purpose is to improve the design of a guiding sign system design for the greatest convenience functions and explore a feasible train of thought and method,which can provide a certain positive significance for guiding a user familiar with the subway space.
This design of subway space' s information point layout is taken design as the core problem,by using environmental psychology and behavior psychology as the main theoretical basis,and combining the Xi' an metro' s logo-oriented design in practical application of project. In the mastery of subway integral space environment feature, the model and questionnaire are used on basis of sampling to evaluate and analyze area,node,use of population human scale and wayfinding behavior habit comprehensively. Whose purpose is to improve the design of a guiding sign system design for the greatest convenience functions and explore a feasible train of thought and method,which can provide a certain positive significance for guiding a user familiar with the subway space.
