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2011 Vol. 41, No. 10
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2011, 41(10): 1-5.
doi: 10.13204/j.gyjz201110001
Abstract:
According to the experimental research on 8 composite columns，the axial compression property of GFRP tube filled with steel reinforced concrete was studied． The test results show that GFRP tube，concrete and section steel carry loads alone at the beginning of loading． Then the fiber surface of GFRP tube grows stretch marks when the loads reach 60% ultimate loads and GFRP tube has an obvious hooped effect on concrete when the loads reach 70% ultimate loads． While the loads reach 80% ultimate loads，GFRP tube can generate frequent noise． The damage of test specimen begins with the fracture of GFRP tube，the yield of steel and the crushing of concrete． The nonlinear analysis program of composite columns was developed，and the calculated results agree well with the experimented results． According to the computing and analyses，the bearing capacity of composite columns is enhanced with the increase of GFRP tube wall thickness，concrete strength grade and steel ratio．
According to the experimental research on 8 composite columns，the axial compression property of GFRP tube filled with steel reinforced concrete was studied． The test results show that GFRP tube，concrete and section steel carry loads alone at the beginning of loading． Then the fiber surface of GFRP tube grows stretch marks when the loads reach 60% ultimate loads and GFRP tube has an obvious hooped effect on concrete when the loads reach 70% ultimate loads． While the loads reach 80% ultimate loads，GFRP tube can generate frequent noise． The damage of test specimen begins with the fracture of GFRP tube，the yield of steel and the crushing of concrete． The nonlinear analysis program of composite columns was developed，and the calculated results agree well with the experimented results． According to the computing and analyses，the bearing capacity of composite columns is enhanced with the increase of GFRP tube wall thickness，concrete strength grade and steel ratio．
2011, 41(10): 6-9,5.
doi: 10.13204/j.gyjz201110002
Abstract:
In order to investigate the seismic behavior of earthquake-damaged GFRP (Glass Fiber Reinforced Polymer) tubed reinforced concrete bridge piers repaired with wrapped CFRP (carbon fiber reinforced polymer or plastics) sheets，four GFRP tubed RC bridge piers repaired with wrapped CFRP sheets were tested under repeat low cyclic load． The hysteresis loops，skeleton curves，ductility and energy dissipation ability of the repaired RC bridge piers were compared with those of the original piers． Research show that the bearing capacity and ductility of the repaired bridge piers can be restored or even improved．
In order to investigate the seismic behavior of earthquake-damaged GFRP (Glass Fiber Reinforced Polymer) tubed reinforced concrete bridge piers repaired with wrapped CFRP (carbon fiber reinforced polymer or plastics) sheets，four GFRP tubed RC bridge piers repaired with wrapped CFRP sheets were tested under repeat low cyclic load． The hysteresis loops，skeleton curves，ductility and energy dissipation ability of the repaired RC bridge piers were compared with those of the original piers． Research show that the bearing capacity and ductility of the repaired bridge piers can be restored or even improved．
2011, 41(10): 10-14,19.
doi: 10.13204/j.gyjz201110003
Abstract:
Based on two-layer industry workshops as project background，three RC frame models with the scale 1/3 was designed and produced，with the same size and reinforcement． First，low-cyclic repeated load is imposed on the three RC frame models so that they are in a different degree of damage，then，strengthened by CFRP in conditions of constant loading． Second，the same experiments for the strengthened frames are done again． Based on the data from test，the curves such as load-displacement hysteresis curve，load-skeleton curve and seismic capacity of damaged RC frame strengthened by CFRP are analyzed． And seismic properties of the different damaged RC frames strengthened by CFRP are compared． The results show that the different damaged RC frames strengthened by CFRP have good seismic performance and serviceability． Which provides a theoryetic basis for strengthening a damaged RC frame after rare earthquake．
Based on two-layer industry workshops as project background，three RC frame models with the scale 1/3 was designed and produced，with the same size and reinforcement． First，low-cyclic repeated load is imposed on the three RC frame models so that they are in a different degree of damage，then，strengthened by CFRP in conditions of constant loading． Second，the same experiments for the strengthened frames are done again． Based on the data from test，the curves such as load-displacement hysteresis curve，load-skeleton curve and seismic capacity of damaged RC frame strengthened by CFRP are analyzed． And seismic properties of the different damaged RC frames strengthened by CFRP are compared． The results show that the different damaged RC frames strengthened by CFRP have good seismic performance and serviceability． Which provides a theoryetic basis for strengthening a damaged RC frame after rare earthquake．
2011, 41(10): 15-19.
