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2009 Vol. 39, No. 12
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2009, 39(12): 1-4.
doi: 10.13204/j.gyjz200912001
Abstract:
Modern prestressing technique has been applied to many large-scale complex concrete structures.Scientific analysis measures should be adopted to evaluate the nonlinear bearing capacity of the whole structure.This paper focuses on some relevant key issues of nonlinear analysis of prestressed concrete complex structures using FEM software ANSYS and ABAQUS
Modern prestressing technique has been applied to many large-scale complex concrete structures.Scientific analysis measures should be adopted to evaluate the nonlinear bearing capacity of the whole structure.This paper focuses on some relevant key issues of nonlinear analysis of prestressed concrete complex structures using FEM software ANSYS and ABAQUS
2009, 39(12): 5-9.
doi: 10.13204/j.gyjz200912002
Abstract:
Three PC beams with draped tendons and one RC beam were tested and the primary variable is the longitudinal reinforcement ratio .All the beams had a shear span to depth ratio,a/h_0,of 1.8.Several results were obtained: beams with both small a/h_0 and normal amount of were inclined to suffer a flexural-shear failure;the lower the ,the faster the damage of beams;there seems to be a critical longitudinal reinforcement ratio,_(crit),that is,if is lower than it,the arch action would weaken,or else the arch action would be significant.Besides,sectional design methods and modified strut-and-tie model(MSTM) were used to predict the beam shear strengths,and comparisons with test results indicate that sectional methods are not suitable for such predictions but MSTM not only gives accurate results,but also well account for the effect of the longitudinal reinforcement.
Three PC beams with draped tendons and one RC beam were tested and the primary variable is the longitudinal reinforcement ratio .All the beams had a shear span to depth ratio,a/h_0,of 1.8.Several results were obtained: beams with both small a/h_0 and normal amount of were inclined to suffer a flexural-shear failure;the lower the ,the faster the damage of beams;there seems to be a critical longitudinal reinforcement ratio,_(crit),that is,if is lower than it,the arch action would weaken,or else the arch action would be significant.Besides,sectional design methods and modified strut-and-tie model(MSTM) were used to predict the beam shear strengths,and comparisons with test results indicate that sectional methods are not suitable for such predictions but MSTM not only gives accurate results,but also well account for the effect of the longitudinal reinforcement.
2009, 39(12): 10-13.
doi: 10.13204/j.gyjz200912003
Abstract:
Three PC beams with draped tendons and one RC beam were tested and the primary variable is the angle of the tendons,.All the beams had a shear span to depth ratio,a/h_0,of 2.2.Several results were obtained: beams with both small a/h_0 and normal amount of were inclined to fail in a flexural-shear mode;the greater the ,the faster of the damage of beams.Besides,sectional design methods and modified strut-and-tie model(MSTM) were used to predict the beam shear strengths,and comparisons with test results indicate that sectional methods are not suitable for such predictions but MSTM not only gives accurate results,but also well account for the effect of the angle of the draped tendons.
Three PC beams with draped tendons and one RC beam were tested and the primary variable is the angle of the tendons,.All the beams had a shear span to depth ratio,a/h_0,of 2.2.Several results were obtained: beams with both small a/h_0 and normal amount of were inclined to fail in a flexural-shear mode;the greater the ,the faster of the damage of beams.Besides,sectional design methods and modified strut-and-tie model(MSTM) were used to predict the beam shear strengths,and comparisons with test results indicate that sectional methods are not suitable for such predictions but MSTM not only gives accurate results,but also well account for the effect of the angle of the draped tendons.
2009, 39(12): 14-17.
doi: 10.13204/j.gyjz200912004
Abstract:
This paper pointed out the shortage of equivalent frame method to design unbonded prestressed concrete flat-floors.By analyzing the moment distribution of such a structure,it was indicated that the design of the serviceability limit state should be based on the elastic moment in order to control the crack width,and as to the ultimate state,the internal force redistribution should be taken into consideration while the crack width under service load was guaranteed.Based on the above mentioned principles and some calculations,the paper concluded the magnitude of internal force redistribution and discussed the moment distribution after modification.Finally several design suggestions were put forward.
This paper pointed out the shortage of equivalent frame method to design unbonded prestressed concrete flat-floors.By analyzing the moment distribution of such a structure,it was indicated that the design of the serviceability limit state should be based on the elastic moment in order to control the crack width,and as to the ultimate state,the internal force redistribution should be taken into consideration while the crack width under service load was guaranteed.Based on the above mentioned principles and some calculations,the paper concluded the magnitude of internal force redistribution and discussed the moment distribution after modification.Finally several design suggestions were put forward.
