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2009 Vol. 39, No. 6
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2009, 39(6): 1-4,12.
doi: 10.13204/j.gyjz200906001
Abstract:
It is first introduced the writing process of the first Design Code for Steel Structures TJ 1774 as well as its special features.Afterwards,the major amendments in the two successive revisions are given in brief.It is mainly discussed the forthcoming revision work of the code,including the necessity of a comprehensive revision,principles to be followed in the revision and specified items to be revised.
It is first introduced the writing process of the first Design Code for Steel Structures TJ 1774 as well as its special features.Afterwards,the major amendments in the two successive revisions are given in brief.It is mainly discussed the forthcoming revision work of the code,including the necessity of a comprehensive revision,principles to be followed in the revision and specified items to be revised.
2009, 39(6): 5-12.
doi: 10.13204/j.gyjz200906002
Abstract:
It is given the comparison of specifications for the stability design formulas in American ANSI/AISC 3602005,British 595012000,Canadian CAN/CSAS162001,Australian AS 41001998,Japanese AIJ2002 and Chinese GB 500172003.The theoretical analyses and experimental researches are given.The equivalent moment factors of non-uniform bending beams,on various loading cases by finite element and finite difference methods are presented.From Chinese specifications of steel structures TJ 1774 to GB 500172003,the equivalent moment factor _b for the simply supported beam,under linear non-uniform bending,is adopted,which is its approximate minimum value and is derived by M.G.Salvadori,taken from L.Rayleigh,W.Ritz,method at 1956.The value _b is different from that in other specifications for design of steel structures.Referring the academic researches,a closed-form expression of calculating equivalent moment factor for any moment distribution and end support conditions is presented.This expression together with the revised flexural-torsional buckling design formula of beam may be provided for next cycle revision of Chinese Code for Design of Steel Structures.
It is given the comparison of specifications for the stability design formulas in American ANSI/AISC 3602005,British 595012000,Canadian CAN/CSAS162001,Australian AS 41001998,Japanese AIJ2002 and Chinese GB 500172003.The theoretical analyses and experimental researches are given.The equivalent moment factors of non-uniform bending beams,on various loading cases by finite element and finite difference methods are presented.From Chinese specifications of steel structures TJ 1774 to GB 500172003,the equivalent moment factor _b for the simply supported beam,under linear non-uniform bending,is adopted,which is its approximate minimum value and is derived by M.G.Salvadori,taken from L.Rayleigh,W.Ritz,method at 1956.The value _b is different from that in other specifications for design of steel structures.Referring the academic researches,a closed-form expression of calculating equivalent moment factor for any moment distribution and end support conditions is presented.This expression together with the revised flexural-torsional buckling design formula of beam may be provided for next cycle revision of Chinese Code for Design of Steel Structures.
2009, 39(6): 13-17,21.
doi: 10.13204/j.gyjz200906003
Abstract:
It's proposed that the effect of the connections' deformation should be considered in structural analysis of semi-rigid steel structures in Code for Design of Steel Structures(GB 500172003),but there is no specific provision for its analysis and design method.The present research situation of semi-rigid connection of steel structures is introduced,including experimental study,theoretic analysis and design methods,etc.Furthermore,the classification and design methods of semi-rigid connections in steel structure design specifications of the USA,Europe,Canada,Australia,Hong Kong are discussed and summarized,providing the reference for the revision of our country's steel structure design code.
It's proposed that the effect of the connections' deformation should be considered in structural analysis of semi-rigid steel structures in Code for Design of Steel Structures(GB 500172003),but there is no specific provision for its analysis and design method.The present research situation of semi-rigid connection of steel structures is introduced,including experimental study,theoretic analysis and design methods,etc.Furthermore,the classification and design methods of semi-rigid connections in steel structure design specifications of the USA,Europe,Canada,Australia,Hong Kong are discussed and summarized,providing the reference for the revision of our country's steel structure design code.
2009, 39(6): 18-21.
doi: 10.13204/j.gyjz200906004
Abstract:
The application of Q420 and Q460 high strength hot-rolled steel angles in steel structures is increasing,but because of the high strength,the widthto-thickness ratio of some steel angles exceeds the code limitation,which does not satisfy the requirement of local buckling.The Chinese Code for Design of Steel Structures(GB 500172003)doesn't provide the corresponding design method for solving this problem.Based on the related Codes of the Chinese Technical Regulation of Design for Tower and Pole Structures of Overhead Transmission Line(DL/T 51542002)and the ASCE Design of Latticed Steel Transmission Structures(ANSI/ASCE 1097),it was studied the stability design methods of Q420 and Q460 high strength hot-rolled steel angle members under axial compression,and analyzed the rationality of these methods,which provides a reference for the corresponding design.
