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2011 Vol. 41, No. 7
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2011, 41(7): 1-8.
doi: 10.13204/j.gyjz201107001
Abstract:
When designing a strurcture according to partial factor specified in the current standard,there are quite great differences between reliability index corresponding to each load effect ratio and target reliability index,and it does not establish the relationships between partial factors and target reliability index.To solve these two problems,the method of determining partial factor was developed in accordance with design value method.The values of sensitive coefficients were optimized and analyzed,thereby establishing the relationships between partial factors and the ratios of the nominal value of the variable load to that of permanent load.The research shows the error of the reliability index obtained and target reliability index reached the minimum as the sensitive coefficients were represented as functions of the ratios of the nominal value of the variable load to that of permanent load;the coefficient of combination of each variable load can be taken as a constant.
When designing a strurcture according to partial factor specified in the current standard,there are quite great differences between reliability index corresponding to each load effect ratio and target reliability index,and it does not establish the relationships between partial factors and target reliability index.To solve these two problems,the method of determining partial factor was developed in accordance with design value method.The values of sensitive coefficients were optimized and analyzed,thereby establishing the relationships between partial factors and the ratios of the nominal value of the variable load to that of permanent load.The research shows the error of the reliability index obtained and target reliability index reached the minimum as the sensitive coefficients were represented as functions of the ratios of the nominal value of the variable load to that of permanent load;the coefficient of combination of each variable load can be taken as a constant.
2011, 41(7): 9-11,25.
doi: 10.13204/j.gyjz201107002
Abstract:
The reliability evaluation of building structure based on similarity measures between Vague sets is proposed.With relevant regulations and experts experiences,the similarity measures between Vague sets was combined with reliability factors,and the typical knowledge pattern of structural reliability was obtained.Based on the knowledge pattern,counted the analogical degree between the test structural swatch of Vague set and typical reliability model of Vague set was counted,so as to determine the reliability level of test sample.Through evaluated actual structures,the feasibility and rationality of the building structures based on similarity measures between Vague sets were elaborated and verified.
The reliability evaluation of building structure based on similarity measures between Vague sets is proposed.With relevant regulations and experts experiences,the similarity measures between Vague sets was combined with reliability factors,and the typical knowledge pattern of structural reliability was obtained.Based on the knowledge pattern,counted the analogical degree between the test structural swatch of Vague set and typical reliability model of Vague set was counted,so as to determine the reliability level of test sample.Through evaluated actual structures,the feasibility and rationality of the building structures based on similarity measures between Vague sets were elaborated and verified.
2011, 41(7): 12-15.
doi: 10.13204/j.gyjz201107003
Abstract:
A damage index based on wavelet transform could not only represent the damage extent at every load stage,but also be referred to judge when the structure was yielded.The selection of wavelet base function was the difficulty in use of the damage index.The appropriate wavelet base function was selected.This seismic damage model for four superimposed slab shear walls with edge restricted measures of two different forms and two general shear walls were analyzed.The calculating results and the experimental phenomenon were in good agreement.The experiment results showed that the method was reasonable and reliable.
A damage index based on wavelet transform could not only represent the damage extent at every load stage,but also be referred to judge when the structure was yielded.The selection of wavelet base function was the difficulty in use of the damage index.The appropriate wavelet base function was selected.This seismic damage model for four superimposed slab shear walls with edge restricted measures of two different forms and two general shear walls were analyzed.The calculating results and the experimental phenomenon were in good agreement.The experiment results showed that the method was reasonable and reliable.
2011, 41(7): 16-20,37.
doi: 10.13204/j.gyjz201107004
Abstract:
Taking the truss structure damage as object of study,based on the unit strain characteristics of truss structure,it is done the sensitive analysis of the curvature mode rate and strain modal rate relating to the stem unit damage.Meanwhile the change rate is taken as input characteristic parameters to build support vector machine and identify the unit damage of the stem,with which a more ideal result has been obtained.
Taking the truss structure damage as object of study,based on the unit strain characteristics of truss structure,it is done the sensitive analysis of the curvature mode rate and strain modal rate relating to the stem unit damage.Meanwhile the change rate is taken as input characteristic parameters to build support vector machine and identify the unit damage of the stem,with which a more ideal result has been obtained.
2011, 41(7): 21-25.
doi: 10.13204/j.gyjz201107005
Abstract:
Compared with displacement mode,strain mode is better in steel truss damage detection.A new structural nondestructive detection indictor,a dynamic and static combining indictor is presented,which is based on dynamic indictor and static indictor.The new indictor has advantages of method of dynamic and static.It can filter much effect of non-damaged elements.It is much exact than only used dynamic and static indictor for damage detection.Then its availability is verified through a steel truss numerical simulation,and by comparing with dynamic and static detection indictors.The result shows that new indictor is the best.Furthermore,the second-detection and repeated detection methods are presented to solve shortcoming of little strain is difficult to detect in different kinds of components' damage in numerical example.
