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2005 Vol. 35, No. 8
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2005, 35(8): 1-4.
doi: 10.13204/j.gyjz200508001
Abstract:
Fiber reinforced polymer(FRP)material,which is a kind of advanced structural material,has been expanded in civil engineering.It is essential to establish a normative checking method for its research and application.It is also a guarantee to normalize FRP materials market.There is not a normal checking method that is suit for civil engineering now because of short period application.Thus the FRP materials are checked by standard of composite materials.A large amount of experimental studies on FRP materials have been finished,which focus on the effect of speciment size on property;and the size of speciment includes length,width and layer of FRP sheets.Finally,suggestions on FRP sheet standard size are proposed for checking property,which provides an essential basis for establishing a normative checking method.
Fiber reinforced polymer(FRP)material,which is a kind of advanced structural material,has been expanded in civil engineering.It is essential to establish a normative checking method for its research and application.It is also a guarantee to normalize FRP materials market.There is not a normal checking method that is suit for civil engineering now because of short period application.Thus the FRP materials are checked by standard of composite materials.A large amount of experimental studies on FRP materials have been finished,which focus on the effect of speciment size on property;and the size of speciment includes length,width and layer of FRP sheets.Finally,suggestions on FRP sheet standard size are proposed for checking property,which provides an essential basis for establishing a normative checking method.
2005, 35(8): 5-6,4.
doi: 10.13204/j.gyjz200508002
Abstract:
The application and study of the repair technique with fiber reinforced polymer(FRP) are more and more widely in the world.One of the key issues of the technique is to guarantee all the properties of FRP.The lap shear strength is an important index to assess the property of the matched resin.But currently,the lap length and adhesive thickness are variable because there is no specific mould to control the factors in the fabrication of the shear specimens.The checking of the matched resins of FRP for structure repairs in civil engineering are non -normative because of the different fabrication processes of the specimens.So the test data are discrete and cant represent the actual properties of the resins.In order to meet the needs of the application of the technique,a large amount of specimens were fabricated and tested.Based on the analysis of the influencing factors of checking and repeating test,a standard mould of the fabrication of shear specimens was developed.Test results showed that the mould was highly normative and easily operateds,which provides basic condition for testing the property of resins.
The application and study of the repair technique with fiber reinforced polymer(FRP) are more and more widely in the world.One of the key issues of the technique is to guarantee all the properties of FRP.The lap shear strength is an important index to assess the property of the matched resin.But currently,the lap length and adhesive thickness are variable because there is no specific mould to control the factors in the fabrication of the shear specimens.The checking of the matched resins of FRP for structure repairs in civil engineering are non -normative because of the different fabrication processes of the specimens.So the test data are discrete and cant represent the actual properties of the resins.In order to meet the needs of the application of the technique,a large amount of specimens were fabricated and tested.Based on the analysis of the influencing factors of checking and repeating test,a standard mould of the fabrication of shear specimens was developed.Test results showed that the mould was highly normative and easily operateds,which provides basic condition for testing the property of resins.
2005, 35(8): 7-12.
doi: 10.13204/j.gyjz200508003
Abstract:
Seven 7m long reinforced concrete T- beams strengthened with prestressed CFRP sheets are tested under the simulated actual working conditions. T he equipment for prestessing CFRP sheets is developed and designed also . Several parameters, including the amount of strengthening CFRP sheets, the prestressing degree, the reinforcement ratio, two- stage load and the strengthened beam with or without prestressed tendon, are studied in the test program. The momen-t curvature curves of the tested beams which are acquired with a beam simulating numerical program are corresponded with the test resluts well. The prestressed CFRP sheets strengthening can increase the load capacity and decrease the deflection and the width of crack. The practicability of the technique of the prestressed CFRP sheets strengthening is proved.
Seven 7m long reinforced concrete T- beams strengthened with prestressed CFRP sheets are tested under the simulated actual working conditions. T he equipment for prestessing CFRP sheets is developed and designed also . Several parameters, including the amount of strengthening CFRP sheets, the prestressing degree, the reinforcement ratio, two- stage load and the strengthened beam with or without prestressed tendon, are studied in the test program. The momen-t curvature curves of the tested beams which are acquired with a beam simulating numerical program are corresponded with the test resluts well. The prestressed CFRP sheets strengthening can increase the load capacity and decrease the deflection and the width of crack. The practicability of the technique of the prestressed CFRP sheets strengthening is proved.
