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2015 Vol. 45, No. 4
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2015, 45(4): 1-6.
doi: 10.13204/j.gyjz201504001
Abstract:
Modern bamboo structure is a new kind of structural system，receiving more and more attentions in today's move towards sustainable construction． Comparing with conventional systems，such as steel and concrete structures， the modern bamboo structural system is based on the natural bamboo as raw materials． Similar to but even better than timber materials，bamboo is a carbon negative material． Modern bamboo structure is essentially a bamboo fiber-based composite material，adopting similar forms as modern wooden structures which are widely used in industrialized countries． A systematic research work was done by domestic and overseas researchers in modern bamboo structures， through which the modern bamboo structure system was gradually shaping． This paper analyzed the development of the system，and summarized the research progress，and finally，some application demonstrations of modern bamboo structures in prefabricated movable house，light bamboo house and large-space frame system etc were described． Clearly，it is shown that modern bamboo structure system will have bright prospects in near future and at least is an alternative choice for consideration of sustainability．
Modern bamboo structure is a new kind of structural system，receiving more and more attentions in today's move towards sustainable construction． Comparing with conventional systems，such as steel and concrete structures， the modern bamboo structural system is based on the natural bamboo as raw materials． Similar to but even better than timber materials，bamboo is a carbon negative material． Modern bamboo structure is essentially a bamboo fiber-based composite material，adopting similar forms as modern wooden structures which are widely used in industrialized countries． A systematic research work was done by domestic and overseas researchers in modern bamboo structures， through which the modern bamboo structure system was gradually shaping． This paper analyzed the development of the system，and summarized the research progress，and finally，some application demonstrations of modern bamboo structures in prefabricated movable house，light bamboo house and large-space frame system etc were described． Clearly，it is shown that modern bamboo structure system will have bright prospects in near future and at least is an alternative choice for consideration of sustainability．
2015, 45(4): 7-12.
doi: 10.13204/j.gyjz201504002
Abstract:
Based on current specifications timber materials，such as Wood Physical and Mechanical Properties Test Methods and Standard Test Methods for Small Clear Specimens of Timber ( ASTM D 143 －94) ，it was conducted shear tests of glue laminated bamboo ( GluBam) ，with different loading configurations related to the main fiber orientation． It was obtained the average value of in-plane and out-of-plane shear strengths and found out by statistical analysis of the shear test data that: Weibull distribution could be used to describe the distribution of the out-of-plane shear strength，normal distribution could better meet in-plane shear strength． The results showed that fiber arrangement and loading have great influence on shear strength． By comparing with several other common building materials，GluBam could meet the shear strength requirements of structure．
Based on current specifications timber materials，such as Wood Physical and Mechanical Properties Test Methods and Standard Test Methods for Small Clear Specimens of Timber ( ASTM D 143 －94) ，it was conducted shear tests of glue laminated bamboo ( GluBam) ，with different loading configurations related to the main fiber orientation． It was obtained the average value of in-plane and out-of-plane shear strengths and found out by statistical analysis of the shear test data that: Weibull distribution could be used to describe the distribution of the out-of-plane shear strength，normal distribution could better meet in-plane shear strength． The results showed that fiber arrangement and loading have great influence on shear strength． By comparing with several other common building materials，GluBam could meet the shear strength requirements of structure．
2015, 45(4): 13-17.
doi: 10.13204/j.gyjz201504003
Abstract:
It was presented the axial compression tests of GluBam columns with different slenderness ratio，and made a comparison between the test results and calculation results by the Chinese Code for Design of Timber Structures and American National Design Specification for Wood Construction．Recommendations for the design of GluBam columns were also provided．
It was presented the axial compression tests of GluBam columns with different slenderness ratio，and made a comparison between the test results and calculation results by the Chinese Code for Design of Timber Structures and American National Design Specification for Wood Construction．Recommendations for the design of GluBam columns were also provided．
2015, 45(4): 18-25.