Compared with displacement mode,strain mode is better in steel truss damage detection.A new structural nondestructive detection indictor,a dynamic and static combining indictor is presented,which is based on dynamic indictor and static indictor.The new indictor has advantages of method of dynamic and static.It can filter much effect of non-damaged elements.It is much exact than only used dynamic and static indictor for damage detection.Then its availability is verified through a steel truss numerical simulation,and by comparing with dynamic and static detection indictors.The result shows that new indictor is the best.Furthermore,the second-detection and repeated detection methods are presented to solve shortcoming of little strain is difficult to detect in different kinds of components' damage in numerical example.
2011, 41(7): 26-30.
doi: 10.13204/j.gyjz201107006
Abstract:
The generalized inverse technique was used to solve the first order equation,and the trust-region reflective Newton method was used to solve the second order sensitivity equation.Considering the fast solving speed by the first order sensitivity equation and the high solving precision by the second order equation,a mixed iteration algorithm which was applied in structure damage detection was put forward.This algorithm uses the second order nonlinear analytical solution as the first substituting value,and then the first substituting value is modified based on the taylor series bias error using the solution of the first order sensitivity equation.The modal analysis program and damage identification program about space frame based on the finite element theory were carried out.Damage identification was studied using the mixed iteration algorithm which was mentioned in this paper.It shows that the mixed iteration algorithm has a better convergence and a faster iteration speed because the higher precision second order nonlinear analytical solution is adopted.
The generalized inverse technique was used to solve the first order equation,and the trust-region reflective Newton method was used to solve the second order sensitivity equation.Considering the fast solving speed by the first order sensitivity equation and the high solving precision by the second order equation,a mixed iteration algorithm which was applied in structure damage detection was put forward.This algorithm uses the second order nonlinear analytical solution as the first substituting value,and then the first substituting value is modified based on the taylor series bias error using the solution of the first order sensitivity equation.The modal analysis program and damage identification program about space frame based on the finite element theory were carried out.Damage identification was studied using the mixed iteration algorithm which was mentioned in this paper.It shows that the mixed iteration algorithm has a better convergence and a faster iteration speed because the higher precision second order nonlinear analytical solution is adopted.
2011, 41(7): 31-37.
doi: 10.13204/j.gyjz201107007
Abstract:
Through numerical simulation of the whole process of heat transfer and deformation on three different conditions groups of reinfored concrete beams,it is analysed the non-linear changing process of the temperature distribution and structural deformation of reinfored concrete beams in fire.Based on thermal characteristics and the temperature-strain-stress constitutive characteristics of reinforced concrete beams it is analysied the influences of the evolutionary processes of the reinfored concrete beams temperature distribution in fire,as well as reinforcement ratio,initial load and heating time on the fire resistance capacity of reinfored concrete beams.Results show that the overall instability of the beams is caused by the reduction of material strength,weight and the initial load,as well as the internal stress because of the uneven heating in fire.The influences of initial load on the residual bearing capacity is little,but increase the number of rebars can effectively improve the fire resistance capacity of reinforced concrete beams.
Through numerical simulation of the whole process of heat transfer and deformation on three different conditions groups of reinfored concrete beams,it is analysed the non-linear changing process of the temperature distribution and structural deformation of reinfored concrete beams in fire.Based on thermal characteristics and the temperature-strain-stress constitutive characteristics of reinforced concrete beams it is analysied the influences of the evolutionary processes of the reinfored concrete beams temperature distribution in fire,as well as reinforcement ratio,initial load and heating time on the fire resistance capacity of reinfored concrete beams.Results show that the overall instability of the beams is caused by the reduction of material strength,weight and the initial load,as well as the internal stress because of the uneven heating in fire.The influences of initial load on the residual bearing capacity is little,but increase the number of rebars can effectively improve the fire resistance capacity of reinforced concrete beams.
2011, 41(7): 38-41,44.
doi: 10.13204/j.gyjz201107008
Abstract:
Taking reinforced concrete columns which are seriously damaged as the research subjects,it is researched the seismic behaviors of the repaired columns.The concrete of columns in the plastic-hinge zone is replaced with grout material and the columns are strengthened with unidirectional CFRP.Then,the experiments are done under low-cyclic and repeated load for the strengthened columns.The cracks development and the deformations of the specimens are observed.The normal section bearing capacity of the columns is analyzed,and the hysteretic curves of loading and displacement are drawn out.Whose results are compared with the performance of the column without pretreatment in order to study the behaviors of capacity and deformability of the repaired and strengthened specimens.By contrasting the experimental values with the values calculated by The Code for Reinforcement Design of Concrete Structures(GB 503672006),the repaired and strengthened specimens are safety.Compared with the column without pretreatment under the same condition,the bearing capacity and the hysteretic area of the repaired and strengthened ones are increased,and the ductility and energy-absorbing capacity are significantly improved.