2009, 39(12): 18-20.
doi: 10.13204/j.gyjz200912005
Abstract:
According to current code for design of concrete structures,the formula of crack width checking on eccentrically tensioned prestressed members was deduced.Meanwhile,another form of the formula of crack width checking was also deduced based on two-stage-working principle.Similar to the union of ultimate bending strength calculation formulas of prestressed members,the union of crack width checking formulas derived from the two methods was also realized.What's more,the latter one simplified the process of crack width checking,making it easier for the crack control of prestressed concrete members.
According to current code for design of concrete structures,the formula of crack width checking on eccentrically tensioned prestressed members was deduced.Meanwhile,another form of the formula of crack width checking was also deduced based on two-stage-working principle.Similar to the union of ultimate bending strength calculation formulas of prestressed members,the union of crack width checking formulas derived from the two methods was also realized.What's more,the latter one simplified the process of crack width checking,making it easier for the crack control of prestressed concrete members.
2009, 39(12): 21-25.
doi: 10.13204/j.gyjz200912006
Abstract:
Experiments on prestressing time-dependent loss of C60 high-performance concrete(HPC) are carried out.By analyzing experimental results of shrinkage,creep,deflection and effective prestress of three prestressed concrete beams under natural environment,it is obtained that the increase in long-term deflection mainly depends on the sectional stress distribution of concrete.Deflection creep coefficient is larger than the one calculated by the code.It will be underestimated if creep coefficient is used to calculate the beam deflection for construction stage.The prestressing time-dependent loss in test will be greater than that in theory.
Experiments on prestressing time-dependent loss of C60 high-performance concrete(HPC) are carried out.By analyzing experimental results of shrinkage,creep,deflection and effective prestress of three prestressed concrete beams under natural environment,it is obtained that the increase in long-term deflection mainly depends on the sectional stress distribution of concrete.Deflection creep coefficient is larger than the one calculated by the code.It will be underestimated if creep coefficient is used to calculate the beam deflection for construction stage.The prestressing time-dependent loss in test will be greater than that in theory.
2009, 39(12): 26-28.
doi: 10.13204/j.gyjz200912007
Abstract:
In order to find out how the high-performance concrete(HPC) used in Sutong continuous rigid-frame bridge affects the long-term behavior of bridge,such as long-term deformation,section stress and prestress loss,experimental study on the long-term behavior of the HPC dual cantilever girder is developed under natural environments,which based on the model test of HPC shrinkage and creep.The results show that the HPC can effectively lower the shrinkage and creep,and also reduce the prestress loss,which made the structure deformation be in control.By using finite element software Midas,long-term performance of the cantilever girder is analyzed.The analytic results agree well with the test data.
In order to find out how the high-performance concrete(HPC) used in Sutong continuous rigid-frame bridge affects the long-term behavior of bridge,such as long-term deformation,section stress and prestress loss,experimental study on the long-term behavior of the HPC dual cantilever girder is developed under natural environments,which based on the model test of HPC shrinkage and creep.The results show that the HPC can effectively lower the shrinkage and creep,and also reduce the prestress loss,which made the structure deformation be in control.By using finite element software Midas,long-term performance of the cantilever girder is analyzed.The analytic results agree well with the test data.
2009, 39(12): 29-31.
doi: 10.13204/j.gyjz200912008
Abstract:
For analysis of serviceability behavior of reinforced concrete beams strengthened with external tendons,external prestressing effects can be modeled as equivalent loads varying with imposed external loads.Formulas of stress increments of external tendons were proposed for serviceability state based on those for capacity ultimate state,and thus current deflection calculation methods can be used.
For analysis of serviceability behavior of reinforced concrete beams strengthened with external tendons,external prestressing effects can be modeled as equivalent loads varying with imposed external loads.Formulas of stress increments of external tendons were proposed for serviceability state based on those for capacity ultimate state,and thus current deflection calculation methods can be used.
2009, 39(12): 32-35.
doi: 10.13204/j.gyjz200912009
Abstract:
With a view to different height of compression region and different prestress reinforcement index,6 reinforced concrete continuous beams strengthened with external prestressed tendons are investigated,including midspan deflection,stress increment of external tendons,midspan deflection and stress increment of external tendons have a good correlative relationship,increasing in 3 stages.Internal force redistribution forms fully under ultimate loads.
