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2004 Vol. 34, No. 7
Display Method:
2004, 34(7): 1-6.
doi: 10.13204/j.gyjz200407001
Abstract:
The concept and features of externally prestressed concrete structure are expounded. The design method of externally prestressed structure are systematically illuminated, including the tendon profiles, analysis of internal force at both the serviceability and ultimate state, the evaluation of prestressing loss, the design of deviator and local bearing capacity.Durability and fire resistance problem are also considered. By doing the above work, a foundation is laid for this new structure to be popularized and applied in our country.
The concept and features of externally prestressed concrete structure are expounded. The design method of externally prestressed structure are systematically illuminated, including the tendon profiles, analysis of internal force at both the serviceability and ultimate state, the evaluation of prestressing loss, the design of deviator and local bearing capacity.Durability and fire resistance problem are also considered. By doing the above work, a foundation is laid for this new structure to be popularized and applied in our country.
2004, 34(7): 7-11,15.
doi: 10.13204/j.gyjz200407002
Abstract:
The method of secondary moment under restraint is a convenient way to solve the interior force of prestressed statically indeterminate structure. Based on this method, the secondary interior force of all kinds of external tendon profile under three restraint conditions are directly provided in accordance with practical requirement in the construction application,and the relationship between profile parameters and prestressing effects on continuous beams are established.
The method of secondary moment under restraint is a convenient way to solve the interior force of prestressed statically indeterminate structure. Based on this method, the secondary interior force of all kinds of external tendon profile under three restraint conditions are directly provided in accordance with practical requirement in the construction application,and the relationship between profile parameters and prestressing effects on continuous beams are established.
2004, 34(7): 12-15.
doi: 10.13204/j.gyjz200407003
Abstract:
The deflection calculation methods of externally prestressed concrete beam both home and abroad are reviewed.The existing methods have considered tendon stress increase and second-order effect, but limited to shor-t term deflection calculation. Further analysis indicate that other factors such as material non-linear, concrete shrinkage and creep, high temperature performance, as well as the interaction among these factors, should also be considered.
The deflection calculation methods of externally prestressed concrete beam both home and abroad are reviewed.The existing methods have considered tendon stress increase and second-order effect, but limited to shor-t term deflection calculation. Further analysis indicate that other factors such as material non-linear, concrete shrinkage and creep, high temperature performance, as well as the interaction among these factors, should also be considered.
2004, 34(7): 16-19.
doi: 10.13204/j.gyjz200407004
Abstract:
The structure and construction method of externally prestressed structures differ greatly from structures with bonded or unbonded tendons, therefore generate the difference in prestressing loss. In this paper, the calculation method of prestressing loss are discussed, and applicable formulae are suggested with regard to the characteristic of external prestressing.
The structure and construction method of externally prestressed structures differ greatly from structures with bonded or unbonded tendons, therefore generate the difference in prestressing loss. In this paper, the calculation method of prestressing loss are discussed, and applicable formulae are suggested with regard to the characteristic of external prestressing.
2004, 34(7): 20-24.
doi: 10.13204/j.gyjz200407005
Abstract:
The corrosion mechanism of externally prestressed tendons and damage mechanism of concrete are analysed. On this basis of analysis, the measures to prevent the erosion of externally prestressed tendons and to improve the durability of concrete are commented. Finally, on the basis of electrochemical corrosion mechanism, the limitations of the protection measures are studied and the suggestions to improve the durability of externally prestressed concrete structure are proposed.
The corrosion mechanism of externally prestressed tendons and damage mechanism of concrete are analysed. On this basis of analysis, the measures to prevent the erosion of externally prestressed tendons and to improve the durability of concrete are commented. Finally, on the basis of electrochemical corrosion mechanism, the limitations of the protection measures are studied and the suggestions to improve the durability of externally prestressed concrete structure are proposed.