Taking reinforced concrete columns which are seriously damaged as the research subjects,it is researched the seismic behaviors of the repaired columns.The concrete of columns in the plastic-hinge zone is replaced with grout material and the columns are strengthened with unidirectional CFRP.Then,the experiments are done under low-cyclic and repeated load for the strengthened columns.The cracks development and the deformations of the specimens are observed.The normal section bearing capacity of the columns is analyzed,and the hysteretic curves of loading and displacement are drawn out.Whose results are compared with the performance of the column without pretreatment in order to study the behaviors of capacity and deformability of the repaired and strengthened specimens.By contrasting the experimental values with the values calculated by The Code for Reinforcement Design of Concrete Structures(GB 503672006),the repaired and strengthened specimens are safety.Compared with the column without pretreatment under the same condition,the bearing capacity and the hysteretic area of the repaired and strengthened ones are increased,and the ductility and energy-absorbing capacity are significantly improved.
2011, 41(7): 42-44.
doi: 10.13204/j.gyjz201107009
Abstract:
For the existing buildings,some limitations have influences on building retrofit,such as lack of knowledge on the existing buildings energy consumptions data during the process of energy-saving retrofit.So energy-saving programs are generally in accordance with the new energy-saving design standards.In this paper,energy-saving ideas and measures based on the actual energy consumption analysis are proposed by taking the renovation of Hezhan Market Town in Wuhan for example.
For the existing buildings,some limitations have influences on building retrofit,such as lack of knowledge on the existing buildings energy consumptions data during the process of energy-saving retrofit.So energy-saving programs are generally in accordance with the new energy-saving design standards.In this paper,energy-saving ideas and measures based on the actual energy consumption analysis are proposed by taking the renovation of Hezhan Market Town in Wuhan for example.
2011, 41(7): 45-49.
doi: 10.13204/j.gyjz201107010
Abstract:
There are poor thermal performances and high energy consumptions in the existing residential buildings in the north of Hubei Province.It has been proposed the strategies and methods for energy-saving renovation of the existing residential buildings by analyzing the climate characteristics of Xiaogan,the thermal properties of the enclosures for the existing residential buildings,as well as the problems of implementing energy-saving renovation of the existing residential buildings in Hubei Province.
There are poor thermal performances and high energy consumptions in the existing residential buildings in the north of Hubei Province.It has been proposed the strategies and methods for energy-saving renovation of the existing residential buildings by analyzing the climate characteristics of Xiaogan,the thermal properties of the enclosures for the existing residential buildings,as well as the problems of implementing energy-saving renovation of the existing residential buildings in Hubei Province.
2011, 41(7): 50-53.
doi: 10.13204/j.gyjz201107011
Abstract:
Solar heating is an applied technology,which is relatively simple,practical,effective,and economically competitive with conventional energy sources in the field of solar energy utilization.It is of great practical significance to save energy,protect the atmospheric environment and improve the living standards of the peasants when using this technology in construction of houses in villages and towns.Intensive study on the features of integrating traditional houses with the nature is the basis for doing village and of town planning,as well as the premise guarant to guide the use of solar heating technology in the construction of rural buildings.
Solar heating is an applied technology,which is relatively simple,practical,effective,and economically competitive with conventional energy sources in the field of solar energy utilization.It is of great practical significance to save energy,protect the atmospheric environment and improve the living standards of the peasants when using this technology in construction of houses in villages and towns.Intensive study on the features of integrating traditional houses with the nature is the basis for doing village and of town planning,as well as the premise guarant to guide the use of solar heating technology in the construction of rural buildings.
2011, 41(7): 54-57,91.
doi: 10.13204/j.gyjz201107012
Abstract:
The industrial cluster district is the space in which the industry and its capital elements are highly concentrated.The development of the industrial cluster district should be consistent with the urban development.Taking Pingyu County of Henan Province for example,the implementation of the industry-city integration concept is discussed from the viewpoint of planning-basis,technical-support and system-security,etc.
The industrial cluster district is the space in which the industry and its capital elements are highly concentrated.The development of the industrial cluster district should be consistent with the urban development.Taking Pingyu County of Henan Province for example,the implementation of the industry-city integration concept is discussed from the viewpoint of planning-basis,technical-support and system-security,etc.
2011, 41(7): 58-61,86.
doi: 10.13204/j.gyjz201107013
Abstract:
Based on 7 beams with grade HRB500 reinforcement of low-cost and high-performance,the failure modes,deformation characteristics and bearing capacities matched different strength concrete are analyzed.To test whether the formulas for calculating the bearing capacity,crack width and deflection in the existing code are suitable for the concrete beams with grade HRB500 reinforcement of high-performance.The result indicates that the value of bearing capacity is larger than the one calculated by the code,crack spacing measured is less than the one calculated by the code,but datas of crack width measured and calculated were represented in a fluctuate form,although the two are very close to each other,its calculated method can not use formula given in the code.And deflections measured are larger than the ones calculated by the code.As a result,a modified factor for calculating the deflections of the beam is given.