doi: 10.13204/j.gyjz201504004
Abstract:
Selecting composite connection is a crucial factor for researching mechanical performance of GluBamconcrete composite beam． An initial stage of research on the feasibility of a type of notched connection for GluBamconcrete composite beam was described． Total 15 groups of bond and anchorage pull-out tests and 3 groups of shearslip tests were conducted respectively． The main mechanical properties such as anchoring capacity，load-slip curves and anti-slip stiffness were measured． The test results showed that liquid adhesive could penetrate GluBam easier and reach higher anchoring strength compared to paste adhesive． There was an optimum diameter for glued-in rebar according to the standardized anchorage strength，which almost did not fluctuate with anchorage depth． Setting inclination on the bearing surface of notched connector could not improve mechanical properties of this type of composite beams． But nailed to sides of GluBam beam prevented cracking of GluBam beam effectively and increased shear capacity significantly． Compared with GluLam-concrete composite beam with the similar notched connector，this type of new connector presents good mechanical performance while improved ductility． However only qualitative conclusions can be drawn at this stage，which needs to be investigated further．
Selecting composite connection is a crucial factor for researching mechanical performance of GluBamconcrete composite beam． An initial stage of research on the feasibility of a type of notched connection for GluBamconcrete composite beam was described． Total 15 groups of bond and anchorage pull-out tests and 3 groups of shearslip tests were conducted respectively． The main mechanical properties such as anchoring capacity，load-slip curves and anti-slip stiffness were measured． The test results showed that liquid adhesive could penetrate GluBam easier and reach higher anchoring strength compared to paste adhesive． There was an optimum diameter for glued-in rebar according to the standardized anchorage strength，which almost did not fluctuate with anchorage depth． Setting inclination on the bearing surface of notched connector could not improve mechanical properties of this type of composite beams． But nailed to sides of GluBam beam prevented cracking of GluBam beam effectively and increased shear capacity significantly． Compared with GluLam-concrete composite beam with the similar notched connector，this type of new connector presents good mechanical performance while improved ductility． However only qualitative conclusions can be drawn at this stage，which needs to be investigated further．
2015, 45(4): 26-32.
doi: 10.13204/j.gyjz201504005
Abstract:
GluBam is a new kind of environmentally friendly and energy efficient composite material in civil engineering developed in recent years． But the mechanical performance after subjected aging under the outdoor conditions is a blank of research． In this paper，a new artificial accelerated aging test method and equipment for GluBam were presented ． The basic material performance，including deformation changing，tensile properties， compressive properties，bending properties and internal bonding strength were tested according to the different equivalent aging duration． The failure mode of specimens showed that delamination of GluBam caused by dry-wet cycle was the main reason for mechanical properties degradation． All test results present monotone decreasing trend and the internal bonding strength was the most sensitive to aging duration． Aging influence factor ，internal bonding strength correlation coefficient and thickness deformation correlation coefficient can be used to evaluate aging performance of GluBam，but the accuracy of evaluation results need further research． GluBam exposed to the dry wet cycle condition needs necessary waterproof measures ，which should be specially investigated further．
GluBam is a new kind of environmentally friendly and energy efficient composite material in civil engineering developed in recent years． But the mechanical performance after subjected aging under the outdoor conditions is a blank of research． In this paper，a new artificial accelerated aging test method and equipment for GluBam were presented ． The basic material performance，including deformation changing，tensile properties， compressive properties，bending properties and internal bonding strength were tested according to the different equivalent aging duration． The failure mode of specimens showed that delamination of GluBam caused by dry-wet cycle was the main reason for mechanical properties degradation． All test results present monotone decreasing trend and the internal bonding strength was the most sensitive to aging duration． Aging influence factor ，internal bonding strength correlation coefficient and thickness deformation correlation coefficient can be used to evaluate aging performance of GluBam，but the accuracy of evaluation results need further research． GluBam exposed to the dry wet cycle condition needs necessary waterproof measures ，which should be specially investigated further．
2015, 45(4): 33-41.
