Login
Register
E-alert
2008 Vol. 38, No. 3
Display Method:
2008, 38(3): 1-4.
doi: 10.13204/j.gyjz200803001
Abstract:
A study was conducted to investigate the composite action in steel2concrete composite beams subjected to torsion. Tests and analysis showed that the composite action definitely existed under torsion. It would underestimate the torsional strength of composite beams if the interaction was neglected between steel beams and concrete flanges. Steel beams play a vital role in restraining concrete flanges from deforming longitudinally. A three2dimensional behavioral truss model capable of analyzing composite beams sections subjected to combined bending and torsion is presented. It is based on the rotating2angle softened truss model (RA2STM) and assumes that plane sections remain plane to account for composite actions. In this model, the section is assumably subjected to one2 and two2dimensional stresses separately. The former is resisting the longitudinal stresses due to bending and torsion, while the latter is resisting the shear stresses due to torsion. Links between the two systems are compatibility of strains and equilibrium of stresses in the longitudinal direction. It satisfies the equilibrium equations, compatibility equations and the constitutive laws of materials. Through analyzing several specimens available in the literature the results predicted by this method are in good agreement with those obtained from tests. In addition, a reported formula is appraised.
A study was conducted to investigate the composite action in steel2concrete composite beams subjected to torsion. Tests and analysis showed that the composite action definitely existed under torsion. It would underestimate the torsional strength of composite beams if the interaction was neglected between steel beams and concrete flanges. Steel beams play a vital role in restraining concrete flanges from deforming longitudinally. A three2dimensional behavioral truss model capable of analyzing composite beams sections subjected to combined bending and torsion is presented. It is based on the rotating2angle softened truss model (RA2STM) and assumes that plane sections remain plane to account for composite actions. In this model, the section is assumably subjected to one2 and two2dimensional stresses separately. The former is resisting the longitudinal stresses due to bending and torsion, while the latter is resisting the shear stresses due to torsion. Links between the two systems are compatibility of strains and equilibrium of stresses in the longitudinal direction. It satisfies the equilibrium equations, compatibility equations and the constitutive laws of materials. Through analyzing several specimens available in the literature the results predicted by this method are in good agreement with those obtained from tests. In addition, a reported formula is appraised.
2008, 38(3): 5-8.
doi: 10.13204/j.gyjz200803002
Abstract:
Research is conducted on the influence of the in-plane stiffness of stee-l concrete composite floor slab to the structure analyses of high-rise building. A simplified model is suggested considering the in-plane deformation of stee-l concrete composite floor slabs. Comparison is made to investigate the effects of different length-width ratios on the analyses of high-rise structure. The predicting results are reasonable and credible. This method is a valid approach to analyze high building with composite floor, which can provide some references for the evaluation of the composite diaphragm in engineering practice.
Research is conducted on the influence of the in-plane stiffness of stee-l concrete composite floor slab to the structure analyses of high-rise building. A simplified model is suggested considering the in-plane deformation of stee-l concrete composite floor slabs. Comparison is made to investigate the effects of different length-width ratios on the analyses of high-rise structure. The predicting results are reasonable and credible. This method is a valid approach to analyze high building with composite floor, which can provide some references for the evaluation of the composite diaphragm in engineering practice.
2008, 38(3): 9-11,4.
doi: 10.13204/j.gyjz200803003
Abstract:
The concrete-filled square steel tube column under axial loads is studied based on the unified strength theory. The ultimate load calculation formula for the concrete-filled square steel tubes column is derived. Comparisons are made between the simplified method and large amount of test data both at home and abroad, which verified the correctness of the theoretic formula. This result provides a theoretic basis for calculating the bearing capacity of this sort of column.
The concrete-filled square steel tube column under axial loads is studied based on the unified strength theory. The ultimate load calculation formula for the concrete-filled square steel tubes column is derived. Comparisons are made between the simplified method and large amount of test data both at home and abroad, which verified the correctness of the theoretic formula. This result provides a theoretic basis for calculating the bearing capacity of this sort of column.