Based on 7 beams with grade HRB500 reinforcement of low-cost and high-performance,the failure modes,deformation characteristics and bearing capacities matched different strength concrete are analyzed.To test whether the formulas for calculating the bearing capacity,crack width and deflection in the existing code are suitable for the concrete beams with grade HRB500 reinforcement of high-performance.The result indicates that the value of bearing capacity is larger than the one calculated by the code,crack spacing measured is less than the one calculated by the code,but datas of crack width measured and calculated were represented in a fluctuate form,although the two are very close to each other,its calculated method can not use formula given in the code.And deflections measured are larger than the ones calculated by the code.As a result,a modified factor for calculating the deflections of the beam is given.
2011, 41(7): 62-65.
doi: 10.13204/j.gyjz201107014
Abstract:
Based on the experiment on 3 simple beams reinforced with HRBF500 steel bars,the flexual behavior is studied.The research indicate that deformation characteristics and failure pattern are basically in accord with the common beams.The measured deflection of HRBF500 beams is well agreed with the code value and is relatively large in general,as well as HRB500 beams,based on the data of 500 MPa steel bars.It is suggest that short-time stiffness be multiplied by coefficient 0.95 for calculating deflection.
Based on the experiment on 3 simple beams reinforced with HRBF500 steel bars,the flexual behavior is studied.The research indicate that deformation characteristics and failure pattern are basically in accord with the common beams.The measured deflection of HRBF500 beams is well agreed with the code value and is relatively large in general,as well as HRB500 beams,based on the data of 500 MPa steel bars.It is suggest that short-time stiffness be multiplied by coefficient 0.95 for calculating deflection.
2011, 41(7): 66-69,113.
doi: 10.13204/j.gyjz201107015
Abstract:
Based on unconsolidated undrained dynamic triaxial compression test,the reinforced clays were researched.Test results proves that disposing reinforced geo-grid material in clay can increase its dynamic shear strength.The more reinforced geo-grid layers is,the bigger dynamic strength is.Reinforced dynamic reinforcement effect can be better to play on high confining pressures.The dynamic reinforcement effect of reinforced clays with geo-grid reflect just on increasing of dynamic cohesion,but almost no influence on increasing of the dynamic friction angle.Cycle times of dynamic vibration force had little impact on dynamic strength index.The cycle dynamic stress amplitude exert a tremendous influence on reinforced deformation.The deformation increases quickly under large cycle dynamic stress,the sample destructs in smaller vibration times.Conversely,the sample destructs in larger vibration times under small cycle dynamic stress.There is a critical damage dynamic stress,when the setting dynamic stress amplitude is less than the dynamic critical stress,regardless of how many vibrating times,sample can not attain to damage strain,and when the dynamic stress amplitude is too large,the sample is instantaneous destroyed on the beginning vibration.
Based on unconsolidated undrained dynamic triaxial compression test,the reinforced clays were researched.Test results proves that disposing reinforced geo-grid material in clay can increase its dynamic shear strength.The more reinforced geo-grid layers is,the bigger dynamic strength is.Reinforced dynamic reinforcement effect can be better to play on high confining pressures.The dynamic reinforcement effect of reinforced clays with geo-grid reflect just on increasing of dynamic cohesion,but almost no influence on increasing of the dynamic friction angle.Cycle times of dynamic vibration force had little impact on dynamic strength index.The cycle dynamic stress amplitude exert a tremendous influence on reinforced deformation.The deformation increases quickly under large cycle dynamic stress,the sample destructs in smaller vibration times.Conversely,the sample destructs in larger vibration times under small cycle dynamic stress.There is a critical damage dynamic stress,when the setting dynamic stress amplitude is less than the dynamic critical stress,regardless of how many vibrating times,sample can not attain to damage strain,and when the dynamic stress amplitude is too large,the sample is instantaneous destroyed on the beginning vibration.
2011, 41(7): 70-73.
doi: 10.13204/j.gyjz201107016
Abstract:
By using the method of soaking in laboratory,the change laws between the liquid limit,plastic limit and plasticity index of the polluted soil and the pH value were studied.The values of the liquid limit and plastic limit of the soil samples were measured before and after soaking in the hydrochloric acid and sodium hydroxide solution with respective pH value.Then,the change laws indicate that,with the pH value increasing,the liquid limit and the plasticity index increase while the plastic limit presents that both ends are big and the middle is small;when fixing the pH value,the liquid limit is increasing proportional to the time of soaking,while the plastic limit is diminishing.Finally,the reasons causing these change laws were analyzed.
By using the method of soaking in laboratory,the change laws between the liquid limit,plastic limit and plasticity index of the polluted soil and the pH value were studied.The values of the liquid limit and plastic limit of the soil samples were measured before and after soaking in the hydrochloric acid and sodium hydroxide solution with respective pH value.Then,the change laws indicate that,with the pH value increasing,the liquid limit and the plasticity index increase while the plastic limit presents that both ends are big and the middle is small;when fixing the pH value,the liquid limit is increasing proportional to the time of soaking,while the plastic limit is diminishing.Finally,the reasons causing these change laws were analyzed.