doi: 10.13204/j.gyjz201504006
Abstract:
Because of the special shape and structure，bamboo pole is not fit to the requirements of construction industry and therefore its research and use are rare in the field of building structures． Moso bamboo，a kind of rich forest resource in China，was selected as building material and tested． The test results showed that the main mechanical properties of bamboo pole were better than those of coniferous wood of TC13 grade and could be used as structural material． Several types of metal connections were presented for connecting bamboo poles with other materials and it was realized basically the manufacture standardization and prefabrication of bamboo members． The lateral resistance tests of two pieces of shear walls made by bamboo poles were conducted． The lateral resistance capacity of this kind of shear wall was about 65% of that of the same wall of light wood structure． The static tests of three pieces of bamboo pole roof trusses were done and the average ultimate loading capacity was 12. 3 kN． A prefabricated bamboo pole demonstration house with construction area of 50 m2 was designed and constructed according to the testing results and code for design of timber structures．
Because of the special shape and structure，bamboo pole is not fit to the requirements of construction industry and therefore its research and use are rare in the field of building structures． Moso bamboo，a kind of rich forest resource in China，was selected as building material and tested． The test results showed that the main mechanical properties of bamboo pole were better than those of coniferous wood of TC13 grade and could be used as structural material． Several types of metal connections were presented for connecting bamboo poles with other materials and it was realized basically the manufacture standardization and prefabrication of bamboo members． The lateral resistance tests of two pieces of shear walls made by bamboo poles were conducted． The lateral resistance capacity of this kind of shear wall was about 65% of that of the same wall of light wood structure． The static tests of three pieces of bamboo pole roof trusses were done and the average ultimate loading capacity was 12. 3 kN． A prefabricated bamboo pole demonstration house with construction area of 50 m2 was designed and constructed according to the testing results and code for design of timber structures．
2015, 45(4): 42-47.
doi: 10.13204/j.gyjz201504007
Abstract:
Fire-resistant performance of GluBam wall is one of most important factors for the modern bamboo structural buildings． However，the research in this field is still in the blank． In this paper，a fire-resistant test of the full-scale GluBam wall was conducted under ISO standard temperature curve． The temperature characteristics，fireresistant influence factors and failure mode were gained after the test． Temperature curves of each measuring point， temperature distribution and fire-resistant limit were also recorded． Using fire dynamics simulation software FDS to simulate the gluing bamboo wall structure under ISO 834 standard fire conditions． The research results showed that the unexposed surface highest temperature did not exceed 90 ℃ and the temperature distribution was closely related to the measuring point location． The failure mode was E class． The duration of fire resistance was more than 60 min， which could well meet the requirements of code． The fire dynamics simulator，FDS，could be well used to simulate the temperature of GluBam structural wall under the test conditions． The temperature rising trend and distribution were basically consistent between the simulated results and measured ones． The factors which influence fire-resistant performance of GluBam wall need to be researched further．
Fire-resistant performance of GluBam wall is one of most important factors for the modern bamboo structural buildings． However，the research in this field is still in the blank． In this paper，a fire-resistant test of the full-scale GluBam wall was conducted under ISO standard temperature curve． The temperature characteristics，fireresistant influence factors and failure mode were gained after the test． Temperature curves of each measuring point， temperature distribution and fire-resistant limit were also recorded． Using fire dynamics simulation software FDS to simulate the gluing bamboo wall structure under ISO 834 standard fire conditions． The research results showed that the unexposed surface highest temperature did not exceed 90 ℃ and the temperature distribution was closely related to the measuring point location． The failure mode was E class． The duration of fire resistance was more than 60 min， which could well meet the requirements of code． The fire dynamics simulator，FDS，could be well used to simulate the temperature of GluBam structural wall under the test conditions． The temperature rising trend and distribution were basically consistent between the simulated results and measured ones． The factors which influence fire-resistant performance of GluBam wall need to be researched further．
2015, 45(4): 48-51.
doi: 10.13204/j.gyjz201504008
Abstract:
This paper introduced the general situation of thethird frontconstruction in Guizhou Province first，and then analyzed the heritages status of thethird frontindustrial buildings in Guizhou Province． A thorough thinking about the value evaluation and the dilemma of protection ofthird frontindustrial building heritages; and finally，it was put forward the method of heritages protection and reuse of thethird frontindustrial buildings in Guizhou Province．
This paper introduced the general situation of thethird frontconstruction in Guizhou Province first，and then analyzed the heritages status of thethird frontindustrial buildings in Guizhou Province． A thorough thinking about the value evaluation and the dilemma of protection ofthird frontindustrial building heritages; and finally，it was put forward the method of heritages protection and reuse of thethird frontindustrial buildings in Guizhou Province．
2015, 45(4): 52-55.