With a view to different height of compression region and different prestress reinforcement index,6 reinforced concrete continuous beams strengthened with external prestressed tendons are investigated,including midspan deflection,stress increment of external tendons,midspan deflection and stress increment of external tendons have a good correlative relationship,increasing in 3 stages.Internal force redistribution forms fully under ultimate loads.
2009, 39(12): 36-38.
doi: 10.13204/j.gyjz200912010
Abstract:
It has been analyzed the creative clusters of Shanghai which are reformed by industrial heritage from rent,trade composition and opening mode.It is pointed out the faced questions about the preservation and rehabilitation of Shanghai industrial heritage,and it is compared with the preservation and rehabilitation of western countries to use for reference.
It has been analyzed the creative clusters of Shanghai which are reformed by industrial heritage from rent,trade composition and opening mode.It is pointed out the faced questions about the preservation and rehabilitation of Shanghai industrial heritage,and it is compared with the preservation and rehabilitation of western countries to use for reference.
2009, 39(12): 39-41.
doi: 10.13204/j.gyjz200912011
Abstract:
Roof is one of the main structures of a building,and it plays an important role in improving the degree of indoor thermal comfort so as to reduce the using of air-conditioner.Through a contrastive study on the water-storing green roof and the common roof in a certain living district in Xiangtan city,the article comes to the conclusion: the water-storing green roof not only can enhance the urban eco-environment,but also can modulate the indoor thermal property and decrease the using of air-conditioner,so it is a comprehensive method to save both water resource and energy and can be popularized in the south urban areas.
Roof is one of the main structures of a building,and it plays an important role in improving the degree of indoor thermal comfort so as to reduce the using of air-conditioner.Through a contrastive study on the water-storing green roof and the common roof in a certain living district in Xiangtan city,the article comes to the conclusion: the water-storing green roof not only can enhance the urban eco-environment,but also can modulate the indoor thermal property and decrease the using of air-conditioner,so it is a comprehensive method to save both water resource and energy and can be popularized in the south urban areas.
2009, 39(12): 42-44,38.
doi: 10.13204/j.gyjz200912012
Abstract:
Reinforced concrete coupling beam is an important member of a major lateral load-resisting structure-coupled shear wall or core wall.Under seismic actions,local failure of coupling beams may lead to a more serious global failure of the whole lateral load resisting system of the building.Along with the development of economy and society,it is necessary and important to strengthen coupling beams that are substandard under seismic actions due to the lack of safety margin and new service in old RC buildings.This paper presents an experimental study into the effects on seismic strengthening of coupling beams with or without bolt connections in beam span.The study shows that the strengthened coupling beam without bolt connections in beam span subjected to cyclic loads has better energy dissipation,larger strength,less stiffness degradation.
Reinforced concrete coupling beam is an important member of a major lateral load-resisting structure-coupled shear wall or core wall.Under seismic actions,local failure of coupling beams may lead to a more serious global failure of the whole lateral load resisting system of the building.Along with the development of economy and society,it is necessary and important to strengthen coupling beams that are substandard under seismic actions due to the lack of safety margin and new service in old RC buildings.This paper presents an experimental study into the effects on seismic strengthening of coupling beams with or without bolt connections in beam span.The study shows that the strengthened coupling beam without bolt connections in beam span subjected to cyclic loads has better energy dissipation,larger strength,less stiffness degradation.
2009, 39(12): 45-50.
doi: 10.13204/j.gyjz200912013
Abstract:
In this paper,two groups of experiments on multi-ribbed composite walls which include oblique section shear bearing capacity tests and normal section bending capacity tests are represented.Based on the results of the experiments,the composite wall's two typical failure modes and failure mechanisms are contrastively analyzed.The bearing capacity,deformation performance and other seismic performances of the walls with two different failure modes are studied.The results show that the wall with shear failure mode which is considered as an advantageous mode has several anti-seismic defending lines,for the three-part members of the load-bearing system(filler blocks,concrete frame grids and concealed frame) can play a key role gradually in three stages(elastic stage,elastic-plastic stage and failure stage).Contrastively,a reasonable failure mechanism is difficult to form in the wall with bending failure mode which is considered to be disadvantageous,for concrete crush or steel failure will be found at the feet of the end frame columns prior to the serious damage of the inner slab.As the ductility and deformability of wall occurring shear failure are absolutely superior to that of bending failure,a reasonable matching between the outer frame and the inner slab should be guaranteed.Finally,the formulas for normal section bending capacity of the wall are deduced,and the judgment criterion of large and small eccentric compression of the composite wall is established.