2011, 41(7): 74-77,81.
doi: 10.13204/j.gyjz201107017
Abstract:
For the search of modern marine clay's creep rule,it was carried out one-dimensional compression creep test and triaxial undrained consolidation shear creep test on marine soft clay in Shenzhen under different consoildatation pressure.The experiment indicates that the marine clay creep's nonlinear feature is remarkable,which is revealed gradually with increase in stress;because of the confinement in the one-dimensional compression creep test,there is no fast creep damage phenomenon;a peak value occurs in the coefficient of secondary consolidation with the increase in consolidation,and the pressure corresponding to the peak value is a consolidation pressure ahead of time.The research also indicate that the consolidation pressure shall be increased as far as possible in the project,the consolidation and drainage of soil shall be accelerated,which may reduce the harm of creep to a building.
For the search of modern marine clay's creep rule,it was carried out one-dimensional compression creep test and triaxial undrained consolidation shear creep test on marine soft clay in Shenzhen under different consoildatation pressure.The experiment indicates that the marine clay creep's nonlinear feature is remarkable,which is revealed gradually with increase in stress;because of the confinement in the one-dimensional compression creep test,there is no fast creep damage phenomenon;a peak value occurs in the coefficient of secondary consolidation with the increase in consolidation,and the pressure corresponding to the peak value is a consolidation pressure ahead of time.The research also indicate that the consolidation pressure shall be increased as far as possible in the project,the consolidation and drainage of soil shall be accelerated,which may reduce the harm of creep to a building.
2011, 41(7): 78-81.
doi: 10.13204/j.gyjz201107018
Abstract:
Using ANSYS software,,it was simulated and analyzed the load transfer characteristics of post-grouting bored piles from the following three aspects: the pile axial force,pile side friction and static load curve,and the results were compared and analyzed with that for project example.The results provide an evidence of the pile design and construction,and also have a certain reference for enhancing the bearing capacity of pile a bored.
Using ANSYS software,,it was simulated and analyzed the load transfer characteristics of post-grouting bored piles from the following three aspects: the pile axial force,pile side friction and static load curve,and the results were compared and analyzed with that for project example.The results provide an evidence of the pile design and construction,and also have a certain reference for enhancing the bearing capacity of pile a bored.
2011, 41(7): 82-86.
doi: 10.13204/j.gyjz201107019
Abstract:
Using micro-structure observation,instrusive mercury and mineral analyses of consolidation process of typical soft soil samples from the Pearl River Delta,it is quantitatively researched into the changing low of micro-parameters,such as the form of micropores,the pore-scale distribution,the directionality of particles,etc with variation of its consolidation loads.The results show that the pore-scale distribution,the directionality of particles,the compressibility and permeability of the silt soil are significantly changed by the consolidation loads.In the early consolidation,the soil is large pore-scale,disordered particles,large compression coefficient and permeability coefficient,which rapidly decrease with the increase of pressure.However,in the late consolidation,the pore-scale reduces,the directionality of particles increases obviously,compression coefficient and permeability coefficient are also smaller and change slowly.
Using micro-structure observation,instrusive mercury and mineral analyses of consolidation process of typical soft soil samples from the Pearl River Delta,it is quantitatively researched into the changing low of micro-parameters,such as the form of micropores,the pore-scale distribution,the directionality of particles,etc with variation of its consolidation loads.The results show that the pore-scale distribution,the directionality of particles,the compressibility and permeability of the silt soil are significantly changed by the consolidation loads.In the early consolidation,the soil is large pore-scale,disordered particles,large compression coefficient and permeability coefficient,which rapidly decrease with the increase of pressure.However,in the late consolidation,the pore-scale reduces,the directionality of particles increases obviously,compression coefficient and permeability coefficient are also smaller and change slowly.
2011, 41(7): 87-91.
doi: 10.13204/j.gyjz201107020
Abstract:
Some mix tests were carried out for the main factors that effect the 28 d mechanical properties of the layer carbon fiber and polypropylene fiber concrete,such as water-binder ratio,the content of fly ash,the content of the polypropylene fiber and the content of the carbon fiber;then a mathematical model was set up and the optimal mix was determined through the secondary regressive rotating combination design of four factors.The result shows that quadratic polynomial regression model can be used to establish the regression equation of the 28 d compressive strength and flexural strength of the layer carbon fiber and polypropylene fiber conrete.When the water-binder ratio is 0.3,the content of fly ash,the content of the polypropylene fiber and the carbon fiber are zero,the 28 d compressive strength of the layer carbon fiber and polypropylene fiber can reach the maximum 68.21 MPa;while the four factors respectively are 0.3,0,1.2% and 1.6%,the maximum 28 d flexural strength is 8.84 MPa.The effect of polypropylene fiber and the layer carbon fiber on the concrete compressive strength is little,but significant on the concrete flexural strength.