2008, 38(3): 12-15.
doi: 10.13204/j.gyjz200803004
Abstract:
The formulae for calculating bearing capacity of square concrete-filled steel tube (CFT) stub column with binding bars subjected to axial load are deduced based on the constitutive relationship of square concrete-filled steel tube, which are followed by a simplified method for the need of applying in practice conveniently. A calculation for the ultimate bearing capacity of square CFT stub columns with or without binding bars is conducted by the formulae put forward in this paper, the method of EC4(1996) and that of GJB(2000) respectively. The comparison between the results of calculation and those of experiments show that: 1) for the square CFT stub columns without binding bars, results got by all of the three methods are reasonable and close to each other; 2) for the square CFT stub columns with binding bars, results got by the method put forward in this paper are more reasonable because of considering the confining effect of binding bars.
The formulae for calculating bearing capacity of square concrete-filled steel tube (CFT) stub column with binding bars subjected to axial load are deduced based on the constitutive relationship of square concrete-filled steel tube, which are followed by a simplified method for the need of applying in practice conveniently. A calculation for the ultimate bearing capacity of square CFT stub columns with or without binding bars is conducted by the formulae put forward in this paper, the method of EC4(1996) and that of GJB(2000) respectively. The comparison between the results of calculation and those of experiments show that: 1) for the square CFT stub columns without binding bars, results got by all of the three methods are reasonable and close to each other; 2) for the square CFT stub columns with binding bars, results got by the method put forward in this paper are more reasonable because of considering the confining effect of binding bars.
2008, 38(3): 16-19.
doi: 10.13204/j.gyjz200803005
Abstract:
As compared to the normal SRC structures, concrete filled steel tube (CFST) structures and steel structures, the research on the mechanics under axial force of column reinforced by inner circular steel tube is in initial stage, not only in normal temperature but also in and after fire. Through establishing appropriate computational model, and based on simulation test, it is researched into the forced mechanism and influencing factors of this sort of column.
As compared to the normal SRC structures, concrete filled steel tube (CFST) structures and steel structures, the research on the mechanics under axial force of column reinforced by inner circular steel tube is in initial stage, not only in normal temperature but also in and after fire. Through establishing appropriate computational model, and based on simulation test, it is researched into the forced mechanism and influencing factors of this sort of column.
2008, 38(3): 20-22,8.
doi: 10.13204/j.gyjz200803006
Abstract:
The joint design of heavy-load is very important to prevent the collapse of a structure. Repeat low cycle loading tests are carried out on a new type of joint of heavy-load columns. The evaluations are made for the earthquake-resistant behavior of the joints. The test results show the new type of joint of heavy-load columns can provide higher shear bearing capacity and excellent aseismatic behavior.
The joint design of heavy-load is very important to prevent the collapse of a structure. Repeat low cycle loading tests are carried out on a new type of joint of heavy-load columns. The evaluations are made for the earthquake-resistant behavior of the joints. The test results show the new type of joint of heavy-load columns can provide higher shear bearing capacity and excellent aseismatic behavior.
2008, 38(3): 23-26.
doi: 10.13204/j.gyjz200803007
Abstract:
A new type of through high strength bolts-end plate connection for concrete filled square steel tube column and steel beams is proposed. A total of 3 pseudo-static experiments has been conducted in which the horizontal cyclic load is applied on the top of the column. The nonlinear finite element models involving geometric, material and contact nonlinearities are presented using 3D solid elements. The ANSYS finite element package is used to simulate the nonlinear behavior of the experimental specimens under the monotone and cyclic loading. The results obtained from the finite element and the experiments show that the connections have ex cellent strength, stiffness, ductility and energy dissipation capacity.
A new type of through high strength bolts-end plate connection for concrete filled square steel tube column and steel beams is proposed. A total of 3 pseudo-static experiments has been conducted in which the horizontal cyclic load is applied on the top of the column. The nonlinear finite element models involving geometric, material and contact nonlinearities are presented using 3D solid elements. The ANSYS finite element package is used to simulate the nonlinear behavior of the experimental specimens under the monotone and cyclic loading. The results obtained from the finite element and the experiments show that the connections have ex cellent strength, stiffness, ductility and energy dissipation capacity.