2005, 35(8): 13-19.
doi: 10.13204/j.gyjz200508004
Abstract:
Externally bonded prestressed carbon fiber reinforced polymer(CFRP)sheets for reinforced concrete(RC) beams strengthening is becoming an effectiveness strengthening method recently,especially to increase the service life under fatigue loading.Though there are some researches on the behavior of RC beams strengthened with prestressed CFRP sheets under static loading,however,researches on the improvement of fatigue performance are very limited. In this paper, the flexural fatigue behavior of RC beams strengthened with prestressed CFRP sheets is investigated with 7 specimens,in which the influences of strengthening amount of prestressed CFRP sheets,ratio of reinforcement,variable -amplitude fatigue loading and damage before strengthening are taken into consideration.Experimental results show that the stress amplitude of the tensioned bar is decreased remarkably and the fatigue life is then obviously increased as compared to normal strengthening method.
Externally bonded prestressed carbon fiber reinforced polymer(CFRP)sheets for reinforced concrete(RC) beams strengthening is becoming an effectiveness strengthening method recently,especially to increase the service life under fatigue loading.Though there are some researches on the behavior of RC beams strengthened with prestressed CFRP sheets under static loading,however,researches on the improvement of fatigue performance are very limited. In this paper, the flexural fatigue behavior of RC beams strengthened with prestressed CFRP sheets is investigated with 7 specimens,in which the influences of strengthening amount of prestressed CFRP sheets,ratio of reinforcement,variable -amplitude fatigue loading and damage before strengthening are taken into consideration.Experimental results show that the stress amplitude of the tensioned bar is decreased remarkably and the fatigue life is then obviously increased as compared to normal strengthening method.
2005, 35(8): 20-25,34.
doi: 10.13204/j.gyjz200508005
Abstract:
Defects of a steel structure may be produced during its design,fabrication and construction;and cumulative damage may also occur in its service period due to overloading,corrosion and fatigue etc,which influences the safety of the structure.The traditional methods for strengthening steel structures are welding steel plates,connection by bolts and riveting or bonding,which have many short -comings,such as result in new damages and residual stress by welding etc.Fiber reinforced plastic/polymer(FRP) has been widely used for strengthening concrete structures because of its higher specific strength and stiffness as well as good anticorrosion.The recent researches show that excellent effect is also displayed when a steel structure is reinforced with FRP.The state -of -art of strengthening steel structures with FRP at home and abroad is reviewed comprehensively,which involves in strengthening tests of steel members,adhesive and its forced analysis etc.
Defects of a steel structure may be produced during its design,fabrication and construction;and cumulative damage may also occur in its service period due to overloading,corrosion and fatigue etc,which influences the safety of the structure.The traditional methods for strengthening steel structures are welding steel plates,connection by bolts and riveting or bonding,which have many short -comings,such as result in new damages and residual stress by welding etc.Fiber reinforced plastic/polymer(FRP) has been widely used for strengthening concrete structures because of its higher specific strength and stiffness as well as good anticorrosion.The recent researches show that excellent effect is also displayed when a steel structure is reinforced with FRP.The state -of -art of strengthening steel structures with FRP at home and abroad is reviewed comprehensively,which involves in strengthening tests of steel members,adhesive and its forced analysis etc.
2005, 35(8): 26-30,109.
doi: 10.13204/j.gyjz200508006
Abstract:
Fibre reinforced polymers(FRP) can be used to restore the stiffness and load carrying capacity of the damaged steel structures and improve their fatigue resistance.The load transfer between steel and FRP affect the behavior of the repaired components directly and the effectiveness of FRP.But there was no systemic analysis of this subject.The influencing factors of load transfer were analyzed systematically,such as surface preparation,properties of steel,FRP and adhesive,thickness of FRP and adhesive,interface debonding.Several measures for improving load transfer effect were also presented,which was useful for the application of the technique.
Fibre reinforced polymers(FRP) can be used to restore the stiffness and load carrying capacity of the damaged steel structures and improve their fatigue resistance.The load transfer between steel and FRP affect the behavior of the repaired components directly and the effectiveness of FRP.But there was no systemic analysis of this subject.The influencing factors of load transfer were analyzed systematically,such as surface preparation,properties of steel,FRP and adhesive,thickness of FRP and adhesive,interface debonding.Several measures for improving load transfer effect were also presented,which was useful for the application of the technique.
