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2015 Vol. 45, No. 1
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2015, 45(1): 1-9.
doi: 10.13204/j.gyjz201501001
Abstract:
The study history of large span spatial structure considering cooperative work is generalized based on recent research results of academic methods and its application, and also the adaptability of presently computed model about soil-structure interaction to large span spatial structure considering cooperative work is analyzed. The methods for gaining damping ratio of large span spatial structure considering cooperative work are summarized. The possibility of multiple vibration table array system for studying large span structure cooperative work is discussed. Finally, the prospects and study directions of large spatial structure considering soil-structure interaction are given.
The study history of large span spatial structure considering cooperative work is generalized based on recent research results of academic methods and its application, and also the adaptability of presently computed model about soil-structure interaction to large span spatial structure considering cooperative work is analyzed. The methods for gaining damping ratio of large span spatial structure considering cooperative work are summarized. The possibility of multiple vibration table array system for studying large span structure cooperative work is discussed. Finally, the prospects and study directions of large spatial structure considering soil-structure interaction are given.
2015, 45(1): 10-15.
doi: 10.13204/j.gyjz201501002
Abstract:
With the application of large span reticulated shells in significant projects, the fundamental theory of failure mechanism of such structures subjected to severe earthquakes becomes more and more important and becomes one of the primary concerns of the researchers. The paper sums up the research progress in the failure mechanism of large span reticulated shells under severe earthquakes in recent years. The analysis method reviewing full-range responses based on load domain is introduced. The two kinds of failure modes of reticulated shells, dynamic instability due to geometrical nonlinearity and the dynamic strength failure attributable to over-plastic damage accumulation, and their failure mechanism are presented. The paper also proposes the dynamic damage model of reticulated shells and the determination methods of the ultimate load of reticulated shells subjected to severe earthquakes is summarized. Then, three important effects on failure mechanism for reticulated shells under earthquakes, the material damage accumulation, supporting structure and multi-support excitation, are discussed.
With the application of large span reticulated shells in significant projects, the fundamental theory of failure mechanism of such structures subjected to severe earthquakes becomes more and more important and becomes one of the primary concerns of the researchers. The paper sums up the research progress in the failure mechanism of large span reticulated shells under severe earthquakes in recent years. The analysis method reviewing full-range responses based on load domain is introduced. The two kinds of failure modes of reticulated shells, dynamic instability due to geometrical nonlinearity and the dynamic strength failure attributable to over-plastic damage accumulation, and their failure mechanism are presented. The paper also proposes the dynamic damage model of reticulated shells and the determination methods of the ultimate load of reticulated shells subjected to severe earthquakes is summarized. Then, three important effects on failure mechanism for reticulated shells under earthquakes, the material damage accumulation, supporting structure and multi-support excitation, are discussed.
2015, 45(1): 16-22.
doi: 10.13204/j.gyjz201501003
Abstract:
The traditional mode superposition scheme seems not so suitable while applied to dynamic analysis of spatial lattice structures. The reason that accounts for this inapplicability is analyzed and summarized in this paper. Based on deep understanding of free vibration mode characteristics and the high computational efficiency of LDR method, a modified mode superposition method, named Eigen-LDR method, is proposed. The computational method is programmed with Matlab. And the dynamic responses of 2 typical spatial lattice structures are computed with the new method. The numerical results show that the proposed method is effective, accurate and with high efficiency.
The traditional mode superposition scheme seems not so suitable while applied to dynamic analysis of spatial lattice structures. The reason that accounts for this inapplicability is analyzed and summarized in this paper. Based on deep understanding of free vibration mode characteristics and the high computational efficiency of LDR method, a modified mode superposition method, named Eigen-LDR method, is proposed. The computational method is programmed with Matlab. And the dynamic responses of 2 typical spatial lattice structures are computed with the new method. The numerical results show that the proposed method is effective, accurate and with high efficiency.
2015, 45(1): 23-26.
doi: 10.13204/j.gyjz201501004
Abstract:
The threaded-sleeve connection (TSC) is a new kind of grid structure connection which is developed from the welded ball joint. The TSC could be fabricated easily through its threads of the extended end. In this paper, the butt type of TSC is analyzed to verify the feasibility of the connection. The tension mechanical properties and failure mechanism of the extended end is analyzed by axial tension and eccentric tension experiment. Numerical analysis results are obtained as well. It is shown that the TSC shares good properties and its bearing capacity for axial and eccentric tension load are nearly similar, which is about 71% of the pipe with same diameter and wall thickness. The extended part of threads is the weak part of the connection, which occurs obvious necking before failure (ductile failure). It is found that the experimental result is well in agreement with the theoretical model, which proved the reasonable of analytical model.
The threaded-sleeve connection (TSC) is a new kind of grid structure connection which is developed from the welded ball joint. The TSC could be fabricated easily through its threads of the extended end. In this paper, the butt type of TSC is analyzed to verify the feasibility of the connection. The tension mechanical properties and failure mechanism of the extended end is analyzed by axial tension and eccentric tension experiment. Numerical analysis results are obtained as well. It is shown that the TSC shares good properties and its bearing capacity for axial and eccentric tension load are nearly similar, which is about 71% of the pipe with same diameter and wall thickness. The extended part of threads is the weak part of the connection, which occurs obvious necking before failure (ductile failure). It is found that the experimental result is well in agreement with the theoretical model, which proved the reasonable of analytical model.
2015, 45(1): 27-31.
doi: 10.13204/j.gyjz201501005
Abstract:
There is a lack of research on how roof elements participate in the work with the space frame together to resist wind suction effect. This paper discussed all kinds of connections of every elements，and then established a finite element analytical model of the integrated structure considering roof elements such as purlin and roof panel. Combined with a practical project，by analysing and comparing the influence on displacements of structure and forces of bars from purlin and roof panel，it could be drawn a conclusion that under wind suction effect，considering the participation of roof elements in the work with space frame together was feasible． At the same time it was also discussed the problem that a special measure should be taken for a cantilevered end．
There is a lack of research on how roof elements participate in the work with the space frame together to resist wind suction effect. This paper discussed all kinds of connections of every elements，and then established a finite element analytical model of the integrated structure considering roof elements such as purlin and roof panel. Combined with a practical project，by analysing and comparing the influence on displacements of structure and forces of bars from purlin and roof panel，it could be drawn a conclusion that under wind suction effect，considering the participation of roof elements in the work with space frame together was feasible． At the same time it was also discussed the problem that a special measure should be taken for a cantilevered end．
2015, 45(1): 32-35.
doi: 10.13204/j.gyjz201501006
Abstract:
The progressive collapse resistance of the large-span pre-stressed spatial structures raises widely concerns. A new-type pre-stressed cable-strut structure whose typology is advantageous to resisting progressive collapse, named Annular Crossed Cable-truss Structure (ACCTS), is proposed. In aim to prove the progressive collapse resistance of the new-type structure, simulations based on Instantaneous Component-Removing Method of ANSYS/LS-DYNA are put forwards. Instantaneous removals of different kinds of cables or rods are considered respectively. It turns out that the ACCTS doesnt turn geometrically unstable in all removal conditions. Increasing the strength reserve as appropriate makes senses and becomes effective way to resist progressive collapse.