2008, 38(3): 27-30.
doi: 10.13204/j.gyjz200803008
Abstract:
Based on theory of fiber model method, a nonlinear analysis of computer program is developed. As compared with experimental data of corresponding documents, the results agree well with each other. Then the influences of strength of concrete, stirrup ratio, stee-l reinforced ratio, changes of shape on the mechanical property of bending members are also analyzed. Through regressive analysis of the results of numerical calculation, a practical formula is got.
Based on theory of fiber model method, a nonlinear analysis of computer program is developed. As compared with experimental data of corresponding documents, the results agree well with each other. Then the influences of strength of concrete, stirrup ratio, stee-l reinforced ratio, changes of shape on the mechanical property of bending members are also analyzed. Through regressive analysis of the results of numerical calculation, a practical formula is got.
2008, 38(3): 31-34.
doi: 10.13204/j.gyjz200803009
Abstract:
Tests on three non-un-i thickness walled rectangular CFT(concrete-filled steel tube) members subjected to pure bending are carried out. The mechanical behavior of the member is studied. The experimental results show that non-un-i thickness walled rectangular CFT members subjected to pure bending have good ductility and high bearing capacity. The bearing capacity of non-un-i thickness walled rectangular CFT members subjected to pure bending is prior to un-i thickness walled rectangular CFT members under the same stee-l ratio condition. The conclusions can be a reference for the design and the theory study of non-uni-thickness walled rectangular CFT members.
Tests on three non-un-i thickness walled rectangular CFT(concrete-filled steel tube) members subjected to pure bending are carried out. The mechanical behavior of the member is studied. The experimental results show that non-un-i thickness walled rectangular CFT members subjected to pure bending have good ductility and high bearing capacity. The bearing capacity of non-un-i thickness walled rectangular CFT members subjected to pure bending is prior to un-i thickness walled rectangular CFT members under the same stee-l ratio condition. The conclusions can be a reference for the design and the theory study of non-uni-thickness walled rectangular CFT members.
2008, 38(3): 35-38.
doi: 10.13204/j.gyjz200803010
Abstract:
It is investigated the sustainable use of the old residential buildings built in 1970s and 1980s in Handan, after introducing and learning from the theoretical researches and practical experiences both at home and abroad, this paper expounds the methods of energy-saving alteration suitable for these sorts of cities.
It is investigated the sustainable use of the old residential buildings built in 1970s and 1980s in Handan, after introducing and learning from the theoretical researches and practical experiences both at home and abroad, this paper expounds the methods of energy-saving alteration suitable for these sorts of cities.
2008, 38(3): 39-41.
doi: 10.13204/j.gyjz200803011
Abstract:
The resource circulation housing is a new kind of the sustainable housing, it can embody the request of building energy-saving much more. From the angle of entire life cycle, this paper discusses the energy-saving construction main point and measures of the resource circulation housing during its whole course of scheme and proposal, layout and design, build and construction, running, backout, disposal and regeneration. So it has far-reaching practical instructive meaning to realize the resource-saving and environmen-t friendly society and the building energy-saving.
The resource circulation housing is a new kind of the sustainable housing, it can embody the request of building energy-saving much more. From the angle of entire life cycle, this paper discusses the energy-saving construction main point and measures of the resource circulation housing during its whole course of scheme and proposal, layout and design, build and construction, running, backout, disposal and regeneration. So it has far-reaching practical instructive meaning to realize the resource-saving and environmen-t friendly society and the building energy-saving.
2008, 38(3): 42-44,89.
doi: 10.13204/j.gyjz200803012
Abstract:
Using designer. s simulation toolkit DeST-h developed by Tsinghua University, it is analysed the building energy consumption of a typical residential building according to heat transfer coefficient of roof in Ningbo, and is measured the changes in the temperature and heat flux of roof. Result shows that heat transfer coefficient of roof takes big effects on heating energy consumption in winter, less on cooling energy consumption in summer, and aerial roof makes big contributions to cooling energy consumption. Which has a certain guidance to building design in hot summer and cold winter zones.