2005, 35(8): 31-34.
doi: 10.13204/j.gyjz200508007
Abstract:
Near -surface mounted(NSM) FRP reinforcement is emerging as a promising technique for the strengthening of concrete structures.It is presented an experimental study on the bond behavior of NSM CFRP strips using a simple shear test set -up.The effect of bond length on bond performance is examined.The failure mode,the FRP strain and bond stress distributions,and the local bond -slip relationship are all discussed.
Near -surface mounted(NSM) FRP reinforcement is emerging as a promising technique for the strengthening of concrete structures.It is presented an experimental study on the bond behavior of NSM CFRP strips using a simple shear test set -up.The effect of bond length on bond performance is examined.The failure mode,the FRP strain and bond stress distributions,and the local bond -slip relationship are all discussed.
2005, 35(8): 35-39.
doi: 10.13204/j.gyjz200508008
Abstract:
A test on timber beams pasting different quantity of carbon fiber sheets was carried out,and it has been analyzed that the performance indexes such as the bearing capacity,deflection,etc of reference beams and reinforced beams.The test shows that the carbon fiber sheets have a good reinforcement effect to the wooden beams.
A test on timber beams pasting different quantity of carbon fiber sheets was carried out,and it has been analyzed that the performance indexes such as the bearing capacity,deflection,etc of reference beams and reinforced beams.The test shows that the carbon fiber sheets have a good reinforcement effect to the wooden beams.
2005, 35(8): 40-44,55.
doi: 10.13204/j.gyjz200508009
Abstract:
Eight groups of timber columns components reinforced by carbon fiber reinforced polymer(CFRP) with various enwrapping forms have been studied at laboratory.The enhancing effect of their axial compressive bearing capacity and the failure mode are investigated.Based on the data collected in the test,load -strain curves have been drawn and analysed.Finally,the influence of quantity,space and wide of CFRP on test result is discussed.
Eight groups of timber columns components reinforced by carbon fiber reinforced polymer(CFRP) with various enwrapping forms have been studied at laboratory.The enhancing effect of their axial compressive bearing capacity and the failure mode are investigated.Based on the data collected in the test,load -strain curves have been drawn and analysed.Finally,the influence of quantity,space and wide of CFRP on test result is discussed.
2005, 35(8): 45-47.
doi: 10.13204/j.gyjz200508010
Abstract:
Based on introducing the renewal of the old industrial architectures at home and abroad and taking the 798 factory where many modern artists live in for an example,it is analysed and appreciated the original indoor and outdoor landscape created by artists,showing the self -renewal and self -improvement of old industrial architectures area.A new mode of metabolism of old industrial architectures is also proposed
Based on introducing the renewal of the old industrial architectures at home and abroad and taking the 798 factory where many modern artists live in for an example,it is analysed and appreciated the original indoor and outdoor landscape created by artists,showing the self -renewal and self -improvement of old industrial architectures area.A new mode of metabolism of old industrial architectures is also proposed
2005, 35(8): 48-49,59.
doi: 10.13204/j.gyjz200508011
Abstract:
Technology reform of enterprise production process certainly leads to modification of original general plan design with development and progress of economics, science and people'value notion.Reform and renewal of general plan not only stress connecting relation of all consisting factors of old general plan and new one,coordinating and unification but also have specific feature of times trend of plants so as to form a regenerating synthesized -body of a general plan with inheriting and renvoation.
Technology reform of enterprise production process certainly leads to modification of original general plan design with development and progress of economics, science and people'value notion.Reform and renewal of general plan not only stress connecting relation of all consisting factors of old general plan and new one,coordinating and unification but also have specific feature of times trend of plants so as to form a regenerating synthesized -body of a general plan with inheriting and renvoation.
2005, 35(8): 50-51,102.
doi: 10.13204/j.gyjz200508012
Abstract:
Discarded building of industry,as a part of the urban cell,is the non -traditional cityscape;utilization again after is transformation is not only the inevitable outcome of historical development,but also the objective request for its own development of the building.When our country adjusts urban industrial structure and area structure on a large scale at present,it is faced the problem that transforming a large number of the discarded industrial buildings to utilize again.The discarded industrial buildings and ruins of some cities have already been considered to be a kind of special language of the city,to these buildings'utilization again after transformation,should not merely consider its economic benefits,but consider its historical culture and ecological value even more.Using the concrete instance,it is analyzed the essence factor and reform principle of transforming discarded building of industry to utilize again.
