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2013 Vol. 43, No. 4
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2013, 43(4): 1-7,53.
doi: 10.13204/j.gyjz201304001
Abstract:
Through revisiting the classic problems of elastic and elastic-plastic buckling of frames, elastic-plastic stability of beam-columns, buckling of column braced at midspan by a horizontal brace and the buckling of dual structural system, it was proposed the concept of residual stiffness, i.e.the residual part of the total stiffness after deducting the stiffness depleted by horizontal forces and bending moments in the members.Check for stability of members and structures in real steel structures is to assure a minimum residual stiffness of the members and structures to resist against the destabilizing effect of gravity loads.Through analysis of the instability of beam-columns and dual structural systems, it was revealed that in the limit state, the stiffness was linearly or more than linearly decreased due to the horizontal load(bending moment).
Through revisiting the classic problems of elastic and elastic-plastic buckling of frames, elastic-plastic stability of beam-columns, buckling of column braced at midspan by a horizontal brace and the buckling of dual structural system, it was proposed the concept of residual stiffness, i.e.the residual part of the total stiffness after deducting the stiffness depleted by horizontal forces and bending moments in the members.Check for stability of members and structures in real steel structures is to assure a minimum residual stiffness of the members and structures to resist against the destabilizing effect of gravity loads.Through analysis of the instability of beam-columns and dual structural systems, it was revealed that in the limit state, the stiffness was linearly or more than linearly decreased due to the horizontal load(bending moment).
2013, 43(4): 8-12,18.
doi: 10.13204/j.gyjz201304002
Abstract:
The paper investigated the buckling of cantilevered Timoshenko columns whose cross-sectional flexural and shear rigidities and axial forces were varied along length.Finite element method was used to carry out buckling analysis.Physical and geometrical stiffness matrices were derived for elements with linearly varied rigidities and axial forces.In presenting the results, buckling of Timoshenko columns was understood as interactive buckling between flexural and shear buckling.and the interactive curves were presented.Approximate formulas for critical loads of cantilevered Timoshenko columns with linearly varied rigidities and linearly varied axial forces along length were presented, which could be used in determining the coefficient of second-order effect.
The paper investigated the buckling of cantilevered Timoshenko columns whose cross-sectional flexural and shear rigidities and axial forces were varied along length.Finite element method was used to carry out buckling analysis.Physical and geometrical stiffness matrices were derived for elements with linearly varied rigidities and axial forces.In presenting the results, buckling of Timoshenko columns was understood as interactive buckling between flexural and shear buckling.and the interactive curves were presented.Approximate formulas for critical loads of cantilevered Timoshenko columns with linearly varied rigidities and linearly varied axial forces along length were presented, which could be used in determining the coefficient of second-order effect.
2013, 43(4): 13-18.
doi: 10.13204/j.gyjz201304003
Abstract:
The lateral buckling of cantilevers of doubly symmetric I-section with different boundary conditions at tip was investigated in this paper, where three boundary conditions at tip in terms of practical use, both the lateral translation and torsion displacements clamped, torsion displacement clamped and torsion displacement elastically restrained, were mainly concerned.The solutions for the buckling load of these cantilevers under two typical load cases, the uniformly distributed loads and one concentrated load at tip, were proposed, in which the effects of the beam length and loading position in the vertical direction along the cross-section on the buckling load could be considered.Comparisons of lateral buckling loads from the presented solutions and the finite element analyses showed very good agreements between each other, which indicated the good accuracy of the proposed solutions.
The lateral buckling of cantilevers of doubly symmetric I-section with different boundary conditions at tip was investigated in this paper, where three boundary conditions at tip in terms of practical use, both the lateral translation and torsion displacements clamped, torsion displacement clamped and torsion displacement elastically restrained, were mainly concerned.The solutions for the buckling load of these cantilevers under two typical load cases, the uniformly distributed loads and one concentrated load at tip, were proposed, in which the effects of the beam length and loading position in the vertical direction along the cross-section on the buckling load could be considered.Comparisons of lateral buckling loads from the presented solutions and the finite element analyses showed very good agreements between each other, which indicated the good accuracy of the proposed solutions.
2013, 43(4): 19-21,27.
doi: 10.13204/j.gyjz201304004
Abstract:
It was derived the warping and free torsional rigidities of hot-rolled steel cross-sections with flanges of tapered thickness.Tables were provided to find these properties of all hot-rolled sections available in China.It was found that the warping inertia moments of hot-rolled channels are 13%~18% smaller than channels with assumed uniform thickness, and those of hot-rolled I sections were 16%~22% smaller than I-sections with uniform thickness.The warping inertia moments of all the series of hot-rolled channels and I sections were listed, and the formulas for calculating the free torsional constants of the sections considering the change in flange thickness were also given.
It was derived the warping and free torsional rigidities of hot-rolled steel cross-sections with flanges of tapered thickness.Tables were provided to find these properties of all hot-rolled sections available in China.It was found that the warping inertia moments of hot-rolled channels are 13%~18% smaller than channels with assumed uniform thickness, and those of hot-rolled I sections were 16%~22% smaller than I-sections with uniform thickness.The warping inertia moments of all the series of hot-rolled channels and I sections were listed, and the formulas for calculating the free torsional constants of the sections considering the change in flange thickness were also given.
2013, 43(4): 22-27.
doi: 10.13204/j.gyjz201304005
Abstract:
The buckling of simply supported rectangular plates under bending, shear and local bearing stresses was analysed using ANSYS.The interaction equations between any two kinds of stresses were first studied and approximate formulas were proposed.The shapes of the interactive curves were explained using the buckling wave similarities.Finaly, the interactive surfaces of the three stresses were studied and correlative formula was also suggested.