The progressive collapse resistance of the large-span pre-stressed spatial structures raises widely concerns. A new-type pre-stressed cable-strut structure whose typology is advantageous to resisting progressive collapse, named Annular Crossed Cable-truss Structure (ACCTS), is proposed. In aim to prove the progressive collapse resistance of the new-type structure, simulations based on Instantaneous Component-Removing Method of ANSYS/LS-DYNA are put forwards. Instantaneous removals of different kinds of cables or rods are considered respectively. It turns out that the ACCTS doesnt turn geometrically unstable in all removal conditions. Increasing the strength reserve as appropriate makes senses and becomes effective way to resist progressive collapse.
2015, 45(1): 36-42.
doi: 10.13204/j.gyjz201501007
Abstract:
Based on the finite element model and discrete model of soil surrounding pile, the space S-R model and finite element method was adopted to establish a simplified model and an integrative model which contains a single-layer cylindrical latticed shell, pile and its foundation soil. The soil was replaced with spring in the simplified model, and it was compared with the integrative model. The applicability and accuracy of the space S-R model for analyzing the large span space structure considering pile-soil-structure interaction (PSSI) are studied. The results show that the simplified model can simulate natural vibration characteristic and seismic response of the shell fairly well, and it is convenient to be used in engineering. The error of the first vibration frequency of the shell calculated by the simplified model is less than 10% compared with the results of the integrative model. The maximal error of the peak acceleration of node is 13.05% when it subjected to earthquake loads. The maximal error of the nodal displacement is 7.2%, and the maximal error of the internal force of the members was 9.59%.
Based on the finite element model and discrete model of soil surrounding pile, the space S-R model and finite element method was adopted to establish a simplified model and an integrative model which contains a single-layer cylindrical latticed shell, pile and its foundation soil. The soil was replaced with spring in the simplified model, and it was compared with the integrative model. The applicability and accuracy of the space S-R model for analyzing the large span space structure considering pile-soil-structure interaction (PSSI) are studied. The results show that the simplified model can simulate natural vibration characteristic and seismic response of the shell fairly well, and it is convenient to be used in engineering. The error of the first vibration frequency of the shell calculated by the simplified model is less than 10% compared with the results of the integrative model. The maximal error of the peak acceleration of node is 13.05% when it subjected to earthquake loads. The maximal error of the nodal displacement is 7.2%, and the maximal error of the internal force of the members was 9.59%.
2015, 45(1): 43-49.
doi: 10.13204/j.gyjz201501008
Abstract:
In this paper, the friction bearing conbined with large size SMA coil springs is put forward to develop a new type of isolator entitled as SMA spring-friction bearing(SFB). Based on the configuration and working principle, theoretical model of mechanical performance of the SFB is derived. In order to investigate feasibility and vibration reduction effect of the SFB in double layer spherical lattice shell structures, column top isolation structrue including such SMA-based bearings between the lattice shell roof and substructure is considered. The finite element analysis software SAP2000 is utilized to establish the numerical model of isolated lattice shell structure with substructure. Numerical simulation of dynamic response of the seismically isolated structure is carried out. The calculation results indicate that the proposed SFB can reduce the seismic response of the lattice shell structures effectively. The results also show that the SFB has excellent bearing displacement control performance and re-centring capability.
In this paper, the friction bearing conbined with large size SMA coil springs is put forward to develop a new type of isolator entitled as SMA spring-friction bearing(SFB). Based on the configuration and working principle, theoretical model of mechanical performance of the SFB is derived. In order to investigate feasibility and vibration reduction effect of the SFB in double layer spherical lattice shell structures, column top isolation structrue including such SMA-based bearings between the lattice shell roof and substructure is considered. The finite element analysis software SAP2000 is utilized to establish the numerical model of isolated lattice shell structure with substructure. Numerical simulation of dynamic response of the seismically isolated structure is carried out. The calculation results indicate that the proposed SFB can reduce the seismic response of the lattice shell structures effectively. The results also show that the SFB has excellent bearing displacement control performance and re-centring capability.
2015, 45(1): 50-55.
doi: 10.13204/j.gyjz201501009
Abstract:
This article presents an investigation on the earthquake damping effect by applying isolation bearing and buckling restrained brace to the steel tube arch truss system. By using SAP 2000 software and based on concentrated plastic hinge theory including geometric and material nonlinearity，many dynamic increment analyses of both original and damping structure systems were carried out under earthquake waves. Their dynamic performance including plastic hinge distribution，deformation，failure form and structure ductility coefficient obtained. Their dynamic performances were evaluated and compared. The results showed that the self-vibration period of the damping structure was extended; the critical failure limitation capability of damping structure was 131. 2% higher than the original structure，and its seismic performance was improved significantly; The failure types of both original structure and damping structure were elastic-plastic dynamic buckling; the quantity of plastic hinges for them were less before their failure，and their distributions of plastic hinges were uniform; They all had some ductility，their absolute deformation was small before failure，and their failure sign was not significant．
This article presents an investigation on the earthquake damping effect by applying isolation bearing and buckling restrained brace to the steel tube arch truss system. By using SAP 2000 software and based on concentrated plastic hinge theory including geometric and material nonlinearity，many dynamic increment analyses of both original and damping structure systems were carried out under earthquake waves. Their dynamic performance including plastic hinge distribution，deformation，failure form and structure ductility coefficient obtained. Their dynamic performances were evaluated and compared. The results showed that the self-vibration period of the damping structure was extended; the critical failure limitation capability of damping structure was 131. 2% higher than the original structure，and its seismic performance was improved significantly; The failure types of both original structure and damping structure were elastic-plastic dynamic buckling; the quantity of plastic hinges for them were less before their failure，and their distributions of plastic hinges were uniform; They all had some ductility，their absolute deformation was small before failure，and their failure sign was not significant．
2015, 45(1): 56-61.