Discarded building of industry,as a part of the urban cell,is the non -traditional cityscape;utilization again after is transformation is not only the inevitable outcome of historical development,but also the objective request for its own development of the building.When our country adjusts urban industrial structure and area structure on a large scale at present,it is faced the problem that transforming a large number of the discarded industrial buildings to utilize again.The discarded industrial buildings and ruins of some cities have already been considered to be a kind of special language of the city,to these buildings'utilization again after transformation,should not merely consider its economic benefits,but consider its historical culture and ecological value even more.Using the concrete instance,it is analyzed the essence factor and reform principle of transforming discarded building of industry to utilize again.
2005, 35(8): 52-55.
doi: 10.13204/j.gyjz200508013
Abstract:
Based on derive beam-column element model of reinforced concrete,reinforced concrete structures are analized to take into account the effect of the number of Gauss point on the nonlinear analysis results when finite element stiffness is integrated.The difference between two concrete - relations are compared with nonlinear analysis of cross -section.The two relations are suggested by the current code for design of concrete structures,one is used for calculation of bearing capacity under bending and compression, the other is used for nonlinear analysis of concrete structures.The analytic results are compared with experimental data and suggestions on suitable Gauss integration points are given for reinforced concrete beam -colimn element.
Based on derive beam-column element model of reinforced concrete,reinforced concrete structures are analized to take into account the effect of the number of Gauss point on the nonlinear analysis results when finite element stiffness is integrated.The difference between two concrete - relations are compared with nonlinear analysis of cross -section.The two relations are suggested by the current code for design of concrete structures,one is used for calculation of bearing capacity under bending and compression, the other is used for nonlinear analysis of concrete structures.The analytic results are compared with experimental data and suggestions on suitable Gauss integration points are given for reinforced concrete beam -colimn element.
2005, 35(8): 56-59.
doi: 10.13204/j.gyjz200508014
Abstract:
Multi -ribbed composite wall is the main bearing member of a multi -ribbed slab structure.Based on the tests of multi -rib slab wall under monotone vertical loading and finite element analysis,the mechanical properties and simplified calculation model of multi -rib slab wall are discussed,and the bearing capacity formula under axial press of multi -rib slab wall is presented.
Multi -ribbed composite wall is the main bearing member of a multi -ribbed slab structure.Based on the tests of multi -rib slab wall under monotone vertical loading and finite element analysis,the mechanical properties and simplified calculation model of multi -rib slab wall are discussed,and the bearing capacity formula under axial press of multi -rib slab wall is presented.
2005, 35(8): 60-63.
doi: 10.13204/j.gyjz200508015
Abstract:
Wall-beam-column combined structure is a new structure system with excellences of light weight,environment protection,energy saving and good construction performance.It can be widely applied to low-middle story buildings.Its structural behavior is a key to decide whether it can satisfy building safety and working function.For examining it,a two-story structure with full size was loaded horizontally under constant vertical load.The corresponding failure mode,weak positions and stiffness degrading property are discussed.From these test results,some important conclusions will be provided to further optimize and rationally design this structure.
Wall-beam-column combined structure is a new structure system with excellences of light weight,environment protection,energy saving and good construction performance.It can be widely applied to low-middle story buildings.Its structural behavior is a key to decide whether it can satisfy building safety and working function.For examining it,a two-story structure with full size was loaded horizontally under constant vertical load.The corresponding failure mode,weak positions and stiffness degrading property are discussed.From these test results,some important conclusions will be provided to further optimize and rationally design this structure.
2005, 35(8): 64-66,74.
doi: 10.13204/j.gyjz200508016
Abstract:
The site test of super -length concrete structure is introduced in detail.The results show that it is effectual to take some measures,such as pre -stressing,constructing the later poured bands,to control thermal deformation and insure the security of structure,the super -length design is achieved,and it may be a reference for similar projects.
The site test of super -length concrete structure is introduced in detail.The results show that it is effectual to take some measures,such as pre -stressing,constructing the later poured bands,to control thermal deformation and insure the security of structure,the super -length design is achieved,and it may be a reference for similar projects.