In this paper,two groups of experiments on multi-ribbed composite walls which include oblique section shear bearing capacity tests and normal section bending capacity tests are represented.Based on the results of the experiments,the composite wall's two typical failure modes and failure mechanisms are contrastively analyzed.The bearing capacity,deformation performance and other seismic performances of the walls with two different failure modes are studied.The results show that the wall with shear failure mode which is considered as an advantageous mode has several anti-seismic defending lines,for the three-part members of the load-bearing system(filler blocks,concrete frame grids and concealed frame) can play a key role gradually in three stages(elastic stage,elastic-plastic stage and failure stage).Contrastively,a reasonable failure mechanism is difficult to form in the wall with bending failure mode which is considered to be disadvantageous,for concrete crush or steel failure will be found at the feet of the end frame columns prior to the serious damage of the inner slab.As the ductility and deformability of wall occurring shear failure are absolutely superior to that of bending failure,a reasonable matching between the outer frame and the inner slab should be guaranteed.Finally,the formulas for normal section bending capacity of the wall are deduced,and the judgment criterion of large and small eccentric compression of the composite wall is established.
2009, 39(12): 51-56,73.
doi: 10.13204/j.gyjz200912014
Abstract:
In new steel-concrete combinatory concealed-beam floor structure,the changes of the parameters of the steel concealed-beam are important factors,which impact the performance of the new combinatory concealed-beam floor structure.In order to investigate the effects on force bearing and deformation characteristics of the new combinatory structure,which caused by parameters such as the span,pitch,cross-section height and hole rate of web plate of steel concealed-beam.ANSYS is used to do the nonlinear analysis of the changes in the parameters.The result shows that the span of concealed-beam is significant to the bending stiffness and ultimate strength of the new combinatory concealed-beam floor;its influence is limited when the rate of opening in the web is within 26 percent.The pitch and cross-section height have less impact.The stress state of steel concealed-beam and concrete floor are changed with different span,pitch,cross-section height and hole rate of abdomen plate of steel concealed-beam.
In new steel-concrete combinatory concealed-beam floor structure,the changes of the parameters of the steel concealed-beam are important factors,which impact the performance of the new combinatory concealed-beam floor structure.In order to investigate the effects on force bearing and deformation characteristics of the new combinatory structure,which caused by parameters such as the span,pitch,cross-section height and hole rate of web plate of steel concealed-beam.ANSYS is used to do the nonlinear analysis of the changes in the parameters.The result shows that the span of concealed-beam is significant to the bending stiffness and ultimate strength of the new combinatory concealed-beam floor;its influence is limited when the rate of opening in the web is within 26 percent.The pitch and cross-section height have less impact.The stress state of steel concealed-beam and concrete floor are changed with different span,pitch,cross-section height and hole rate of abdomen plate of steel concealed-beam.
2009, 39(12): 57-60.
doi: 10.13204/j.gyjz200912015
Abstract:
A stress analysis of the interior anchorage zones of post-tensioned concrete structures(IAZPTCS) is conducted using FEM.According to the analytical results,it is found that there are some limitations of the present design method(strut-and-tie model,STM) for IAZPTCS as recommended by International Federation for Prestressing(FIP) in 1996.A modified approach of STM is proposed.Comparing with the original FIP model,in the proposed approach,the locations and the internal forces of the ties and struts are adjusted,and the dimensional ratio of the width of the anchorage over the width of the member(b/h) can be varied in a wide range.By using the proposed model,the amount of reinforcement can be decreased by about 30% in the interior anchorage zones.
A stress analysis of the interior anchorage zones of post-tensioned concrete structures(IAZPTCS) is conducted using FEM.According to the analytical results,it is found that there are some limitations of the present design method(strut-and-tie model,STM) for IAZPTCS as recommended by International Federation for Prestressing(FIP) in 1996.A modified approach of STM is proposed.Comparing with the original FIP model,in the proposed approach,the locations and the internal forces of the ties and struts are adjusted,and the dimensional ratio of the width of the anchorage over the width of the member(b/h) can be varied in a wide range.By using the proposed model,the amount of reinforcement can be decreased by about 30% in the interior anchorage zones.
2009, 39(12): 61-64.
doi: 10.13204/j.gyjz200912016
Abstract:
Based on the bonding anchors which used in the first CFRP cable-stayed bridge and obtained the national patent,a main research was given to the bonding anchors composed of direct and inner cone type of tube.The radial stress of CFRP tendons is selected as major research parameters and the influencing factors were analyzed for it.At last,corresponding optimization schemes were given.The results show that radial stress of CFRP tendons is decreased and the distribution tends to uniform,anchoring ability is also increased after the optimization of bonding anchors.Which show that the optimization schemes for bonding anchors are feasible.
