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2010 Vol. 40, No. 11
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2010, 40(11): 1-5,31.
doi: 10.13204/j.gyjz201011001
Abstract:
The diffusion performance of chloride ion in concrete under the coupling action of dynamic load and environment was researched by a new set of experimental mechanism.The experiment was composed of study on saturated performance of concrete,diffusion performance of chloride ion with different stress levels and under coupling action of dynamic load and temperature.The results showed that the transport mechanism of chloride ion in concrete accounted with diffusion due to the 99% of degree of saturation of concrete;diffusion coefficient of chloride ion was increased with the stress level and temperature increase;and the activation energy for chloride diffusion was 19.9 kJ / mol;life of reinforced concrete bridge was 89.1 years obtained by the model of life prediction of reinforced concrete.
The diffusion performance of chloride ion in concrete under the coupling action of dynamic load and environment was researched by a new set of experimental mechanism.The experiment was composed of study on saturated performance of concrete,diffusion performance of chloride ion with different stress levels and under coupling action of dynamic load and temperature.The results showed that the transport mechanism of chloride ion in concrete accounted with diffusion due to the 99% of degree of saturation of concrete;diffusion coefficient of chloride ion was increased with the stress level and temperature increase;and the activation energy for chloride diffusion was 19.9 kJ / mol;life of reinforced concrete bridge was 89.1 years obtained by the model of life prediction of reinforced concrete.
2010, 40(11): 6-8.
doi: 10.13204/j.gyjz201011002
Abstract:
From the entire process of deteriorated performance of bending fatigue damage,combined with residual strain and accumulated energy release,the second linear and steadily developing phase was described,which almost occupies 80% of the whole fatigue life.Aimed at the second phase of fatigue damage,the durability of structural concrete under the effect of multi-factors of fatigue loading and environmental factors was investigated mainly in the paper.As the residual strain exceeds 60 10-6,both the diffusion coefficient of chloride ion and the air permeability coefficient increased with the increment of residual strain.Especially,when the residual strain is 120 10-6,the corresponding coefficient raised 10 times.In the case of freeze-thaw cycles,there is also the same tendency.Therefore,the values of residual strain from 30 10-6-60 10-6 and its 120 10-6 are considered as the starting range and the accelerating point of affecting the durability of structural concrete,respectively.
From the entire process of deteriorated performance of bending fatigue damage,combined with residual strain and accumulated energy release,the second linear and steadily developing phase was described,which almost occupies 80% of the whole fatigue life.Aimed at the second phase of fatigue damage,the durability of structural concrete under the effect of multi-factors of fatigue loading and environmental factors was investigated mainly in the paper.As the residual strain exceeds 60 10-6,both the diffusion coefficient of chloride ion and the air permeability coefficient increased with the increment of residual strain.Especially,when the residual strain is 120 10-6,the corresponding coefficient raised 10 times.In the case of freeze-thaw cycles,there is also the same tendency.Therefore,the values of residual strain from 30 10-6-60 10-6 and its 120 10-6 are considered as the starting range and the accelerating point of affecting the durability of structural concrete,respectively.
2010, 40(11): 9-12.
doi: 10.13204/j.gyjz201011003
Abstract:
This paper selects 4 factors(mass of binder,proportion of fly ash(FA),proportion of Granulated blast furnace slag(SL),water to binder ratio(W /B)) and 3 levels for each factor,then an orthogonal test table(L9(34)) is used to respectively analyse the compressive strength of 10 d and 28 d.The results show that the proportion of FA is the first main factor to affect the compression strength of early age(10 d) concrete.The W /B is the second factor.But for 28 d concrete,the W /B is the first main factor and the mass of binder is the second factor.For all of the test ages,the proportion of SL has the least effect on the compressive strength.According to the analysis result and the need of engineering,it has been designed a concrete mix sufficient to meet a standard requirement and construction need.
This paper selects 4 factors(mass of binder,proportion of fly ash(FA),proportion of Granulated blast furnace slag(SL),water to binder ratio(W /B)) and 3 levels for each factor,then an orthogonal test table(L9(34)) is used to respectively analyse the compressive strength of 10 d and 28 d.The results show that the proportion of FA is the first main factor to affect the compression strength of early age(10 d) concrete.The W /B is the second factor.But for 28 d concrete,the W /B is the first main factor and the mass of binder is the second factor.For all of the test ages,the proportion of SL has the least effect on the compressive strength.According to the analysis result and the need of engineering,it has been designed a concrete mix sufficient to meet a standard requirement and construction need.
2010, 40(11): 13-14,12.
doi: 10.13204/j.gyjz201011004
Abstract:
By analyzing the process of temperature rising CRTSⅡ track board concrete in the conditions of different construction ambient temperature,different mineral admixture,and different concrete mix,it is put forward the measures for speeding up the tensioning of reinforced concrete,shortening ejection time of concrete and improving the economic efficiency of enterprises.
By analyzing the process of temperature rising CRTSⅡ track board concrete in the conditions of different construction ambient temperature,different mineral admixture,and different concrete mix,it is put forward the measures for speeding up the tensioning of reinforced concrete,shortening ejection time of concrete and improving the economic efficiency of enterprises.