doi: 10.13204/j.gyjz201110004
Abstract:
In order to develop an effective seismic shear strengthening method for improving the earthquake behavior of RC short columns，experimental studies are conducted by using four beam-column sub assemblage specimens with a short column． Three short columns of these specimens are strengthened by CFRP in loading，while the other is without any strengthening． All the specimens are tested under a constant gravity load and alternately repeated lateral forces．Test results demonstrate that if the short column is strengthened by CFRP，then brittle shear failure does not occur and the column can develop its ultimate flexural moment capacity． It is also shown by tests that the proposed strengthening method is applicable to repair and rehabilitate the damaged short columns failed in the brittle shear mode．
In order to develop an effective seismic shear strengthening method for improving the earthquake behavior of RC short columns，experimental studies are conducted by using four beam-column sub assemblage specimens with a short column． Three short columns of these specimens are strengthened by CFRP in loading，while the other is without any strengthening． All the specimens are tested under a constant gravity load and alternately repeated lateral forces．Test results demonstrate that if the short column is strengthened by CFRP，then brittle shear failure does not occur and the column can develop its ultimate flexural moment capacity． It is also shown by tests that the proposed strengthening method is applicable to repair and rehabilitate the damaged short columns failed in the brittle shear mode．
2011, 41(10): 20-24.
doi: 10.13204/j.gyjz201110005
Abstract:
The objective of this study is to investigate the flexural behaviors of reinforced concrete beam with nearsurfacemounted (NSM) GFRP bars． The tests of a group of simply supported rectangular cross-section beams strengthened with NSM GFRP bars and two control beams are carried out． The mode of failure，load-deflection relationship，and load-strain curve of the all specimens are analyzed． Cracks propagation is discussed based on measured data． The two effect factors of ratio of steel reinforcement in the beam and amount of GFRP bars on flexural behaviour are studied further． The studies indicate that not only yield and ultimate load of the beam are significantly enhanced，but also the flexural stiffness in the yield and ultimate behavior state of the beam is improved by using NSM-GFRP bars． The studies also show that there has a beneficial contribution to restriction on crack propagation．
The objective of this study is to investigate the flexural behaviors of reinforced concrete beam with nearsurfacemounted (NSM) GFRP bars． The tests of a group of simply supported rectangular cross-section beams strengthened with NSM GFRP bars and two control beams are carried out． The mode of failure，load-deflection relationship，and load-strain curve of the all specimens are analyzed． Cracks propagation is discussed based on measured data． The two effect factors of ratio of steel reinforcement in the beam and amount of GFRP bars on flexural behaviour are studied further． The studies indicate that not only yield and ultimate load of the beam are significantly enhanced，but also the flexural stiffness in the yield and ultimate behavior state of the beam is improved by using NSM-GFRP bars． The studies also show that there has a beneficial contribution to restriction on crack propagation．
2011, 41(10): 25-28,63.
doi: 10.13204/j.gyjz201110006
Abstract:
In order to study the mechanical behavior of concrete continuous beams strengthened with CFRP sheets，3 two-span continuous beams were fabricated，and strengthened with CFRP sheets at each span． The test of loading on two-point was completed，from which the bearing capacity，cracks distribution，the test value of the length of plastic hinge region，curves of load-deformation and curves of internal force redistribution were obtained． The test results showed that the failure of concrete continuous beams strengthened with CFRP sheets was characterized by longtitudinal reinforcement yielded in intermediate support sections，then the longtitudinal reinforcement yielded in the middle span sections，at last carbon fiber polymer sheets were pulled off． The internal force redistribution appeared apparently in beams during loading process and the redistribution rate was over 50% in the state of ultimate bearing capacity． As CFRP confined the deflection of beams，the length of the plastic hinge region near the sections of intermediate support was reduced as compared to ordinary continuous reinforced beams．
In order to study the mechanical behavior of concrete continuous beams strengthened with CFRP sheets，3 two-span continuous beams were fabricated，and strengthened with CFRP sheets at each span． The test of loading on two-point was completed，from which the bearing capacity，cracks distribution，the test value of the length of plastic hinge region，curves of load-deformation and curves of internal force redistribution were obtained． The test results showed that the failure of concrete continuous beams strengthened with CFRP sheets was characterized by longtitudinal reinforcement yielded in intermediate support sections，then the longtitudinal reinforcement yielded in the middle span sections，at last carbon fiber polymer sheets were pulled off． The internal force redistribution appeared apparently in beams during loading process and the redistribution rate was over 50% in the state of ultimate bearing capacity． As CFRP confined the deflection of beams，the length of the plastic hinge region near the sections of intermediate support was reduced as compared to ordinary continuous reinforced beams．
2011, 41(10): 29-32.
doi: 10.13204/j.gyjz201110007
Abstract:
In order to study the prestressing loss of fiber reinforced plastics (FRP) tendons，the prestressing loss experiment of six concrete beams prestressed with CFRP tendons is carried out． Based on the measured values of experiment，combined with relevant calculating， the prestressing loss of FRP tendons are studied， and the corresponding design suggestions are proposed． The results show that the contents of prestressing loss of CFRP tendons are similar to steel cables，and the approach of subentry calculating total loss of prestressing can be used for CFRP tendons． The calculated results were close to those of the tests，and the error is within 15%．
In order to study the prestressing loss of fiber reinforced plastics (FRP) tendons，the prestressing loss experiment of six concrete beams prestressed with CFRP tendons is carried out． Based on the measured values of experiment，combined with relevant calculating， the prestressing loss of FRP tendons are studied， and the corresponding design suggestions are proposed． The results show that the contents of prestressing loss of CFRP tendons are similar to steel cables，and the approach of subentry calculating total loss of prestressing can be used for CFRP tendons． The calculated results were close to those of the tests，and the error is within 15%．
2011, 41(10): 33-36,32.