Based on the bonding anchors which used in the first CFRP cable-stayed bridge and obtained the national patent,a main research was given to the bonding anchors composed of direct and inner cone type of tube.The radial stress of CFRP tendons is selected as major research parameters and the influencing factors were analyzed for it.At last,corresponding optimization schemes were given.The results show that radial stress of CFRP tendons is decreased and the distribution tends to uniform,anchoring ability is also increased after the optimization of bonding anchors.Which show that the optimization schemes for bonding anchors are feasible.
2009, 39(12): 65-69,129.
doi: 10.13204/j.gyjz200912017
Abstract:
The determination of critical slip surfaces within soil slope stability analysis based on limit equilibrium method is a complicated optimization problem.However,there may exist such disadvantages as more related parameters,difficult to be determined and the possibility of exceeding the allowed ranges,when original particle swarm optimization(PSO) is used to locate the critical slip surfaces of soil slopes.The search procedure used in original PSO and the harmony search procedure are combined to generate a new position of particle in the new algorithm presented in this paper.The new algorithm takes good advantage of both PSO and HSA(harmony search algorithm),the new algorithm is applied to perform the slope stability analysis and the comparative study shows that the new algorithm is simple and can be used for slope stability analysis.
The determination of critical slip surfaces within soil slope stability analysis based on limit equilibrium method is a complicated optimization problem.However,there may exist such disadvantages as more related parameters,difficult to be determined and the possibility of exceeding the allowed ranges,when original particle swarm optimization(PSO) is used to locate the critical slip surfaces of soil slopes.The search procedure used in original PSO and the harmony search procedure are combined to generate a new position of particle in the new algorithm presented in this paper.The new algorithm takes good advantage of both PSO and HSA(harmony search algorithm),the new algorithm is applied to perform the slope stability analysis and the comparative study shows that the new algorithm is simple and can be used for slope stability analysis.
2009, 39(12): 70-73.
doi: 10.13204/j.gyjz200912018
Abstract:
Settlement rate method is often used to decide surcharge removal time for embankment on soft ground.Post-construction settlements controlled by empirical settlement rate standards used in some highways can not be obtained.A equation that describes the relationship between settlement rate during surcharge preloading and the post-construction settlements is derived by means of Terzaghi's consolidation theory for multistage loading.The settlement rate standards relevant to the allowed post-construction settlements are presented based on this equation.Numerical simulation analysis shows that the post-construction settlements controlled by the regional empirical settlement rate standards are much more less than the allowed values,the settlements controlled by the proposed settlement rate standards meet the requirement of specifications.Finally,one case history is analyzed to verify the use of the proposed standards.
Settlement rate method is often used to decide surcharge removal time for embankment on soft ground.Post-construction settlements controlled by empirical settlement rate standards used in some highways can not be obtained.A equation that describes the relationship between settlement rate during surcharge preloading and the post-construction settlements is derived by means of Terzaghi's consolidation theory for multistage loading.The settlement rate standards relevant to the allowed post-construction settlements are presented based on this equation.Numerical simulation analysis shows that the post-construction settlements controlled by the regional empirical settlement rate standards are much more less than the allowed values,the settlements controlled by the proposed settlement rate standards meet the requirement of specifications.Finally,one case history is analyzed to verify the use of the proposed standards.
2009, 39(12): 74-79.
doi: 10.13204/j.gyjz200912019
Abstract:
The value of width parameter i of surface settlement trough induced by shield tunnel is related to tunnel radius R,tunnel axis depth h,and soil condition(internal friction angle of soil).The analyses of 22 actual values from 13 constructional cases show that value of i is linear with [R+htan〔45-/2〕].20 values of i/[R+htan〔45-/2〕] are in the range of [0.45,0.50].Only 2 values(0.43,0.51) are beyond but close to the bounds,generally within 10% difference.The values of i is linear with h,but their dispersion is great.The values of i/h are in the range of [0.37,0.66] for cohesive soil.The result shows that the contribution of relationship curve of i/R values with h/(2R) values obtained from exponential function fitting is better than that obtained from power function fitting,but the scope of empirical parameter range is large.Based on the above-mentioned results,new calculation method for i is put forward.This method is applicable in cohesive soil,and R,h and are taken into account.The possible error induced by large scope of empirical parameters range is avoided because of small parameter range in this method.