2010, 40(11): 15-17.
doi: 10.13204/j.gyjz201011005
Abstract:
It is studied the influence of fly ash,granulated blast furnace slag and high early admixtures on compressive strength of concrete.The results of experiments show that high early admixtures can promote the early strength and the elastic modulus to satisfy the design standard.But the creep of concrete will be doubled when loading at early age,Based on the conclusion of this paper,it is suggested that the tension of reinforcement should be pressesed later,so as to guarantee the quality of the prestressed members.
It is studied the influence of fly ash,granulated blast furnace slag and high early admixtures on compressive strength of concrete.The results of experiments show that high early admixtures can promote the early strength and the elastic modulus to satisfy the design standard.But the creep of concrete will be doubled when loading at early age,Based on the conclusion of this paper,it is suggested that the tension of reinforcement should be pressesed later,so as to guarantee the quality of the prestressed members.
EXPERIMENTAL RESEARCH ON HRBF500 HIGH STRENGTH RC BEAMS FOR HIGH SPEED RAILWAY UNDER FATIGUE LOADING
2010, 40(11): 18-21,26.
doi: 10.13204/j.gyjz201011006
Abstract:
The study on fatigue properties of HRBF500 high strength reinforced concrete structures is rarely reported.The two rectangle and two T-section HRBF500 R C beams are designed and produced.And the static loading and fatigue experiments are conducted on these specimens.Based on the experimental results,the tensile strain of the steel,midspan deflection and the cracks developing law are analyzed under the static loading on the specimen with different cross-section and steel ratio.The mechanical properties of the beams are evaluated when the steel stress is over 150 MPa under fatigue experiment.The test result shows that the maximum fatigue load and amplitude are the main factors to decide if fatigue failure would occur on the beam.
The study on fatigue properties of HRBF500 high strength reinforced concrete structures is rarely reported.The two rectangle and two T-section HRBF500 R C beams are designed and produced.And the static loading and fatigue experiments are conducted on these specimens.Based on the experimental results,the tensile strain of the steel,midspan deflection and the cracks developing law are analyzed under the static loading on the specimen with different cross-section and steel ratio.The mechanical properties of the beams are evaluated when the steel stress is over 150 MPa under fatigue experiment.The test result shows that the maximum fatigue load and amplitude are the main factors to decide if fatigue failure would occur on the beam.
2010, 40(11): 22-26.
doi: 10.13204/j.gyjz201011007
Abstract:
In this paper,two high-strength prestressed concrete T girders with HRBF500 steel bar have been designed and made.To compare the measured values and the theoretical values of prestress losses,the measured values of prestress losses are more than its theoretical values.Based on the test result under fatigue load,load-stress curves of HRBF500 steel bar and prestressed steel bar and midspan deflection curves of 2 girders are drawn out,and the fatigue performance of high-strength prestressed concrete girder with HRBF500 steel bar is studied.The result shows that HRBF500 steel bar,prestressing strand and midspan deflection in the girders meet the limits of service stage.It also means that the fatigue performance of the prestressed concrete girders with HRBF500 steel bar can still satisfy design requirements after 2.5 millions circles amplitude fatigue loads on the condition that tensile stress of HRBF500 steel bar is more than 150 MPa.
In this paper,two high-strength prestressed concrete T girders with HRBF500 steel bar have been designed and made.To compare the measured values and the theoretical values of prestress losses,the measured values of prestress losses are more than its theoretical values.Based on the test result under fatigue load,load-stress curves of HRBF500 steel bar and prestressed steel bar and midspan deflection curves of 2 girders are drawn out,and the fatigue performance of high-strength prestressed concrete girder with HRBF500 steel bar is studied.The result shows that HRBF500 steel bar,prestressing strand and midspan deflection in the girders meet the limits of service stage.It also means that the fatigue performance of the prestressed concrete girders with HRBF500 steel bar can still satisfy design requirements after 2.5 millions circles amplitude fatigue loads on the condition that tensile stress of HRBF500 steel bar is more than 150 MPa.
2010, 40(11): 27-31.
doi: 10.13204/j.gyjz201011008
Abstract:
Tests were conducted on high temperature properties of normal strength high-performance concrete to explore its explosive spalling and mechanical properties at high temperature,to ensure satisfactory fire resistance of concrete structures.The results reveal that both moisture content and density are the two main factors influencing the spalling.When moisture content is over a critical value,the higher the moisture content,the more the spalling frequency.The more dense the concrete,the greater the degree of spalling.Polypropylene fiber at a volume fraction of 0.05 % can prohibit the occurrence of spalling of normal strength high-performance concrete.Moreover,the higher the fiber dosage,the less the thermal damage.Polypropylene fiber has also improvement in residual mechanical properties of concrete subjected to high temperature.
Tests were conducted on high temperature properties of normal strength high-performance concrete to explore its explosive spalling and mechanical properties at high temperature,to ensure satisfactory fire resistance of concrete structures.The results reveal that both moisture content and density are the two main factors influencing the spalling.When moisture content is over a critical value,the higher the moisture content,the more the spalling frequency.The more dense the concrete,the greater the degree of spalling.Polypropylene fiber at a volume fraction of 0.05 % can prohibit the occurrence of spalling of normal strength high-performance concrete.Moreover,the higher the fiber dosage,the less the thermal damage.Polypropylene fiber has also improvement in residual mechanical properties of concrete subjected to high temperature.