doi: 10.13204/j.gyjz201501010
Abstract:
Rigid bracing dome is a new type of prestressed space structure，its upper part is a cable net system，and the lower part is a rigid rods supporting system，and the rigid rods of lower part are high strength steel tie rod except the brace rod． From the perspective of engineering application，the methods and steps for analysis of design and construction integration were given，and the key problems were pointed out． The key parameters for determining the geometric shape are span，rise，circumferential equivalent fraction，total number of radial divisions and node coordinate，and the parameters should be determined according to the concrete requirements of engineering practice， relevant specifications and high-strength steel tie rod materials． A new node of brace rod was given and determining method of key parameters also was given． The construction methods of node-by-node assembling and integral tensioning and lifting and concrete installation steps were provided． Simulation analysis was conducted on the construction process by FEDR ( finite element dynamic relaxation) method． The research results provided necessary theoretical reference for design and construction of engineering practice of rigid bracing dome．
Rigid bracing dome is a new type of prestressed space structure，its upper part is a cable net system，and the lower part is a rigid rods supporting system，and the rigid rods of lower part are high strength steel tie rod except the brace rod． From the perspective of engineering application，the methods and steps for analysis of design and construction integration were given，and the key problems were pointed out． The key parameters for determining the geometric shape are span，rise，circumferential equivalent fraction，total number of radial divisions and node coordinate，and the parameters should be determined according to the concrete requirements of engineering practice， relevant specifications and high-strength steel tie rod materials． A new node of brace rod was given and determining method of key parameters also was given． The construction methods of node-by-node assembling and integral tensioning and lifting and concrete installation steps were provided． Simulation analysis was conducted on the construction process by FEDR ( finite element dynamic relaxation) method． The research results provided necessary theoretical reference for design and construction of engineering practice of rigid bracing dome．
2015, 45(1): 62-65.
doi: 10.13204/j.gyjz201501011
Abstract:
The construction industry is in an important period of transition to industrialization. Based on an entry projecti-Yardfrom Beijing Jiaotong University of SD China 2013，it was analyzed the issues such as architectural component systems division，industrialization of construction process，etc. Which provided a useful reference for zero energy consumption study and sustainable architectural design，as well as rapid industrialization production.
The construction industry is in an important period of transition to industrialization. Based on an entry projecti-Yardfrom Beijing Jiaotong University of SD China 2013，it was analyzed the issues such as architectural component systems division，industrialization of construction process，etc. Which provided a useful reference for zero energy consumption study and sustainable architectural design，as well as rapid industrialization production.
2015, 45(1): 66-69.
doi: 10.13204/j.gyjz201501012
Abstract:
Wuhan is one of the biggest industry cities in Yangtse River Basin. The relationship between the city and their waterfronts is a key issue to urban sustainable development. It was focused on the changes in Wuhans waterfronts in modern age. Through the analysis of urban form in different scales，it was also investigated the mechanism of interaction between the industrialization process and the transformation of urban waterfronts，which provided experience for developing the city in the future.
Wuhan is one of the biggest industry cities in Yangtse River Basin. The relationship between the city and their waterfronts is a key issue to urban sustainable development. It was focused on the changes in Wuhans waterfronts in modern age. Through the analysis of urban form in different scales，it was also investigated the mechanism of interaction between the industrialization process and the transformation of urban waterfronts，which provided experience for developing the city in the future.
2015, 45(1): 70-72.
doi: 10.13204/j.gyjz201501013
Abstract:
It was introduced the winning scheme of international design competition of Irish island power station Regeneration. The historic landmark building was retained with new function and shape to build multi-faceted new landscape and landmark on various experience. Therefore the new plant and the surrounding community can participate and enjoy the regeneration of industrial landscape.
It was introduced the winning scheme of international design competition of Irish island power station Regeneration. The historic landmark building was retained with new function and shape to build multi-faceted new landscape and landmark on various experience. Therefore the new plant and the surrounding community can participate and enjoy the regeneration of industrial landscape.
2015, 45(1): 73-79.
doi: 10.13204/j.gyjz201501014
Abstract:
An experiment on shear of reinforced concrete beams with high strength rebars was carried out. According to observing the deflection，diagonal crack width and strain of stirrups，the diagonal cracking rules were analyzed. The effects of concrete strength，shear span ratio，ratio of stirrup，section size and section shape on diagonal cracking loads were studied and the calculation method of the diagonal cracking loads was discussed. The results showed that concrete strength，shear span ratio and section size were the major factors for the diagonal cracking loads of reinforced concrete beams with high strength rebars. Meanwhile，the calculation formula of the diagonal cracking loads was suggested，which provided a basis for calculation of the diagonal cracking loads and promoting the use of HRBF500 high strength rebars in practical engineering.
An experiment on shear of reinforced concrete beams with high strength rebars was carried out. According to observing the deflection，diagonal crack width and strain of stirrups，the diagonal cracking rules were analyzed. The effects of concrete strength，shear span ratio，ratio of stirrup，section size and section shape on diagonal cracking loads were studied and the calculation method of the diagonal cracking loads was discussed. The results showed that concrete strength，shear span ratio and section size were the major factors for the diagonal cracking loads of reinforced concrete beams with high strength rebars. Meanwhile，the calculation formula of the diagonal cracking loads was suggested，which provided a basis for calculation of the diagonal cracking loads and promoting the use of HRBF500 high strength rebars in practical engineering.
2015, 45(1): 80-84.
doi: 10.13204/j.gyjz201501015
Abstract:
In order to study the mechanical behaviors of post-tensioned unbonded prestressed concrete hollow flat floors，a 1 /4 scale post-tensioned unbonded prestressed reinforced concrete hollow slab-column structure model was made and test under the uniformly distributed load on the plate was done. The test results showed that the floor had a certain load carrying capacity. The deflection of concrete hollow flat floor by vertical load was abowlshape. The point of maximan displacement was in the middle of concrete hollow flat floor. By means of finite element analysis methods，the calculation results showed that post-tensioned unbonded prestressed concrete hollow flat floor existed anisotropy with parallel circular-tubes. In parallel tube direction，the continuity of plate was destructed and the stiffness of the plate was decreased greatly. The plate deformation could still be regarded as continuous cross-plate in parallel tube directions and in vertical tube direction.