The buckling of simply supported rectangular plates under bending, shear and local bearing stresses was analysed using ANSYS.The interaction equations between any two kinds of stresses were first studied and approximate formulas were proposed.The shapes of the interactive curves were explained using the buckling wave similarities.Finaly, the interactive surfaces of the three stresses were studied and correlative formula was also suggested.
2013, 43(4): 28-33,41.
doi: 10.13204/j.gyjz201304006
Abstract:
It was studied the bucklings of horizontally elastically supported arches, and the linear analytic results of the horizontally elastically-supported arches under three loads were also presented.The symmetrical and antisym-metrical bucklings of such arches were analyzed, and a demarcation between the symmetrical buckling and antisymmetrical one was got.The formula for calculating the critical axial force as well as the recommendations on design were put forward.
It was studied the bucklings of horizontally elastically supported arches, and the linear analytic results of the horizontally elastically-supported arches under three loads were also presented.The symmetrical and antisym-metrical bucklings of such arches were analyzed, and a demarcation between the symmetrical buckling and antisymmetrical one was got.The formula for calculating the critical axial force as well as the recommendations on design were put forward.
2013, 43(4): 34-41.
doi: 10.13204/j.gyjz201304007
Abstract:
The torsional restraint, which the steel sheets exert on the purlins, cann't be neglected when the profiled steel sheets connect the purlins with specially designed splints.It was mainly analyzed the torsional rigidity of the HXY-478 roof system developed by Hangxiao Steel Corp through FEM.With the results of the FEM, relevant stiffness formulas were proposed.In order to confirm the accuracy of the finite element model of the specially designed splints, considered the warping torsional theory, this thesis adopted a kind of theoretical model to analyse the splints and compared this theoretical result with the results of the FEM, and they coincided well.
The torsional restraint, which the steel sheets exert on the purlins, cann't be neglected when the profiled steel sheets connect the purlins with specially designed splints.It was mainly analyzed the torsional rigidity of the HXY-478 roof system developed by Hangxiao Steel Corp through FEM.With the results of the FEM, relevant stiffness formulas were proposed.In order to confirm the accuracy of the finite element model of the specially designed splints, considered the warping torsional theory, this thesis adopted a kind of theoretical model to analyse the splints and compared this theoretical result with the results of the FEM, and they coincided well.
2013, 43(4): 42-44,70.
doi: 10.13204/j.gyjz201304008
Abstract:
With the rapid development of the cities in China, many old industry buildings are needed to be reconstructed and reused.Starting from the goal of sustainable development, the reconstruction of the old industry buildings in urban renewal faces multiple challenges.Based on the analysis of the awarded design, some suitable passive technologies, in the hot summer and cold winter zone, were summarized for the reconstruction of the old industry buildings.The atrium and the vertical green skin were the most efficient technologies and worth to be used.Through the simulation, it was found that in the old industry buildings with large length, the design of the atrium could promote the natural ventilation efficiently by wind pressure and hot pressure.Furthermore, the buffer zone was also created.The simulation also proved that vertical green skin is the efficient shading design for passive cooling.
With the rapid development of the cities in China, many old industry buildings are needed to be reconstructed and reused.Starting from the goal of sustainable development, the reconstruction of the old industry buildings in urban renewal faces multiple challenges.Based on the analysis of the awarded design, some suitable passive technologies, in the hot summer and cold winter zone, were summarized for the reconstruction of the old industry buildings.The atrium and the vertical green skin were the most efficient technologies and worth to be used.Through the simulation, it was found that in the old industry buildings with large length, the design of the atrium could promote the natural ventilation efficiently by wind pressure and hot pressure.Furthermore, the buffer zone was also created.The simulation also proved that vertical green skin is the efficient shading design for passive cooling.
2013, 43(4): 45-48.
doi: 10.13204/j.gyjz201304009
Abstract:
In order to research the summer indoor thermal environment of Shanghai high-rise residential buildings and optimize the energy saving design of Shanghai high-rise residential buildings, the indoor thermal environment conditions were surveyed by questionnaires and measured in summer.Through analyzing the results, it is shown that there is some difference between indoor thermal environments of different floors in Shanghai high-rise residential buildings and the indoor thermal environment of the residential buildings is relatively bad on the whole, but most of Shanghai inhabitants can acclimatize themselves basically to the indoor thermal environment in summer.
In order to research the summer indoor thermal environment of Shanghai high-rise residential buildings and optimize the energy saving design of Shanghai high-rise residential buildings, the indoor thermal environment conditions were surveyed by questionnaires and measured in summer.Through analyzing the results, it is shown that there is some difference between indoor thermal environments of different floors in Shanghai high-rise residential buildings and the indoor thermal environment of the residential buildings is relatively bad on the whole, but most of Shanghai inhabitants can acclimatize themselves basically to the indoor thermal environment in summer.
RESEARCH OF ENERGY EFFICIENCY TECHNOLOGY SYSTEM OF UNIVERSITY EXISTING BUILDING IN COLD CLIMATE ZONE
2013, 43(4): 49-53.
doi: 10.13204/j.gyjz201304010
Abstract:
At present, investment to reduce building energy consumption is about 5 times to reduce industrial energy investment, so the energy efficiency standards and technology economy of building is particularly important.Due to the fact that large number of universities in our country has become an important energy guzzler, using university existing buildings in cold area as research object, it was elaborated that by energy consumption surveys and testing data, simulation and analysis of existing building energy consumption, the key issues of existing building energy consumption could be found;the principle and technology system of energy efficiency retrofitting were established, which was the key to solve the problem of energy efficiency with university existing buildings.The use of technology should be on different characteristics of the existing buildings energy consumption and funds of retrofitting;flexible combination of technologies and applications was done;different levels of energy efficiency technology group were formed, which made the retrofitting be implemented truly.