2005, 35(8): 67-70,119.
doi: 10.13204/j.gyjz200508017
Abstract:
The accidents of soil nailing for foundation excavation in frost -susceptible areas in early spring are more than in other seasons.The soil nailing of Hangyao Building in Beijing was in danger when the lowest temprature was over 0℃.The main reason is the influence of the frost.With the help of Hangyao Building field measurement records,soil finite element program(PLAXIS) is used for calculation of horizontal deformation in construction and in thaw.The results indicate that frost may have significant influence on soil nailing.
The accidents of soil nailing for foundation excavation in frost -susceptible areas in early spring are more than in other seasons.The soil nailing of Hangyao Building in Beijing was in danger when the lowest temprature was over 0℃.The main reason is the influence of the frost.With the help of Hangyao Building field measurement records,soil finite element program(PLAXIS) is used for calculation of horizontal deformation in construction and in thaw.The results indicate that frost may have significant influence on soil nailing.
2005, 35(8): 71-74.
doi: 10.13204/j.gyjz200508018
Abstract:
With the development of underground engineering,its more and more important to the research on soils unloading mechanical properties under high stress.On the basis of plenty of shear tests with clays unloading confining pressure or axial compression after consolidation,the conclusions of the relationship between clay deformation process and the change in strength under unloading stress path are drawn and explored, which provides a reliable basis for projects.
With the development of underground engineering,its more and more important to the research on soils unloading mechanical properties under high stress.On the basis of plenty of shear tests with clays unloading confining pressure or axial compression after consolidation,the conclusions of the relationship between clay deformation process and the change in strength under unloading stress path are drawn and explored, which provides a reliable basis for projects.
2005, 35(8): 75-81.
doi: 10.13204/j.gyjz200508019
Abstract:
Base-isolation is widely used in the field of building structure and bridge.Nowadays,in the code and theory of base-isolation,the soil-structure dynamic interaction(SSI) is not considered.But how SSI influences base-isolation system is necessary to studied.The 3-D model is set up by ANSYS.The nonlinear analysis is done by inputting four natural seismic waves,i.e.El-Centro(N-S) wave,TAFT wave,Luan River records during Tangshan Earthquake and Tianjin records during Ninghe Earthquake.Many factors,influencing the base-isolation system are researched,then some conclusions are provided.
Base-isolation is widely used in the field of building structure and bridge.Nowadays,in the code and theory of base-isolation,the soil-structure dynamic interaction(SSI) is not considered.But how SSI influences base-isolation system is necessary to studied.The 3-D model is set up by ANSYS.The nonlinear analysis is done by inputting four natural seismic waves,i.e.El-Centro(N-S) wave,TAFT wave,Luan River records during Tangshan Earthquake and Tianjin records during Ninghe Earthquake.Many factors,influencing the base-isolation system are researched,then some conclusions are provided.
2005, 35(8): 82-84,88.
doi: 10.13204/j.gyjz200508020
Abstract:
The chemical composition of a pore solution has major effect on concrete permeability evaluated by electrical method.Analysis of test results shows that the conductivity of concrete pore solution and filtered mortar powder solution correlate well.When the ratio of powder to water is 3∶1,the correlation coefficient between the conductivity of the pore solution and the filtered mortar solution is 0855 0.Consequently,it is feasible to modify concrete permeability by the conductivity of a filtered concrete powder solution.
The chemical composition of a pore solution has major effect on concrete permeability evaluated by electrical method.Analysis of test results shows that the conductivity of concrete pore solution and filtered mortar powder solution correlate well.When the ratio of powder to water is 3∶1,the correlation coefficient between the conductivity of the pore solution and the filtered mortar solution is 0855 0.Consequently,it is feasible to modify concrete permeability by the conductivity of a filtered concrete powder solution.
2005, 35(8): 85-88.
doi: 10.13204/j.gyjz200508021
Abstract:
According to the request to the capability of reinforcement used in concrete structure,it was analyzed that the effects of the shapes and shape parameters on the forced properties of all types of reinforcements.Some advice about appliance was put forward to optimize the reinforcement,which may provide the basis for selecting the reinforcement by structural designers and constructors,and it may also be a reference for the production of reinforcements.
According to the request to the capability of reinforcement used in concrete structure,it was analyzed that the effects of the shapes and shape parameters on the forced properties of all types of reinforcements.Some advice about appliance was put forward to optimize the reinforcement,which may provide the basis for selecting the reinforcement by structural designers and constructors,and it may also be a reference for the production of reinforcements.