The application of Q420 and Q460 high strength hot-rolled steel angles in steel structures is increasing,but because of the high strength,the widthto-thickness ratio of some steel angles exceeds the code limitation,which does not satisfy the requirement of local buckling.The Chinese Code for Design of Steel Structures(GB 500172003)doesn't provide the corresponding design method for solving this problem.Based on the related Codes of the Chinese Technical Regulation of Design for Tower and Pole Structures of Overhead Transmission Line(DL/T 51542002)and the ASCE Design of Latticed Steel Transmission Structures(ANSI/ASCE 1097),it was studied the stability design methods of Q420 and Q460 high strength hot-rolled steel angle members under axial compression,and analyzed the rationality of these methods,which provides a reference for the corresponding design.
2009, 39(6): 22-24.
doi: 10.13204/j.gyjz200906005
Abstract:
Single equal leg angles are usually used as axial compression members in steel structures,especially in transmission towers design.However,during design calculation,the ratio of steel angle edge width to its thickness will be a problem either using current Code for Design of Steel Structures(GB 500172003),or using Design of Latticed Steel Transmission Structures(ANSI/ASCE 1097).Based on the elastic stability theory,width to thickness ratio limitation computation was deduced for single equal leg angle axial compression members,and proposed design calculation methods were also proposed.
Single equal leg angles are usually used as axial compression members in steel structures,especially in transmission towers design.However,during design calculation,the ratio of steel angle edge width to its thickness will be a problem either using current Code for Design of Steel Structures(GB 500172003),or using Design of Latticed Steel Transmission Structures(ANSI/ASCE 1097).Based on the elastic stability theory,width to thickness ratio limitation computation was deduced for single equal leg angle axial compression members,and proposed design calculation methods were also proposed.
2009, 39(6): 25-27.
doi: 10.13204/j.gyjz200906006
Abstract:
Hot rolled H-section steel is a kind of highly efficient and economical sectional material.It has a wide flange,good lateral rigidity and better performance in bending.Currently homemade H-section steel is classified as Wide,Medium,Narrow and Thin sections.Provisions of H-section steel beam on stability in Code for Design of Steel Structures are borrowed from those of I-section or buildup section beam.Contribution of good sectional properties of H-section steel to stability is not embodied.It is necessary and urgent to research H-section and I-section steel beam separately so that control condition of stability for homemade H-section beam is obtained and the code is improved timely.Starting from the principle of over-all stability,it calculates reduction coefficients of H-section steel beam according to formulas in the code,and presents control condition of stability more suitable for homemade H-section beam.The conclusion is a basis for the revision of Code for Design of Steel Structures and a reference for steel constructions.
Hot rolled H-section steel is a kind of highly efficient and economical sectional material.It has a wide flange,good lateral rigidity and better performance in bending.Currently homemade H-section steel is classified as Wide,Medium,Narrow and Thin sections.Provisions of H-section steel beam on stability in Code for Design of Steel Structures are borrowed from those of I-section or buildup section beam.Contribution of good sectional properties of H-section steel to stability is not embodied.It is necessary and urgent to research H-section and I-section steel beam separately so that control condition of stability for homemade H-section beam is obtained and the code is improved timely.Starting from the principle of over-all stability,it calculates reduction coefficients of H-section steel beam according to formulas in the code,and presents control condition of stability more suitable for homemade H-section beam.The conclusion is a basis for the revision of Code for Design of Steel Structures and a reference for steel constructions.
2009, 39(6): 28-31.
doi: 10.13204/j.gyjz200906007
Abstract:
The clause 8.9.3 is set up as a mandatory provision in Code for Design of Steel Structures(GB 500172003),which prescribes that concrete cover must be set on the column foot.The code has been put in practice for more than five years,but there are many examples where the clause 8.9.3 is often violated in construction drawing examination,and the main reasons are analyzed.The mechanical analysis of concrete cover has been done,the analytic results indicate that the concrete cover is often in a state of tension under wind load and earthquake;so the fixed column foot is a good choice of structural design,and reinforced concrete cover can be used for protecting steel column foot.
The clause 8.9.3 is set up as a mandatory provision in Code for Design of Steel Structures(GB 500172003),which prescribes that concrete cover must be set on the column foot.The code has been put in practice for more than five years,but there are many examples where the clause 8.9.3 is often violated in construction drawing examination,and the main reasons are analyzed.The mechanical analysis of concrete cover has been done,the analytic results indicate that the concrete cover is often in a state of tension under wind load and earthquake;so the fixed column foot is a good choice of structural design,and reinforced concrete cover can be used for protecting steel column foot.