doi: 10.13204/j.gyjz201110008
Abstract:
It is introduced that the research results of bond behavior between reinforcing steel bar, FRP rebar andconcrete in domestic and overseas, which include bond mechanism, stress process, influence factors, bond strength, bond length and constitutive relation． Finally, the research methods of bond behavior between reinforcing steel bar, FRP rebar and concrete are discussed ．
It is introduced that the research results of bond behavior between reinforcing steel bar, FRP rebar andconcrete in domestic and overseas, which include bond mechanism, stress process, influence factors, bond strength, bond length and constitutive relation． Finally, the research methods of bond behavior between reinforcing steel bar, FRP rebar and concrete are discussed ．
2011, 41(10): 37-40.
doi: 10.13204/j.gyjz201110009
Abstract:
It is proposed the view of evaluating the value of an industrial heritage from the characteristics of an urbanindustrialization; and it is also pointed out that the oriented value of an industrial heritage lies in transferring andcarrying on the valuable cultural information in the process of industrialization, as well as transferring and developingindustrial cultural information for the contemporary and futurity． It is proposed a progressive evaluation method ofstarting from main trades to typical enterprises, and then to architectural heritages, whose essessment indexes havebeen worked out respectively, so as to set up an evaluation system． The industrial city: Chongqing is taken as thecase history using this evaluation method, which provides a useful exploration of evaluating the values of industrialheritages scientifically．
It is proposed the view of evaluating the value of an industrial heritage from the characteristics of an urbanindustrialization; and it is also pointed out that the oriented value of an industrial heritage lies in transferring andcarrying on the valuable cultural information in the process of industrialization, as well as transferring and developingindustrial cultural information for the contemporary and futurity． It is proposed a progressive evaluation method ofstarting from main trades to typical enterprises, and then to architectural heritages, whose essessment indexes havebeen worked out respectively, so as to set up an evaluation system． The industrial city: Chongqing is taken as thecase history using this evaluation method, which provides a useful exploration of evaluating the values of industrialheritages scientifically．
2011, 41(10): 41-43.
doi: 10.13204/j.gyjz201110010
Abstract:
It is presented an architectural creation based on the characteristics of regional culture after analyzing thedesign situation of current domestic large industrial buildings for refuse-fueled power plants． It is also emphasized theimportance of architectural creation for refuse-fueled power plants and proposed ways and means of it, combining withboth foreign and domestic examples．
It is presented an architectural creation based on the characteristics of regional culture after analyzing thedesign situation of current domestic large industrial buildings for refuse-fueled power plants． It is also emphasized theimportance of architectural creation for refuse-fueled power plants and proposed ways and means of it, combining withboth foreign and domestic examples．
2011, 41(10): 44-46.
doi: 10.13204/j.gyjz201110011
Abstract:
The process of urbanization couldnt separate from the development of industrial economy． The industrialenterprises begin to improve the working environment after the first rapid developing period, and pursue the harmonyof working, living and nature． Therefore, during the landscape design of industrial environment, landscape strategyshould be integrated with the particularity of every industrial enterprise, features of field and the order of natureshould also be regarded． Using new angle of view to give the workers poetry inhabitant in an industrial enterprise isone of the main directions in modern enterprises．
The process of urbanization couldnt separate from the development of industrial economy． The industrialenterprises begin to improve the working environment after the first rapid developing period, and pursue the harmonyof working, living and nature． Therefore, during the landscape design of industrial environment, landscape strategyshould be integrated with the particularity of every industrial enterprise, features of field and the order of natureshould also be regarded． Using new angle of view to give the workers poetry inhabitant in an industrial enterprise isone of the main directions in modern enterprises．
2011, 41(10): 47-50.
doi: 10.13204/j.gyjz201110012
Abstract:
The traditional crafts culture of China has a long history, it is not only the most reliable example toembody the diligent work of the chinese nation and its continuation for five thousand years, but also a preciousmaterial and spiritual wealth which our ancestors left us． Today, the wealth has constantly disappeared in the visionand memories of ours． How to make this wealth reproduce and continue to pass down its glory, every chinese shouldthink about it． It is explored the protection and development of the traditional workshops taking an old oil workshop inChingan District for example, thus in a micro ken, researching the protection of cultural heritages．
The traditional crafts culture of China has a long history, it is not only the most reliable example toembody the diligent work of the chinese nation and its continuation for five thousand years, but also a preciousmaterial and spiritual wealth which our ancestors left us． Today, the wealth has constantly disappeared in the visionand memories of ours． How to make this wealth reproduce and continue to pass down its glory, every chinese shouldthink about it． It is explored the protection and development of the traditional workshops taking an old oil workshop inChingan District for example, thus in a micro ken, researching the protection of cultural heritages．
2011, 41(10): 51-54,58.