Some mix tests were carried out for the main factors that effect the 28 d mechanical properties of the layer carbon fiber and polypropylene fiber concrete,such as water-binder ratio,the content of fly ash,the content of the polypropylene fiber and the content of the carbon fiber;then a mathematical model was set up and the optimal mix was determined through the secondary regressive rotating combination design of four factors.The result shows that quadratic polynomial regression model can be used to establish the regression equation of the 28 d compressive strength and flexural strength of the layer carbon fiber and polypropylene fiber conrete.When the water-binder ratio is 0.3,the content of fly ash,the content of the polypropylene fiber and the carbon fiber are zero,the 28 d compressive strength of the layer carbon fiber and polypropylene fiber can reach the maximum 68.21 MPa;while the four factors respectively are 0.3,0,1.2% and 1.6%,the maximum 28 d flexural strength is 8.84 MPa.The effect of polypropylene fiber and the layer carbon fiber on the concrete compressive strength is little,but significant on the concrete flexural strength.
2011, 41(7): 92-95,73.
doi: 10.13204/j.gyjz201107021
Abstract:
The foundation type of Henan broadcast and TV tower is a pile raft foundation.The jointless construction technology of mass concrete is analyzed for its foundation slab has no post poured belt and concrete expansion and strengthened belt.It was introduced the jointless construction technology of the TV tower mass concrete.The results showed that temperature difference of two adjacent measuring points at the same position is less than 25 ℃.The technology controlled concrete crack effectively and provided construction experience for construction of similar projects.
The foundation type of Henan broadcast and TV tower is a pile raft foundation.The jointless construction technology of mass concrete is analyzed for its foundation slab has no post poured belt and concrete expansion and strengthened belt.It was introduced the jointless construction technology of the TV tower mass concrete.The results showed that temperature difference of two adjacent measuring points at the same position is less than 25 ℃.The technology controlled concrete crack effectively and provided construction experience for construction of similar projects.
2011, 41(7): 96-100.
doi: 10.13204/j.gyjz201107022
Abstract:
By an example of analyse and design of one single layer cylindrical lattice shell with low rise-span ratio,mechanical characteristic of the shell was analyzed;the effect of support stiffness on the shell was discussed;the method of structure of shell joint and design of shell were introduced;especially the global stability was studied.It was concluded that single layer cylindrical lattice shell with low rise-span ratio was sensitive to stiffness of support and initial geometrical imperfections;and if plastic is considered,the critical load of the shell will be reduced greatly by contrast with elastic critical load;stiffness of support has different effect on the shell in different load cases.
By an example of analyse and design of one single layer cylindrical lattice shell with low rise-span ratio,mechanical characteristic of the shell was analyzed;the effect of support stiffness on the shell was discussed;the method of structure of shell joint and design of shell were introduced;especially the global stability was studied.It was concluded that single layer cylindrical lattice shell with low rise-span ratio was sensitive to stiffness of support and initial geometrical imperfections;and if plastic is considered,the critical load of the shell will be reduced greatly by contrast with elastic critical load;stiffness of support has different effect on the shell in different load cases.
2011, 41(7): 101-106,100.
doi: 10.13204/j.gyjz201107023
Abstract:
In the steel plate shear wall,pulling force of the steel plate can change the force transmission path in the frame.The horizontal component of forces in the upper and lower plates act on the beam,thus bending moment of the beam is reduced.The stiffness requirements of connections can also be reduced.This makes semi-rigid connections possible.Up to this point,the concept of a new type structure named semi-rigid steel frame-steel plate shear wall is presented.In this paper,a single-span and two-story steel plate shear wall with unstiffened welded-bolted connections is designed and low-cycle reverse loading tests and finite element analysis are carried out.There are four conclusions can be drawn: Firstly,the new structure has high ultimate strength and good energy dissipation.Secondly,pulling strips of the first story are more obvious than those of the second story.Thirdly,the steel plate can bear 65.28%~73.87% of lateral load,and 21.98%~33.35% of overturning moment;Fourthly,the connection is not the weak location of the new structure,and semi-rigid connection is reasonable.
In the steel plate shear wall,pulling force of the steel plate can change the force transmission path in the frame.The horizontal component of forces in the upper and lower plates act on the beam,thus bending moment of the beam is reduced.The stiffness requirements of connections can also be reduced.This makes semi-rigid connections possible.Up to this point,the concept of a new type structure named semi-rigid steel frame-steel plate shear wall is presented.In this paper,a single-span and two-story steel plate shear wall with unstiffened welded-bolted connections is designed and low-cycle reverse loading tests and finite element analysis are carried out.There are four conclusions can be drawn: Firstly,the new structure has high ultimate strength and good energy dissipation.Secondly,pulling strips of the first story are more obvious than those of the second story.Thirdly,the steel plate can bear 65.28%~73.87% of lateral load,and 21.98%~33.35% of overturning moment;Fourthly,the connection is not the weak location of the new structure,and semi-rigid connection is reasonable.