In order to study the mechanical behaviors of post-tensioned unbonded prestressed concrete hollow flat floors，a 1 /4 scale post-tensioned unbonded prestressed reinforced concrete hollow slab-column structure model was made and test under the uniformly distributed load on the plate was done. The test results showed that the floor had a certain load carrying capacity. The deflection of concrete hollow flat floor by vertical load was abowlshape. The point of maximan displacement was in the middle of concrete hollow flat floor. By means of finite element analysis methods，the calculation results showed that post-tensioned unbonded prestressed concrete hollow flat floor existed anisotropy with parallel circular-tubes. In parallel tube direction，the continuity of plate was destructed and the stiffness of the plate was decreased greatly. The plate deformation could still be regarded as continuous cross-plate in parallel tube directions and in vertical tube direction.
2015, 45(1): 85-90.
doi: 10.13204/j.gyjz201501016
Abstract:
Four reinforced masonry walls of different types of steel tie bars，whose outer wythes were tested subjected to an out-of-plane loading，were tested under horizontal low cyclic loading. The outer wythescooperation with the inner ones and mechanical behavior of the outer wythes were studied and analyzed. The results of the test showed that the outer wythes cooperated well with the inner ones; the steel tie bar made great contribution to the out-of-plane bearing capacity of the outer withes. Of all the four designed types of steel tie bars，Z-ties worked the worst，which can be used in multilayer buildings and are suggested not to be used in high-rise buildings. However，the other three types can be used in high-rise buildings and considering construction convenience，among them the rectangular ties are the best choice. Seismic behavior under large earthquake of intensity 7 and intensity 8 and the wind load-bearing capacity of the outer wythes of a 20 stories building in Changsha are sufficient.
Four reinforced masonry walls of different types of steel tie bars，whose outer wythes were tested subjected to an out-of-plane loading，were tested under horizontal low cyclic loading. The outer wythescooperation with the inner ones and mechanical behavior of the outer wythes were studied and analyzed. The results of the test showed that the outer wythes cooperated well with the inner ones; the steel tie bar made great contribution to the out-of-plane bearing capacity of the outer withes. Of all the four designed types of steel tie bars，Z-ties worked the worst，which can be used in multilayer buildings and are suggested not to be used in high-rise buildings. However，the other three types can be used in high-rise buildings and considering construction convenience，among them the rectangular ties are the best choice. Seismic behavior under large earthquake of intensity 7 and intensity 8 and the wind load-bearing capacity of the outer wythes of a 20 stories building in Changsha are sufficient.
2015, 45(1): 91-94.
doi: 10.13204/j.gyjz201501017
Abstract:
The experiment of embedded steel L-bar in reinforced concrete under tensile load was carried out. The first important factor was the section steel model of the reinforcing L-bar，next was the depth of the embedded steel L-bar， and the third was the strength of the concrete. Through observing the failure process of the specimens，the failure model，the bond mechanism and the distribution of shear stress were discussed. The maximum value of binding shear stress appeared when the steel L-bar entered into the state of yielding.
The experiment of embedded steel L-bar in reinforced concrete under tensile load was carried out. The first important factor was the section steel model of the reinforcing L-bar，next was the depth of the embedded steel L-bar， and the third was the strength of the concrete. Through observing the failure process of the specimens，the failure model，the bond mechanism and the distribution of shear stress were discussed. The maximum value of binding shear stress appeared when the steel L-bar entered into the state of yielding.
2015, 45(1): 95-99.
doi: 10.13204/j.gyjz201501018
Abstract:
To a dome-cylinder structure，the stress characteristics of flat base，vertical cylindrical wall and spherical dome were analyzed，and the simplified calculation formulae of the characteristics were given，there from the performance evaluation method of the structure was put forward. The core idea of the method was as follows: firstly deducing the concrete performance parameters were deduced from the data of construction stage，and the evaluation standard of test deformation was set up according to the predicted deformation in test，and finally the structure performance was evaluated through confirmatory test and internal-external visual inspections. Further more，the elastic modulus and poisson's ratio were modified for next evaluation. The evaluation method was also applied and discussed at the test of the containment of a nuclear power station. Which could provide theoretical support and reference for similar structure assessment.
To a dome-cylinder structure，the stress characteristics of flat base，vertical cylindrical wall and spherical dome were analyzed，and the simplified calculation formulae of the characteristics were given，there from the performance evaluation method of the structure was put forward. The core idea of the method was as follows: firstly deducing the concrete performance parameters were deduced from the data of construction stage，and the evaluation standard of test deformation was set up according to the predicted deformation in test，and finally the structure performance was evaluated through confirmatory test and internal-external visual inspections. Further more，the elastic modulus and poisson's ratio were modified for next evaluation. The evaluation method was also applied and discussed at the test of the containment of a nuclear power station. Which could provide theoretical support and reference for similar structure assessment.
2015, 45(1): 100-105.
doi: 10.13204/j.gyjz201501019
Abstract:
Based on finite element program ABAQUS，regarding RC multi-age components as research object，the unit C3D8R and unit T3D2 were used to simulate the mechanical behavior of concrete and reinforcement，and the superiority of exponential damping friction model for handling with the problem of contact between corrosion reinforcement and concrete was obviously exhibited，then the Hsich-Ting-Chen strength criterion was taken as concrete failure criterion. The loss of the cross sectional area of reinforcement bars，reduction of the cover and core concrete strength were modified by the single-factor time-dependent corrosion rate. Considering the cracking and spalling in the compressed concrete of compression zone caused by reinforcement corrosion，the modified compressionfield (MCF) was used to predict the time-dependent compressed concrete strength. Finally the modified material constitutive models of corroded reinforcement，concrete and bond-slip were provided. Considering the data of multiage RC component under low frequency cyclic loading，numerical model theory for corroded RC component mentioned above was proved to be reliable，and the achievements can provide a feasible and effective numerical model for the existing RC structures.
Based on finite element program ABAQUS，regarding RC multi-age components as research object，the unit C3D8R and unit T3D2 were used to simulate the mechanical behavior of concrete and reinforcement，and the superiority of exponential damping friction model for handling with the problem of contact between corrosion reinforcement and concrete was obviously exhibited，then the Hsich-Ting-Chen strength criterion was taken as concrete failure criterion. The loss of the cross sectional area of reinforcement bars，reduction of the cover and core concrete strength were modified by the single-factor time-dependent corrosion rate. Considering the cracking and spalling in the compressed concrete of compression zone caused by reinforcement corrosion，the modified compressionfield (MCF) was used to predict the time-dependent compressed concrete strength. Finally the modified material constitutive models of corroded reinforcement，concrete and bond-slip were provided. Considering the data of multiage RC component under low frequency cyclic loading，numerical model theory for corroded RC component mentioned above was proved to be reliable，and the achievements can provide a feasible and effective numerical model for the existing RC structures.