At present, investment to reduce building energy consumption is about 5 times to reduce industrial energy investment, so the energy efficiency standards and technology economy of building is particularly important.Due to the fact that large number of universities in our country has become an important energy guzzler, using university existing buildings in cold area as research object, it was elaborated that by energy consumption surveys and testing data, simulation and analysis of existing building energy consumption, the key issues of existing building energy consumption could be found;the principle and technology system of energy efficiency retrofitting were established, which was the key to solve the problem of energy efficiency with university existing buildings.The use of technology should be on different characteristics of the existing buildings energy consumption and funds of retrofitting;flexible combination of technologies and applications was done;different levels of energy efficiency technology group were formed, which made the retrofitting be implemented truly.
2013, 43(4): 54-56,117.
doi: 10.13204/j.gyjz201304011
Abstract:
Based on the weather characteristic and natural environment in Northwest China, the current conditions of living model and energy conservation of the rural residence were analyzed.And the strategies of environment, economy and culture were proposed, which adapt to the development of the local traditional residence.Then, taking the rural residences in Jiang xigou in Qinghai and Gaolan in Gansu, a suitable constructing partten with a balance between standardized design and traditional culture conservation was put forward.By improving the energy-saving ability of rural buildings in the northwest region, the human habitation environment could be upgraded.
Based on the weather characteristic and natural environment in Northwest China, the current conditions of living model and energy conservation of the rural residence were analyzed.And the strategies of environment, economy and culture were proposed, which adapt to the development of the local traditional residence.Then, taking the rural residences in Jiang xigou in Qinghai and Gaolan in Gansu, a suitable constructing partten with a balance between standardized design and traditional culture conservation was put forward.By improving the energy-saving ability of rural buildings in the northwest region, the human habitation environment could be upgraded.
2013, 43(4): 57-61.
doi: 10.13204/j.gyjz201304012
Abstract:
Based on the freeze-thawing and fatigue alternate experiment of twelve prestressed concrete beams, the effects of fatigue load limit, strength grade of concrete, prestress degree and freeze-thaw fatigue alternating frequency ratio on the variation of specimens appearance, deflection under fatigue load and concrete dynamic elastic modulus of specimens were studied.The effects of prestress degree, fatigue load limit and freeze-thaw fatigue alternating frequency ratio on the attenuation rate of dynamic modulus of elasticity were also studied by using the range analysis method.Test results show that applying prestress and improving the strength of concrete can effectively improve the frost resistance of concrete;freeze-thawing can promote the increment of mid-span deflection and attenuate the stiffness of specimens under fatigue load.The fatigue load limit is always the control factor which affect the dynamic modulus of elasticity attenuation, and the influence of factors that prestress degree and freeze-thaw fatigue alternating frequency ratio gradually go strong with the experiment on the damage of specimens.
Based on the freeze-thawing and fatigue alternate experiment of twelve prestressed concrete beams, the effects of fatigue load limit, strength grade of concrete, prestress degree and freeze-thaw fatigue alternating frequency ratio on the variation of specimens appearance, deflection under fatigue load and concrete dynamic elastic modulus of specimens were studied.The effects of prestress degree, fatigue load limit and freeze-thaw fatigue alternating frequency ratio on the attenuation rate of dynamic modulus of elasticity were also studied by using the range analysis method.Test results show that applying prestress and improving the strength of concrete can effectively improve the frost resistance of concrete;freeze-thawing can promote the increment of mid-span deflection and attenuate the stiffness of specimens under fatigue load.The fatigue load limit is always the control factor which affect the dynamic modulus of elasticity attenuation, and the influence of factors that prestress degree and freeze-thaw fatigue alternating frequency ratio gradually go strong with the experiment on the damage of specimens.
2013, 43(4): 62-65.
doi: 10.13204/j.gyjz201304013
Abstract:
Based on the low cyclic loading experiments on specially shaped columns, it was compared that the results in terms of damage characteristic, bearing capacity, displacement and ductility, hysteretic characteristic, skeleton curve, rigidity degradation and energy dissipation.The effect of axial compression ratios on seismic behavior of specially shaped column with high strength steel bar was analyzed.It was shown that the axial compression ratio had greater influence on seismic behavior of specially shaped column with high strength steel bar.With the decrease of axial compression ratio, the deformation capacity of specially shaped column with high strength steel bar was enhanced, the ductility and hysteretic characteristic was improved and the rigidity degradation becomes slow.The bearing capacity of specially shaped column with high strength steel bar was enhanced with the increase of axial compression ratio.
Based on the low cyclic loading experiments on specially shaped columns, it was compared that the results in terms of damage characteristic, bearing capacity, displacement and ductility, hysteretic characteristic, skeleton curve, rigidity degradation and energy dissipation.The effect of axial compression ratios on seismic behavior of specially shaped column with high strength steel bar was analyzed.It was shown that the axial compression ratio had greater influence on seismic behavior of specially shaped column with high strength steel bar.With the decrease of axial compression ratio, the deformation capacity of specially shaped column with high strength steel bar was enhanced, the ductility and hysteretic characteristic was improved and the rigidity degradation becomes slow.The bearing capacity of specially shaped column with high strength steel bar was enhanced with the increase of axial compression ratio.