doi: 10.13204/j.gyjz201504009
Abstract:
The industrial heritage has a unique cultural meaning，which is an important part of the industrial city，it's reuse is as important as conservation． Based on the industrial heritage conservation，the characteristic industrial landscape and the cultured landscape of the Cultural Revolution remained in the Xinhe Mine were examined． Combining its inherent resources with urban development chance，taking the ecologic restoration as a forerunner， cultural reproduction as a soul，adaptive transformation as a pillar，a new transition mode that would promote the reconstruction and development of the Mine area and urban block was proposed．
The industrial heritage has a unique cultural meaning，which is an important part of the industrial city，it's reuse is as important as conservation． Based on the industrial heritage conservation，the characteristic industrial landscape and the cultured landscape of the Cultural Revolution remained in the Xinhe Mine were examined． Combining its inherent resources with urban development chance，taking the ecologic restoration as a forerunner， cultural reproduction as a soul，adaptive transformation as a pillar，a new transition mode that would promote the reconstruction and development of the Mine area and urban block was proposed．
2015, 45(4): 56-61.
doi: 10.13204/j.gyjz201504010
Abstract:
As an important traffic hub，the middle and upper reaches of Yuan River are the main path linking the eastern and southwestern regions of China in economic technology and supply transfer． Which objectively resulted in the fusion and integration of various cultures and profoundly reflected in all kinds of construction activities in this area，so as to form the particularity of the architectural culture． By summarizing the plane of the type and construction characteristics of a typical buildingYingziwuand analyzing the reasons of its formation，it was pointed out that theYingziwuis the typical regional architecture which was jointly formed by local society，economy，history and natural environment．
As an important traffic hub，the middle and upper reaches of Yuan River are the main path linking the eastern and southwestern regions of China in economic technology and supply transfer． Which objectively resulted in the fusion and integration of various cultures and profoundly reflected in all kinds of construction activities in this area，so as to form the particularity of the architectural culture． By summarizing the plane of the type and construction characteristics of a typical buildingYingziwuand analyzing the reasons of its formation，it was pointed out that theYingziwuis the typical regional architecture which was jointly formed by local society，economy，history and natural environment．
2015, 45(4): 62-66.
doi: 10.13204/j.gyjz201504011
Abstract:
Under the action of earthquake，the vibration of a high-rise industrial gas building is relatively severe． So the study of vibration control under different earthquake action has become more and more important． In this paper，a finite element model of the structure was established，and the modal analysis results showed that torisonal vibration frequency was low and occurred easily． So the torsionsal and bending vibrations of the structure need to be controlled． Therefore，vibration control under interlayer drift，displacement and angle accelerations of top layer was analyzed; and steel support，fluid viscous damper，multiple tuned mass dampers ( MTMD) ，the mixed element of fluid viscous damper and MTMD were installed respectively on the structure，to which seismic loads were applied，which could study the effectiveness of the control effect of the four kinds of measures． The results showed that in most of cases the control effect of the mixed element was better then others．
Under the action of earthquake，the vibration of a high-rise industrial gas building is relatively severe． So the study of vibration control under different earthquake action has become more and more important． In this paper，a finite element model of the structure was established，and the modal analysis results showed that torisonal vibration frequency was low and occurred easily． So the torsionsal and bending vibrations of the structure need to be controlled． Therefore，vibration control under interlayer drift，displacement and angle accelerations of top layer was analyzed; and steel support，fluid viscous damper，multiple tuned mass dampers ( MTMD) ，the mixed element of fluid viscous damper and MTMD were installed respectively on the structure，to which seismic loads were applied，which could study the effectiveness of the control effect of the four kinds of measures． The results showed that in most of cases the control effect of the mixed element was better then others．
2015, 45(4): 67-71.
doi: 10.13204/j.gyjz201504012
Abstract:
Infill walls are considered as non-structural elements，but they are still involved in seismic calculation． This paper considered the interaction between the main structures and fill walls，used OpenSEES to establish simplified model． Infill wall adopted improved equivalent slant strut based on FEMA model． Considering maximum drift as seismic demand parameter，incremental dynamic analysis was performed to obtain infilled RC frame's threshold values on target performance levels． Comparing the calculated results with pure framework and codes，it was indicated that the presence of infill walls could significantly improve lateral stiffness of frame structure and its seismic performance．
Infill walls are considered as non-structural elements，but they are still involved in seismic calculation． This paper considered the interaction between the main structures and fill walls，used OpenSEES to establish simplified model． Infill wall adopted improved equivalent slant strut based on FEMA model． Considering maximum drift as seismic demand parameter，incremental dynamic analysis was performed to obtain infilled RC frame's threshold values on target performance levels． Comparing the calculated results with pure framework and codes，it was indicated that the presence of infill walls could significantly improve lateral stiffness of frame structure and its seismic performance．
2015, 45(4): 72-76.