2004, 34(7): 25-27.
doi: 10.13204/j.gyjz200407006
Abstract:
In the design of prestressed concrete beams, Intergral calculus is needed in calculating the geometric properties of irregular cross section. By presenting a case of externally prestressed beams with U-shaped cross section, a section equivalent conversion method is introduced, and the design process of externally prestressed concrete structure using the method of secondary interior force under restraint are also presented.
In the design of prestressed concrete beams, Intergral calculus is needed in calculating the geometric properties of irregular cross section. By presenting a case of externally prestressed beams with U-shaped cross section, a section equivalent conversion method is introduced, and the design process of externally prestressed concrete structure using the method of secondary interior force under restraint are also presented.
2004, 34(7): 28-29,32.
doi: 10.13204/j.gyjz200407007
Abstract:
The vertical temperature gradient of atrium is big because it has the effects of greenhouse and chimney.Therefore, if its design is improper, there will be a poor thermal amenity in the environment,which results in an increase in energy consumption. It is proposed that rational selection and zonation of the interface between the atrium and peripheral space shall be done,while maintaining a sharing space, which can effectively control the thermal amenity of each zone.
The vertical temperature gradient of atrium is big because it has the effects of greenhouse and chimney.Therefore, if its design is improper, there will be a poor thermal amenity in the environment,which results in an increase in energy consumption. It is proposed that rational selection and zonation of the interface between the atrium and peripheral space shall be done,while maintaining a sharing space, which can effectively control the thermal amenity of each zone.
2004, 34(7): 30-32.
doi: 10.13204/j.gyjz200407008
Abstract:
Using right security color for building and making it be standardized by applying colorcs effect to physiology and psychology have an important meaning to improve the security and comfort of environment. The attribute of color and its application in the design of the inside and outside of an architecture and introduced. The application of security color in architectures over the world, especially in Japan, is particularly expounded. Furthermore, the principle of collocations is pointed out.
Using right security color for building and making it be standardized by applying colorcs effect to physiology and psychology have an important meaning to improve the security and comfort of environment. The attribute of color and its application in the design of the inside and outside of an architecture and introduced. The application of security color in architectures over the world, especially in Japan, is particularly expounded. Furthermore, the principle of collocations is pointed out.
2004, 34(7): 33-35,39.
doi: 10.13204/j.gyjz200407009
Abstract:
Structural mechanics method (SMM)is usually used to analyze rigid pipeline and the interaction between soil and pipeline is ignored.Transfer matrix approach (TMA)is presented to study interaction between soil and buried box pipeline in this paper.The results of comparing TMA to SMM show that the soil constraint influence should be considered.The effects of the changes of model parameters on pipeline-soil interaction are also discussed.
Structural mechanics method (SMM)is usually used to analyze rigid pipeline and the interaction between soil and pipeline is ignored.Transfer matrix approach (TMA)is presented to study interaction between soil and buried box pipeline in this paper.The results of comparing TMA to SMM show that the soil constraint influence should be considered.The effects of the changes of model parameters on pipeline-soil interaction are also discussed.
2004, 34(7): 36-39.
doi: 10.13204/j.gyjz200407010
Abstract:
By discussing the methods of optimum design, a reasonable model for optimum design of piled raft foundation is set up in this paper. From the analyses, some optimum results are achieved. Furthermore, the design of piled raft foundation can be guided by the optimum results, and the potential advantage of optimum design can be exerted.
By discussing the methods of optimum design, a reasonable model for optimum design of piled raft foundation is set up in this paper. From the analyses, some optimum results are achieved. Furthermore, the design of piled raft foundation can be guided by the optimum results, and the potential advantage of optimum design can be exerted.
2004, 34(7): 40-43.
doi: 10.13204/j.gyjz200407011
Abstract:
The bearing capacity of stiffened DCM (Deep Cement Mixing)pile are studied and a new practical bearing capacity design method is presented.The design values are compared with the field test values in two projects.The comparison result shows that the method is reasonable and can be used in projects design.