2009, 39(6): 32-35,41.
doi: 10.13204/j.gyjz200906008
Abstract:
The structural working temperature is an important factor which shall be considered in selecting steel quality.Provisions in this regard in Code for Design of Steel Structure(GB 500172003) are somewhat rough and even irrational in some instances.Discussion on this topic and comparison with provisions in American and European codes are given in this paper.Suggestions are put forth as reference for forthcoming revision of design code.
The structural working temperature is an important factor which shall be considered in selecting steel quality.Provisions in this regard in Code for Design of Steel Structure(GB 500172003) are somewhat rough and even irrational in some instances.Discussion on this topic and comparison with provisions in American and European codes are given in this paper.Suggestions are put forth as reference for forthcoming revision of design code.
2009, 39(6): 36-38,73.
doi: 10.13204/j.gyjz200906009
Abstract:
Some personal views on Code for Design of Steel Structures(GB 500172003)are put forward.These include: design value of gravity load,second-order moments and beam-column formula,scope to checking fatigue,effective section,calculating of frame column braced with weak bracing system,tension capacity of high strength bolts.
Some personal views on Code for Design of Steel Structures(GB 500172003)are put forward.These include: design value of gravity load,second-order moments and beam-column formula,scope to checking fatigue,effective section,calculating of frame column braced with weak bracing system,tension capacity of high strength bolts.
2009, 39(6): 39-41.
doi: 10.13204/j.gyjz200906010
Abstract:
How to re-activating the lost vitality of the industrial wasteland in the center of a city to improve the citys ecological environment and provide a good outdoor public space,has become one of the profound social problems for scholars to explore.In this paper,Seattles Olympic Sculpture Park as a good example,shows that art can intervene in public space and provide a new approach to the landscape restoration.
How to re-activating the lost vitality of the industrial wasteland in the center of a city to improve the citys ecological environment and provide a good outdoor public space,has become one of the profound social problems for scholars to explore.In this paper,Seattles Olympic Sculpture Park as a good example,shows that art can intervene in public space and provide a new approach to the landscape restoration.
2009, 39(6): 42-45,49.
doi: 10.13204/j.gyjz200906011
Abstract:
The modern dwellings in Qingdao are an important part of the modern architecture and the city culture.The Qingdao modern detached houses were the main part in the modern dwellings with the important research value.It was studied that their historical culture intentions and art characteristics from,architecture forms,space arrangement,construction and materials.And it was also analyed that the historical and cultural factors forming these characteristics.
The modern dwellings in Qingdao are an important part of the modern architecture and the city culture.The Qingdao modern detached houses were the main part in the modern dwellings with the important research value.It was studied that their historical culture intentions and art characteristics from,architecture forms,space arrangement,construction and materials.And it was also analyed that the historical and cultural factors forming these characteristics.
2009, 39(6): 46-49.
doi: 10.13204/j.gyjz200906012
Abstract:
The planning and design of the exhibition buildings is the pivotal material facilities of the exhibition economy,it is also the functional core developing exhibition economy and promoting the region economy.Using a building case,it is discussed specific plannings and practical methods for creating a sustainable development of exhibition economy.
The planning and design of the exhibition buildings is the pivotal material facilities of the exhibition economy,it is also the functional core developing exhibition economy and promoting the region economy.Using a building case,it is discussed specific plannings and practical methods for creating a sustainable development of exhibition economy.
2009, 39(6): 50-54,64.
doi: 10.13204/j.gyjz200906013
Abstract:
The design method of shear wall's boundary elements is one of the problems that have not been solved perfectly.The lateral displacement mode of cantilever shear wall in limit state is set up,and the plastic hinge rotation is used to define the fortification objective of each seismic grade.The relationship between plastic hinge rotation and cross section's curvature,axial compression ratio and relative height of compression zone are deduced.The length of confined zone can be determined by plane-section assumption theory,and the transverse reinforcement characteristic value is determined by the stress-strain relationship of confined concrete.The comparison of 20 shear wall specimens' calculation results and test results illustrates that this design procedure is feasible.The length of confined zones and the transverse reinforcement characteristic values of boundary element in different seismic grades and axial compression ratios are proposed.
The design method of shear wall's boundary elements is one of the problems that have not been solved perfectly.The lateral displacement mode of cantilever shear wall in limit state is set up,and the plastic hinge rotation is used to define the fortification objective of each seismic grade.The relationship between plastic hinge rotation and cross section's curvature,axial compression ratio and relative height of compression zone are deduced.The length of confined zone can be determined by plane-section assumption theory,and the transverse reinforcement characteristic value is determined by the stress-strain relationship of confined concrete.The comparison of 20 shear wall specimens' calculation results and test results illustrates that this design procedure is feasible.The length of confined zones and the transverse reinforcement characteristic values of boundary element in different seismic grades and axial compression ratios are proposed.