2015, 45(1): 106-108.
doi: 10.13204/j.gyjz201501020
Abstract:
The calculation for the main cable curve during the design and construction control of suspension bridge is very important. Contrary to the fault of precise calculation theory which is difficult to converge in iteration of finite element and spends a lot of calculation time，taking account of the particularity of small sag on main cable of medium span suspension bridge，the theoretical basis on the transformation between beam element and cable element under different gravity stiffness was proposed. The feasibility of using beam element to simulate cable for calculating the curve of suspension was theoretically ensured. The basic principle and method of geometric nonlinear calculation for beam element was introduced，and the reliability of this method in this paper was proved by calculating the cable curve of the second bridge on Huihe River in Guzhen County. The actual result of the calculation indicated the advantage of rapid computing speed，stable calculating steps and easily converging for the simplified calculating method of cable curve of medium span suspension bridge．
The calculation for the main cable curve during the design and construction control of suspension bridge is very important. Contrary to the fault of precise calculation theory which is difficult to converge in iteration of finite element and spends a lot of calculation time，taking account of the particularity of small sag on main cable of medium span suspension bridge，the theoretical basis on the transformation between beam element and cable element under different gravity stiffness was proposed. The feasibility of using beam element to simulate cable for calculating the curve of suspension was theoretically ensured. The basic principle and method of geometric nonlinear calculation for beam element was introduced，and the reliability of this method in this paper was proved by calculating the cable curve of the second bridge on Huihe River in Guzhen County. The actual result of the calculation indicated the advantage of rapid computing speed，stable calculating steps and easily converging for the simplified calculating method of cable curve of medium span suspension bridge．
2015, 45(1): 109-112.
doi: 10.13204/j.gyjz201501021
Abstract:
To consider reasonably the cyclic softening effect with strength degradation of soft clay，a nonlinear elasto-plastic model based on the concept of cyclic shear strength of clay was proposed. In the model，the concept of cyclic strength was combined with the Duncan-Chang nonlinear elastic relationship and Mises yield criterion under undrained condition. Then a series of finite element analysis were conducted to explore the stability and cyclic and static coupling effect of skirted foundations in soft ground. The results computed were verified through comparing with the available model test under monotonic loading. The results indicated that the peak cyclic load was reduced considerably with respect to ultimate bearing capacity. Parametric studies showed that the peak cyclic load without considering the nonlinear elastic relationship was higher than that reflecting the effect. When the static vertical load level was smaller，the instability of foundation was caused mainly by cyclic load，whereas the level was larger，the failure of foundations was due to static load.
To consider reasonably the cyclic softening effect with strength degradation of soft clay，a nonlinear elasto-plastic model based on the concept of cyclic shear strength of clay was proposed. In the model，the concept of cyclic strength was combined with the Duncan-Chang nonlinear elastic relationship and Mises yield criterion under undrained condition. Then a series of finite element analysis were conducted to explore the stability and cyclic and static coupling effect of skirted foundations in soft ground. The results computed were verified through comparing with the available model test under monotonic loading. The results indicated that the peak cyclic load was reduced considerably with respect to ultimate bearing capacity. Parametric studies showed that the peak cyclic load without considering the nonlinear elastic relationship was higher than that reflecting the effect. When the static vertical load level was smaller，the instability of foundation was caused mainly by cyclic load，whereas the level was larger，the failure of foundations was due to static load.
2015, 45(1): 113-117.
doi: 10.13204/j.gyjz201501022
Abstract:
This paper researched the qualitative and quantitative relationships among loaded swelling ratio of weathered sand improved expansive soil，weathered sand content and cycles of freeze-thaw tests by adding respectively 0， 10%， 20%， 30%， 40% and 50% of the weathered sand into the expansive soil. The loaded swelling ratio test under 25 kPa and 50 kPa was done with leveraged consolidation apparatus after 0，1，3，6，9，and 12 cycles of freezing and thawing. Test results showed that with the increasing of cycles of freeze-thaw，the loaded swelling ratio of weathered sand improved expansive soil decreased with different change magnitude under the same sand ratio. With the increasing of weathered sand proportion，the loaded swelling ratio first increased and then decreased under the same freeze-thaw cycles. When the content of sand was 10%，the loaded swelling ratio reached the maximum. The relationship between the loaded swelling ratio of weathered sand improved expansive soil and freeze-thaw cycles expressed a logarithmic function in the same sand ratio under the action of 25 kPa overlying load，and linear function under 50 kPa .
This paper researched the qualitative and quantitative relationships among loaded swelling ratio of weathered sand improved expansive soil，weathered sand content and cycles of freeze-thaw tests by adding respectively 0， 10%， 20%， 30%， 40% and 50% of the weathered sand into the expansive soil. The loaded swelling ratio test under 25 kPa and 50 kPa was done with leveraged consolidation apparatus after 0，1，3，6，9，and 12 cycles of freezing and thawing. Test results showed that with the increasing of cycles of freeze-thaw，the loaded swelling ratio of weathered sand improved expansive soil decreased with different change magnitude under the same sand ratio. With the increasing of weathered sand proportion，the loaded swelling ratio first increased and then decreased under the same freeze-thaw cycles. When the content of sand was 10%，the loaded swelling ratio reached the maximum. The relationship between the loaded swelling ratio of weathered sand improved expansive soil and freeze-thaw cycles expressed a logarithmic function in the same sand ratio under the action of 25 kPa overlying load，and linear function under 50 kPa .
2015, 45(1): 118-121.
doi: 10.13204/j.gyjz201501023
Abstract:
With the sustainable development of global economy，the pollution of heavy metal increases greatly in the foundation soil，thus bringing great harm to engineering construction. A series of tests were performed to study engineering properties of artificial zinc contaminated clay. The results showed that relative density of solid particles and plasticity index increased with the increase in zinc concentration，liquid limit and plastic limit decreased with the increase in zinc concentration. As zinc concentration increased，the compression coefficient of zinc polluted soil was increased whereas the compression modulus was decreased. Shear strength of contaminated soil decreased with the increase of zinc concentration. Stress-strain curves showed that it was a strain-hardening characteristics of zinc contaminated soil under unconsolidated undrained triaxial tests，the destruction of zinc contaminated soil showed a plastic damage characteristics.