2013, 43(4): 66-70.
doi: 10.13204/j.gyjz201304014
Abstract:
Cyclic loading test of six T-shaped and six L-shaped short pier shear wall specimens were conducted to investigate the fundamental mechanical properties and failure mode.Nonlinear mechanical properties of specimens were analyzed by software ANSYS.Finite element model was reasonably proved by the satisfactory agreement between analytical and test results.The effect of parameter variation on mechanical properties of specimens was investigated by changing parameter.Nonlinear finite element analysis showed that seismic performance of short pier shear wall was greatly improved by adding steel tubes in the confined boundary elements.
Cyclic loading test of six T-shaped and six L-shaped short pier shear wall specimens were conducted to investigate the fundamental mechanical properties and failure mode.Nonlinear mechanical properties of specimens were analyzed by software ANSYS.Finite element model was reasonably proved by the satisfactory agreement between analytical and test results.The effect of parameter variation on mechanical properties of specimens was investigated by changing parameter.Nonlinear finite element analysis showed that seismic performance of short pier shear wall was greatly improved by adding steel tubes in the confined boundary elements.
2013, 43(4): 71-75.
doi: 10.13204/j.gyjz201304015
Abstract:
For the interior slab, the edge slab and the corner slab of cast-in-situ reinforced concrete two-way slab-and-beam floor system, it was carried out the static loading test under uniformly distributed load respectively, and metered the beams and slabs deflections of three slabs.Through considering the influence of boundary supporting condition, the deflection calculation formulas of three typical slabs of two-way slab were established, and comparing the deflection values calculated by the formulas to the experimental results.The results showed that under uniformly distributed load the two-way slab deflections at the midspan section calculated by elastic thin plate theory differed significantly from the test results, and the deflection values obtained by the deflection calculation formulas in this paper matched well with the test results.
For the interior slab, the edge slab and the corner slab of cast-in-situ reinforced concrete two-way slab-and-beam floor system, it was carried out the static loading test under uniformly distributed load respectively, and metered the beams and slabs deflections of three slabs.Through considering the influence of boundary supporting condition, the deflection calculation formulas of three typical slabs of two-way slab were established, and comparing the deflection values calculated by the formulas to the experimental results.The results showed that under uniformly distributed load the two-way slab deflections at the midspan section calculated by elastic thin plate theory differed significantly from the test results, and the deflection values obtained by the deflection calculation formulas in this paper matched well with the test results.
2013, 43(4): 76-81.
doi: 10.13204/j.gyjz201304016
Abstract:
The temperature deformation analysis of a long industrial plant structure was carried out.The temperature loads included the weather changes, such as seasonal temperature changes, sudden temperature changes and sunshine temperature changes, and the effect of concrete shrinkage.The normal limit state load standard combination was adopted.The finite element software ETABS was used for simulation to study the structural temperature deformation.Furthermore, structure II was set up for research of the influence of the situation of the expansion joints on the temperature deformation of the structure.Finally, a simplified frame model was built to expose the distribution law of the structure's internal force and deformation in multi-stories or high-rise structures with large longitudinal length.Some reasonable suggestions on the position of expansion joints were presented, which could save the construction cost, improve the using effectiveness, and could be referenced for engineering construction.
The temperature deformation analysis of a long industrial plant structure was carried out.The temperature loads included the weather changes, such as seasonal temperature changes, sudden temperature changes and sunshine temperature changes, and the effect of concrete shrinkage.The normal limit state load standard combination was adopted.The finite element software ETABS was used for simulation to study the structural temperature deformation.Furthermore, structure II was set up for research of the influence of the situation of the expansion joints on the temperature deformation of the structure.Finally, a simplified frame model was built to expose the distribution law of the structure's internal force and deformation in multi-stories or high-rise structures with large longitudinal length.Some reasonable suggestions on the position of expansion joints were presented, which could save the construction cost, improve the using effectiveness, and could be referenced for engineering construction.
2013, 43(4): 82-85.
doi: 10.13204/j.gyjz201304017
Abstract:
For the stress calculation of a reinforced concrete chimney under serviceability limit state, thermal stress must be considered.Based on the Code for Design of Chimneys(GB 500512002)[1] chereafter referred to as standard), it was found by the numerical analysis and theoretic study on vertical reinforcement tensile stress on windward side during service that under co-action of temperature and load(weight and wind load), there was a discontinuity in the tensile stress calculation formula in the code, therefore, the causes for the discontinuity were analyzed, and a modified calculation method of temperature stress was also proposed.
For the stress calculation of a reinforced concrete chimney under serviceability limit state, thermal stress must be considered.Based on the Code for Design of Chimneys(GB 500512002)[1] chereafter referred to as standard), it was found by the numerical analysis and theoretic study on vertical reinforcement tensile stress on windward side during service that under co-action of temperature and load(weight and wind load), there was a discontinuity in the tensile stress calculation formula in the code, therefore, the causes for the discontinuity were analyzed, and a modified calculation method of temperature stress was also proposed.
2013, 43(4): 86-91.
doi: 10.13204/j.gyjz201304018
Abstract:
Taking silt soil image photographed by scanning electron microscope as the research object, using image treatment technology for microstructure observation and quantitative analysis of soil, the parameters of particle composition of soil were solved, such as porosity, grain diameter, granular shape, which provided physical parameters for setting up granular flow model.And then it was simulated the tri-axial test of the soil and studied the variation rules of property of silt soil with micro-parameters, such as friction coefficient, parallel-bond and stiffness ratio.The result showed that using clump model and particle repulsion method, the granular shape and grain diameter distribution could can be simulated.The model developed by this method fitted the stress-strain curves of soil and simulated the phenomenon of shear contraction and shear dilatation, the influence laws of friction coefficient, parallel-bond and stiffness ratio to the initial modulus and residual strength were different.The development process of shear zone could be reflected by monitoring the change of porosities.