2009, 39(6): 55-58.
doi: 10.13204/j.gyjz200906014
Abstract:
Six specimens of abnormal interior joints were tested under reversed cyclic loading.Experimental studies were carried out to investigate the influence of joint core dimensions and axial compression ratio on crack resistance of abnormal joints.The results showed that the crack resistance capacity was mainly provided by the minor core concrete(determined by the top column and the small beam),and the minor core concrete was in elastic stage before cracks appeared.Furthermore,axial compression ratio was a significant parameter to increase the crack resistance capacity.Based on the test results,a theoretical formula of crack resistance capacity was proposed.The calculated crack resistance capacities of 11 abnormal interior joints were compared with the experimental results,and a good agreement was obtained.
Six specimens of abnormal interior joints were tested under reversed cyclic loading.Experimental studies were carried out to investigate the influence of joint core dimensions and axial compression ratio on crack resistance of abnormal joints.The results showed that the crack resistance capacity was mainly provided by the minor core concrete(determined by the top column and the small beam),and the minor core concrete was in elastic stage before cracks appeared.Furthermore,axial compression ratio was a significant parameter to increase the crack resistance capacity.Based on the test results,a theoretical formula of crack resistance capacity was proposed.The calculated crack resistance capacities of 11 abnormal interior joints were compared with the experimental results,and a good agreement was obtained.
2009, 39(6): 59-64.
doi: 10.13204/j.gyjz200906015
Abstract:
A bi-steel ladder framework is formed by two parallel longitudinal reinforcements and short transverse reinforcements plumbing longitudinal reinforcement.In theory adopting bi-steel technique can improve bonding function between reinforcement and concrete and decrease width and space of cracks of bending member,thus producing fine cracks appear slight and dense.However,at present bi-steel is made from cold-drawn wire or cold-rolled ribbed steel,and is often used in some members such as small span one-way concrete slab,lintel and stairs.The study on bisteel made of Ⅲ grades big-diameter hot rolled ribbed steel has not been reported at present in China and abroad.In order to take enough advantage of bi-steel and extend application,it is analyzed the bi-steel structure which is welded by hot rolled ribbed steel,and emphasized the methods of calculating the cracking and deformation,and also analyzed the feature of cracking completely.At the same time,it is presented the suggested formula of calculating cracks on a bi-steel concret structure with hot rolled ribbed steel by the observation and theoretical analysis.A nice technical and economic benefit may be got by comparing it with common beam.
A bi-steel ladder framework is formed by two parallel longitudinal reinforcements and short transverse reinforcements plumbing longitudinal reinforcement.In theory adopting bi-steel technique can improve bonding function between reinforcement and concrete and decrease width and space of cracks of bending member,thus producing fine cracks appear slight and dense.However,at present bi-steel is made from cold-drawn wire or cold-rolled ribbed steel,and is often used in some members such as small span one-way concrete slab,lintel and stairs.The study on bisteel made of Ⅲ grades big-diameter hot rolled ribbed steel has not been reported at present in China and abroad.In order to take enough advantage of bi-steel and extend application,it is analyzed the bi-steel structure which is welded by hot rolled ribbed steel,and emphasized the methods of calculating the cracking and deformation,and also analyzed the feature of cracking completely.At the same time,it is presented the suggested formula of calculating cracks on a bi-steel concret structure with hot rolled ribbed steel by the observation and theoretical analysis.A nice technical and economic benefit may be got by comparing it with common beam.
2009, 39(6): 65-69.
doi: 10.13204/j.gyjz200906016
Abstract:
Mega-sub controlled structure(MSCS),an isolated substructure used in mega-frame building,has attracted more and more attention of designers for its prominent controlling effectiveness in mega-frame building.An active control,for mega-sub controlled structure subjected to random along-wind loads is investigated based on LQR algorithm.Dynamic equation and method for assembling parameter matrixes for the mega-sub controlled structure under random wind loads are presented.A change in control parameter and time lag that influences the response controlling effectiveness,control force and dynamic characteristic of the MSCS under active control are discussed.The result indicates that the new structure employing active control can offer an effective means of controlling and the controlling responses of this building are sensitive to weight matrix.The controlling effectiveness under active control will be decreased when time lag is considered.