2010, 40(11): 32-35,42.
doi: 10.13204/j.gyjz201011009
Abstract:
The strength development law of normal weight,combined aggregate and lightweight aggregate concretes as well as the internal relative humidity of concrete under different curing conditions were studied.The results show that,under outdoor natural curing condition,the strength of normal weight concrete has little increase after 28d.Under standard curing condition,the concrete with low water-cement ratio containing ceramsite has higher growth rate of long-term strength.Under water curing condition,the contribution of self-curing effect of ceramsite to the growth of the concrete strength is lower.
The strength development law of normal weight,combined aggregate and lightweight aggregate concretes as well as the internal relative humidity of concrete under different curing conditions were studied.The results show that,under outdoor natural curing condition,the strength of normal weight concrete has little increase after 28d.Under standard curing condition,the concrete with low water-cement ratio containing ceramsite has higher growth rate of long-term strength.Under water curing condition,the contribution of self-curing effect of ceramsite to the growth of the concrete strength is lower.
2010, 40(11): 36-38,97.
doi: 10.13204/j.gyjz201011010
Abstract:
The core idea of architectural design is the harmony betweenpermanentandchange.A locality can reach to an overallPermanentstate through itschange.The educational buildings rebuilt after disaster are local and provisional,yet nature and society before us are systemic and permanent.Andchangeis the normal state of nature.So we must not only solve the urgent problems efficienty,but also adapt thepermanentchange of nature and society.Both the traditional standardization production or contemporary individuation design cannot solve this problem perfectly.So the scheme summarizes the advantages of both ways.It is organized standardization production with variable ideas,and formed the always-change whole nature with unchange units,which can gain more natural and social benefits.
The core idea of architectural design is the harmony betweenpermanentandchange.A locality can reach to an overallPermanentstate through itschange.The educational buildings rebuilt after disaster are local and provisional,yet nature and society before us are systemic and permanent.Andchangeis the normal state of nature.So we must not only solve the urgent problems efficienty,but also adapt thepermanentchange of nature and society.Both the traditional standardization production or contemporary individuation design cannot solve this problem perfectly.So the scheme summarizes the advantages of both ways.It is organized standardization production with variable ideas,and formed the always-change whole nature with unchange units,which can gain more natural and social benefits.
2010, 40(11): 39-42.
doi: 10.13204/j.gyjz201011011
Abstract:
Solid clay bricks as the main building material were widely used in the rural dwellings in North Henan Province,but their production process destroys the land seriously and their energy consumption is so large,so there is a new research direction to find a new building material to take the place of solid clay bricks.In this paper,the straw bale is analyzed in terms of raw materials,thermal properties,environmental protection,manufacturing energy consumption etc,and the the prospects of straw-bales in the rural dwellings in North Henan is analyzed in combination with other energy-saving technologies.In the end,it is concluded that straw-bale building is a energy-efficient building along with benefits of society,economy and environment and has good application prospects in the rural dwellings in North Henan Province.
Solid clay bricks as the main building material were widely used in the rural dwellings in North Henan Province,but their production process destroys the land seriously and their energy consumption is so large,so there is a new research direction to find a new building material to take the place of solid clay bricks.In this paper,the straw bale is analyzed in terms of raw materials,thermal properties,environmental protection,manufacturing energy consumption etc,and the the prospects of straw-bales in the rural dwellings in North Henan is analyzed in combination with other energy-saving technologies.In the end,it is concluded that straw-bale building is a energy-efficient building along with benefits of society,economy and environment and has good application prospects in the rural dwellings in North Henan Province.
2010, 40(11): 43-46.
doi: 10.13204/j.gyjz201011012
Abstract:
It has been explored mainly the utilization measures for overall energy-saving of industrial architectoues and process production by taking external walls,doors,windows and roofs etc of industrial architectures for example,according to the anulysis of overall energy-saving measures for water,electicity,coal and gas etc of process production eguipments,It has been shown the evident effect,huge p;otenteal and bright future of overall energy-saving of industrial enterprises.It is expected to set up the unified standard of relevant energy-saving specifications of industrial enterprises in China,thus forming a husiness conception,which will make the energy-saving industries of industrial enterprises obtain good economic,social and environmental benefits.
It has been explored mainly the utilization measures for overall energy-saving of industrial architectoues and process production by taking external walls,doors,windows and roofs etc of industrial architectures for example,according to the anulysis of overall energy-saving measures for water,electicity,coal and gas etc of process production eguipments,It has been shown the evident effect,huge p;otenteal and bright future of overall energy-saving of industrial enterprises.It is expected to set up the unified standard of relevant energy-saving specifications of industrial enterprises in China,thus forming a husiness conception,which will make the energy-saving industries of industrial enterprises obtain good economic,social and environmental benefits.
2010, 40(11): 47-50.
doi: 10.13204/j.gyjz201011013
Abstract:
According to the experimental investigation on ten specimens of interior joints with different depth beams under low cyclic reversed loading,the failure process and failure patterns were obtained.The experimental study was conducted that focused on the effect of vertical beam depth eccentricity on seismic behavior of the joint.Test results indicated that vertical beam depth eccentricity had an obvious effect on seismic behavior of the beam-column subassemblage.With the increasing of vertical beam depth eccentricity,the shear force of the joint increased gradually until reached its peak,and then decreased gradually;when vertical beam eccentricity was greater than the column section height,an exterior joint model would be better for this case analysis.According to the relative relation between the height of column and the vertical depth eccentricity of beam,the abnormal joints can be divided into two types,and the suggested formulas for characteristic calculation of the joints are also put forward.