The bearing capacity of stiffened DCM (Deep Cement Mixing)pile are studied and a new practical bearing capacity design method is presented.The design values are compared with the field test values in two projects.The comparison result shows that the method is reasonable and can be used in projects design.
2004, 34(7): 44-46.
doi: 10.13204/j.gyjz200407012
Abstract:
This paper describes a series of tests carried out on the uniaxial compression of ex isting un-carbonated concrete that had been in service for 10, 20 and 40 years, respectively, and 24 complete stress-strain curves in total were obtained.Compared with fresh concrete of the same strength ( 28 days of curing period), the behavior parameters in terms of ductility ratio, peak strain, ultimate strain and elastic modulus were found to decline to different degrees and the chang ing laws of these parameters with the increase of service life were generalized based on the test results. It is therefore recommended that the adverse effects of these parameters should be taken into account if members are planned to be used further.
This paper describes a series of tests carried out on the uniaxial compression of ex isting un-carbonated concrete that had been in service for 10, 20 and 40 years, respectively, and 24 complete stress-strain curves in total were obtained.Compared with fresh concrete of the same strength ( 28 days of curing period), the behavior parameters in terms of ductility ratio, peak strain, ultimate strain and elastic modulus were found to decline to different degrees and the chang ing laws of these parameters with the increase of service life were generalized based on the test results. It is therefore recommended that the adverse effects of these parameters should be taken into account if members are planned to be used further.
2004, 34(7): 47-49.
doi: 10.13204/j.gyjz200407013
Abstract:
Wavelet neural network is a kind of neural networks, which can closely combine wavelet theory with neural network theory, and avoid the blindness of framework designs for BP neural networks and the problem of nonlinear optimizations, such as local optimization.So it can greatly simplify the training of neural networks.It has good abilities of function learning and dissemination with a vast range of prospects for application.In this paper, the wavelet neural network is applied to predict the strength of concrete.The results show that the convergence speed of wavelet neural network is faster and its predicting result is more accurate than that of BP network
Wavelet neural network is a kind of neural networks, which can closely combine wavelet theory with neural network theory, and avoid the blindness of framework designs for BP neural networks and the problem of nonlinear optimizations, such as local optimization.So it can greatly simplify the training of neural networks.It has good abilities of function learning and dissemination with a vast range of prospects for application.In this paper, the wavelet neural network is applied to predict the strength of concrete.The results show that the convergence speed of wavelet neural network is faster and its predicting result is more accurate than that of BP network
2004, 34(7): 50-53,60.
doi: 10.13204/j.gyjz200407014
Abstract:
The current applied fields of external prestressing mainly includes externally prestressed concrete bridge,structure rehabilitation and prestressed steel structure, etc.The materials and systems of various applications are introduced herein, the select principle of anchorage system are discussed, finally the future studies and application efforts in these aspects are pointed out.
The current applied fields of external prestressing mainly includes externally prestressed concrete bridge,structure rehabilitation and prestressed steel structure, etc.The materials and systems of various applications are introduced herein, the select principle of anchorage system are discussed, finally the future studies and application efforts in these aspects are pointed out.
2004, 34(7): 54-56.
doi: 10.13204/j.gyjz200407015
Abstract:
Various methods on nonlinear analytical techniques for externally prestressed concrete presented by scholars from both home and abroad was reviewed, in which more emphasis is paid to such issues as the nonlinearity factors, element model types and implementation methods and some aspects which deserve further study are given as well.
Various methods on nonlinear analytical techniques for externally prestressed concrete presented by scholars from both home and abroad was reviewed, in which more emphasis is paid to such issues as the nonlinearity factors, element model types and implementation methods and some aspects which deserve further study are given as well.