doi: 10.13204/j.gyjz201110013
Abstract:
Starting from the necessity of developing eco-architectures, it is analysed the intension and characteristicof an eco-architecture． Then it is shown that the principle of adapting to surrounding conditions is very importantthrough an analysis of influence factors of ecological architectures． At last, it is put forward some developmentstrategies of ecological architectures．
Starting from the necessity of developing eco-architectures, it is analysed the intension and characteristicof an eco-architecture． Then it is shown that the principle of adapting to surrounding conditions is very importantthrough an analysis of influence factors of ecological architectures． At last, it is put forward some developmentstrategies of ecological architectures．
2011, 41(10): 55-58.
doi: 10.13204/j.gyjz201110014
Abstract:
In order to avoid brittle failure of short columns, starting from the mechanics definition of the shortcolumns, pointed out the cause of the error judging method commonly used on the short column and gaved a universaldiscriminant equations． Then according to the design experience and previous research results, 9 proposed treatmenton short columns options to choose, a nd pointed out their advantages and disadvantages and scope． It would be able toselect treatment scheme according to the above in practice．
In order to avoid brittle failure of short columns, starting from the mechanics definition of the shortcolumns, pointed out the cause of the error judging method commonly used on the short column and gaved a universaldiscriminant equations． Then according to the design experience and previous research results, 9 proposed treatmenton short columns options to choose, a nd pointed out their advantages and disadvantages and scope． It would be able toselect treatment scheme according to the above in practice．
2011, 41(10): 59-63.
doi: 10.13204/j.gyjz201110015
Abstract:
The detailed formations of precast floor slab connectors have significant effect on its axial capacity, butthere is no such specific provision on it at present． The effects of detailed formations on the in-plane tension(compression) strength, stiffness and deformation capacity of hairpin connectors (HPC) are studied, throughnumerical simulation analysis of it under in-plane tension (compression) force． The slug length (h) , steel platethickness (t) and its stickout (s) are taken as parameters． On the basis of analysis, the recommendations onformation details of HPC are proposed for design and construction．
The detailed formations of precast floor slab connectors have significant effect on its axial capacity, butthere is no such specific provision on it at present． The effects of detailed formations on the in-plane tension(compression) strength, stiffness and deformation capacity of hairpin connectors (HPC) are studied, throughnumerical simulation analysis of it under in-plane tension (compression) force． The slug length (h) , steel platethickness (t) and its stickout (s) are taken as parameters． On the basis of analysis, the recommendations onformation details of HPC are proposed for design and construction．
2011, 41(10): 64-67.
doi: 10.13204/j.gyjz201110016
Abstract:
It has been found that the actual pre-stress effect is hard to reach its expected theoretic value during thetension process in many large-span bridges. It can be explained in a large part by the excess friction loss of pre-stressby the statistical analysis of the measured results of the friction loss of numerous bridges． Based on current calculationmodel for friction loss, the analysis of the theoretic value and the measured results shows that the non-linearrelationship between friction loss and cable length, the ignorance of plane-bending angle in calculation and the effectof stress state are the main reasons for the smaller theoretic value regularly as compared with the measured results．Finally some suggestions are made to improve the calculation of friction loss．
It has been found that the actual pre-stress effect is hard to reach its expected theoretic value during thetension process in many large-span bridges. It can be explained in a large part by the excess friction loss of pre-stressby the statistical analysis of the measured results of the friction loss of numerous bridges． Based on current calculationmodel for friction loss, the analysis of the theoretic value and the measured results shows that the non-linearrelationship between friction loss and cable length, the ignorance of plane-bending angle in calculation and the effectof stress state are the main reasons for the smaller theoretic value regularly as compared with the measured results．Finally some suggestions are made to improve the calculation of friction loss．
2011, 41(10): 68-71.
doi: 10.13204/j.gyjz201110017
Abstract:
High-pressure oedometer tests were conducted on soils pre-densified with the same amount of verticaldeformation formed by static load and impact load under confined compression conditions． Compaction curves, preconsolidation pressures and compression indexes of same pre-densification deformation soil formed in different waywere comparatively investigated． The results showed that compression indexes of same pre-densification soil were closeand irrelevant to the cause of pre-densification; compression curves and preconsolidation pressures were varied with soiltypes． For lower saturated soils, compression curves and preconsolidation pressures after compression were only relevantto pre-densification deformation amounts and irrelevant to the cause of pre-densification in same pre-densificationcondition; for nearly saturated soils, over-consolidated states were formed due to static loads and preconsolidationpressures increased with the amounts of pre-deformation; but over-consolidation states formed by impact load were notobviouse, preconsolidation pressures were irrelevant to pre-densification deformation formed by impact load．
High-pressure oedometer tests were conducted on soils pre-densified with the same amount of verticaldeformation formed by static load and impact load under confined compression conditions． Compaction curves, preconsolidation pressures and compression indexes of same pre-densification deformation soil formed in different waywere comparatively investigated． The results showed that compression indexes of same pre-densification soil were closeand irrelevant to the cause of pre-densification; compression curves and preconsolidation pressures were varied with soiltypes． For lower saturated soils, compression curves and preconsolidation pressures after compression were only relevantto pre-densification deformation amounts and irrelevant to the cause of pre-densification in same pre-densificationcondition; for nearly saturated soils, over-consolidated states were formed due to static loads and preconsolidationpressures increased with the amounts of pre-deformation; but over-consolidation states formed by impact load were notobviouse, preconsolidation pressures were irrelevant to pre-densification deformation formed by impact load．
2011, 41(10): 72-74,94.