Mega-sub controlled structure(MSCS),an isolated substructure used in mega-frame building,has attracted more and more attention of designers for its prominent controlling effectiveness in mega-frame building.An active control,for mega-sub controlled structure subjected to random along-wind loads is investigated based on LQR algorithm.Dynamic equation and method for assembling parameter matrixes for the mega-sub controlled structure under random wind loads are presented.A change in control parameter and time lag that influences the response controlling effectiveness,control force and dynamic characteristic of the MSCS under active control are discussed.The result indicates that the new structure employing active control can offer an effective means of controlling and the controlling responses of this building are sensitive to weight matrix.The controlling effectiveness under active control will be decreased when time lag is considered.
2009, 39(6): 70-73.
doi: 10.13204/j.gyjz200906017
Abstract:
A special-shaped frame structure system is developed based on common frame structures.By setting fringe component on the structure,the stiffnesses of frame column,beam and beam-column joint are increased,and therefore the whole stiffness of frame structure is also enhanced.It includes special-shaped frame-frame structure,special-shaped frame-shear wall structure,etc.It can solve the shortage in displacement of simple frame structure or frame shear-wall structure effectively,and adjust the plane rotation.The whole distortion and bearing of special-shaped frame structure are analyzed,and yielding order of component is brought forth,which can increase the line number of earthquake defense.
A special-shaped frame structure system is developed based on common frame structures.By setting fringe component on the structure,the stiffnesses of frame column,beam and beam-column joint are increased,and therefore the whole stiffness of frame structure is also enhanced.It includes special-shaped frame-frame structure,special-shaped frame-shear wall structure,etc.It can solve the shortage in displacement of simple frame structure or frame shear-wall structure effectively,and adjust the plane rotation.The whole distortion and bearing of special-shaped frame structure are analyzed,and yielding order of component is brought forth,which can increase the line number of earthquake defense.
2009, 39(6): 74-78.
doi: 10.13204/j.gyjz200906018
Abstract:
The long-term internal force and deformation of pile foundation are directly related to the viscoelasticity of soil,especially in soft clay region.According to the displacement coordinative relationship between vertical pile and soil,the viscoelastic deformation mechanism of soil-pile interaction subjected to horizontal loads is analyzed by the concentrated spring model,taking account of viscoelastic characteristics of soil.The computer program is developed for applying to engineering practice.Selected example was given by making use of the presented method.The proposed method is more perfect in theory and calculation amount is moderate to practical application.The calculation results show that the new theory is feasible and applicable.The solution of this paper is of some significance both to engineering practice and to the theoretical research of pile foundation.
The long-term internal force and deformation of pile foundation are directly related to the viscoelasticity of soil,especially in soft clay region.According to the displacement coordinative relationship between vertical pile and soil,the viscoelastic deformation mechanism of soil-pile interaction subjected to horizontal loads is analyzed by the concentrated spring model,taking account of viscoelastic characteristics of soil.The computer program is developed for applying to engineering practice.Selected example was given by making use of the presented method.The proposed method is more perfect in theory and calculation amount is moderate to practical application.The calculation results show that the new theory is feasible and applicable.The solution of this paper is of some significance both to engineering practice and to the theoretical research of pile foundation.
2009, 39(6): 79-83.
doi: 10.13204/j.gyjz200906019
Abstract:
The difference of site classification and site effects between Chinese Code GB 500112001 and FEMA450 is studied in this paper.Firstly,comparative analysis of site class of ordinary site,site with soft interlayer within 20 m depth and site with soft soil layer below 20m depth is presented,it is found that the thickness of soft soil layer is more vulnerable to change site class of FEMA450 than that of GB500112001 for site with soft interlayer within 20 m depth,and more careful to be considered in FEMA450 for site with soft soil layer below 20m depth.Then,the response spectrums at all sites under different ground shaking are compared,and the results indicate that the effects of soil conditions on ground motion characteristics is more reasonable to be considered in FEMA450 than that in GB500112001.
The difference of site classification and site effects between Chinese Code GB 500112001 and FEMA450 is studied in this paper.Firstly,comparative analysis of site class of ordinary site,site with soft interlayer within 20 m depth and site with soft soil layer below 20m depth is presented,it is found that the thickness of soft soil layer is more vulnerable to change site class of FEMA450 than that of GB500112001 for site with soft interlayer within 20 m depth,and more careful to be considered in FEMA450 for site with soft soil layer below 20m depth.Then,the response spectrums at all sites under different ground shaking are compared,and the results indicate that the effects of soil conditions on ground motion characteristics is more reasonable to be considered in FEMA450 than that in GB500112001.