Using designer. s simulation toolkit DeST-h developed by Tsinghua University, it is analysed the building energy consumption of a typical residential building according to heat transfer coefficient of roof in Ningbo, and is measured the changes in the temperature and heat flux of roof. Result shows that heat transfer coefficient of roof takes big effects on heating energy consumption in winter, less on cooling energy consumption in summer, and aerial roof makes big contributions to cooling energy consumption. Which has a certain guidance to building design in hot summer and cold winter zones.
2008, 38(3): 45-47,34.
doi: 10.13204/j.gyjz200803013
Abstract:
Recently, the global countries have an agreement on the building energy conservation; every country is taking measures to carry out the energy conservation in building actively. The outer wall surface is an emphasis for energy saving in construction and an important factor of composing of construction image. It is analysed the influence on wall face, and is also set forth the application of the energy saving technologies in design to express the outer wall surface artistically so that the construction image of a new era can be created.
Recently, the global countries have an agreement on the building energy conservation; every country is taking measures to carry out the energy conservation in building actively. The outer wall surface is an emphasis for energy saving in construction and an important factor of composing of construction image. It is analysed the influence on wall face, and is also set forth the application of the energy saving technologies in design to express the outer wall surface artistically so that the construction image of a new era can be created.
2008, 38(3): 48-51,30.
doi: 10.13204/j.gyjz200803014
Abstract:
Based on field investigation on traditional earth wal-l timber frame structure in loess areas and statistical analysis of previous earthquake damage characteristics, the existing of it is proved to be reasonable regionally. The congenital inadequacy on seismic behavior of such structure is also pointed out in the paper. Some effective measures beneficial to seismic behavior improvement of earth wal-l timber frame structure are proposed, and the seismic capacity of this type of structure is checked and evaluated by an example.
Based on field investigation on traditional earth wal-l timber frame structure in loess areas and statistical analysis of previous earthquake damage characteristics, the existing of it is proved to be reasonable regionally. The congenital inadequacy on seismic behavior of such structure is also pointed out in the paper. Some effective measures beneficial to seismic behavior improvement of earth wal-l timber frame structure are proposed, and the seismic capacity of this type of structure is checked and evaluated by an example.
ANALYSIS OF UNBONDED PRESTRESSED TECHNIQUE IN CONTROLLING TEMPERATURE STRESS OF SUPER-LONG STRUCTURE
2008, 38(3): 52-55,83.
doi: 10.13204/j.gyjz200803015
Abstract:
Based a typical super-long structure, the internal force and deformation of the structure under the function of linear unbonded prestressed tendons are analyzed by ANSYS, and the effect of the distributed unbonded prestress on controlling super-long structure temperature stress is also taken, whose results prove that it is more reasonable to place prestressed tendons in floorslab strip under column which should be partly tensioned, which can provide experience for similar projects.
Based a typical super-long structure, the internal force and deformation of the structure under the function of linear unbonded prestressed tendons are analyzed by ANSYS, and the effect of the distributed unbonded prestress on controlling super-long structure temperature stress is also taken, whose results prove that it is more reasonable to place prestressed tendons in floorslab strip under column which should be partly tensioned, which can provide experience for similar projects.
2008, 38(3): 56-58.
doi: 10.13204/j.gyjz200803016
Abstract:
A comparative experiment on the externally prestressed simple beams and frame beams is conducted. Through this experiment, the theory is proved that shearing force of frame columns is enhanced and effective prestressing of horizontal members is decreased because of effective lateral restraint of the frame columns. And the suggestions are proposed that secondary axial force in frame and shear wall structure must be considered and that of how to increase shearing capacity of frame columns.
A comparative experiment on the externally prestressed simple beams and frame beams is conducted. Through this experiment, the theory is proved that shearing force of frame columns is enhanced and effective prestressing of horizontal members is decreased because of effective lateral restraint of the frame columns. And the suggestions are proposed that secondary axial force in frame and shear wall structure must be considered and that of how to increase shearing capacity of frame columns.