doi: 10.13204/j.gyjz201110018
Abstract:
Influence of foundation excavation on nearby underground pipeline is a key problem relating safe andeconomic construction of city foundation, which is a difficult and hot research subject． Based on the elastic foundationbeam theory proposed by the predecessors, the calculation method based on field test ground subsidence curve ofcalculating the influence of deep excavation on nearby underground pipeline was proposed． This method made up theshortage of supposing the ground subsidence curve above underground pipeline to be parabola, which made thecalculation result more accurate． Finally, the solution process of this method was illustrated through an engineeringexample． The vertical displacement equation of underground pipeline was obtained, and its value solution was solvedwith Matlab software, which was in good agreement with that of field test．
Influence of foundation excavation on nearby underground pipeline is a key problem relating safe andeconomic construction of city foundation, which is a difficult and hot research subject． Based on the elastic foundationbeam theory proposed by the predecessors, the calculation method based on field test ground subsidence curve ofcalculating the influence of deep excavation on nearby underground pipeline was proposed． This method made up theshortage of supposing the ground subsidence curve above underground pipeline to be parabola, which made thecalculation result more accurate． Finally, the solution process of this method was illustrated through an engineeringexample． The vertical displacement equation of underground pipeline was obtained, and its value solution was solvedwith Matlab software, which was in good agreement with that of field test．
2011, 41(10): 75-80.
doi: 10.13204/j.gyjz201110019
Abstract:
Counterweight construction method, which is commonly used in installation of a large single-layer planecable net curtain wall, has lots of disadvantages． It is intended to present a new method to overcome theseshortcomings． The elastic deformation in the construction process of the vertical cable is deeply analyzed． Based onthe improved form-finding method with nonlinear inverse iteration that was proposed in preliminary study, anautomatic emplacement construction method for single-layer plane cable net curtain wall is brought forward． Theproposed method combines the principles and the fundamental purposes of the counterweight method, as well as thefeasibility of the construction site． This construction simulation-based method without counterweight can achieve thesame effect as the counterweight method, so as to save a lot of construction costs and reduce security risks． Thepractice applications show that the self-horizontal and self-vertical construction method can completely replace thecounterweight construction method, which has strong feasibility and significant superiority in application because it isa more economic, safer and simpler method．
Counterweight construction method, which is commonly used in installation of a large single-layer planecable net curtain wall, has lots of disadvantages． It is intended to present a new method to overcome theseshortcomings． The elastic deformation in the construction process of the vertical cable is deeply analyzed． Based onthe improved form-finding method with nonlinear inverse iteration that was proposed in preliminary study, anautomatic emplacement construction method for single-layer plane cable net curtain wall is brought forward． Theproposed method combines the principles and the fundamental purposes of the counterweight method, as well as thefeasibility of the construction site． This construction simulation-based method without counterweight can achieve thesame effect as the counterweight method, so as to save a lot of construction costs and reduce security risks． Thepractice applications show that the self-horizontal and self-vertical construction method can completely replace thecounterweight construction method, which has strong feasibility and significant superiority in application because it isa more economic, safer and simpler method．
2011, 41(10): 81-84.
doi: 10.13204/j.gyjz201110020
Abstract:
Using project measurement of an actual, it is examined the vertical deformation of a tall steel reinforcedconcrete frame-core wall structure during construction． The results show that there is a difference in deformationmagnitude between the steel and concrete in steel reinforced concrete columns, and that deformation compatible timebetween concrete and steel is associated with the concrete strength grade: the higher the concrete strength grade, thelonger the time for deformation compatibility． The maximum value of column vertical deformation is 40710－6 , andthe maximum value of shear wall vertical deformation is 35910－6 ． The rate of vertical deformation is faster withinthe initial 14 d; and the ratio of vertical deformation to total deformation after finishing the construction of 42 floors forthe column and shear wall is about 0. 35 and 0.34, and follows a linear relation thereafter．
Using project measurement of an actual, it is examined the vertical deformation of a tall steel reinforcedconcrete frame-core wall structure during construction． The results show that there is a difference in deformationmagnitude between the steel and concrete in steel reinforced concrete columns, and that deformation compatible timebetween concrete and steel is associated with the concrete strength grade: the higher the concrete strength grade, thelonger the time for deformation compatibility． The maximum value of column vertical deformation is 40710－6 , andthe maximum value of shear wall vertical deformation is 35910－6 ． The rate of vertical deformation is faster withinthe initial 14 d; and the ratio of vertical deformation to total deformation after finishing the construction of 42 floors forthe column and shear wall is about 0. 35 and 0.34, and follows a linear relation thereafter．
2011, 41(10): 85-89.