doi: 10.13204/j.gyjz201504013
Abstract:
Based on the flexural static loading test of six concrete beams，the crack distribution and development of CFRP － PCPs ( carbon fiber reinforced plastics prestressed concrete prisms) composites reinforced concrete beams under service load were researched． Considering the influence of CFRP － PCPs composites reinforcement，the calculation methods of maximum crack width and mean crack spacing of concrete beams with CFRP － PCPs composites reinforcement in current Chinese design code for concrete structures were modified． Whose results were compared with experimental results，showing a better agreement between test values and the calculated values given by the modified formulas．
Based on the flexural static loading test of six concrete beams，the crack distribution and development of CFRP － PCPs ( carbon fiber reinforced plastics prestressed concrete prisms) composites reinforced concrete beams under service load were researched． Considering the influence of CFRP － PCPs composites reinforcement，the calculation methods of maximum crack width and mean crack spacing of concrete beams with CFRP － PCPs composites reinforcement in current Chinese design code for concrete structures were modified． Whose results were compared with experimental results，showing a better agreement between test values and the calculated values given by the modified formulas．
2015, 45(4): 77-82.
doi: 10.13204/j.gyjz201504014
Abstract:
Using finite element analysis software，considering the non-linear behavior of core concrete under tri-axial state and interaction between the PVC tube and the core concrete，a finite element analysis model of PVC-FRP confined concrete short column was established． The results showed that the brittleness of plain concrete was greatly improved by PVC-FRP tube，and the non-linear finite element analysis results agreed well with test results． On this basis，the variation rules of the internal forces of core concrete，PVC tube and FRP strips during loading were analyzed by using the established finite element analysis model． The influence law of concrete strength，the layers of FRP strips，the thickness of PVC tube and the width of FRP strips on the stress-strain curve of PVC-FRP confined concrete short column was also discussed．
Using finite element analysis software，considering the non-linear behavior of core concrete under tri-axial state and interaction between the PVC tube and the core concrete，a finite element analysis model of PVC-FRP confined concrete short column was established． The results showed that the brittleness of plain concrete was greatly improved by PVC-FRP tube，and the non-linear finite element analysis results agreed well with test results． On this basis，the variation rules of the internal forces of core concrete，PVC tube and FRP strips during loading were analyzed by using the established finite element analysis model． The influence law of concrete strength，the layers of FRP strips，the thickness of PVC tube and the width of FRP strips on the stress-strain curve of PVC-FRP confined concrete short column was also discussed．
2015, 45(4): 83-87.
doi: 10.13204/j.gyjz201504015
Abstract:
Based on the experimental study，using the finite element software ABAQUS，the reasonable constitutive relations of CFRP strips，PVC tube，steel and concrete were chosen，the mesh of finite element model was divided，the boundary condition and load were applied to finite element model，the reasonable loading mode was chosen，the convergence criteria was defined． The finite element analysis model of PVC-FRP confined reinforced concrete column was established and then verified． The mechanical behavior of PVC-FRP confined reinforced concrete columns was analyzed by using the model，and the working mechanism of FRP strips，PVC tube and concrete were revealed．
Based on the experimental study，using the finite element software ABAQUS，the reasonable constitutive relations of CFRP strips，PVC tube，steel and concrete were chosen，the mesh of finite element model was divided，the boundary condition and load were applied to finite element model，the reasonable loading mode was chosen，the convergence criteria was defined． The finite element analysis model of PVC-FRP confined reinforced concrete column was established and then verified． The mechanical behavior of PVC-FRP confined reinforced concrete columns was analyzed by using the model，and the working mechanism of FRP strips，PVC tube and concrete were revealed．
2015, 45(4): 88-91.