2008, 38(3): 59-63.
doi: 10.13204/j.gyjz200803017
Abstract:
Magnetorheological (MR) damper is one of the most excellent new devices for sem-i active control. The research on design of MR dampers should be improved to accelerate the application of MR dampers. In this paper, after a review of the features and models of MR materials and devices, geometrical design and magnetic circuit design of MR dampers are presented and discussed in detail, then an example is provided. The theory can provide a guidance for the design of MR dampers applied in civil engineering.
Magnetorheological (MR) damper is one of the most excellent new devices for sem-i active control. The research on design of MR dampers should be improved to accelerate the application of MR dampers. In this paper, after a review of the features and models of MR materials and devices, geometrical design and magnetic circuit design of MR dampers are presented and discussed in detail, then an example is provided. The theory can provide a guidance for the design of MR dampers applied in civil engineering.
2008, 38(3): 64-67.
doi: 10.13204/j.gyjz200803018
Abstract:
A kind of lateral and vertical compound seismic isolation system is proposed, and the model of test is also designed. The test is conducted in dynamic character, verifies the rigidity and damping properties of the model, it proved the theory of design. The property of the compound seismic isolation system is analysed in different frequency, the equilibrium position and amplitude; and the influences of disk spring and the lead rubber bearing are also discussed on the compound seismic isolation system. It is not only with vertical appropriate stiffness and damper performance, but also with stable performance and compact system, which is a good seismic isolation system as well.
A kind of lateral and vertical compound seismic isolation system is proposed, and the model of test is also designed. The test is conducted in dynamic character, verifies the rigidity and damping properties of the model, it proved the theory of design. The property of the compound seismic isolation system is analysed in different frequency, the equilibrium position and amplitude; and the influences of disk spring and the lead rubber bearing are also discussed on the compound seismic isolation system. It is not only with vertical appropriate stiffness and damper performance, but also with stable performance and compact system, which is a good seismic isolation system as well.
2008, 38(3): 68-71114.
doi: 10.13204/j.gyjz200803019
Abstract:
Soil structure has significant influence on its engineering properties, the formation of soft soil structure in Ningbo area is analyzed from the internal cause and external cause. To analyze the soil structural effects, by means of onedimensional consolidation test and consolidated undrained triaxial test, differences of compression properties, properties of pore water pressure, and strength properties which are caused by structural property are systematic analyzed by contrast with the test data of undisturbed sample with remolded sample of typical mucky soft soil in Ningbo area. Finally problems which should be considered in constitutive model for Ningbo clay on the basis of experiment results are presented.
Soil structure has significant influence on its engineering properties, the formation of soft soil structure in Ningbo area is analyzed from the internal cause and external cause. To analyze the soil structural effects, by means of onedimensional consolidation test and consolidated undrained triaxial test, differences of compression properties, properties of pore water pressure, and strength properties which are caused by structural property are systematic analyzed by contrast with the test data of undisturbed sample with remolded sample of typical mucky soft soil in Ningbo area. Finally problems which should be considered in constitutive model for Ningbo clay on the basis of experiment results are presented.
2008, 38(3): 72-74105.
doi: 10.13204/j.gyjz200803020
Abstract:
To study reinforcement effect and bearing characteristics of long-short cemen-t soil piles composite foundation in deep soft soils, the loading test in situ on the bearing characteristics of long-short cemen-t soil piles composite ground in deep soft soils is carried out. The stresses of long piles, short piles and soil have been measured; and pile-soil stress ratio of composite ground with cemen-t soil long-short piles and its variation with the load have been studied in deep soils. According to pile-soil stress ratio, it has been found that stress ratio increases firstly and then decreases and finally tends to stability. It has also been revealed that the sequence of primary piles and secondary pile have been changed before and after critical load.
To study reinforcement effect and bearing characteristics of long-short cemen-t soil piles composite foundation in deep soft soils, the loading test in situ on the bearing characteristics of long-short cemen-t soil piles composite ground in deep soft soils is carried out. The stresses of long piles, short piles and soil have been measured; and pile-soil stress ratio of composite ground with cemen-t soil long-short piles and its variation with the load have been studied in deep soils. According to pile-soil stress ratio, it has been found that stress ratio increases firstly and then decreases and finally tends to stability. It has also been revealed that the sequence of primary piles and secondary pile have been changed before and after critical load.