According to the experimental investigation on ten specimens of interior joints with different depth beams under low cyclic reversed loading,the failure process and failure patterns were obtained.The experimental study was conducted that focused on the effect of vertical beam depth eccentricity on seismic behavior of the joint.Test results indicated that vertical beam depth eccentricity had an obvious effect on seismic behavior of the beam-column subassemblage.With the increasing of vertical beam depth eccentricity,the shear force of the joint increased gradually until reached its peak,and then decreased gradually;when vertical beam eccentricity was greater than the column section height,an exterior joint model would be better for this case analysis.According to the relative relation between the height of column and the vertical depth eccentricity of beam,the abnormal joints can be divided into two types,and the suggested formulas for characteristic calculation of the joints are also put forward.
2010, 40(11): 51-54,64.
doi: 10.13204/j.gyjz201011014
Abstract:
Shear failure occurs easily on SRC-RC transfer columns,which looks like failure pattern of short RC column,shear crack runs through the whole reinforced concrete.Shear pattern and failure mechanism are analyzed based on established shear model of SRC-RC transfer column which comes from 9 specimens,including 7 SRC-RC transfer columns and 2 RC columns,all specimens are tested under low cyclic reversed loading.Hysteretic performance of SRC-RC transfer columns with shear cracking failure show serious pinch effect,rigidity dearades rapidly with increasing amount of cycles.More stirrups can improve the seismic resistance performance of SRC-RC transfer columns,the shear capacity and displacement ductility of SRC-RC transfer columns are better than those of RC columns.
Shear failure occurs easily on SRC-RC transfer columns,which looks like failure pattern of short RC column,shear crack runs through the whole reinforced concrete.Shear pattern and failure mechanism are analyzed based on established shear model of SRC-RC transfer column which comes from 9 specimens,including 7 SRC-RC transfer columns and 2 RC columns,all specimens are tested under low cyclic reversed loading.Hysteretic performance of SRC-RC transfer columns with shear cracking failure show serious pinch effect,rigidity dearades rapidly with increasing amount of cycles.More stirrups can improve the seismic resistance performance of SRC-RC transfer columns,the shear capacity and displacement ductility of SRC-RC transfer columns are better than those of RC columns.
2010, 40(11): 55-58.
doi: 10.13204/j.gyjz201011015
Abstract:
New type of two-way concrete composite slab with precast prestressed ribbed panel(including preparative holes in the rib) is put forward to solve the problems in traditional prestressed concrete composite floor.Based on the particular structural feature and integral action between precast ribbed panel and combined interface concrete two-way effects are proposed.The finite element analysis by ANSYS10.0 program is conducted.The existence and the variation tendency of two-way effects under the loads in different conditions are researched by large numbers of models,which provides a basis for the further investigation on property of the floor structure.
New type of two-way concrete composite slab with precast prestressed ribbed panel(including preparative holes in the rib) is put forward to solve the problems in traditional prestressed concrete composite floor.Based on the particular structural feature and integral action between precast ribbed panel and combined interface concrete two-way effects are proposed.The finite element analysis by ANSYS10.0 program is conducted.The existence and the variation tendency of two-way effects under the loads in different conditions are researched by large numbers of models,which provides a basis for the further investigation on property of the floor structure.
2010, 40(11): 59-64.
doi: 10.13204/j.gyjz201011016
Abstract:
It was conducted the construction monitoring and load test of the national first highway concrete bridge externally prestressed with CFRP tendons,the test results show that concrete cracks can be eliminated or reduced significantly produced at the stage of frames removal,and thus the service behavior of girders are improved due to tension of CFRP tendons.In each test case,girders performed elastically with its strain varying at a linear phase;moreover,the testing force increment of external CFRP tendons was consistent with the theoretical values.All these suggest the concrete girder and external CFRP tendons may serve together in a good pace.In addition,no wear signs and any other defects have been founded at the shift block as well as the anchors.Therefore,all these proved that external prestressed CFRP tendons with a fold line layout can be applied for concrete girders with a good performance.
It was conducted the construction monitoring and load test of the national first highway concrete bridge externally prestressed with CFRP tendons,the test results show that concrete cracks can be eliminated or reduced significantly produced at the stage of frames removal,and thus the service behavior of girders are improved due to tension of CFRP tendons.In each test case,girders performed elastically with its strain varying at a linear phase;moreover,the testing force increment of external CFRP tendons was consistent with the theoretical values.All these suggest the concrete girder and external CFRP tendons may serve together in a good pace.In addition,no wear signs and any other defects have been founded at the shift block as well as the anchors.Therefore,all these proved that external prestressed CFRP tendons with a fold line layout can be applied for concrete girders with a good performance.