With the sustainable development of global economy，the pollution of heavy metal increases greatly in the foundation soil，thus bringing great harm to engineering construction. A series of tests were performed to study engineering properties of artificial zinc contaminated clay. The results showed that relative density of solid particles and plasticity index increased with the increase in zinc concentration，liquid limit and plastic limit decreased with the increase in zinc concentration. As zinc concentration increased，the compression coefficient of zinc polluted soil was increased whereas the compression modulus was decreased. Shear strength of contaminated soil decreased with the increase of zinc concentration. Stress-strain curves showed that it was a strain-hardening characteristics of zinc contaminated soil under unconsolidated undrained triaxial tests，the destruction of zinc contaminated soil showed a plastic damage characteristics.
2015, 45(1): 122-125.
doi: 10.13204/j.gyjz201501024
Abstract:
The inversion analysis is an important way to obtain the geotechnical strength parameters，especially，for weak intercalated layer slope，weighted displacement back analysis is an effective method to get its soil parameters. Based on the inclination data and basic idea of block division，a new calculated approach for displacement weight was proposed. By displacement curve and least square method，the slope soil was divided into several blocks with different displacement characteristics. The displacement for single block could be expressed by two variables: sliding and deformation displacement. The deformation displacement，which reflects itself soil strength，was regarded as the weight of weighted back analysis. And the new inversion objective function was presented. Finally，depending on entity project，this presented method was used to calculated soil strength which matched well with the test values. Meanwhile，the sensitivity result also indicated the effectiveness of the method.
The inversion analysis is an important way to obtain the geotechnical strength parameters，especially，for weak intercalated layer slope，weighted displacement back analysis is an effective method to get its soil parameters. Based on the inclination data and basic idea of block division，a new calculated approach for displacement weight was proposed. By displacement curve and least square method，the slope soil was divided into several blocks with different displacement characteristics. The displacement for single block could be expressed by two variables: sliding and deformation displacement. The deformation displacement，which reflects itself soil strength，was regarded as the weight of weighted back analysis. And the new inversion objective function was presented. Finally，depending on entity project，this presented method was used to calculated soil strength which matched well with the test values. Meanwhile，the sensitivity result also indicated the effectiveness of the method.
2015, 45(1): 126-129.
doi: 10.13204/j.gyjz201501025
Abstract:
Based on the tensile test of 63 steel specimens at different temperatures from 20 ℃ to －165 ℃，mechanical properties and changing trend of three types steel bars ( HRB335，HRB400 and cryogenic reinforcements) were analyzed. The results showed that the yield strength fy，the ultimate strength fu of the steel bars increased whereas the percentage elongation after fracture 5，percentage reduction of area decreased with the temperature decreasing，which means the reducing plasticity of steel bars. The influence of temperature on elastic modulus was little and the elastic modulus fluctuated around a certain value. The shape of the stress-strain curve changed little at different temperatures，however，the cooling environment led to the reducing plasticity and improving brittleness， reflected in the dropping ultimate strain.
Based on the tensile test of 63 steel specimens at different temperatures from 20 ℃ to －165 ℃，mechanical properties and changing trend of three types steel bars ( HRB335，HRB400 and cryogenic reinforcements) were analyzed. The results showed that the yield strength fy，the ultimate strength fu of the steel bars increased whereas the percentage elongation after fracture 5，percentage reduction of area decreased with the temperature decreasing，which means the reducing plasticity of steel bars. The influence of temperature on elastic modulus was little and the elastic modulus fluctuated around a certain value. The shape of the stress-strain curve changed little at different temperatures，however，the cooling environment led to the reducing plasticity and improving brittleness， reflected in the dropping ultimate strain.
2015, 45(1): 130-135.
doi: 10.13204/j.gyjz201501026
Abstract:
In order to research mechanical properties and failure mechanism of recycled concrete with different recycled coarse aggregate replacement rate. Using waste concrete as recycled coarse aggregate，33 standard cubes，33standard prisms and 33 prisms ( 150 mm 150 mm 550 mm) were made as recycled concrete specimens，whose replacement rate changed from 0% to 100%，level difference was 10%. Through the test，the relationships among replacement rate and the mechanical properties indexes of cube compressive strength，axial compressive strength，flexural strength，strain ductility coefficient，energy dissipative coefficient，secant stiffness and damage degree of the recycled concrete were obtained. The research results showed that with increasing replacement rate，cube compressive strength and axial compressive strength of recycled concrete presented increasing trend. Flexural strength presented decreasing first and then increasing trend. Elastic modulus also presented decreasing trend. Ductility，energy dissipation and stiffness presented decreasing trend; secant stiffness and damage degree of the recycled concrete had the same trend as natural concrete. Considering comprehensively the basic mechanics and economic performance index，it was suggested that 30% ～ 40% should be taken the optimal replacement rate.
In order to research mechanical properties and failure mechanism of recycled concrete with different recycled coarse aggregate replacement rate. Using waste concrete as recycled coarse aggregate，33 standard cubes，33standard prisms and 33 prisms ( 150 mm 150 mm 550 mm) were made as recycled concrete specimens，whose replacement rate changed from 0% to 100%，level difference was 10%. Through the test，the relationships among replacement rate and the mechanical properties indexes of cube compressive strength，axial compressive strength，flexural strength，strain ductility coefficient，energy dissipative coefficient，secant stiffness and damage degree of the recycled concrete were obtained. The research results showed that with increasing replacement rate，cube compressive strength and axial compressive strength of recycled concrete presented increasing trend. Flexural strength presented decreasing first and then increasing trend. Elastic modulus also presented decreasing trend. Ductility，energy dissipation and stiffness presented decreasing trend; secant stiffness and damage degree of the recycled concrete had the same trend as natural concrete. Considering comprehensively the basic mechanics and economic performance index，it was suggested that 30% ～ 40% should be taken the optimal replacement rate.
2015, 45(1): 136-138.
doi: 10.13204/j.gyjz201501027
Abstract:
Fatigue properties of two kinds of adhesive binders for FRP strengthened steel structure cured at different temperature，20，30，50 ，60，70 ℃ were studied under three load amplitudes; By studying the fatigue properties of the two adhesive bonders under different temperature and load amplitudes，the influences of curing temperature as well as load amplitude on the binder fatigue life were analyzed. As a result，an appropriate range of curing temperature of 30 ～ 50 ℃ was brought out，which provided a guide to engineering practice.
Fatigue properties of two kinds of adhesive binders for FRP strengthened steel structure cured at different temperature，20，30，50 ，60，70 ℃ were studied under three load amplitudes; By studying the fatigue properties of the two adhesive bonders under different temperature and load amplitudes，the influences of curing temperature as well as load amplitude on the binder fatigue life were analyzed. As a result，an appropriate range of curing temperature of 30 ～ 50 ℃ was brought out，which provided a guide to engineering practice.