2008, 38(3): 75-79.
doi: 10.13204/j.gyjz200803021
Abstract:
Based on Biot consolidation theory and adopting Duncan-Chang model, a lot of nonlinear finite element calculations have been performed on a calculating case. The different sensitivities of eight parameters of Duncan-Chang model have been analyzed. At the same time, it is discussed corresponding measures of the design of controlling embankment foundation deformation, which has practical and significant function for parameters testing and the design of controlling embankment foundation deformation.
Based on Biot consolidation theory and adopting Duncan-Chang model, a lot of nonlinear finite element calculations have been performed on a calculating case. The different sensitivities of eight parameters of Duncan-Chang model have been analyzed. At the same time, it is discussed corresponding measures of the design of controlling embankment foundation deformation, which has practical and significant function for parameters testing and the design of controlling embankment foundation deformation.
2008, 38(3): 80-83.
doi: 10.13204/j.gyjz200803022
Abstract:
By the splitting tensile strength experiments on the specimens with the dimension of 100mm @ 100mm @ 100mm, it is explored that the influence of the number of freeze-thaw cycle and steel fiber volume fraction upon the splitting tensile behavior of the bonding interface between fresh steel fiber concrete and old concrete through quickly freeze-thaw testing. The result demonstrates that the splitting tensile strength of the bonding specimen declines with the escalating of the freeze-thaw cycle. s number and the strength aggrandizes a certain extent with the increasing of the steel fiber volume fraction. At last, the calculating formula of the splitting tensile strength of the bonding interface is established, which considers the influence of old concrete. s splitting tensile strength, number of freeze-thaw cycle and steel fiber volume fraction.
By the splitting tensile strength experiments on the specimens with the dimension of 100mm @ 100mm @ 100mm, it is explored that the influence of the number of freeze-thaw cycle and steel fiber volume fraction upon the splitting tensile behavior of the bonding interface between fresh steel fiber concrete and old concrete through quickly freeze-thaw testing. The result demonstrates that the splitting tensile strength of the bonding specimen declines with the escalating of the freeze-thaw cycle. s number and the strength aggrandizes a certain extent with the increasing of the steel fiber volume fraction. At last, the calculating formula of the splitting tensile strength of the bonding interface is established, which considers the influence of old concrete. s splitting tensile strength, number of freeze-thaw cycle and steel fiber volume fraction.
2008, 38(3): 84-89.
doi: 10.13204/j.gyjz200803023
Abstract:
The behavior of FRP-confined concrete square columns under uniaxial compression is analyzed by 3-D nonlinear finite element method. Based on the analysis result, the columns section stress distribution and mechanism are discussed and pointed out that there is shear stress and shear strain in the columns cross section which is under uniaxial compression. It is also explained the cause of FRP stress asymmetrical distribution around the cross section. A suggestion of dividing weakly confined region from cross section by the ratio of the first principal stress and the third principal stress is developed. It is also discussed the affection of fillet radius of cross section on stress distribution.
The behavior of FRP-confined concrete square columns under uniaxial compression is analyzed by 3-D nonlinear finite element method. Based on the analysis result, the columns section stress distribution and mechanism are discussed and pointed out that there is shear stress and shear strain in the columns cross section which is under uniaxial compression. It is also explained the cause of FRP stress asymmetrical distribution around the cross section. A suggestion of dividing weakly confined region from cross section by the ratio of the first principal stress and the third principal stress is developed. It is also discussed the affection of fillet radius of cross section on stress distribution.