2010, 40(11): 65-69.
doi: 10.13204/j.gyjz201011017
Abstract:
Based on the experiment of six simply supported reinforced concrete beams strengthened with pre-stressed inclined stirrups and one contrastive beam,the failure process was observed.The results indicate that the strengthened way used in this paper increased the shear bearing capacity of these specimens: crack load and limit load of the beam has been increased in different degree.And the strengthened beamsshear-crack width was certainly limited.The strut-arch model is used to study the pre-stressed inclined stirrups strengthened beams,and a formula is presented.The formulas for calculating cracking load and shear capacity of reinforced concrete beams with different strengthening cases strengthened by pre-stressed inclined stirrups are proposed through regression analysis of experiment data,and the calculated results coincidence well with the experiment results.
Based on the experiment of six simply supported reinforced concrete beams strengthened with pre-stressed inclined stirrups and one contrastive beam,the failure process was observed.The results indicate that the strengthened way used in this paper increased the shear bearing capacity of these specimens: crack load and limit load of the beam has been increased in different degree.And the strengthened beamsshear-crack width was certainly limited.The strut-arch model is used to study the pre-stressed inclined stirrups strengthened beams,and a formula is presented.The formulas for calculating cracking load and shear capacity of reinforced concrete beams with different strengthening cases strengthened by pre-stressed inclined stirrups are proposed through regression analysis of experiment data,and the calculated results coincidence well with the experiment results.
2010, 40(11): 70-74.
doi: 10.13204/j.gyjz201011018
Abstract:
The shear carrying capacity experiment of Z-shaped column was carried out,through the synthetic analysis of both crack expanding condition and failure modes,the shear failure mechanism and shear failure law were studied,it was obfained the effect of the factors,such as axial compression ratio,shear span ratio,stirrup reinforcement ratio and ratio of section height to section thickness of column 1eg,which affected the shear carrying capacity and ductility capacity of Z-shaped column.And based on the results of the experiment,the regression formula,the formula for the structure design and some suggestions on design of practical projects were presented,which provided a reference for structure designer.
The shear carrying capacity experiment of Z-shaped column was carried out,through the synthetic analysis of both crack expanding condition and failure modes,the shear failure mechanism and shear failure law were studied,it was obfained the effect of the factors,such as axial compression ratio,shear span ratio,stirrup reinforcement ratio and ratio of section height to section thickness of column 1eg,which affected the shear carrying capacity and ductility capacity of Z-shaped column.And based on the results of the experiment,the regression formula,the formula for the structure design and some suggestions on design of practical projects were presented,which provided a reference for structure designer.
2010, 40(11): 75-80.
doi: 10.13204/j.gyjz201011019
Abstract:
Different from normal tunnel,the deformation characteristics of the multi-arch tunnel are more complex because of complex construction processes and many construction conversions.Based on the multi-arch tunnel project,the monitoring of support system deformation was carried out.And the law of the deformation developing with time and deformation characteristic of different construction procedures was analyzed.The surrounding rock deformation could be better controlled by using the bench method.Under construction of tunnel,the excavation of the upper bench and the down bench of the right drift has a great effect on surrounding rock deformation.So they are the main stages to control the support structure deformation.The longitudinal incidence of the excavation of the upper bench in the left tunnel and the down bench of the right tunnel is about two times of the span of the tunnel.And the incidence of the down bench in the left tunnel and the upper bench of the right tunnel is about the span of the tunnel.
Different from normal tunnel,the deformation characteristics of the multi-arch tunnel are more complex because of complex construction processes and many construction conversions.Based on the multi-arch tunnel project,the monitoring of support system deformation was carried out.And the law of the deformation developing with time and deformation characteristic of different construction procedures was analyzed.The surrounding rock deformation could be better controlled by using the bench method.Under construction of tunnel,the excavation of the upper bench and the down bench of the right drift has a great effect on surrounding rock deformation.So they are the main stages to control the support structure deformation.The longitudinal incidence of the excavation of the upper bench in the left tunnel and the down bench of the right tunnel is about two times of the span of the tunnel.And the incidence of the down bench in the left tunnel and the upper bench of the right tunnel is about the span of the tunnel.
2010, 40(11): 81-84.
doi: 10.13204/j.gyjz201011020
Abstract:
According to the distribution character of ion consistency in ground water and the purpose of changing soil strength,samplings of soil and ground water experiments were executed to carry through statistic and analysis of soil strength,which were made up of chemical action of water-soil and mechanics experiments.The results show the weakened effect occurs on soil cohesion with Ca2 +,HCO 3-,K + and Na + consistency change in ground water and Cl-consistency change is very small.Synchronously,the effect of ion consistency on inner friction angle and modulus index is smaller than that on cohesion for above ion.The study provides experience for improving stability of geotechnical construction.
According to the distribution character of ion consistency in ground water and the purpose of changing soil strength,samplings of soil and ground water experiments were executed to carry through statistic and analysis of soil strength,which were made up of chemical action of water-soil and mechanics experiments.The results show the weakened effect occurs on soil cohesion with Ca2 +,HCO 3-,K + and Na + consistency change in ground water and Cl-consistency change is very small.Synchronously,the effect of ion consistency on inner friction angle and modulus index is smaller than that on cohesion for above ion.The study provides experience for improving stability of geotechnical construction.