2009, 39(6): 84-87,107.
doi: 10.13204/j.gyjz200906020
Abstract:
In order to investigate the effect of primary compression settlement of municipal solid waste landfill on the total settlement,and make an accurate prediction on primary compression settlement,the computation model of primary compression settlement was established by the compression tests of waste sample and theoretical analysis,and using the least square method to carry on the optimization to the fitting curve with experimental data.Modified coefficient of primary compression was avoided with this model,which is difficult to determine.The results showed that modified coefficient of primary compression of waste samples was not a constant in the compression.It is related to initial dry density.The computation model of primary compression settlement was established using the initial dry density,which obtained a more satisfactory result by forecasting the actual primary compression settlement.
In order to investigate the effect of primary compression settlement of municipal solid waste landfill on the total settlement,and make an accurate prediction on primary compression settlement,the computation model of primary compression settlement was established by the compression tests of waste sample and theoretical analysis,and using the least square method to carry on the optimization to the fitting curve with experimental data.Modified coefficient of primary compression was avoided with this model,which is difficult to determine.The results showed that modified coefficient of primary compression of waste samples was not a constant in the compression.It is related to initial dry density.The computation model of primary compression settlement was established using the initial dry density,which obtained a more satisfactory result by forecasting the actual primary compression settlement.
2009, 39(6): 88-91,104.
doi: 10.13204/j.gyjz200906021
Abstract:
Unloading engineering is often met as a matter of fact,and the path of keep major stress-strain invariant and minor stress-strain reduced exist indeed in all the sress pathes.A series of experimental researches on the deformation character were made about typical clay in Wuhan and on the base of analysis of a great number of experiments the study were made on the relation of stress-strain、 volume strain-axle strain and parameter of reflecting deformation of side.This study improve the pratical deformation theory of saturated clay appropriate for the P-decreasing path and lay the foundations of seeking practice of excavation study.
Unloading engineering is often met as a matter of fact,and the path of keep major stress-strain invariant and minor stress-strain reduced exist indeed in all the sress pathes.A series of experimental researches on the deformation character were made about typical clay in Wuhan and on the base of analysis of a great number of experiments the study were made on the relation of stress-strain、 volume strain-axle strain and parameter of reflecting deformation of side.This study improve the pratical deformation theory of saturated clay appropriate for the P-decreasing path and lay the foundations of seeking practice of excavation study.
2009, 39(6): 92-95,78.
doi: 10.13204/j.gyjz200906022
Abstract:
Based on Moelands-Reinhardt single parameter exponential constitutive equation,steel fiber concrete damage development equation is obtained using equivalent strain hypothesis.Modified damage development equation of steel fiber concrete is proposed for eliminating mesh correlation of element characteristic length and reflecting the action of tensile strength and fracture energy on the damage development equation.The modified damage development equation comprehensively reflects the action of steel fiber volume ratio and aspect ratio on damage development.Relation of displacement force is obtained by splitting test and theoretical relation of displacement-force obtained by damage FEM calculation.Through comparison of empirical D-P relation and theoretical D-P relation,damage development equation of steel fiber concrete is verified in this paper.
Based on Moelands-Reinhardt single parameter exponential constitutive equation,steel fiber concrete damage development equation is obtained using equivalent strain hypothesis.Modified damage development equation of steel fiber concrete is proposed for eliminating mesh correlation of element characteristic length and reflecting the action of tensile strength and fracture energy on the damage development equation.The modified damage development equation comprehensively reflects the action of steel fiber volume ratio and aspect ratio on damage development.Relation of displacement force is obtained by splitting test and theoretical relation of displacement-force obtained by damage FEM calculation.Through comparison of empirical D-P relation and theoretical D-P relation,damage development equation of steel fiber concrete is verified in this paper.
2009, 39(6): 96-100.
doi: 10.13204/j.gyjz200906023
Abstract:
The influence of the concrete strength,volume of steel fiber and filling range of steel fiber on punching shear performance of slabs was discussed through the experiment on the 13 steel fiber high-strength reinforced concrete two-way simple slabs.Furthermore,the failure mechanism of slabs subjected to punching shear was discussed.The test results show that steel fiber can improve obviously the punching shear performance of slabs.With the increases of the volume or filling range of steel fiber,the punching shear bearing capacity and ductility of local steel fiber high-strength reinforced concrete slabs increased.It was observed that the punching shear ultimate bearing capacity and ductility hardly increased when the filling range of steel fiber was two times of slab thickness.The measure can reduce the steel fiber content.