2005, 35(8): 89-92,105.
doi: 10.13204/j.gyjz200508022
Abstract:
The cracking sensitivity of concrete is determined by the stress development at early age,and the creep of young concrete is an important factor influencing the development of restrained stresses in concrete structures due to autogenous contraction and thermal deformation.It is studied that the properties of creep in restrained concrete at early age,and the effect of creep/relaxation on cracking sensitivity of concrete.
The cracking sensitivity of concrete is determined by the stress development at early age,and the creep of young concrete is an important factor influencing the development of restrained stresses in concrete structures due to autogenous contraction and thermal deformation.It is studied that the properties of creep in restrained concrete at early age,and the effect of creep/relaxation on cracking sensitivity of concrete.
2005, 35(8): 93-96.
doi: 10.13204/j.gyjz200508023
Abstract:
Fire hazard does have great harm to the safety and suitability of concrete structures.But in fact,fire also weakens the durability of concrete significantly.Serious problems of chloride ions erosion have been found in the post-fire concrete structures because of the high temperature and the smoke full of chloride ions.Fire also aggravates the carbonation of concrete.There are other common factors that influence the durability of the post-fire concrete as well, such as sulphate erosion.However,the mechanism of the impression that fire acts on the durability of concrete is different from common one.So,several problems of the durability of post-fire concrete structures have been studied.The mechanisms of impression due to chloride ions and carbonation at high temperature are presented.The prediction of service life of concrete structure is considered as well.Those have shown that the action of fire on concrete structures is one of important research contents of durability of concrete structures.
Fire hazard does have great harm to the safety and suitability of concrete structures.But in fact,fire also weakens the durability of concrete significantly.Serious problems of chloride ions erosion have been found in the post-fire concrete structures because of the high temperature and the smoke full of chloride ions.Fire also aggravates the carbonation of concrete.There are other common factors that influence the durability of the post-fire concrete as well, such as sulphate erosion.However,the mechanism of the impression that fire acts on the durability of concrete is different from common one.So,several problems of the durability of post-fire concrete structures have been studied.The mechanisms of impression due to chloride ions and carbonation at high temperature are presented.The prediction of service life of concrete structure is considered as well.Those have shown that the action of fire on concrete structures is one of important research contents of durability of concrete structures.
2005, 35(8): 97-99,120.
doi: 10.13204/j.gyjz200508024
Abstract:
Sandwich panels consisting of two thin metal faces and a foamed plastic core represent the optimum use of dissimilar materials as composite elements. There are several factors which make the structural design of sandwich panels different from conventional building components. The structural performance and modes of failure analysis of sandwich panels are summarized for practical design.
Sandwich panels consisting of two thin metal faces and a foamed plastic core represent the optimum use of dissimilar materials as composite elements. There are several factors which make the structural design of sandwich panels different from conventional building components. The structural performance and modes of failure analysis of sandwich panels are summarized for practical design.
2005, 35(8): 100-102.
doi: 10.13204/j.gyjz200508025
Abstract:
The seismic responses of steel tower that is built atop of Jiangsu Electricity-Net Dispatcher Center are obtained with respect to each vibration mode using the direct dynamic analysis method based on the mode-superposition.The contributions of each vibration mode to seismic response of steel tower are studied and the influences of high-order modes on the seismic response are investigated.The calculation results reveal that due to the whiplash effect of steel tower,the considered number of vibration modes need to be appropriate to calculate the response of steel tower using the mode-superposition response spectrum method.
The seismic responses of steel tower that is built atop of Jiangsu Electricity-Net Dispatcher Center are obtained with respect to each vibration mode using the direct dynamic analysis method based on the mode-superposition.The contributions of each vibration mode to seismic response of steel tower are studied and the influences of high-order modes on the seismic response are investigated.The calculation results reveal that due to the whiplash effect of steel tower,the considered number of vibration modes need to be appropriate to calculate the response of steel tower using the mode-superposition response spectrum method.