Taking silt soil image photographed by scanning electron microscope as the research object, using image treatment technology for microstructure observation and quantitative analysis of soil, the parameters of particle composition of soil were solved, such as porosity, grain diameter, granular shape, which provided physical parameters for setting up granular flow model.And then it was simulated the tri-axial test of the soil and studied the variation rules of property of silt soil with micro-parameters, such as friction coefficient, parallel-bond and stiffness ratio.The result showed that using clump model and particle repulsion method, the granular shape and grain diameter distribution could can be simulated.The model developed by this method fitted the stress-strain curves of soil and simulated the phenomenon of shear contraction and shear dilatation, the influence laws of friction coefficient, parallel-bond and stiffness ratio to the initial modulus and residual strength were different.The development process of shear zone could be reflected by monitoring the change of porosities.
2013, 43(4): 92-97.
doi: 10.13204/j.gyjz201304019
Abstract:
The heavy metal tailing samples were taken from tailing pond and landfill site of wastes, which were then mixed with typical uncontaiminated soil.The heavy metal contaminated samples with different incorporation ratio, different density and ages were prepared.Under their respective optimum moisture content, direct shear test and the compaction test were done in order to study the effect rules of compaction and strength shear by heavy metal pollution.The results showed: 1) Heavy metal pollution affected the compaction characteristics of soil.Mn had a weak impact on the soil.Pb, Zn, Cd, and Cr had great impacts on the soil, the maximum dry density of soil increased, optimum moisture content decreased with the different incorporation ratio increasing;2) with the degree of consolidation increasing, cvalue gradually increased, value decreased;3) the diffusion effect on the mechanical characteristics of soil was a slow process, cvalue gradually decreased, and value increased with time;and 4) with the increasing of concentration of heavy metal, cvalue gradually increased, and value decreased.
The heavy metal tailing samples were taken from tailing pond and landfill site of wastes, which were then mixed with typical uncontaiminated soil.The heavy metal contaminated samples with different incorporation ratio, different density and ages were prepared.Under their respective optimum moisture content, direct shear test and the compaction test were done in order to study the effect rules of compaction and strength shear by heavy metal pollution.The results showed: 1) Heavy metal pollution affected the compaction characteristics of soil.Mn had a weak impact on the soil.Pb, Zn, Cd, and Cr had great impacts on the soil, the maximum dry density of soil increased, optimum moisture content decreased with the different incorporation ratio increasing;2) with the degree of consolidation increasing, cvalue gradually increased, value decreased;3) the diffusion effect on the mechanical characteristics of soil was a slow process, cvalue gradually decreased, and value increased with time;and 4) with the increasing of concentration of heavy metal, cvalue gradually increased, and value decreased.
2013, 43(4): 98-101.
doi: 10.13204/j.gyjz201304020
Abstract:
The coefficient of elastic uniform compression of natural soil is the most important parameter in dynamic machine foundation design.Based on the definition for coefficient of elastic uniform compression of natural soil, several methods of defermination for this coefficient at present were analyzed.The analysis results showed that the method adopted by Design Code for Dynamic Machine Foundation(GB 5004096)and the one by deformation modulus of soil in stratified subgrade were incorrect.The coefficient should be determined by the elastic modulus of each layer soil.To conveniently applying in practice engineering, the elastic modulus value corresponding to the characteristicvalue of the relative bearing capacity of soil in GB 5004096 was presented.Finally, the achievements of determination for coefficient of elastic uniform compression by shear wave velocity or SPT blow count were introduced.
The coefficient of elastic uniform compression of natural soil is the most important parameter in dynamic machine foundation design.Based on the definition for coefficient of elastic uniform compression of natural soil, several methods of defermination for this coefficient at present were analyzed.The analysis results showed that the method adopted by Design Code for Dynamic Machine Foundation(GB 5004096)and the one by deformation modulus of soil in stratified subgrade were incorrect.The coefficient should be determined by the elastic modulus of each layer soil.To conveniently applying in practice engineering, the elastic modulus value corresponding to the characteristicvalue of the relative bearing capacity of soil in GB 5004096 was presented.Finally, the achievements of determination for coefficient of elastic uniform compression by shear wave velocity or SPT blow count were introduced.
2013, 43(4): 102-105.
doi: 10.13204/j.gyjz201304021
Abstract:
The influence of confining and mixing ratio on small-strain dynamic properties(dynamic shear modulus and damping ratio)of cemented soft soil was studied through GDS resonance column, and the changing regularity of small-strain dynamic properties of cemented soft soil was obtained.The dynamic shear modulus decreased with the increased of strain amplitude.The maximum dynamic shear modulus increased linearly with the increase of confining pressure, the influence of confining pressure on dynamic shear modulus decreased with the increasd of mixing ratio under the same strain amplitude.The damping ratio increases with the increase of strain amplitude.Damping ratio decreased slightly with the increase of confining pressure.The influence of mixing ratios was damping ratio was small, damping ratio increased slightly with the increase of mixing ratio under the same strain amplitude.Comparing with the dynamic shear modulus, damping ratio was unsensitive to the variation of confining pressure and mixing ratio.
The influence of confining and mixing ratio on small-strain dynamic properties(dynamic shear modulus and damping ratio)of cemented soft soil was studied through GDS resonance column, and the changing regularity of small-strain dynamic properties of cemented soft soil was obtained.The dynamic shear modulus decreased with the increased of strain amplitude.The maximum dynamic shear modulus increased linearly with the increase of confining pressure, the influence of confining pressure on dynamic shear modulus decreased with the increasd of mixing ratio under the same strain amplitude.The damping ratio increases with the increase of strain amplitude.Damping ratio decreased slightly with the increase of confining pressure.The influence of mixing ratios was damping ratio was small, damping ratio increased slightly with the increase of mixing ratio under the same strain amplitude.Comparing with the dynamic shear modulus, damping ratio was unsensitive to the variation of confining pressure and mixing ratio.