2011, 41(7): 107-113.
doi: 10.13204/j.gyjz201107024
Abstract:
When lateral load is applied on steel plate shear wall connected with frame beams,the buckling of plate corner appears,which causes the lost of bearing capacity and energy dissipation ability.Stiffeners connected on two free sides not only prevent corner plate from early buckling but also increase the bearing capacity and energy dissipation ability.Finite element software ANSYS is used to analyze the effect when the two free sides are well strengthened.The results show that the strengthened sides make the tension field easy to form and this leads to the increasing of aseismatic performance of steel plate shear wall with two-side connections.With the increase of height-to-thickness ratio,the effect of stiffeners increases;when span-to-height ratio increases,the effect of stiffeners decrease.
When lateral load is applied on steel plate shear wall connected with frame beams,the buckling of plate corner appears,which causes the lost of bearing capacity and energy dissipation ability.Stiffeners connected on two free sides not only prevent corner plate from early buckling but also increase the bearing capacity and energy dissipation ability.Finite element software ANSYS is used to analyze the effect when the two free sides are well strengthened.The results show that the strengthened sides make the tension field easy to form and this leads to the increasing of aseismatic performance of steel plate shear wall with two-side connections.With the increase of height-to-thickness ratio,the effect of stiffeners increases;when span-to-height ratio increases,the effect of stiffeners decrease.
2011, 41(7): 114-119.
doi: 10.13204/j.gyjz201107025
Abstract:
In order to ensure a safe design of a new building and obtain optimum design,an experimental program consisting of the tests of three full-scale connections with different connections details under cyclic loading,which were alternative design schemes for a twenty-eight-story prototype office building,was conducted to evaluate the seismic behavior of concrete filled rectangular tube column-to-H beam connections.Performance of test specimens was evaluated in terms of failure mode,hysteresis curve,ductility and energy dissipation capacity,etc.Test results showed that all specimens performed in a ductile manner with plastic hinges formed in the beam end near the column face,and exhibited a strong column-weak beam failure mechanism.The hysteresis curves of all connections were full and showed good energy dissipation.There were no obvious discrepancies in load bearing capacity and energy dissipation among three connections when story drift was not beyond 2%.The stiffness degradation trends were similar to each other.
In order to ensure a safe design of a new building and obtain optimum design,an experimental program consisting of the tests of three full-scale connections with different connections details under cyclic loading,which were alternative design schemes for a twenty-eight-story prototype office building,was conducted to evaluate the seismic behavior of concrete filled rectangular tube column-to-H beam connections.Performance of test specimens was evaluated in terms of failure mode,hysteresis curve,ductility and energy dissipation capacity,etc.Test results showed that all specimens performed in a ductile manner with plastic hinges formed in the beam end near the column face,and exhibited a strong column-weak beam failure mechanism.The hysteresis curves of all connections were full and showed good energy dissipation.There were no obvious discrepancies in load bearing capacity and energy dissipation among three connections when story drift was not beyond 2%.The stiffness degradation trends were similar to each other.
2011, 41(7): 120-124.
doi: 10.13204/j.gyjz201107026
Abstract:
It has been finished wind tunnel test based on the latticed shell according to the engineering design and experimental study's need.By taking account of the impacts of wind direction,coal piles and the elevation-angle on the shape coefficient of the dry coal shed,extrema of shape coefficient obtained.By data analysis,the surface of the latticed shell has been divided into seven areas that is named the first division method and twenty-one areas that is named the second division method according to the shape of the latticed shell and different loads.Shape coefficients of the sections of the latticed shell are given.Shape coefficient of lateral end is too large,it is proposed that rib should be added on both ends or the section size should be increased;and attention is also paid to strengthening the connection of the roof and dry coal shed to adapt to different changes in wind direction.The test may supply the design reference for dry coal shed expanding or similar projects.
It has been finished wind tunnel test based on the latticed shell according to the engineering design and experimental study's need.By taking account of the impacts of wind direction,coal piles and the elevation-angle on the shape coefficient of the dry coal shed,extrema of shape coefficient obtained.By data analysis,the surface of the latticed shell has been divided into seven areas that is named the first division method and twenty-one areas that is named the second division method according to the shape of the latticed shell and different loads.Shape coefficients of the sections of the latticed shell are given.Shape coefficient of lateral end is too large,it is proposed that rib should be added on both ends or the section size should be increased;and attention is also paid to strengthening the connection of the roof and dry coal shed to adapt to different changes in wind direction.The test may supply the design reference for dry coal shed expanding or similar projects.
2011, 41(7): 125-128.
doi: 10.13204/j.gyjz201107027
Abstract:
Three methods of strengthening structures in the inflexed angle zones are put forward for CFRP reinforced concrete members,which are made to do destructive experiments with comparison specimens.Through analysis of the load-ultimate strain relationship and cross-section capacity,the anchorage effects are evaluated.These researches can be of help to the design of practical project and can be adopted by other projects.The experiment's results indicate that the strengthening effect of mechanical anchorage is better than the one of CFRP.The paper recommends the method of strengthening structure by angle steel.