2005, 35(8): 103-105.
doi: 10.13204/j.gyjz200508026
Abstract:
Stress distribution in membrane structures can be either homogeneous and isotropic resulting in a minimum surface or inhomogeneous and anisotropic resulting in a equilibrium surface.As one of the most frequently used form-finding method for membrane structures,dynamic relaxation features the facility of no need to assemble and solve structure stiffness equations,whereas its defect is the relatively numerous iterations.Dynamic relaxation was modified to accelerate the convergence.During the form-finding procedure the calculating parameters were continuously adjusted according to changing of the structure,and the iteration steps to convergence were greatly reduced as compared with those without parameter adjusting.The excess distortion of elements,which may occur due to omitting of the in-plane shear stiffness and can be overcome by sequential designation of node coordinates.
Stress distribution in membrane structures can be either homogeneous and isotropic resulting in a minimum surface or inhomogeneous and anisotropic resulting in a equilibrium surface.As one of the most frequently used form-finding method for membrane structures,dynamic relaxation features the facility of no need to assemble and solve structure stiffness equations,whereas its defect is the relatively numerous iterations.Dynamic relaxation was modified to accelerate the convergence.During the form-finding procedure the calculating parameters were continuously adjusted according to changing of the structure,and the iteration steps to convergence were greatly reduced as compared with those without parameter adjusting.The excess distortion of elements,which may occur due to omitting of the in-plane shear stiffness and can be overcome by sequential designation of node coordinates.
2005, 35(8): 106-109.
doi: 10.13204/j.gyjz200508027
Abstract:
Based on the summarization of all kinds of sustaining structures of glass roof,some modifications of the beam string structures(BSS)were made.A new type of beam string structure was presented.This new type has reasonable structural behaviors,in addition to fewer bars and more beautiful configuration.Through analyzing,some useful data were got.These data reflected the structure performance under the changes in special height -span ratio and the height of pivot.The behavior of new type of BSS and normal BSS is compared.Last,a new type of space BSS was presented.
Based on the summarization of all kinds of sustaining structures of glass roof,some modifications of the beam string structures(BSS)were made.A new type of beam string structure was presented.This new type has reasonable structural behaviors,in addition to fewer bars and more beautiful configuration.Through analyzing,some useful data were got.These data reflected the structure performance under the changes in special height -span ratio and the height of pivot.The behavior of new type of BSS and normal BSS is compared.Last,a new type of space BSS was presented.
2005, 35(8): 110-113,116.
doi: 10.13204/j.gyjz200508028
Abstract:
It was carried out the research on the problems related to The Code for Aseismic Design of Buildings (GB 50011-2001).The problems existed in the code were pointed out as follows:whether plastic sidesway met the demands or not should be originally confirmed while design beginning.But defect of code was that it was confirmed when design was finished.In fact,at this time sidesway calculation did not have the guidance function.The code stipulates that two sidesways must be calculated was unreasonable,because only one was enough.The maximal suitable height of the frame in seismic areas was obviously mistaken,which should be reduced.Actural earthquake hat proved that the width of seismic joint was too small.Which should be widened to a large margin.Infilled frame in seismic area had two steps of seismic resistance was wrong.Because there was only one step.Finally,the suggestions on solving the above problems were proposed for revision of the code.
It was carried out the research on the problems related to The Code for Aseismic Design of Buildings (GB 50011-2001).The problems existed in the code were pointed out as follows:whether plastic sidesway met the demands or not should be originally confirmed while design beginning.But defect of code was that it was confirmed when design was finished.In fact,at this time sidesway calculation did not have the guidance function.The code stipulates that two sidesways must be calculated was unreasonable,because only one was enough.The maximal suitable height of the frame in seismic areas was obviously mistaken,which should be reduced.Actural earthquake hat proved that the width of seismic joint was too small.Which should be widened to a large margin.Infilled frame in seismic area had two steps of seismic resistance was wrong.Because there was only one step.Finally,the suggestions on solving the above problems were proposed for revision of the code.
2005, 35(8): 114-116.
doi: 10.13204/j.gyjz200508029
Abstract:
It was concretely introduced an accident of drill bit being buried during the process of large diameter driling without circulation of slurry by hydraulic piling rig.It was analyzed the cause of the accident and the universalities,the importance of the slurry to the techniques was also explored.Some preventive measures and successful methods for treating the accident of drill bit being buried were finally enumerated.
It was concretely introduced an accident of drill bit being buried during the process of large diameter driling without circulation of slurry by hydraulic piling rig.It was analyzed the cause of the accident and the universalities,the importance of the slurry to the techniques was also explored.Some preventive measures and successful methods for treating the accident of drill bit being buried were finally enumerated.