2004, 34(7): 57-60.
doi: 10.13204/j.gyjz200407016
Abstract:
Axial compression regidity and flexural rigidity of concrete-filled steel tubular are very important parameters for seismic behavior analysis. An attempt to predict the load-deformation behavior of concrete-filled steel tubular axial loaded members and pure bending members with the effects of initial stress in the steel tubes considered is proposed in this paper.Based on the theoretical model, influence of the initial stress coefficient, sectional steel ratio, as well as strength of the materials is discussed. Finally, formulas for the calculation of the bending rigidity of concrete- filled steel tubular members with the effects of initial stress in the steel tubes considered are developed.
Axial compression regidity and flexural rigidity of concrete-filled steel tubular are very important parameters for seismic behavior analysis. An attempt to predict the load-deformation behavior of concrete-filled steel tubular axial loaded members and pure bending members with the effects of initial stress in the steel tubes considered is proposed in this paper.Based on the theoretical model, influence of the initial stress coefficient, sectional steel ratio, as well as strength of the materials is discussed. Finally, formulas for the calculation of the bending rigidity of concrete- filled steel tubular members with the effects of initial stress in the steel tubes considered are developed.
2004, 34(7): 61-63.
doi: 10.13204/j.gyjz200407017
Abstract:
In this paper, the instability paths of two typical structural systems of Chengdu airport terminals, composed of single-layer reticulated cylindrical shell and supporting system, were investigated by non-linear analysis program based on Beam-Column theory, considering the vertical symmetric load combination, vertical asymmetric load combination and wind load combination.The results indicate that, compared with the single-layer reticulated cylindrical shell, both the ultimate load bearing capacity and the sensitivity of geometric imperfection of the whole structural system will decrease.
In this paper, the instability paths of two typical structural systems of Chengdu airport terminals, composed of single-layer reticulated cylindrical shell and supporting system, were investigated by non-linear analysis program based on Beam-Column theory, considering the vertical symmetric load combination, vertical asymmetric load combination and wind load combination.The results indicate that, compared with the single-layer reticulated cylindrical shell, both the ultimate load bearing capacity and the sensitivity of geometric imperfection of the whole structural system will decrease.
2004, 34(7): 64-66.
doi: 10.13204/j.gyjz200407018
Abstract:
Three specimens of warpped steel concrete exterior joints which varied in axial compression ratio and the form of angle steel for beam, are put to test;and the forced feature of the angle steel as well as the aseismic behavior of the joints under the high axial compression ratio are studied.Based on the analyses, formula of shear carrying capacity is given.
Three specimens of warpped steel concrete exterior joints which varied in axial compression ratio and the form of angle steel for beam, are put to test;and the forced feature of the angle steel as well as the aseismic behavior of the joints under the high axial compression ratio are studied.Based on the analyses, formula of shear carrying capacity is given.
2004, 34(7): 67-69.
doi: 10.13204/j.gyjz200407019
Abstract:
Because of the crane loads, columns in portal frames are stepped.The effective length of the stepped columns is not available either from the specifications or from the literature, when the column base is fixed.This paper analyses the buckling of hinged portal frame with crane loads.Formulas and tables of the effective length factors for the base-fixed column both in plane and out of plane are proposed.The results from the proposed method are in good agreement with those of FEM,based on which the formulas of the effective length factors are also simplified.
Because of the crane loads, columns in portal frames are stepped.The effective length of the stepped columns is not available either from the specifications or from the literature, when the column base is fixed.This paper analyses the buckling of hinged portal frame with crane loads.Formulas and tables of the effective length factors for the base-fixed column both in plane and out of plane are proposed.The results from the proposed method are in good agreement with those of FEM,based on which the formulas of the effective length factors are also simplified.
2004, 34(7): 70-72.
doi: 10.13204/j.gyjz200407020
Abstract:
A 3D nonlinear finite element method is used to analyze the distribution of prying forces of semi-rigid beam-column connections of a steel structure and the effect of the prying forces on the forced performance of the connections. The maximum of the prying force is deduced according to plastic design theory. And the corresponding computational method ensuring the safety and credibility of such connections is advanced.