2010, 40(11): 85-87.
doi: 10.13204/j.gyjz201011021
Abstract:
Building foundation design includes the calculations of subgrade bearing capacity,subsoil deformation and foundation design.Bearing capacity is involved in the determination of base pressure pk and depth correction.Deformation calculation requires the solution of base supplementary pressure p0.The foundation reaction needs to be determined in the calculations of foundation design.When groundwater exists in the subgrade foundation soils,the calculation of base pressure,foundation reaction,base supplementary pressure and how to correct depth of bearing capacity become more complicated.Through discussing the impact of groundwater in the calculation of base pressure,foundation reaction,base supplementary pressure and depth correction of bearing capacity,this paper educes the calculation method of these design parameters.
Building foundation design includes the calculations of subgrade bearing capacity,subsoil deformation and foundation design.Bearing capacity is involved in the determination of base pressure pk and depth correction.Deformation calculation requires the solution of base supplementary pressure p0.The foundation reaction needs to be determined in the calculations of foundation design.When groundwater exists in the subgrade foundation soils,the calculation of base pressure,foundation reaction,base supplementary pressure and how to correct depth of bearing capacity become more complicated.Through discussing the impact of groundwater in the calculation of base pressure,foundation reaction,base supplementary pressure and depth correction of bearing capacity,this paper educes the calculation method of these design parameters.
2010, 40(11): 88-92.
doi: 10.13204/j.gyjz201011022
Abstract:
The main destruction forms of granular-pile composite foundation is destruction of bulging,and bulging damage is mainly due to the inadequate maintenance of the shallow soil between piles,and the bearing capacity of the soil between piles itself depends also on the mechanical properties of shallow part of soil between piles.Based on the above principle,the after-work shallow reinforcement optimization technology of granular pile composite foundation that stabilized the site of shallow soil between piles to greatly improve the bearing capacity of the composite foundation was offered and the load-bearing characteristics changes of the foundation after and before the reinforcement were compared and analyzed,and the influences of different reinforcement depth on the bearing capacity were demonstrated.Through practical project,it is proved shallow reinforcement technology is reasonable and effective.The conclusion is:that as long as shallow depth of 0.5 ～ 1.0 times granular pile diameter would be reinforced,it could greatly improve the bearing capacity of granular-pile composite foundation.
The main destruction forms of granular-pile composite foundation is destruction of bulging,and bulging damage is mainly due to the inadequate maintenance of the shallow soil between piles,and the bearing capacity of the soil between piles itself depends also on the mechanical properties of shallow part of soil between piles.Based on the above principle,the after-work shallow reinforcement optimization technology of granular pile composite foundation that stabilized the site of shallow soil between piles to greatly improve the bearing capacity of the composite foundation was offered and the load-bearing characteristics changes of the foundation after and before the reinforcement were compared and analyzed,and the influences of different reinforcement depth on the bearing capacity were demonstrated.Through practical project,it is proved shallow reinforcement technology is reasonable and effective.The conclusion is:that as long as shallow depth of 0.5 ～ 1.0 times granular pile diameter would be reinforced,it could greatly improve the bearing capacity of granular-pile composite foundation.
2010, 40(11): 93-97.
doi: 10.13204/j.gyjz201011023
Abstract:
Considering the movability and randomness together of the interference source,the dynamical response of an infinite Kirchhoff thin slab on two-parameter elastic foundation is studied.The theoretical solutions of the Greens function,pulse response function,frequency response function and displacement field of this thin slab generated by a moving definite or a moving random point load are obtained.The statistical properties of the random dynamical response in time domain are analyzed in detail.It is found that the stochastic responses of the ground floor system under moving stationary random load are no longer stationary random processes.This paper will provide theoretical basis for the reliability design and fatigue design of a ground structure in later days.
Considering the movability and randomness together of the interference source,the dynamical response of an infinite Kirchhoff thin slab on two-parameter elastic foundation is studied.The theoretical solutions of the Greens function,pulse response function,frequency response function and displacement field of this thin slab generated by a moving definite or a moving random point load are obtained.The statistical properties of the random dynamical response in time domain are analyzed in detail.It is found that the stochastic responses of the ground floor system under moving stationary random load are no longer stationary random processes.This paper will provide theoretical basis for the reliability design and fatigue design of a ground structure in later days.
2010, 40(11): 98-101.
doi: 10.13204/j.gyjz201011024
Abstract:
The method of the second intrusion mercury in MIP is used to investigate the pore characteristics of hardened cement paste with water to cement ratio(w /c) 0.23,0.35 and 0.53 respectively,in order to research the quantitative relationship between transport properties and pore characteristics in cement-based composite materials.The results show the second intrusion mercury could well determine the effective pore characteristics,and effective porosity accounts for 25% to 50% of total porosity in cement paste.At the same time,The existence of the first and second peak in the MIP pore size distribution curves is confirmed,such as,the first peak in hardened cement paste with water to cement ratio 0.53 is very distinct,however,with the decrease of water to cement ratio,the first peak gradually disappears.The pore diameter corresponding to the first and second peak is critical pore diameter of capillary pore and gel pore,respectively.The first peak value of hardened cement paste with w /c 0.23,0.35 and 0.53,respectively,is 0.053,0.062 and 0.077 m.