The influence of the concrete strength,volume of steel fiber and filling range of steel fiber on punching shear performance of slabs was discussed through the experiment on the 13 steel fiber high-strength reinforced concrete two-way simple slabs.Furthermore,the failure mechanism of slabs subjected to punching shear was discussed.The test results show that steel fiber can improve obviously the punching shear performance of slabs.With the increases of the volume or filling range of steel fiber,the punching shear bearing capacity and ductility of local steel fiber high-strength reinforced concrete slabs increased.It was observed that the punching shear ultimate bearing capacity and ductility hardly increased when the filling range of steel fiber was two times of slab thickness.The measure can reduce the steel fiber content.
2009, 39(6): 101-104.
doi: 10.13204/j.gyjz200906024
Abstract:
High-performance ferrocement laminate(HPFL) is a new method to reinforce RC component.It adopts HPFL as inorganic material,and possesses numerous merits.In order to study the shear pins' impact on the interfacial bonding properties at high-temperatures,the test include 6 RC beams strengthened with U-shaped HPFL (ferrocement was put onto the tension face and two profile faces) and 1 reference RC beam.All the beams strengthened with U-shaped HPFL are divided into three groups.The two beams strengthened with U-shaped HPFL in the first group without implanting shear pins.However,the two beams strengthened with U-shaped HPFL in the second group with shear pins by larger spacing.And the last two beams strengthened with U-shaped HPFL in the third group are also implanted with shear pins by smaller spacing.After the test,there is a comparison of their duration of fire resistance,deflection and destruction mode,and an analysis of the interface's failure mechanism is done at high-temperature.The results show that the implanted shear pin can significantly improve the interfacial bonding properties at high-temperature,and the strengthened beams' fire resistance at high-temperature has been greatly improved.
High-performance ferrocement laminate(HPFL) is a new method to reinforce RC component.It adopts HPFL as inorganic material,and possesses numerous merits.In order to study the shear pins' impact on the interfacial bonding properties at high-temperatures,the test include 6 RC beams strengthened with U-shaped HPFL (ferrocement was put onto the tension face and two profile faces) and 1 reference RC beam.All the beams strengthened with U-shaped HPFL are divided into three groups.The two beams strengthened with U-shaped HPFL in the first group without implanting shear pins.However,the two beams strengthened with U-shaped HPFL in the second group with shear pins by larger spacing.And the last two beams strengthened with U-shaped HPFL in the third group are also implanted with shear pins by smaller spacing.After the test,there is a comparison of their duration of fire resistance,deflection and destruction mode,and an analysis of the interface's failure mechanism is done at high-temperature.The results show that the implanted shear pin can significantly improve the interfacial bonding properties at high-temperature,and the strengthened beams' fire resistance at high-temperature has been greatly improved.
2009, 39(6): 105-107.
doi: 10.13204/j.gyjz200906025
Abstract:
The methods of compression-testing machine,MIP(mercury intrusion porosity)and SEM(scanning electron microscope) are used to study the relationship between strength and pore characteristics of HPC(high performance concrete) at minus temperature.The experiment result shows that minus temperature HPC strength is obviously influenced by the pore structure.When compression increases,the porosity decreases.The strength is affected by pore gradation,pore pattern and pore spatial distribution.
The methods of compression-testing machine,MIP(mercury intrusion porosity)and SEM(scanning electron microscope) are used to study the relationship between strength and pore characteristics of HPC(high performance concrete) at minus temperature.The experiment result shows that minus temperature HPC strength is obviously influenced by the pore structure.When compression increases,the porosity decreases.The strength is affected by pore gradation,pore pattern and pore spatial distribution.
2009, 39(6): 108-111.
doi: 10.13204/j.gyjz200906026
Abstract:
In order to reduce the construction time as far as possible in a blast furnace construction process,because the blast furnace main body space is narrow and small,many upper air overlapping operations should be done,which causes the construction to be more complex.Therefore,to guarantee the blast furnace system's construction safety,the method of the fuzzy mathematics and AHP method are used for a quantitative expression of general safety state of a construction.The computation is not only simple,but the operational is strong and easy to grasp by managers in the construction site to discover the potential safety problems as early as possible.As compared with other theoretic methods,it is suitable to the managers at worksite.Through the example of analysis,it has proven that the method is reasonable.
In order to reduce the construction time as far as possible in a blast furnace construction process,because the blast furnace main body space is narrow and small,many upper air overlapping operations should be done,which causes the construction to be more complex.Therefore,to guarantee the blast furnace system's construction safety,the method of the fuzzy mathematics and AHP method are used for a quantitative expression of general safety state of a construction.The computation is not only simple,but the operational is strong and easy to grasp by managers in the construction site to discover the potential safety problems as early as possible.As compared with other theoretic methods,it is suitable to the managers at worksite.Through the example of analysis,it has proven that the method is reasonable.