A 3D nonlinear finite element method is used to analyze the distribution of prying forces of semi-rigid beam-column connections of a steel structure and the effect of the prying forces on the forced performance of the connections. The maximum of the prying force is deduced according to plastic design theory. And the corresponding computational method ensuring the safety and credibility of such connections is advanced.
2004, 34(7): 73-77.
doi: 10.13204/j.gyjz200407021
Abstract:
Formr finding is the first step in a membrane structure design, which is paramount for the structural performance of a membrane structure.To understant the principle of form??finding, there are four questions being discussed, that are the relationship of form and pretension, four basic types of membrane structures, some rules for form??finding and numerical methods. Moreover, this paper also introduces some architectural requirements which should be considered during formr finding stage, such as drainage, fire, lighting, acoustic, thermal insulation, and so on.
Formr finding is the first step in a membrane structure design, which is paramount for the structural performance of a membrane structure.To understant the principle of form??finding, there are four questions being discussed, that are the relationship of form and pretension, four basic types of membrane structures, some rules for form??finding and numerical methods. Moreover, this paper also introduces some architectural requirements which should be considered during formr finding stage, such as drainage, fire, lighting, acoustic, thermal insulation, and so on.
2004, 34(7): 78-80,82.
doi: 10.13204/j.gyjz200407022
Abstract:
Two methods of synthetic fuzzy evaluation for site types are given based on the current Chinese Seismic Design Code for Buildings(GB 50011-2001). And a method for determining site characteristic period( the corner period of design response spectra) is also put forward. The membership function and coefficient g iven in this paper is used directly for engineering. The results by the different methods are similar on the whole, but somewhat different in the vicinity of the boundary of two neighboring site types. According to the results, the methods g iven in this paper are more reasonable.
Two methods of synthetic fuzzy evaluation for site types are given based on the current Chinese Seismic Design Code for Buildings(GB 50011-2001). And a method for determining site characteristic period( the corner period of design response spectra) is also put forward. The membership function and coefficient g iven in this paper is used directly for engineering. The results by the different methods are similar on the whole, but somewhat different in the vicinity of the boundary of two neighboring site types. According to the results, the methods g iven in this paper are more reasonable.
2004, 34(7): 81-82.
doi: 10.13204/j.gyjz200407023
Abstract:
Revising the articles of Fireproof Code of Building Design timely, accurately and coordinately is the basis for doing a good job of safety fireproofing of building design.So, it is practical to reinforce the emendation of fireproof regulations so as to make it move cooperatively and timely and exerting the consulting role of academies.
Revising the articles of Fireproof Code of Building Design timely, accurately and coordinately is the basis for doing a good job of safety fireproofing of building design.So, it is practical to reinforce the emendation of fireproof regulations so as to make it move cooperatively and timely and exerting the consulting role of academies.
2004, 34(7): 83-84.
doi: 10.13204/j.gyjz200407024
Abstract:
The steel-encased strengthening method was used widely in the field of the structural strengthening.Based on Technical Specification for Strengthening Concrete Structures (CECS 25∶90), the principle and the design method of reinforced concrete beam strengthened with steel-encased were described.Strengthening model and calculating method of steel-encased strengthening method of bending member in SEU-DEEP were further given, finally an example was used to show this course in detail.
The steel-encased strengthening method was used widely in the field of the structural strengthening.Based on Technical Specification for Strengthening Concrete Structures (CECS 25∶90), the principle and the design method of reinforced concrete beam strengthened with steel-encased were described.Strengthening model and calculating method of steel-encased strengthening method of bending member in SEU-DEEP were further given, finally an example was used to show this course in detail.