The method of the second intrusion mercury in MIP is used to investigate the pore characteristics of hardened cement paste with water to cement ratio(w /c) 0.23,0.35 and 0.53 respectively,in order to research the quantitative relationship between transport properties and pore characteristics in cement-based composite materials.The results show the second intrusion mercury could well determine the effective pore characteristics,and effective porosity accounts for 25% to 50% of total porosity in cement paste.At the same time,The existence of the first and second peak in the MIP pore size distribution curves is confirmed,such as,the first peak in hardened cement paste with water to cement ratio 0.53 is very distinct,however,with the decrease of water to cement ratio,the first peak gradually disappears.The pore diameter corresponding to the first and second peak is critical pore diameter of capillary pore and gel pore,respectively.The first peak value of hardened cement paste with w /c 0.23,0.35 and 0.53,respectively,is 0.053,0.062 and 0.077 m.
2010, 40(11): 102-104.
doi: 10.13204/j.gyjz201011025
Abstract:
Through analyzing the development situation of the new walling material in Hunan,and aiming at the existing problems of new walling materia1,it is pute forward the development strategy and research direction,which provides an important guidance for the research and application of the new walling materia1.
Through analyzing the development situation of the new walling material in Hunan,and aiming at the existing problems of new walling materia1,it is pute forward the development strategy and research direction,which provides an important guidance for the research and application of the new walling materia1.
2010, 40(11): 105-110.
doi: 10.13204/j.gyjz201011026
Abstract:
For the problems of different layers,different heights and the existence of dislocation,the accumulation-hoisting construction technology of unit assembly-unit lifting-integral assembly-integral lifting is proposed for Xinhua airlines hangar in Beijing International Aairport.The related issues of this construction technology is analyzed and studied,such as the closure construction method,numerical simulation and structural analysis based on integral model.This construction technology is proved to be effective through the accumulation-hoisting construction of long-span lattice framed structure for Xinhua airlines hangar,and the research results can be used as the reference for the construction process of this kind of structures.
For the problems of different layers,different heights and the existence of dislocation,the accumulation-hoisting construction technology of unit assembly-unit lifting-integral assembly-integral lifting is proposed for Xinhua airlines hangar in Beijing International Aairport.The related issues of this construction technology is analyzed and studied,such as the closure construction method,numerical simulation and structural analysis based on integral model.This construction technology is proved to be effective through the accumulation-hoisting construction of long-span lattice framed structure for Xinhua airlines hangar,and the research results can be used as the reference for the construction process of this kind of structures.
2010, 40(11): 111-115.
doi: 10.13204/j.gyjz201011027
Abstract:
Today the leading position of two scientific thoughts has occupied by reductionism.It believes that any complex structure and phenomenon could be decomposed reduce to a number of elements,which separate each other,and do not change because of explicit influences.People can transpire the nature of holistic phenomena through research on elements.The influences of reductionism scientific thoughts and their limitations on concrete design and process with examples are presented in this paper,which can contrast the necessity of holistic scientific thoughts for application of construction materials as concrete in complicated construction practice.
Today the leading position of two scientific thoughts has occupied by reductionism.It believes that any complex structure and phenomenon could be decomposed reduce to a number of elements,which separate each other,and do not change because of explicit influences.People can transpire the nature of holistic phenomena through research on elements.The influences of reductionism scientific thoughts and their limitations on concrete design and process with examples are presented in this paper,which can contrast the necessity of holistic scientific thoughts for application of construction materials as concrete in complicated construction practice.
2010, 40(11): 116-121,130.
doi: 10.13204/j.gyjz201011028
Abstract:
It is studied the seismic design of steel braced frames in which the braces are configured in a chevron pattern.Strength deterioration in post-buckling phase varies with the slenderness ratio of brace.Because the present chinese seismic code method for the calculation of brace strength supplies significantly different elastic stiffness and actual strength for different values of slenderness ratio of brace,it is complicated for the design of chevron brace.A new procedure to estimate the strength of a chevron brace is proposed,in which the strength of a brace pair is the sum of the yield strength for the brace in tension and the post-buckling strength for the brace in compression.The new method ensures an identical elastic stiffness and a similar strength regardless of the slenderness ratio of brace.The advantage of the proposed method over the conventional chinese seismic code method is demonstrate for the capacity of the proposed method to control the maximum inter-story drift.Finally,concentration of multi-story chevron-braced frames is discussed.
It is studied the seismic design of steel braced frames in which the braces are configured in a chevron pattern.Strength deterioration in post-buckling phase varies with the slenderness ratio of brace.Because the present chinese seismic code method for the calculation of brace strength supplies significantly different elastic stiffness and actual strength for different values of slenderness ratio of brace,it is complicated for the design of chevron brace.A new procedure to estimate the strength of a chevron brace is proposed,in which the strength of a brace pair is the sum of the yield strength for the brace in tension and the post-buckling strength for the brace in compression.The new method ensures an identical elastic stiffness and a similar strength regardless of the slenderness ratio of brace.The advantage of the proposed method over the conventional chinese seismic code method is demonstrate for the capacity of the proposed method to control the maximum inter-story drift.Finally,concentration of multi-story chevron-braced frames is discussed.
2010, 40(11): 122-125.
doi: 10.13204/j.gyjz201011029
Abstract:
Considering the characteristics of concrete-filled steel tube(CFST) tubular joints and comparing its endurance failure with hollow tubular joints,it is known that the fatigue failure mode of the two is basically the same.The method based on bilinear model of forecasting fatigue life of CFST tubular joints is brought forward in this paper.And the rationality of the method is validated in rational range by a real example.