2015, 45(1): 139-142.
doi: 10.13204/j.gyjz201501028
Abstract:
Many problems of latent danger and environmental impact of infrastructure are due to leakage.The latest research of microbially-induced clogging shows that，suitable survival conditions for microorganisms lead to an effective microbial clogging in a relative short time，to reach the aim of decreasing hydraulic conductivity in soils. In this study，tests of microbial-induced clogging were performed in 2 sand columns，where potato soup and glucose were added，and water was added to another column only for a control. The hydraulic conductivity of the sand column supplied with potato soup decreased to 1 /50 of its initial discharge in 3 weeks，and clogging occurred near the leak. The hydraulic conductivity of the sand column supplied with glucose did not change a lot. Then，potato soup was added to the sand column initially served with glucose，and clogging happened near its leak. Clogging stability was tested by increasing water head. The water gradient in the test system was increased from 0. 267 to 1. 067，and the clogging reached a failure gradually. Tests showed microbial-induced clogging in sands was a combination of leakage detection and leakage sealing，which was stable in the case of increasing the water head of the inlet.
Many problems of latent danger and environmental impact of infrastructure are due to leakage.The latest research of microbially-induced clogging shows that，suitable survival conditions for microorganisms lead to an effective microbial clogging in a relative short time，to reach the aim of decreasing hydraulic conductivity in soils. In this study，tests of microbial-induced clogging were performed in 2 sand columns，where potato soup and glucose were added，and water was added to another column only for a control. The hydraulic conductivity of the sand column supplied with potato soup decreased to 1 /50 of its initial discharge in 3 weeks，and clogging occurred near the leak. The hydraulic conductivity of the sand column supplied with glucose did not change a lot. Then，potato soup was added to the sand column initially served with glucose，and clogging happened near its leak. Clogging stability was tested by increasing water head. The water gradient in the test system was increased from 0. 267 to 1. 067，and the clogging reached a failure gradually. Tests showed microbial-induced clogging in sands was a combination of leakage detection and leakage sealing，which was stable in the case of increasing the water head of the inlet.
2015, 45(1): 143-147.
doi: 10.13204/j.gyjz201501029
Abstract:
The steel-tube truss supporting system made of rotating-fastening members was studied，a FE model of the remaining structural model was established by ANSYS software to do experimental research and analyze local cable failure or member failure of the support platform during silo construction，which would occur. Two of the most unfavorable conditions of construction were considered，one was the bearing capacity of the structure when local cable failed，the other was local stressed member failure. The results showed that when failure occurred in the first lap suspension strand with maximum tension，the rest of the strand through the stress redistribution，truss vertical displacement increased slightly，strand stress increased，which could still provide truss to undertake construction load. There would be less impact after the members with largest stresses of the bottom chord，as well as the upper chord and the diagonals of the truss failed，which could not influence the ability of the structure to bear construction loads，hence the support system has a higher security.
The steel-tube truss supporting system made of rotating-fastening members was studied，a FE model of the remaining structural model was established by ANSYS software to do experimental research and analyze local cable failure or member failure of the support platform during silo construction，which would occur. Two of the most unfavorable conditions of construction were considered，one was the bearing capacity of the structure when local cable failed，the other was local stressed member failure. The results showed that when failure occurred in the first lap suspension strand with maximum tension，the rest of the strand through the stress redistribution，truss vertical displacement increased slightly，strand stress increased，which could still provide truss to undertake construction load. There would be less impact after the members with largest stresses of the bottom chord，as well as the upper chord and the diagonals of the truss failed，which could not influence the ability of the structure to bear construction loads，hence the support system has a higher security.
2015, 45(1): 148-151.
doi: 10.13204/j.gyjz201501030
Abstract:
It was focused on a construction technology of super high-rise steel buildings that could make second column be under the truss layer. With a specially designed temporary support system，reasonable arrangements for the construction sequence and a series of measures to control loading procedure and do deformation monitoring，this technology ensured that the upper truss could be freely deformed before the loading was completed，and the entire structure could transfer the force with the envisaged collaborative approach. Horizontal load and vertical load in the mega frame structure are carried primarily by the column and truss of the mega frame structure. Second column only carries vertical loads of the layer or few vertical load transfered by the upper layer.
It was focused on a construction technology of super high-rise steel buildings that could make second column be under the truss layer. With a specially designed temporary support system，reasonable arrangements for the construction sequence and a series of measures to control loading procedure and do deformation monitoring，this technology ensured that the upper truss could be freely deformed before the loading was completed，and the entire structure could transfer the force with the envisaged collaborative approach. Horizontal load and vertical load in the mega frame structure are carried primarily by the column and truss of the mega frame structure. Second column only carries vertical loads of the layer or few vertical load transfered by the upper layer.
2015, 45(1): 152-155.
doi: 10.13204/j.gyjz201501031
Abstract:
Composite ground technology was widely used in many engineering fields，such as water conservancy，highway，high-speed railway and other industrial and civil engineering. So far，research on consolidation theory of composite ground was made great progress. The recent advancements in theoretical solutions for consolidation of composite ground were summarized，and problems in present solutions were pointed out in the paper. Valuable proposals for further research on the project were offered .
Composite ground technology was widely used in many engineering fields，such as water conservancy，highway，high-speed railway and other industrial and civil engineering. So far，research on consolidation theory of composite ground was made great progress. The recent advancements in theoretical solutions for consolidation of composite ground were summarized，and problems in present solutions were pointed out in the paper. Valuable proposals for further research on the project were offered .
2015, 45(1): 156-160.
doi: 10.13204/j.gyjz201501032
Abstract:
ABAQUS 6. 10 was used to do a nonlinear numerical analysis of the four concrete filled square steel tube (CFT) frames-thin steel plate shear walls with side openings. Mechanical behavior，failure pattern and effect of side stiffening components on the stiffness，loading capacity，ductility and hysteretic behavior were researched. And the theoretical formula of cross-section selection of side stiffening components was proposed. Results obtained from this study were as follows. The concrete filled square steel tube (CFT) frames-thin steel plate shear walls with side openings had good mechanical behavior and hysteretic behavior. When the side stiffening components had hinged connections with steel girders，the side stiffening components could significantly increase the bearing capacity，stiffness，ductility and energy dissipation. The results of finite element analysis and design formula calculation were in good agreement，which provided a reference for engineering application.