2008, 38(3): 90-93.
doi: 10.13204/j.gyjz200803024
Abstract:
The damage processes of an ordinary concrete and a high strength concrete, attacked by solutions of 10% Na2 SO4 (in mass, the same below), 10%MgSO4 and Qinghai salt lake solution in cycles of drying-immersion are studied. The results show that the damage process of concretes attacked by Na2 SO4 exhibits a decreasing stage followed by improved performance stage, finally the failure stage because the SO2- 4 ions lead to expansion damage to concrete. Abrasion and mass loss of concrete are the main deterioration form when concrete exposed toMgSO4 solution or to Qinghai salt lake solutions, its relative dynamic elastic modulus and mass decreased first, then kept stable, lastly to failure. Moreover, corrosion elements of concretes attacked by sulfates are studied by SEM, EDS and XRD.
The damage processes of an ordinary concrete and a high strength concrete, attacked by solutions of 10% Na2 SO4 (in mass, the same below), 10%MgSO4 and Qinghai salt lake solution in cycles of drying-immersion are studied. The results show that the damage process of concretes attacked by Na2 SO4 exhibits a decreasing stage followed by improved performance stage, finally the failure stage because the SO2- 4 ions lead to expansion damage to concrete. Abrasion and mass loss of concrete are the main deterioration form when concrete exposed toMgSO4 solution or to Qinghai salt lake solutions, its relative dynamic elastic modulus and mass decreased first, then kept stable, lastly to failure. Moreover, corrosion elements of concretes attacked by sulfates are studied by SEM, EDS and XRD.
2008, 38(3): 94-96.
doi: 10.13204/j.gyjz200803025
Abstract:
Based on plenty of experimental studies, the effect of curing period of specimens, volume content of polypropylene fiber and cement content on compressive strength of cement stabilized macadam is analyzed. The study results indicate that the addition of polypropylene fiber has certain reinforcement to the compressive strength of cement stabilized macadam. The compressive strength is increasing with the increase of curing period. Within the range of the fiber content that is less than 1j in this study, there is a tendency of increase in compressive strength and tensile strength with the increase of polypropylene fiber volume content. With the increase of cement content, the compressive strength of cement stabilized macadam is increasing in linearity.
Based on plenty of experimental studies, the effect of curing period of specimens, volume content of polypropylene fiber and cement content on compressive strength of cement stabilized macadam is analyzed. The study results indicate that the addition of polypropylene fiber has certain reinforcement to the compressive strength of cement stabilized macadam. The compressive strength is increasing with the increase of curing period. Within the range of the fiber content that is less than 1j in this study, there is a tendency of increase in compressive strength and tensile strength with the increase of polypropylene fiber volume content. With the increase of cement content, the compressive strength of cement stabilized macadam is increasing in linearity.
2008, 38(3): 97-100.
doi: 10.13204/j.gyjz200803026
Abstract:
There are often quality problems, such as low strength of high-grade concrete, cracks of beams and slabs etc in the production and use of ready-mixed concrete, which can bring hidden dangers to the quality of a project. It is analyzed systematically the causes of these problems of the projects with ready-mixed concrete. The prevention measures are also proposed.
There are often quality problems, such as low strength of high-grade concrete, cracks of beams and slabs etc in the production and use of ready-mixed concrete, which can bring hidden dangers to the quality of a project. It is analyzed systematically the causes of these problems of the projects with ready-mixed concrete. The prevention measures are also proposed.
2008, 38(3): 101-105.
doi: 10.13204/j.gyjz200803027
Abstract:
The chance and challenge of earth building development in current ecology civilization time are discussed and research state and earthquake damage characteristics of earth buildings are indicated in this paper. The trend and requirements for developing earth building in China are proposed that for the opportunity of building new rural areas in China it is important to make full use of traditional experience and advanced research results from abroad, so as to explore and design earth buildings to meet the human life forms and the requirements for seismic resistance.
The chance and challenge of earth building development in current ecology civilization time are discussed and research state and earthquake damage characteristics of earth buildings are indicated in this paper. The trend and requirements for developing earth building in China are proposed that for the opportunity of building new rural areas in China it is important to make full use of traditional experience and advanced research results from abroad, so as to explore and design earth buildings to meet the human life forms and the requirements for seismic resistance.