2013, 43(4): 106-110.
doi: 10.13204/j.gyjz201304022
Abstract:
An experimental study was made, which focused on the suitability and construction technique of eliminating silt liquefaction using dynamic compaction.During the trial program several items such as surface settlement and groundwater table and excess pore water pressure were monitored, and in-situ test such as standard penetration test(SPT) and cone penetration test(CPT) were carried out before and after compaction.The results showed that after dynamic compaction the liquefaction of silt up to 6 m was eliminated and the properties of the in-place soils were also improved.Dewatering process was needed before compaction to lower the water level of the site.The dissipation of excess pore water pressure after compaction was found quite fast, with 80 percent of excess pore water pressure dissipated after one day within different depth of the site and complete dissipation after 5 days.The results also showed that with less energy of single tamping combined with full tamping would come to better effect of improvement at this site, so the construction technique of 2 passes single tamping with 1 500 kNm and one pass of full tamping with 800 kNm was recommended.
An experimental study was made, which focused on the suitability and construction technique of eliminating silt liquefaction using dynamic compaction.During the trial program several items such as surface settlement and groundwater table and excess pore water pressure were monitored, and in-situ test such as standard penetration test(SPT) and cone penetration test(CPT) were carried out before and after compaction.The results showed that after dynamic compaction the liquefaction of silt up to 6 m was eliminated and the properties of the in-place soils were also improved.Dewatering process was needed before compaction to lower the water level of the site.The dissipation of excess pore water pressure after compaction was found quite fast, with 80 percent of excess pore water pressure dissipated after one day within different depth of the site and complete dissipation after 5 days.The results also showed that with less energy of single tamping combined with full tamping would come to better effect of improvement at this site, so the construction technique of 2 passes single tamping with 1 500 kNm and one pass of full tamping with 800 kNm was recommended.
2013, 43(4): 111-114,101.
doi: 10.13204/j.gyjz201304023
Abstract:
As the green building material, ceramsite has good social and economic benefits.But the ceramsite produced in China has the problems of large size, bad gradation and smooth surface, which lead to segregation of ceramsite concrete.By means of experimental study, a good gradation lightweight aggregate can be obtained by crushing the ceramsite.The results show that the segregation of crushed ceramsite concrete is improved compared with the complete ceramsite concrete.At the same time the crushed ceramsite concrete meets not only the requirements of pumpability but also can improve strength.In addition, this paper focuses on the cube compressive strength that whether the high fluidity crushed ceramsite concrete can meet the requirements of strength at low temperature-25 ℃, the comparative tests of the strength at room temperature 20 ℃ and low temperature-25 ℃ indicate the strength of the latter is improved, which shows high fluidity crushed ceramsite concrete meets the requirement of strength.
As the green building material, ceramsite has good social and economic benefits.But the ceramsite produced in China has the problems of large size, bad gradation and smooth surface, which lead to segregation of ceramsite concrete.By means of experimental study, a good gradation lightweight aggregate can be obtained by crushing the ceramsite.The results show that the segregation of crushed ceramsite concrete is improved compared with the complete ceramsite concrete.At the same time the crushed ceramsite concrete meets not only the requirements of pumpability but also can improve strength.In addition, this paper focuses on the cube compressive strength that whether the high fluidity crushed ceramsite concrete can meet the requirements of strength at low temperature-25 ℃, the comparative tests of the strength at room temperature 20 ℃ and low temperature-25 ℃ indicate the strength of the latter is improved, which shows high fluidity crushed ceramsite concrete meets the requirement of strength.
2013, 43(4): 115-117.
doi: 10.13204/j.gyjz201304024
Abstract:
The insulation masonry mortars were prepared from waste aerated concrete.The product is light and has good insulation properties, consuming lots of solid wastes.The mortar is an environment friendly building material, which conforms to China's strategy of energy-savin emission reduction and sustainable development.
The insulation masonry mortars were prepared from waste aerated concrete.The product is light and has good insulation properties, consuming lots of solid wastes.The mortar is an environment friendly building material, which conforms to China's strategy of energy-savin emission reduction and sustainable development.
2013, 43(4): 118-121,155.
doi: 10.13204/j.gyjz201304025
Abstract:
To better understand the performance of multi-bond type anchorage encapsulated epoxy for CFRP tendons, static load tests for seven groups of anchor assemblies were carried out.It was studied the destroyed form, load-ship behavior and the strain development in the loading process, and introduced primary factors influencing the performance of resin bond type anchors for CFRP tendons.The results of the tests and study provided reliable basis for applying the resin bond type anchors to the project of suspend building.
To better understand the performance of multi-bond type anchorage encapsulated epoxy for CFRP tendons, static load tests for seven groups of anchor assemblies were carried out.It was studied the destroyed form, load-ship behavior and the strain development in the loading process, and introduced primary factors influencing the performance of resin bond type anchors for CFRP tendons.The results of the tests and study provided reliable basis for applying the resin bond type anchors to the project of suspend building.
2013, 43(4): 122-126.
doi: 10.13204/j.gyjz201304026
Abstract:
A structural stress monitoring system was used to conduct a field experimental study on concrete side pressure and steel component stress during pouring pumpable concrete by largy formwork.It was revealed that the side pressure distribution law and influencing factors during pouring the pumpable concrete.It was also explained the inadaptability of the calculation formulas of concrete side pressure from large formwork, which were specified in some codes, based on the test data and the analysis of the results by code formulas, which could provide a basis for improving the design of large formwork.