The value of width parameter i of surface settlement trough induced by shield tunnel is related to tunnel radius R,tunnel axis depth h,and soil condition(internal friction angle of soil).The analyses of 22 actual values from 13 constructional cases show that value of i is linear with [R+htan〔45-/2〕].20 values of i/[R+htan〔45-/2〕] are in the range of [0.45,0.50].Only 2 values(0.43,0.51) are beyond but close to the bounds,generally within 10% difference.The values of i is linear with h,but their dispersion is great.The values of i/h are in the range of [0.37,0.66] for cohesive soil.The result shows that the contribution of relationship curve of i/R values with h/(2R) values obtained from exponential function fitting is better than that obtained from power function fitting,but the scope of empirical parameter range is large.Based on the above-mentioned results,new calculation method for i is put forward.This method is applicable in cohesive soil,and R,h and are taken into account.The possible error induced by large scope of empirical parameters range is avoided because of small parameter range in this method.
2009, 39(12): 80-83.
doi: 10.13204/j.gyjz200912020
Abstract:
A zigzag line tunnel in Tianhe Passenger Station of Guangzhou Subway is constructed by whole-section extra-long horizontal freezing method.One integrated model experiment system is established based on similar theory.Frost heaving and thawing settlement displacement of the tunnel is analyzed by model experiment on condition of ensuring freezing wall's similar intensity,which provides a scientific basis for design and construction of the project.
A zigzag line tunnel in Tianhe Passenger Station of Guangzhou Subway is constructed by whole-section extra-long horizontal freezing method.One integrated model experiment system is established based on similar theory.Frost heaving and thawing settlement displacement of the tunnel is analyzed by model experiment on condition of ensuring freezing wall's similar intensity,which provides a scientific basis for design and construction of the project.
2009, 39(12): 84-89.
doi: 10.13204/j.gyjz200912021
Abstract:
From 1998 to 2008 one-way cable-supported structures(CSS),two-way CSS and spatial CSS have been developed rapidly.In recent year a new kind of structure,which would be formed when the cable through tube was tensioned,was paid attention.It is called cable-supported forming structure.The concept of cable-supported forming structures was discussed,whose progress in the latest research was also introduced.
From 1998 to 2008 one-way cable-supported structures(CSS),two-way CSS and spatial CSS have been developed rapidly.In recent year a new kind of structure,which would be formed when the cable through tube was tensioned,was paid attention.It is called cable-supported forming structure.The concept of cable-supported forming structures was discussed,whose progress in the latest research was also introduced.
2009, 39(12): 90-94.
doi: 10.13204/j.gyjz200912022
Abstract:
A finite beam element model is established to study out-of-plane elastic buckling behaviors and elasto-plastic stability behaviors of pin-ended circular steel arch with circular sections.Firstly,elastic buckling of arches subject to hydrostatic pressure is studied and compared with classic buckling theroy.It is pointed out that the finite element analysis results are in good agreement with the Timoshenko classical solutions. Secondly,on the basis of elastic-plastic stability analysis,referring to the stability design method of monosymmetric section axially loaded compression members,equivalent slenderness of pin-ended circular steel arch subject to hydrostatic pressure are deduced from the expression of out-of-plane elastic buckling load.Combined with the column curves in current Chinese Code for Design of Steel Structures(GB 500172003),the design formula of ultimate load-carrying capacity as well as out-of-plane stability design curves are presented.
A finite beam element model is established to study out-of-plane elastic buckling behaviors and elasto-plastic stability behaviors of pin-ended circular steel arch with circular sections.Firstly,elastic buckling of arches subject to hydrostatic pressure is studied and compared with classic buckling theroy.It is pointed out that the finite element analysis results are in good agreement with the Timoshenko classical solutions. Secondly,on the basis of elastic-plastic stability analysis,referring to the stability design method of monosymmetric section axially loaded compression members,equivalent slenderness of pin-ended circular steel arch subject to hydrostatic pressure are deduced from the expression of out-of-plane elastic buckling load.Combined with the column curves in current Chinese Code for Design of Steel Structures(GB 500172003),the design formula of ultimate load-carrying capacity as well as out-of-plane stability design curves are presented.