doi: 10.13204/j.gyjz201110021
Abstract:
The progressive collapse analysis of structures becomes a hotspot for study over the world． The search of the key element is an important task for the alternative path method． On the basis of comparing the methods for the estimate of important elements，some conclusions were discussed． Furthermore，the three requirements for the method to judge the key elements of a structure were also given．
The progressive collapse analysis of structures becomes a hotspot for study over the world． The search of the key element is an important task for the alternative path method． On the basis of comparing the methods for the estimate of important elements，some conclusions were discussed． Furthermore，the three requirements for the method to judge the key elements of a structure were also given．
2011, 41(10): 90-94.
doi: 10.13204/j.gyjz201110022
Abstract:
This paper studies on the failure mode and the hysteretic characteristics of the key steel underpinning truss-STCC joint，which lies in the large-span roof of Hohhot East Railway Station，by constructing a mixed-scales finite element model． It is explored the feasibility of using Drucker-Prager Cap material model in concrete hysteretic analysis． And it is constructed the joint model based on it to discuss the mechanical property differences of the joint model with and without filled concrete and the impact of the grade of the concrete． Also it is studied the mechanical differences between adopting internal stiffened method and local strength method combined procedures mechanical property of complicated joint in order to present some advices for structure design．
This paper studies on the failure mode and the hysteretic characteristics of the key steel underpinning truss-STCC joint，which lies in the large-span roof of Hohhot East Railway Station，by constructing a mixed-scales finite element model． It is explored the feasibility of using Drucker-Prager Cap material model in concrete hysteretic analysis． And it is constructed the joint model based on it to discuss the mechanical property differences of the joint model with and without filled concrete and the impact of the grade of the concrete． Also it is studied the mechanical differences between adopting internal stiffened method and local strength method combined procedures mechanical property of complicated joint in order to present some advices for structure design．
2011, 41(10): 95-99.
doi: 10.13204/j.gyjz201110023
Abstract:
Experiments on eight circular rubber concrete-filled steel tubular stub columns subjected to axial loadingare carried out． The influence of rubber replacing ratio and rubber particle size on the bearing capacity of the circularrubber concrete-filled steel tubular stub columns is analyzed． The bearing capacity of these specimens is calculated respectively by different codes，including ACI (2005，American)，AISC-LRFD (2005，American)，AIJ (2008，Japan)，BS5400 (2005，British)，EC4 (2004，Europe)，DL /T 50851999(1999，China)，DB21 /T 17462009(2009，China)，which are also compared respectively． The test results show that the bearing capacity and stiffness both decrease with the increase of rubber replacing ratio，and with the increase of rubber particle size． All results are somewhat conservative，the results of code DL /T 50851999(1999，China) are in agreement well with those of the tests． It is suitable to adopt the code DL /T 50851999(1999，China) to design circular rubber concrete-filled steel tubular columns．
Experiments on eight circular rubber concrete-filled steel tubular stub columns subjected to axial loadingare carried out． The influence of rubber replacing ratio and rubber particle size on the bearing capacity of the circularrubber concrete-filled steel tubular stub columns is analyzed． The bearing capacity of these specimens is calculated respectively by different codes，including ACI (2005，American)，AISC-LRFD (2005，American)，AIJ (2008，Japan)，BS5400 (2005，British)，EC4 (2004，Europe)，DL /T 50851999(1999，China)，DB21 /T 17462009(2009，China)，which are also compared respectively． The test results show that the bearing capacity and stiffness both decrease with the increase of rubber replacing ratio，and with the increase of rubber particle size． All results are somewhat conservative，the results of code DL /T 50851999(1999，China) are in agreement well with those of the tests． It is suitable to adopt the code DL /T 50851999(1999，China) to design circular rubber concrete-filled steel tubular columns．
2011, 41(10): 100-105.
doi: 10.13204/j.gyjz201110024
Abstract:
Two finite element models of buckling-restrained composite steel plate shear wall (BR-CSPW) named as BR-CSPWⅠand BR-CSPWⅡ were constructed with the consideration of infill steel plate bearing vertical load． The difference between two models is the concrete plate and steel plate work together to bear vertical load in BR-CSPWⅡ．ABAQUS was used to conduct the analysis for the influence of vertical load on shear performance，stress distribution of infill steel plate and damage of concrete plate of BR-CSPW． Experimental studies on 2 shear wall specimens were carried out under cyclic lateral load． Analysis results show that with increasing of vertical load，the interaction between concrete plate and steel plate is enhanced and the damage of concrete plate is getting worse． The shear bearing capacity，initial stiffness and energy dissipation capacity of BR-CSPW will not decrease significantly under vertical load if the concrete plate is properly designed and detailed to provide sufficient out-of-plane restraining for steel plate． Under the action of vertical load，the bending capacity of boundary column is reduced for bearing more pressure．
Two finite element models of buckling-restrained composite steel plate shear wall (BR-CSPW) named as BR-CSPWⅠand BR-CSPWⅡ were constructed with the consideration of infill steel plate bearing vertical load． The difference between two models is the concrete plate and steel plate work together to bear vertical load in BR-CSPWⅡ．ABAQUS was used to conduct the analysis for the influence of vertical load on shear performance，stress distribution of infill steel plate and damage of concrete plate of BR-CSPW． Experimental studies on 2 shear wall specimens were carried out under cyclic lateral load． Analysis results show that with increasing of vertical load，the interaction between concrete plate and steel plate is enhanced and the damage of concrete plate is getting worse． The shear bearing capacity，initial stiffness and energy dissipation capacity of BR-CSPW will not decrease significantly under vertical load if the concrete plate is properly designed and detailed to provide sufficient out-of-plane restraining for steel plate． Under the action of vertical load，the bending capacity of boundary column is reduced for bearing more pressure．
2011, 41(10): 106-110,105.