A structural stress monitoring system was used to conduct a field experimental study on concrete side pressure and steel component stress during pouring pumpable concrete by largy formwork.It was revealed that the side pressure distribution law and influencing factors during pouring the pumpable concrete.It was also explained the inadaptability of the calculation formulas of concrete side pressure from large formwork, which were specified in some codes, based on the test data and the analysis of the results by code formulas, which could provide a basis for improving the design of large formwork.
2013, 43(4): 127-130.
doi: 10.13204/j.gyjz201304027
Abstract:
Based on the practical projects, adopting the nonlinear finite element method, the construction process of cable dome was analyzed.The integral lifting process of the structure was realized through changing the length of the cables and the temperature could simulate the variations of the cable length.Based on the ANSYS, the cable strut beam finite element model was established, and the positive constant force cables and the subsidiary cables, the passive cables and the mast were simulated with the two node curved element(link10 element), multistage link10 element, the link8 element and the beam4 element respectively.By the ANSYS powerful APDL programming function, the development program of cable dome structure construction process inverse simulation was made.Helpful reference was offered for the application of integral lifting in large-span cable dome.
Based on the practical projects, adopting the nonlinear finite element method, the construction process of cable dome was analyzed.The integral lifting process of the structure was realized through changing the length of the cables and the temperature could simulate the variations of the cable length.Based on the ANSYS, the cable strut beam finite element model was established, and the positive constant force cables and the subsidiary cables, the passive cables and the mast were simulated with the two node curved element(link10 element), multistage link10 element, the link8 element and the beam4 element respectively.By the ANSYS powerful APDL programming function, the development program of cable dome structure construction process inverse simulation was made.Helpful reference was offered for the application of integral lifting in large-span cable dome.
2013, 43(4): 131-138,164.
doi: 10.13204/j.gyjz201304028
Abstract:
This paper systematically introduced the technological progress and application of the large span spatial structures in the last thirty years since the establishment of Committee on Spatial Structures.The following topics were reviewed and discussed: application of spatial structures in different kinds of public buildings, development and technological advancement of the structural systems and situation of compilation and revision of standards and specification in the field of spatial structures.In the end, the prospect of the development focus of research and development of the large span spatial structure discipline was presented, including the development strategy, green construction, innovation of structural system, application of high-strength material, research in wind engineering, earthquake resistance and prevention of progressive collapses, structural health monitoring, safety evaluation, and strengthening technique for existing large span public buildings.
This paper systematically introduced the technological progress and application of the large span spatial structures in the last thirty years since the establishment of Committee on Spatial Structures.The following topics were reviewed and discussed: application of spatial structures in different kinds of public buildings, development and technological advancement of the structural systems and situation of compilation and revision of standards and specification in the field of spatial structures.In the end, the prospect of the development focus of research and development of the large span spatial structure discipline was presented, including the development strategy, green construction, innovation of structural system, application of high-strength material, research in wind engineering, earthquake resistance and prevention of progressive collapses, structural health monitoring, safety evaluation, and strengthening technique for existing large span public buildings.
2013, 43(4): 139-143,174.
doi: 10.13204/j.gyjz201304029
Abstract:
Comparison of drift limitations in codes and their recommendations for seismic design of building structures in China, Japan, Europe and USA was carried out.It is found through the comparison that there are drift limitations of four levels: the serviceability requirement of the return period of 8~95 years, design seismic action level, medium and strong earthquake level.The design philosophies in different codes have great differences, these are avoiding interfering the use of facilities, confining the damage to the partition wall, avoiding crack in concrete members and life save in medium and/or strong earthquake.China has the stringent requirements for the reinforced concrete structures.
Comparison of drift limitations in codes and their recommendations for seismic design of building structures in China, Japan, Europe and USA was carried out.It is found through the comparison that there are drift limitations of four levels: the serviceability requirement of the return period of 8~95 years, design seismic action level, medium and strong earthquake level.The design philosophies in different codes have great differences, these are avoiding interfering the use of facilities, confining the damage to the partition wall, avoiding crack in concrete members and life save in medium and/or strong earthquake.China has the stringent requirements for the reinforced concrete structures.
2013, 43(4): 144-148.
doi: 10.13204/j.gyjz201304030
Abstract:
To study the mechanical behavior of conical double skin steel tubes confined concrete stub columns subjected to axial partial compression, it was set up a finite element analysis(FEA) model and the predicted performances were validated through measured results.Based on the finite element analysis, the interaction between steel tube and sandwich concrete, failure mode, as well as the effect of the main parameters on the load-displacement was analyzed.
To study the mechanical behavior of conical double skin steel tubes confined concrete stub columns subjected to axial partial compression, it was set up a finite element analysis(FEA) model and the predicted performances were validated through measured results.Based on the finite element analysis, the interaction between steel tube and sandwich concrete, failure mode, as well as the effect of the main parameters on the load-displacement was analyzed.
2013, 43(4): 149-155.
doi: 10.13204/j.gyjz201304031
Abstract:
A finite element analysis(FEA) model for conical concrete-filled double-skin steel tubular stub columns with endplate under axial partial compression was developed and the corresponding tests were conducted.The predicted load versus deformation relationship curves and failure modes were in good agreement with the measured results.The FEA model was then used to investigate the mechanisms of such composite columns further.The stress distribution of each component and the interactions between the concrete and the double-skin steel tubes were analyzed.And then, the main parameters influencing on the load-deformation relationship curves such as taper, strength of the materials, hollow ratio, axial partial compression ratio and rigidity of endplate were investigated.