Three methods of strengthening structures in the inflexed angle zones are put forward for CFRP reinforced concrete members,which are made to do destructive experiments with comparison specimens.Through analysis of the load-ultimate strain relationship and cross-section capacity,the anchorage effects are evaluated.These researches can be of help to the design of practical project and can be adopted by other projects.The experiment's results indicate that the strengthening effect of mechanical anchorage is better than the one of CFRP.The paper recommends the method of strengthening structure by angle steel.
2011, 41(7): 129-132.
doi: 10.13204/j.gyjz201107028
Abstract:
Experimental research on fatigue performance of damage beams strengthened with prestressed CFRP sheets is seldom.Based on lever principle,a new loading system for fatigue experiments has been designed.And the tension and anchorage devices were perfected.Three beams,which are presplitted identically,strengthened with CFRP sheets under different pre-stress levels were tested under fatigue load.Results show that the application of prestressing force can restrict cracks propagation,improve the rigidity,reduce the strain of the reinforcement and CFRP,thus the fatigue life of the strengthened beams are increased apparently.Meanwhile,the more the pre-stress level increases,the more the fatigue performance of the strengthened beams improved.
Experimental research on fatigue performance of damage beams strengthened with prestressed CFRP sheets is seldom.Based on lever principle,a new loading system for fatigue experiments has been designed.And the tension and anchorage devices were perfected.Three beams,which are presplitted identically,strengthened with CFRP sheets under different pre-stress levels were tested under fatigue load.Results show that the application of prestressing force can restrict cracks propagation,improve the rigidity,reduce the strain of the reinforcement and CFRP,thus the fatigue life of the strengthened beams are increased apparently.Meanwhile,the more the pre-stress level increases,the more the fatigue performance of the strengthened beams improved.
2011, 41(7): 133-137.
doi: 10.13204/j.gyjz201107029
Abstract:
This article described whole strengthening design of nearly 50-year old workshop added 600-ton superheavy-duty crane in detail.After carrying on the comprehensive quality detection and assessment of the original workshop,effective strengthening plan has been proposed by techno-economic verification and optimization of many kinds of reinforcement plans.Mechanical property of strengthened structural elements could meet the requests by computation result of various software computations and manually computing result.Rebirth has been given to the nearly 50-year old workshop.
This article described whole strengthening design of nearly 50-year old workshop added 600-ton superheavy-duty crane in detail.After carrying on the comprehensive quality detection and assessment of the original workshop,effective strengthening plan has been proposed by techno-economic verification and optimization of many kinds of reinforcement plans.Mechanical property of strengthened structural elements could meet the requests by computation result of various software computations and manually computing result.Rebirth has been given to the nearly 50-year old workshop.
2011, 41(7): 138-142,137.
doi: 10.13204/j.gyjz201107030
Abstract:
Foundation excavation of a construction has a large area excavation,large differences within the soil layer,complex geological conditions,the surroundings being adjacent to buildings,urban roads,ramp slopes,and other different environments.According to the conditions of site,foundation excavation support is divided into seven representative profile to joint support,the support structure is both realistic and economically rational.It is analyzed the construction difficulties such as doing an excavation facing the flow of mud pile,collapse between piles,long side effects,hillside reinforcement and the existing shelter etc;and the corresponding measures are worked out.By carring out safety monitoring of foundation excavation construction,using informational design and constructional technology,the safety of foundation excavation and the surrounding environment is ensured.
Foundation excavation of a construction has a large area excavation,large differences within the soil layer,complex geological conditions,the surroundings being adjacent to buildings,urban roads,ramp slopes,and other different environments.According to the conditions of site,foundation excavation support is divided into seven representative profile to joint support,the support structure is both realistic and economically rational.It is analyzed the construction difficulties such as doing an excavation facing the flow of mud pile,collapse between piles,long side effects,hillside reinforcement and the existing shelter etc;and the corresponding measures are worked out.By carring out safety monitoring of foundation excavation construction,using informational design and constructional technology,the safety of foundation excavation and the surrounding environment is ensured.
2011, 41(7): 143-146.
doi: 10.13204/j.gyjz201107031
Abstract:
Utilizing the advantages of the interdisciplinary studies,it is attempted to research on the innovations of Art Nouveau referred to the theories of the diffusion of innovations in communication studies.Based on these analyses,it is put forward the enlightenments for the architecture creation and pointed out that the architect should not only seek for the breakthrough of the methodology,but also establish a dialectical unity relation between moderate innovation and high innovation according to the different conditions.In addition,the architect should pay more attention to the exertion of ecological thought and the diversity of the creation in order to obtain the good effects of the diffusion of architecture innovations.
Utilizing the advantages of the interdisciplinary studies,it is attempted to research on the innovations of Art Nouveau referred to the theories of the diffusion of innovations in communication studies.Based on these analyses,it is put forward the enlightenments for the architecture creation and pointed out that the architect should not only seek for the breakthrough of the methodology,but also establish a dialectical unity relation between moderate innovation and high innovation according to the different conditions.In addition,the architect should pay more attention to the exertion of ecological thought and the diversity of the creation in order to obtain the good effects of the diffusion of architecture innovations.