2004, 34(7): 85-87.
doi: 10.13204/j.gyjz200407025
Abstract:
Experimental research on the flexural behavior of 17 RC beams strengthened by carbon fiber sheet( CFS) under quadratic loading has been carried out. The experimental researches considered that how the reinforcement ratio of the longitudinal reinforcing bar, the quantity of carbon fiber sheet as well as stress level of the beam influence the CFS strengthening effect. Test research showed that the carbon fiber sheet has good strengthening performance, the stress at first stage can reduce the strengthening effect, and the reinforcement ratio and the CFS quantity have greater influence on the strain of CFS.
Experimental research on the flexural behavior of 17 RC beams strengthened by carbon fiber sheet( CFS) under quadratic loading has been carried out. The experimental researches considered that how the reinforcement ratio of the longitudinal reinforcing bar, the quantity of carbon fiber sheet as well as stress level of the beam influence the CFS strengthening effect. Test research showed that the carbon fiber sheet has good strengthening performance, the stress at first stage can reduce the strengthening effect, and the reinforcement ratio and the CFS quantity have greater influence on the strain of CFS.
2004, 34(7): 88-90,96.
doi: 10.13204/j.gyjz200407026
Abstract:
The effects of two strengthening manners of GFRP and the initial crack on aseismic behavior of the strengthened porous brick masonry walls are explored through experimental study on three specimens strengthened with GFRP.At the same time, the calculating methods for ultimate shear bearing capacity of the walls strengthened with GFRP are established on the basis of two strengthening manners, whose results are basically agreed with the test data.
The effects of two strengthening manners of GFRP and the initial crack on aseismic behavior of the strengthened porous brick masonry walls are explored through experimental study on three specimens strengthened with GFRP.At the same time, the calculating methods for ultimate shear bearing capacity of the walls strengthened with GFRP are established on the basis of two strengthening manners, whose results are basically agreed with the test data.
2004, 34(7): 91-92,98.
doi: 10.13204/j.gyjz200407027
Abstract:
Carbon Fiber Reinforced Polymer seldom used in strengthening steel structures reinforcement due to lack of experimental research and theoretic support. This article introduced a series of experiments of strengthening steel structures with CFRP. The mechanical properties of some kinds of CFRP materials were given. The carrying capacity, loaddisplacement curves of steel beam with different reinforced methods were obtained. The results may be a reference for engineering application.
Carbon Fiber Reinforced Polymer seldom used in strengthening steel structures reinforcement due to lack of experimental research and theoretic support. This article introduced a series of experiments of strengthening steel structures with CFRP. The mechanical properties of some kinds of CFRP materials were given. The carrying capacity, loaddisplacement curves of steel beam with different reinforced methods were obtained. The results may be a reference for engineering application.
2004, 34(7): 93-96.
doi: 10.13204/j.gyjz200407028
Abstract:
Light steel portal frames have been extensively used for industrial mill buildings in recent years, and much attention is being paid to the fireproofing of steel structures.It is introduced that the detection analysis of the structural damage to a combined mill building after a fire on September 6, 2002 and its rehabilitation, which were undertaken by Shanghai Building Research Academy and Shanghai Electromechanical Design and Research Institute.
Light steel portal frames have been extensively used for industrial mill buildings in recent years, and much attention is being paid to the fireproofing of steel structures.It is introduced that the detection analysis of the structural damage to a combined mill building after a fire on September 6, 2002 and its rehabilitation, which were undertaken by Shanghai Building Research Academy and Shanghai Electromechanical Design and Research Institute.
2004, 34(7): 97-98.
doi: 10.13204/j.gyjz200407029
Abstract:
Windows are the opening parts of a building envelope, the energy loss through windows may amount to half of the total energy loss of a building envelope. Windows are the key sections of building energy conservation. The recent advances in technology of energy-saving windows both at home and abroad are summarized; and some techniques of energysaving windows that are being developed are also introduced.
Windows are the opening parts of a building envelope, the energy loss through windows may amount to half of the total energy loss of a building envelope. Windows are the key sections of building energy conservation. The recent advances in technology of energy-saving windows both at home and abroad are summarized; and some techniques of energysaving windows that are being developed are also introduced.