doi: 10.13204/j.gyjz201110025
Abstract:
The double-T-shaped innovative buckling-restrained brace is a new kind of energy-dissipation brace，so the factors affecting its performance are to be numerous． In order to study the influence of the buckling-restrained mechanism，the buckling restraining ratio， defined as the ratio of Euler load of the outer buckling-restrained mechanism to the yielding load of the steel core，width to thickness ratio of the steel core，the incising mode of the steel core etc lon the energy-dissipation capability of the brace，low cyclic loading tests were conducted on six reduced scale brace specimens． The destruction modality， the hysteretic behavior， energy-dissipation， the displacement ductibility，the rigidity degeneration etc of the innovative brace were studied． The test study demonstrates that the joint of the buckling-restrained mechanism and the steel core of this innovative brace is reliable，and the influence of the buckling-restrained mechanism and the buckling restraining ratio is obvious among all the examined factors，and then the brace with rational composition has a full hysteretic loop， stable energy-dissipation behavior， better displacement ductibility，slower rigidity degeneration．
The double-T-shaped innovative buckling-restrained brace is a new kind of energy-dissipation brace，so the factors affecting its performance are to be numerous． In order to study the influence of the buckling-restrained mechanism，the buckling restraining ratio， defined as the ratio of Euler load of the outer buckling-restrained mechanism to the yielding load of the steel core，width to thickness ratio of the steel core，the incising mode of the steel core etc lon the energy-dissipation capability of the brace，low cyclic loading tests were conducted on six reduced scale brace specimens． The destruction modality， the hysteretic behavior， energy-dissipation， the displacement ductibility，the rigidity degeneration etc of the innovative brace were studied． The test study demonstrates that the joint of the buckling-restrained mechanism and the steel core of this innovative brace is reliable，and the influence of the buckling-restrained mechanism and the buckling restraining ratio is obvious among all the examined factors，and then the brace with rational composition has a full hysteretic loop， stable energy-dissipation behavior， better displacement ductibility，slower rigidity degeneration．
2011, 41(10): 111-114,128.
doi: 10.13204/j.gyjz201110026
Abstract:
The construction tension control is a key technique for reticulated shell-string structure． The whole construction process of structure was traced by inverse analysis method based on the theory of controlling the original length of cable． First，the initial status and the initial cable length were calculated by means of controlling the cable force and the internal force of all members in the pre-stressed state were obtained at the same time． Then，the tension force at each grade and batch was obtained，via controlling the initial cable length of every grade and calculating by the iterative algorithm of nonlinear finite element． A piece of software calculating cable tension was built by using VC ++ 6．0 program，which avoids the repeated calculation in the large current FEM program． Finally，an experiment on the reticulated shell-string model was done，with which the construction was simulated by the multi-times and batching tensioning method，which traced the stress state of bar member during construction process． It was shown that the calculation results by the proposed method were matched the experimental results and the method could accurately simulate the shape-forming process of structure． cables were tensioned only once and the construction was simplified．
The construction tension control is a key technique for reticulated shell-string structure． The whole construction process of structure was traced by inverse analysis method based on the theory of controlling the original length of cable． First，the initial status and the initial cable length were calculated by means of controlling the cable force and the internal force of all members in the pre-stressed state were obtained at the same time． Then，the tension force at each grade and batch was obtained，via controlling the initial cable length of every grade and calculating by the iterative algorithm of nonlinear finite element． A piece of software calculating cable tension was built by using VC ++ 6．0 program，which avoids the repeated calculation in the large current FEM program． Finally，an experiment on the reticulated shell-string model was done，with which the construction was simulated by the multi-times and batching tensioning method，which traced the stress state of bar member during construction process． It was shown that the calculation results by the proposed method were matched the experimental results and the method could accurately simulate the shape-forming process of structure． cables were tensioned only once and the construction was simplified．
2011, 41(10): 115-118.
doi: 10.13204/j.gyjz201110027
Abstract:
The main building of new terminal building of Zhangjiajie Hehua Airport is composed of concrete frame and space truss，and the steel roof is formed by intersecting lattice truss system and square pyramid system． The structural system，analysis and design conditions，related results，overall stability checking and design of joint for support etc are mainly introduced． The analytic results show that the safety of structural design is ensured as all indexes meet the relevant codesrequirements． Which has reference significance to other similar structural designs．
The main building of new terminal building of Zhangjiajie Hehua Airport is composed of concrete frame and space truss，and the steel roof is formed by intersecting lattice truss system and square pyramid system． The structural system，analysis and design conditions，related results，overall stability checking and design of joint for support etc are mainly introduced． The analytic results show that the safety of structural design is ensured as all indexes meet the relevant codesrequirements． Which has reference significance to other similar structural designs．
2011, 41(10): 119-122.