2009, 39(12): 95-97.
doi: 10.13204/j.gyjz200912023
Abstract:
Planar BSS with top chords of H-section can be made conveniently,and its joints can be connected easily,but the system is sensitive to the imperfection out of plane because the member of H-section has small stiffness out of plane.The system will be unstable if no effective measure is taken in construction,which tells failure of construction.The paper builds spatial model of the system by FEA and analyzes the stages of prestress-tension and use,researches the spatial results brought by lateral supports,gives out rational scheme of construction,and points out the key problems,which ensures the safety of construction of BSS and can be a reference for other similar projects.
Planar BSS with top chords of H-section can be made conveniently,and its joints can be connected easily,but the system is sensitive to the imperfection out of plane because the member of H-section has small stiffness out of plane.The system will be unstable if no effective measure is taken in construction,which tells failure of construction.The paper builds spatial model of the system by FEA and analyzes the stages of prestress-tension and use,researches the spatial results brought by lateral supports,gives out rational scheme of construction,and points out the key problems,which ensures the safety of construction of BSS and can be a reference for other similar projects.
2009, 39(12): 98-101.
doi: 10.13204/j.gyjz200912024
Abstract:
Through the on-site testing of the concrete pressure in a project of Baosteel, the curves of change in the pressure with the height in steel tube are analyzed.The pumping pressure is a kind of pulse pressure which changes from top to bottom along a particular straight line.The main reason of pumping burst is overflow hole blockage.And the solution of pumping burst is proposed by the analysis of overflow hole blockage.The method of reasonable pumping pressure is obtained.Finally,the project verifies the applicability of the suggested method.
Through the on-site testing of the concrete pressure in a project of Baosteel, the curves of change in the pressure with the height in steel tube are analyzed.The pumping pressure is a kind of pulse pressure which changes from top to bottom along a particular straight line.The main reason of pumping burst is overflow hole blockage.And the solution of pumping burst is proposed by the analysis of overflow hole blockage.The method of reasonable pumping pressure is obtained.Finally,the project verifies the applicability of the suggested method.
2009, 39(12): 102-104.
doi: 10.13204/j.gyjz200912025
Abstract:
Anti-sliding coefficient is an important index which has important significance for ensuring connection reliability of steel structure.However,many factors can effect on it.Therefore,friction-typed high-strength bolt connection anti-sliding coefficient was studied on the side of shot peening mode,resting period and pretension controlling method with 5 series specimens(25 sets).Some conclusions were drawed by experiments.Firstly,front shot peening mode was better than conventional mode in increasing anti-sliding coefficient.Secondly,anti-sliding coefficient could be increased by means of prolonging resting period of piece.Lastly,method of pretension controlling by strain gage had higher reliability than using axial-force meter in determining anti-sliding coefficient.
Anti-sliding coefficient is an important index which has important significance for ensuring connection reliability of steel structure.However,many factors can effect on it.Therefore,friction-typed high-strength bolt connection anti-sliding coefficient was studied on the side of shot peening mode,resting period and pretension controlling method with 5 series specimens(25 sets).Some conclusions were drawed by experiments.Firstly,front shot peening mode was better than conventional mode in increasing anti-sliding coefficient.Secondly,anti-sliding coefficient could be increased by means of prolonging resting period of piece.Lastly,method of pretension controlling by strain gage had higher reliability than using axial-force meter in determining anti-sliding coefficient.
2009, 39(12): 105-109.
doi: 10.13204/j.gyjz200912026
Abstract:
This paper introduces the integrated technique of cutting off columns and jacking of building or structure,in which several underpinning jacking platform structures and their comparative analysis is described to show that the steel-concrete composite structure being a more superior underpinning jacking platform system.It also introduces the systems of synchronized jacking and support,the control of jacking construction and the problems needed to be solved etc;finally,an example of the engineering application and its application effect are introduced.
This paper introduces the integrated technique of cutting off columns and jacking of building or structure,in which several underpinning jacking platform structures and their comparative analysis is described to show that the steel-concrete composite structure being a more superior underpinning jacking platform system.It also introduces the systems of synchronized jacking and support,the control of jacking construction and the problems needed to be solved etc;finally,an example of the engineering application and its application effect are introduced.
2009, 39(12): 110-114.
doi: 10.13204/j.gyjz200912027
Abstract:
There is no special design method and code for the design of the holistic lifting-up for the conservation of the masonry ancient construction.The design method and process of the integral lift-up for the conservation of the Jade Emperor Pavilion of Kaifeng Yanqing Taoist Temple are introduced,which included such enhineering methods as reinforcement,high pressure jet grouting piles, pipe-jacking,jacked steel piles and preloaded piles,integral lift-up etc.Some suggestions and specific measures are put forward.