ABAQUS 6. 10 was used to do a nonlinear numerical analysis of the four concrete filled square steel tube (CFT) frames-thin steel plate shear walls with side openings. Mechanical behavior，failure pattern and effect of side stiffening components on the stiffness，loading capacity，ductility and hysteretic behavior were researched. And the theoretical formula of cross-section selection of side stiffening components was proposed. Results obtained from this study were as follows. The concrete filled square steel tube (CFT) frames-thin steel plate shear walls with side openings had good mechanical behavior and hysteretic behavior. When the side stiffening components had hinged connections with steel girders，the side stiffening components could significantly increase the bearing capacity，stiffness，ductility and energy dissipation. The results of finite element analysis and design formula calculation were in good agreement，which provided a reference for engineering application.
2015, 45(1): 161-165.
doi: 10.13204/j.gyjz201501033
Abstract:
A repeatedly loaded experiment of beam-pillar supported joint widely used in steel structure workshop was introduced. Three specimens of different working places were studied. The strength and hysteresis behavior were obtained and the stress analysis of slanting brace and joint board was carried out. The result showed that this kind of joint had good aseismic ability. The joint has different load carrying capacity in different working places.
A repeatedly loaded experiment of beam-pillar supported joint widely used in steel structure workshop was introduced. Three specimens of different working places were studied. The strength and hysteresis behavior were obtained and the stress analysis of slanting brace and joint board was carried out. The result showed that this kind of joint had good aseismic ability. The joint has different load carrying capacity in different working places.
2015, 45(1): 166-172.
doi: 10.13204/j.gyjz201501034
Abstract:
Based on structural engineering optimization theory of composite structure，the minimum project cost and the maximum diagonal shear capacity were taken as the optimization objectives. According to the mechanical characteristics of the steel reinforced concrete，the concrete sectional sizes of the SRC member were optimized with application of optimality criteria K-T conditions under minor earthquakes，and the optimization of steel volume was implemented under moderate earthquake with application of hierarchy process genetic algorithm，thus，the analytic hierarchy process optimization criterion genetic algorithm ( OC-GA) was established. Considering the related design specifications and constraints，the SRC frame column was optimized by analytic hierarchy process OC-GA，and the optimization method and thought were proved by engineering example.
Based on structural engineering optimization theory of composite structure，the minimum project cost and the maximum diagonal shear capacity were taken as the optimization objectives. According to the mechanical characteristics of the steel reinforced concrete，the concrete sectional sizes of the SRC member were optimized with application of optimality criteria K-T conditions under minor earthquakes，and the optimization of steel volume was implemented under moderate earthquake with application of hierarchy process genetic algorithm，thus，the analytic hierarchy process optimization criterion genetic algorithm ( OC-GA) was established. Considering the related design specifications and constraints，the SRC frame column was optimized by analytic hierarchy process OC-GA，and the optimization method and thought were proved by engineering example.
2015, 45(1): 173-178.
doi: 10.13204/j.gyjz201501035
Abstract:
In order to study the actual stress mechanical properties of RC beam strengthened with TRC sheets，one RC beam and five reinforcing beams whose parameters were the initial stress were chosen as the research objects．Magnesium potassium phosphate materials with high temperature resistance and good interfacial bonding propertiesinorganic cementitious (MPC) were used to study the flexural strength of normal section of RC beam strengthened with TRC sheets based on MPC interface agent and to analyse the impact on the failure characteristics，development of cracks and the mechanical properties of the strengthened beams． The results showed that the precast TRC sheets and RC beams have a better interface bonding performance; strain hysteresis of TRC sheets beam became obvious with beam's initial stress increased，and the ultimate load and stiffness of RC beam decreased; prefabricated TRC thin sheets could improve the form of crack which presented fine and dense cracks on the RC beams． For the smaller injury RC beams，the reinforcement effect was better; for the RC beams nearing the yield of steels，the increase intheir capacity was also limited even reinforced RC beam was unloaded．
In order to study the actual stress mechanical properties of RC beam strengthened with TRC sheets，one RC beam and five reinforcing beams whose parameters were the initial stress were chosen as the research objects．Magnesium potassium phosphate materials with high temperature resistance and good interfacial bonding propertiesinorganic cementitious (MPC) were used to study the flexural strength of normal section of RC beam strengthened with TRC sheets based on MPC interface agent and to analyse the impact on the failure characteristics，development of cracks and the mechanical properties of the strengthened beams． The results showed that the precast TRC sheets and RC beams have a better interface bonding performance; strain hysteresis of TRC sheets beam became obvious with beam's initial stress increased，and the ultimate load and stiffness of RC beam decreased; prefabricated TRC thin sheets could improve the form of crack which presented fine and dense cracks on the RC beams． For the smaller injury RC beams，the reinforcement effect was better; for the RC beams nearing the yield of steels，the increase intheir capacity was also limited even reinforced RC beam was unloaded．
2015, 45(1): 179-183.
doi: 10.13204/j.gyjz201501036
Abstract:
Based on an overview and analysis of industrial structures，taking on old water tower as the research object，starting from the potential of waste water tower: value analysis，it was summarized three kinds of renewal ways of the old water tower; according to the different value，combined with the examples，it was put forward the reconstruction mode with pertinence and diversity，it was done an exploratory research on reform of industrial structures with special spaces by taking old water tower as representative．
Based on an overview and analysis of industrial structures，taking on old water tower as the research object，starting from the potential of waste water tower: value analysis，it was summarized three kinds of renewal ways of the old water tower; according to the different value，combined with the examples，it was put forward the reconstruction mode with pertinence and diversity，it was done an exploratory research on reform of industrial structures with special spaces by taking old water tower as representative．
2015, 45(1): 184-188.
doi: 10.13204/j.gyjz201501037
Abstract:
As an effective measure for improvement of building energy efficiency，green roof has obvious biobenefit and landscape value，which is attracting more and more attention both in China and internationally. Through a systematic research on the effects of green roof in improving building energy saving， environment and rain accumulation，it was studied the design methods of green roof and its major influencing factors，including vegetation materials，allocation modes and cultivation substratum; and it was also reviews the progress of governmental policy and practice of green roofs in China and other countries.
As an effective measure for improvement of building energy efficiency，green roof has obvious biobenefit and landscape value，which is attracting more and more attention both in China and internationally. Through a systematic research on the effects of green roof in improving building energy saving， environment and rain accumulation，it was studied the design methods of green roof and its major influencing factors，including vegetation materials，allocation modes and cultivation substratum; and it was also reviews the progress of governmental policy and practice of green roofs in China and other countries.