doi: 10.13204/j.gyjz201110028
Abstract:
A short section concrete of a corner column of a frame prism column on 1th floor is unqualified，the strength of concrete is relatively low，therefore，by comparing the reinforcement schemes of concrete，the method of stage replacing concrete is selected． Because the column has a large part of the structual load，to ensure the structure and the construction operations safety，it is measured the strain of the support structure and the replaced structure and the deformation of unloading points during unloading process，with which the internal forces，deformation，residual deformation of the structure at replaced concrete position can be reflected accurately，which can provides reliable basis for unloading． It is also described the test results of construction and the replacement of the reinforcement effect．Finally，advices of design and construction are also put forward for this sort of project．
A short section concrete of a corner column of a frame prism column on 1th floor is unqualified，the strength of concrete is relatively low，therefore，by comparing the reinforcement schemes of concrete，the method of stage replacing concrete is selected． Because the column has a large part of the structual load，to ensure the structure and the construction operations safety，it is measured the strain of the support structure and the replaced structure and the deformation of unloading points during unloading process，with which the internal forces，deformation，residual deformation of the structure at replaced concrete position can be reflected accurately，which can provides reliable basis for unloading． It is also described the test results of construction and the replacement of the reinforcement effect．Finally，advices of design and construction are also put forward for this sort of project．
2011, 41(10): 123-128.
doi: 10.13204/j.gyjz201110029
Abstract:
Based on reconstructing the RC chimney of the former Nanshi Electric Power Plant，which is a typical RC tube structure，into a sightseeing tower for 2010 Shanghai World Expo，it is presented the structural reinforcement scheme and reform contents，and it is described in detail the design of reinforcement and reform of the stucture． It is calculated the main indexes of the structure before and after the reinforcement． It is also checked and compared the indexes of the bearing capacity at ultimate state and normal service state for the structure before and after the reinforcement，through which the reinforcement effect was analyzed．
Based on reconstructing the RC chimney of the former Nanshi Electric Power Plant，which is a typical RC tube structure，into a sightseeing tower for 2010 Shanghai World Expo，it is presented the structural reinforcement scheme and reform contents，and it is described in detail the design of reinforcement and reform of the stucture． It is calculated the main indexes of the structure before and after the reinforcement． It is also checked and compared the indexes of the bearing capacity at ultimate state and normal service state for the structure before and after the reinforcement，through which the reinforcement effect was analyzed．
2011, 41(10): 129-133.
doi: 10.13204/j.gyjz201110030
Abstract:
Due to the fact that a large-span industrial building with frame and bent structure has a poor aseismic behavior，therefore rational reinforcing measures should be adopted to keep the stability and rebability of the original structural system when rebuilding it into a civil building that meets the requirements of the aseismic code． Taking the rebuiliding and reinforcing methods of a workshop for example，in which two-way addition of braces between columns is used to adjust structural rigidity and load distribution，it is presented that the rebuilding and reinforcing design，evaluation and construction practice of this workshop． The practice shows that the method features less quantity of reinforcement，flexible layout of braces，strong antideformability and good ductility etc，which is worth popularizing and further researching．
Due to the fact that a large-span industrial building with frame and bent structure has a poor aseismic behavior，therefore rational reinforcing measures should be adopted to keep the stability and rebability of the original structural system when rebuilding it into a civil building that meets the requirements of the aseismic code． Taking the rebuiliding and reinforcing methods of a workshop for example，in which two-way addition of braces between columns is used to adjust structural rigidity and load distribution，it is presented that the rebuilding and reinforcing design，evaluation and construction practice of this workshop． The practice shows that the method features less quantity of reinforcement，flexible layout of braces，strong antideformability and good ductility etc，which is worth popularizing and further researching．
2011, 41(10): 134-136,133.
doi: 10.13204/j.gyjz201110031
Abstract:
This paper introduced the domestic and foreign construction examples of large public buildings，erected in recent years，and also their developing tendency． Some suggestions were promoted for the sound development of steel stucture industry in China． On the basis of the former paper Meticulous Designing in the third issue of Industrial Construction in 2011，this paper continuously explained the intentions and the characteristics of the designs of meticulous steel structure，and put forward several proposals and measures for the promotion of the meticulous steel structure projects．
This paper introduced the domestic and foreign construction examples of large public buildings，erected in recent years，and also their developing tendency． Some suggestions were promoted for the sound development of steel stucture industry in China． On the basis of the former paper Meticulous Designing in the third issue of Industrial Construction in 2011，this paper continuously explained the intentions and the characteristics of the designs of meticulous steel structure，and put forward several proposals and measures for the promotion of the meticulous steel structure projects．