There is no special design method and code for the design of the holistic lifting-up for the conservation of the masonry ancient construction.The design method and process of the integral lift-up for the conservation of the Jade Emperor Pavilion of Kaifeng Yanqing Taoist Temple are introduced,which included such enhineering methods as reinforcement,high pressure jet grouting piles, pipe-jacking,jacked steel piles and preloaded piles,integral lift-up etc.Some suggestions and specific measures are put forward.
2009, 39(12): 115-117.
doi: 10.13204/j.gyjz200912028
Abstract:
Based on a real life example,this article analyses all kinds of schemes of adjusting large slanting steel column of a building.It introduces a method to resolving this problem by uprising the column with a jack.The details on how to apply this method is given.The application shows that this is a very economical,safe and simple method to adjust large lean steel columns.
Based on a real life example,this article analyses all kinds of schemes of adjusting large slanting steel column of a building.It introduces a method to resolving this problem by uprising the column with a jack.The details on how to apply this method is given.The application shows that this is a very economical,safe and simple method to adjust large lean steel columns.
2009, 39(12): 118-122.
doi: 10.13204/j.gyjz200912029
Abstract:
In this paper,the shear behavior of concrete beam reinforced with engineered cementitious composites(ECC) and FRP grid is studied for the first time and is compared with the behavior of a beam reinforced with steel and CFRP sheet.The results from the research on crack development,ultimate deflection bearing capacity and failure mode of different specimens are valuable for further application of strengthening technology and the development of design guidelines for ECC and FRP grids.
In this paper,the shear behavior of concrete beam reinforced with engineered cementitious composites(ECC) and FRP grid is studied for the first time and is compared with the behavior of a beam reinforced with steel and CFRP sheet.The results from the research on crack development,ultimate deflection bearing capacity and failure mode of different specimens are valuable for further application of strengthening technology and the development of design guidelines for ECC and FRP grids.
2009, 39(12): 123-126.
doi: 10.13204/j.gyjz200912030
Abstract:
Although the buildings in a petrochemical plant will not possess the main investment,they have influenced on the feeling of users and can protect the core equipments and operators effectively.This article aims at discussing the process and site control of a building design for a completed petrochemical project.It is expected to improve the quality of buildings by optimizing the process of design and construction.
Although the buildings in a petrochemical plant will not possess the main investment,they have influenced on the feeling of users and can protect the core equipments and operators effectively.This article aims at discussing the process and site control of a building design for a completed petrochemical project.It is expected to improve the quality of buildings by optimizing the process of design and construction.
2009, 39(12): 127-129.
doi: 10.13204/j.gyjz200912031
Abstract:
The rapid development of the economy brings tremendous pressure to the environment.How to use the limited resources rationally and minimize the impact on the environment are the problems that must be concerned the whole human society must be concerned about and faced.In urban construction,to develop green building,it is necessary to give priority to the protection of the natural ecological environment and to have a larger success at the smallest possible environmental costs.This is the only way to guarantee the sustainable development of cities,and realize the real implementation of the scientific concept of development in the construction industry and urban construction.
The rapid development of the economy brings tremendous pressure to the environment.How to use the limited resources rationally and minimize the impact on the environment are the problems that must be concerned the whole human society must be concerned about and faced.In urban construction,to develop green building,it is necessary to give priority to the protection of the natural ecological environment and to have a larger success at the smallest possible environmental costs.This is the only way to guarantee the sustainable development of cities,and realize the real implementation of the scientific concept of development in the construction industry and urban construction.
2009, 39(12): 130-132.
doi: 10.13204/j.gyjz200912032
Abstract:
The development and research on the energy-saving measures of building envelope are of great importance to the construction of resource-conserving society and sustainable development strategy in China.As a new and environment-friendly form of building envelope,planted roof has been given more and more attention,because of its purifying the air,reducing urban heat island effect and noise pollution,improving living conditions.Through analyses and research on the characteristics,classification and structure of planted roof as well as description of the typical case in detail,this article offered a new train of thoughts for building envelope energy-saving design on roof.
The development and research on the energy-saving measures of building envelope are of great importance to the construction of resource-conserving society and sustainable development strategy in China.As a new and environment-friendly form of building envelope,planted roof has been given more and more attention,because of its purifying the air,reducing urban heat island effect and noise pollution,improving living conditions.Through analyses and research on the characteristics,classification and structure of planted roof as well as description of the typical case in detail,this article offered a new train of thoughts for building envelope energy-saving design on roof.