2009, 39(6): 112-116.
doi: 10.13204/j.gyjz200906027
Abstract:
There are several advantages of adhesively bonded carbon fiber reinforced polymer(CFRP) laminates to strengthen deteriorated steel members over traditional retrofit methods.The bond behavior of CFRP to steel affects their load transfer and the effectiveness of strengthening,but there was no research on this subject in China.The suitable adhesives for steel structures strengthening with CFRP were selected from many adhesives.Appropriate specimens were fabricated to test the bond strength and bond durability between CFRP and steel.Test results showed that the properties of adhesives Araldite 2015,Sikadur 330 and Tyfo MB were excellent and they were suitable for steel strengthening with CFRP.Tensile tests of steel plates repaired with CFRP sheets were conducted and the tensile strains of CFRP sheets were measured.The bond stress distribution between CFRP sheets and steel plates and effective bond length of CFRP sheets were obtained.The computed results using the formulas are in good agreements with the experiment data.
There are several advantages of adhesively bonded carbon fiber reinforced polymer(CFRP) laminates to strengthen deteriorated steel members over traditional retrofit methods.The bond behavior of CFRP to steel affects their load transfer and the effectiveness of strengthening,but there was no research on this subject in China.The suitable adhesives for steel structures strengthening with CFRP were selected from many adhesives.Appropriate specimens were fabricated to test the bond strength and bond durability between CFRP and steel.Test results showed that the properties of adhesives Araldite 2015,Sikadur 330 and Tyfo MB were excellent and they were suitable for steel strengthening with CFRP.Tensile tests of steel plates repaired with CFRP sheets were conducted and the tensile strains of CFRP sheets were measured.The bond stress distribution between CFRP sheets and steel plates and effective bond length of CFRP sheets were obtained.The computed results using the formulas are in good agreements with the experiment data.
2009, 39(6): 117-119,116.
doi: 10.13204/j.gyjz200906028
Abstract:
After reinforced concrete structures suffered from a fire,because of the impact of high temperature,a chemical change would occur in material of concrete,whose strength and ductility would be decreased,thus reducing the physical and mechanical properties of the whole structure and members,damages would be produced.According to a residential building suffered from a fire,it is mainly discussed the construction technology of strengthening beam and plate with high performance ferrocement.Engineering practice proves that this strengthening method has good effect,convenient construction and less cost.
After reinforced concrete structures suffered from a fire,because of the impact of high temperature,a chemical change would occur in material of concrete,whose strength and ductility would be decreased,thus reducing the physical and mechanical properties of the whole structure and members,damages would be produced.According to a residential building suffered from a fire,it is mainly discussed the construction technology of strengthening beam and plate with high performance ferrocement.Engineering practice proves that this strengthening method has good effect,convenient construction and less cost.
2009, 39(6): 120-122.
doi: 10.13204/j.gyjz200906029
Abstract:
Initial deflection of the floor beam of a project by lateral loads and co-axial role occurs because of the construction defects.Based on the analysis of the initial defect of the beam,it is derived a formula for stability bearing capacity of the bending members under lateral loads,and makes a conclusion of the bearing capacity and normal performance of defective beams that the defective beams with no special treatment are still safe.The analysis process of the defective beams can be a reference for similar projects.
Initial deflection of the floor beam of a project by lateral loads and co-axial role occurs because of the construction defects.Based on the analysis of the initial defect of the beam,it is derived a formula for stability bearing capacity of the bending members under lateral loads,and makes a conclusion of the bearing capacity and normal performance of defective beams that the defective beams with no special treatment are still safe.The analysis process of the defective beams can be a reference for similar projects.
2009, 39(6): 123-125.
doi: 10.13204/j.gyjz200906030
Abstract:
Innovation is the necessary way of development.It is useful for the substantial progress of architectural discipline that studying the methods of innovation of industrial buildings design.By analysing the innovations of petrochemical industrial buildings design recently,it is provided opinions that innovation shall be started from technology,design and evaluating standard according to processing development,the changing function and society developmentetc,and methods are also proposed,and at same time,it is pointed out that the development of related architectural technology and material should be noticed,which will lay a reliable basis for innovation.
Innovation is the necessary way of development.It is useful for the substantial progress of architectural discipline that studying the methods of innovation of industrial buildings design.By analysing the innovations of petrochemical industrial buildings design recently,it is provided opinions that innovation shall be started from technology,design and evaluating standard according to processing development,the changing function and society developmentetc,and methods are also proposed,and at same time,it is pointed out that the development of related architectural technology and material should be noticed,which will lay a reliable basis for innovation.