2008, 38(3): 106-108122.
doi: 10.13204/j.gyjz200803028
Abstract:
The CFRP strengthening has the advantages of low density, high strength, facility, endurance, etc, so it has been widely applied to strengthen reinforced concrete structures. It is also applicable to the rehabilitation of steel structures. A simplified buckling analysis of steel compression members strengthened with CFRP is carried out, and formulae of the buckling loads and stability coefficients of the strengthened compression members are derived.
The CFRP strengthening has the advantages of low density, high strength, facility, endurance, etc, so it has been widely applied to strengthen reinforced concrete structures. It is also applicable to the rehabilitation of steel structures. A simplified buckling analysis of steel compression members strengthened with CFRP is carried out, and formulae of the buckling loads and stability coefficients of the strengthened compression members are derived.
2008, 38(3): 109-111.
doi: 10.13204/j.gyjz200803029
Abstract:
Based on static experimental research, the major factors that influence strengthening effect and the destroyed mode of the steel beam bolt splicing joint strengthened by CFRP are observed. The numerical modeling has been done by the bolt splicing joint finite element analysis model considering the contact friction and the pretightening force. The contribution to the yield load and rigidity by the bolt joint strengthened by CFRP has been analyzed. The finite element analysis result and the test result show that the strengthening method is effective.
Based on static experimental research, the major factors that influence strengthening effect and the destroyed mode of the steel beam bolt splicing joint strengthened by CFRP are observed. The numerical modeling has been done by the bolt splicing joint finite element analysis model considering the contact friction and the pretightening force. The contribution to the yield load and rigidity by the bolt joint strengthened by CFRP has been analyzed. The finite element analysis result and the test result show that the strengthening method is effective.
2008, 38(3): 112-114.
doi: 10.13204/j.gyjz200803030
Abstract:
The skew bridge in a puddling furnace was found to have heavy vibrations when it was working, also it had common structural damages, after structure inspecting, vibration test and computation analysis, the scheme of structural disposal was proposed.
The skew bridge in a puddling furnace was found to have heavy vibrations when it was working, also it had common structural damages, after structure inspecting, vibration test and computation analysis, the scheme of structural disposal was proposed.
2008, 38(3): 115-119.
doi: 10.13204/j.gyjz200803031
Abstract:
For the foundation ex cavation with shallow saturation-fine and sility sand layer which easily results drift sand under hydrodynamic pressure, an economical support system is adopted. Taking the design and construction plan of an apartment foundation excavation in Shanghai as the study object, the project increased the inserting depth of the water insulation curtain, raised the angle of the last rank of soil nailing, and took the wholly pressed grouting technology, which solved the bulge of the slope toe soil and drift sand effectively. To ensure safe construction, informational rea-l time testing system and dynamic design are important assisting means. The support parameters are analyzed by theory of gravity retaining wall and limit equilibrium. The testing results show that it. s safe and practicable to adopt the composite soi-l nailed wall support for the the foundation ex cavation saturation with shallow sand layer (less than 6 meters); for the 51 7m foundation ex cavation with shallow fine and sility sand layer, the subsidence coverage of the ground is 9~ 10m, and the subsidence decreases with the increase in distance; the biggest displacement appears at the internal protrude angle.
For the foundation ex cavation with shallow saturation-fine and sility sand layer which easily results drift sand under hydrodynamic pressure, an economical support system is adopted. Taking the design and construction plan of an apartment foundation excavation in Shanghai as the study object, the project increased the inserting depth of the water insulation curtain, raised the angle of the last rank of soil nailing, and took the wholly pressed grouting technology, which solved the bulge of the slope toe soil and drift sand effectively. To ensure safe construction, informational rea-l time testing system and dynamic design are important assisting means. The support parameters are analyzed by theory of gravity retaining wall and limit equilibrium. The testing results show that it. s safe and practicable to adopt the composite soi-l nailed wall support for the the foundation ex cavation saturation with shallow sand layer (less than 6 meters); for the 51 7m foundation ex cavation with shallow fine and sility sand layer, the subsidence coverage of the ground is 9~ 10m, and the subsidence decreases with the increase in distance; the biggest displacement appears at the internal protrude angle.