A finite element analysis(FEA) model for conical concrete-filled double-skin steel tubular stub columns with endplate under axial partial compression was developed and the corresponding tests were conducted.The predicted load versus deformation relationship curves and failure modes were in good agreement with the measured results.The FEA model was then used to investigate the mechanisms of such composite columns further.The stress distribution of each component and the interactions between the concrete and the double-skin steel tubes were analyzed.And then, the main parameters influencing on the load-deformation relationship curves such as taper, strength of the materials, hollow ratio, axial partial compression ratio and rigidity of endplate were investigated.
2013, 43(4): 156-159.
doi: 10.13204/j.gyjz201304032
Abstract:
Five RC beams strengthened with CFRP using MOC were tested.Crack patterns, failure modes, strength improvements and stiffness behavior were studied.In the mean time, the influence of the layer of CFRP on the performance of strengthened beams was also investigated.The test results show that using MOC as the adhesive to bond CFRP to an RC member is executable.Load-bearing capacity of the RC beams increased with the number of layers of CFRP while the ductility of those beams is reduced compared to the control beam.The failure modes changed from rupture of CFRP to CFRP delamination by increasing the layer.
Five RC beams strengthened with CFRP using MOC were tested.Crack patterns, failure modes, strength improvements and stiffness behavior were studied.In the mean time, the influence of the layer of CFRP on the performance of strengthened beams was also investigated.The test results show that using MOC as the adhesive to bond CFRP to an RC member is executable.Load-bearing capacity of the RC beams increased with the number of layers of CFRP while the ductility of those beams is reduced compared to the control beam.The failure modes changed from rupture of CFRP to CFRP delamination by increasing the layer.
2013, 43(4): 160-164.
doi: 10.13204/j.gyjz201304033
Abstract:
Imitating timber-framed reinforced concrete buildings constructed during the period of the Republic of China are typical architectural heritages with Chinese characteristics.Most of theses buildings bear some important historical and cultural information.They should be rationally strengthened according to the preservation rule of cultural relic.Based on strengthening project of a imitating timber-framed reinforced concrete building constructed during the period of the Republic of China in Zhejiang Province, some key problems in strengthening design of this kind of building were roundly discussed, including methods of testing and appraisement, computing and analyzing, concrete members reinforcement and brick wall reinforcement, etc.Some effective methods were introduced to solve the problems, such as the concrete columns and beams were strengthened with steel wire netting polymer mortar method, the concrete slabs were strengthened with steel meshed polymer mortar method, which could make a continuing service life of the building be more than 30 years.Which provided a reference for strengthening similar projects.
Imitating timber-framed reinforced concrete buildings constructed during the period of the Republic of China are typical architectural heritages with Chinese characteristics.Most of theses buildings bear some important historical and cultural information.They should be rationally strengthened according to the preservation rule of cultural relic.Based on strengthening project of a imitating timber-framed reinforced concrete building constructed during the period of the Republic of China in Zhejiang Province, some key problems in strengthening design of this kind of building were roundly discussed, including methods of testing and appraisement, computing and analyzing, concrete members reinforcement and brick wall reinforcement, etc.Some effective methods were introduced to solve the problems, such as the concrete columns and beams were strengthened with steel wire netting polymer mortar method, the concrete slabs were strengthened with steel meshed polymer mortar method, which could make a continuing service life of the building be more than 30 years.Which provided a reference for strengthening similar projects.
2013, 43(4): 165-167.
doi: 10.13204/j.gyjz201304034
Abstract:
Comfort is the basis for the design of indoor thermal environment, hence the thermal comfort of energy-efficient buildings has become the goal of people.Taking the scientific building of Hubei Institute of Engineering for example, by means of reasonable overall layout and architectural design, selection of energy-saving building materials, ensuring the thermal requirements of the envelope and reducing as far as possible building energy consumption, an ideal energy-saving effect has been got.
Comfort is the basis for the design of indoor thermal environment, hence the thermal comfort of energy-efficient buildings has become the goal of people.Taking the scientific building of Hubei Institute of Engineering for example, by means of reasonable overall layout and architectural design, selection of energy-saving building materials, ensuring the thermal requirements of the envelope and reducing as far as possible building energy consumption, an ideal energy-saving effect has been got.
2013, 43(4): 168-174.
doi: 10.13204/j.gyjz201304035
Abstract:
According to the characteristics of construction of deep foundation pit in Shanghai, combined with the practice of Shanghai Zhongshan Hospital Comprehensive Building, the following technical measures were used, such as the ventilation lighting technology, borrow mouth set technology, the construction technology of underground continuous wall, a column and a pile verticality control technology, a hierarchical underwater concrete perfusion technology, large open partition hidden digging technology etc.The monitoring results showed that a variety of deformations could meet the relevant code requirements, which effectively controlled the deformation of foundation pit, thus protecting the surrounding environment and safety of buildings, solved the key technology of top-down construction of a large irregular deep foundation pit, good economic and environmental benefits were obtained.
According to the characteristics of construction of deep foundation pit in Shanghai, combined with the practice of Shanghai Zhongshan Hospital Comprehensive Building, the following technical measures were used, such as the ventilation lighting technology, borrow mouth set technology, the construction technology of underground continuous wall, a column and a pile verticality control technology, a hierarchical underwater concrete perfusion technology, large open partition hidden digging technology etc.The monitoring results showed that a variety of deformations could meet the relevant code requirements, which effectively controlled the deformation of foundation pit, thus protecting the surrounding environment and safety of buildings, solved the key technology of top-down construction of a large irregular deep foundation pit, good economic and environmental benefits were obtained.