Considering the characteristics of concrete-filled steel tube(CFST) tubular joints and comparing its endurance failure with hollow tubular joints,it is known that the fatigue failure mode of the two is basically the same.The method based on bilinear model of forecasting fatigue life of CFST tubular joints is brought forward in this paper.And the rationality of the method is validated in rational range by a real example.
2010, 40(11): 126-130.
doi: 10.13204/j.gyjz201011030
Abstract:
In order to study the suitable multi-objective optimization design method of components for composite structure,this paper takes the multi-objective optimization design of SRC columns as an example.According to the thoughts of engineering optimization and the theory of composite structure design,the minimum of the project cost and the maximum of the diagonal shear capacity are taken as the optimization objectives whose importance can be adjusted by weighting factors and the linear weighted method is used to establish evaluation function which changes multi-objective into single-objective in optimization.Taking the various constraints into consideration and choosing the sensitive design variables,the mathematical model of the multi-objective optimization design for SRC columns is provided.Based on the optimization thought of the complex method,the nonlinear optimization problems with constrained conditions are solved by MATLAB program.The practical example shows that the optimization method and thought presented in this paper are feasible and effective to SRC columns,which provides experinece for optimization design of members for composite structures and engineering reference and application.
In order to study the suitable multi-objective optimization design method of components for composite structure,this paper takes the multi-objective optimization design of SRC columns as an example.According to the thoughts of engineering optimization and the theory of composite structure design,the minimum of the project cost and the maximum of the diagonal shear capacity are taken as the optimization objectives whose importance can be adjusted by weighting factors and the linear weighted method is used to establish evaluation function which changes multi-objective into single-objective in optimization.Taking the various constraints into consideration and choosing the sensitive design variables,the mathematical model of the multi-objective optimization design for SRC columns is provided.Based on the optimization thought of the complex method,the nonlinear optimization problems with constrained conditions are solved by MATLAB program.The practical example shows that the optimization method and thought presented in this paper are feasible and effective to SRC columns,which provides experinece for optimization design of members for composite structures and engineering reference and application.
2010, 40(11): 131-135.
doi: 10.13204/j.gyjz201011031
Abstract:
In order to research the mechanic behavior of steel encased concrete members subjected to combined force.Experiments were conducted on five SRC beams with various ratios of torque to bending moment Loading process and failure modes of different specimen were described.Two failure modes(failure with torsional feature and failure with flexural feature) were obtained after analysis of the experiment.Tests and analysis results indicate that ratio of torque to bending moment is the important factor affects the failure mode,the ultimate torque moment can increase to some extent under a suitable bending moment.A flexure-torsion-correlation equation in three-phrase expression form of the SRC members is put forward.
In order to research the mechanic behavior of steel encased concrete members subjected to combined force.Experiments were conducted on five SRC beams with various ratios of torque to bending moment Loading process and failure modes of different specimen were described.Two failure modes(failure with torsional feature and failure with flexural feature) were obtained after analysis of the experiment.Tests and analysis results indicate that ratio of torque to bending moment is the important factor affects the failure mode,the ultimate torque moment can increase to some extent under a suitable bending moment.A flexure-torsion-correlation equation in three-phrase expression form of the SRC members is put forward.
2010, 40(11): 136-140.
doi: 10.13204/j.gyjz201011032
Abstract:
According to the construction technical characteristic of the large low temperature LNG storage tank,the large scale bar netting hardly shakes under the action of dynamic load of fluctuating wind load,which can easily cause the unstable failure of bar netting.The finite element model of the bar netting of the large low temperature LNG storage tank(from 9 to 11 section) has been established by using the SAP 2000 finite element software,and the dynamic characteristics of the bar netting has been performed;the wind resistant analysis has been made under the action of dynamic load when considering the P- effect.Besides,the reinforcement analysis and design of the bar netting has been made by using I-section steel reinforced processing technique.The results show that fixing I-section steel in the appropriate position can significantly reduced wind vibration response of the bar netting,thus enhancing stability and security of the netting construction.
According to the construction technical characteristic of the large low temperature LNG storage tank,the large scale bar netting hardly shakes under the action of dynamic load of fluctuating wind load,which can easily cause the unstable failure of bar netting.The finite element model of the bar netting of the large low temperature LNG storage tank(from 9 to 11 section) has been established by using the SAP 2000 finite element software,and the dynamic characteristics of the bar netting has been performed;the wind resistant analysis has been made under the action of dynamic load when considering the P- effect.Besides,the reinforcement analysis and design of the bar netting has been made by using I-section steel reinforced processing technique.The results show that fixing I-section steel in the appropriate position can significantly reduced wind vibration response of the bar netting,thus enhancing stability and security of the netting construction.
2010, 40(11): 141-144.
doi: 10.13204/j.gyjz201011033
Abstract:
The diversity of skin design of buildings for Shanghai Expo has been shown by use of new material,ecological skin and multik-layer skin,according to the analysis of skin design of buildings for Shanghai Expo.It is explored the main characteristics and development trend of the skin of contemporary architectures.
The diversity of skin design of buildings for Shanghai Expo has been shown by use of new material,ecological skin and multik-layer skin,according to the analysis of skin design of buildings for Shanghai Expo.It is explored the main characteristics and development trend of the skin of contemporary architectures.