doi: 10.13204/j.gyjz201504016
Abstract:
The prestress loss of the web for a prestressed concrete continuous rigid frame bridge was studied． The phased accurate measurement of the prestress loss of the web rebars for No. 3 pier was also carried out by the embedded anchor dynamometer; meanwhile the analysis of the prestress loss was done using theoretical calculation method，whose results were compared with the measured ones． The results showed that the measured values of the prestress loss were larger than the theoretical ones，showing an underestimate of the prestress loss in the design phase． Besides the actual prestress loss was larger due to the influencing factors，such as manpower，materials during construction，which would result in adverse effects on late use of the bridge． Hence the observation of late deformation of such sort of bridge should be conducted．
The prestress loss of the web for a prestressed concrete continuous rigid frame bridge was studied． The phased accurate measurement of the prestress loss of the web rebars for No. 3 pier was also carried out by the embedded anchor dynamometer; meanwhile the analysis of the prestress loss was done using theoretical calculation method，whose results were compared with the measured ones． The results showed that the measured values of the prestress loss were larger than the theoretical ones，showing an underestimate of the prestress loss in the design phase． Besides the actual prestress loss was larger due to the influencing factors，such as manpower，materials during construction，which would result in adverse effects on late use of the bridge． Hence the observation of late deformation of such sort of bridge should be conducted．
2015, 45(4): 92-97.
doi: 10.13204/j.gyjz201504017
Abstract:
In order to study the seismic performance assessment method of brick masonry structures with precast slabs，the bi-directional pseudo-dynamic test of 1∶ 2 scaled building model was carried out． The change of rigidity and frequency of the structure was introduced in the test，and a seismic performance assessment method based on frequency was presented． The evaluation results based on frequency were very close to those based on rigidity，and frequency-based method had a simpler calculation process，and the results were also closed to real damage condition． Therefore，the frequency-based method could be applied in seismic performance evaluation of brick masonry structures with precast slabs．
In order to study the seismic performance assessment method of brick masonry structures with precast slabs，the bi-directional pseudo-dynamic test of 1∶ 2 scaled building model was carried out． The change of rigidity and frequency of the structure was introduced in the test，and a seismic performance assessment method based on frequency was presented． The evaluation results based on frequency were very close to those based on rigidity，and frequency-based method had a simpler calculation process，and the results were also closed to real damage condition． Therefore，the frequency-based method could be applied in seismic performance evaluation of brick masonry structures with precast slabs．
2015, 45(4): 98-102.
doi: 10.13204/j.gyjz201504018
Abstract:
To build the risk evaluation system of ancient masonry pagodas under earthquake，vulnerability index was selected based on seismic properties and seismic damage investigation to plot fragility curve． Then it was built a mathematical model of earthquake risk by combining vulnerability analysis with seismic risk analysis，and also considering structural damage probability and seismic damage，which could quantify earthquake risk． With which the probability risk of Xiaoyan Tower was analysed and its risk value was calculated，so that it could be better protected．
To build the risk evaluation system of ancient masonry pagodas under earthquake，vulnerability index was selected based on seismic properties and seismic damage investigation to plot fragility curve． Then it was built a mathematical model of earthquake risk by combining vulnerability analysis with seismic risk analysis，and also considering structural damage probability and seismic damage，which could quantify earthquake risk． With which the probability risk of Xiaoyan Tower was analysed and its risk value was calculated，so that it could be better protected．
2015, 45(4): 103-106.
doi: 10.13204/j.gyjz201504019
Abstract:
The paper presented a numerical method to simulate the hydraulic fracture in rock engineering． Based on cohesive elements，a pore pressure cohesive fracture model was developed． To reveal the law of fracture initiation and fracture propagation， the criterion for fracture initiation of quadratic nominal stress and fracture propagation of critical energy release rate was applied． In the numerical analysis，the fracture propagations of fluid with different viscosity and rock modulus were analyzed． The influence of fluid viscosity on the pressure gradient on fracture surface was analyzed，and the fracture patterns in different rock was also studied．
The paper presented a numerical method to simulate the hydraulic fracture in rock engineering． Based on cohesive elements，a pore pressure cohesive fracture model was developed． To reveal the law of fracture initiation and fracture propagation， the criterion for fracture initiation of quadratic nominal stress and fracture propagation of critical energy release rate was applied． In the numerical analysis，the fracture propagations of fluid with different viscosity and rock modulus were analyzed． The influence of fluid viscosity on the pressure gradient on fracture surface was analyzed，and the fracture patterns in different rock was also studied．
2015, 45(4): 107-112.
doi: 10.13204/j.gyjz201504020
Abstract:
Some of literatures have investigated the influence on deformation of deep excavations adjacent to buildings，but most of them regarded the adjacent building as a kind of uniform load directly instead of the geometry of the building，and ignored the overload depth． Therefore，taking a typical deep excavation in Qingdao supported by pile-inner bracing structures in soil-rock mixed area as a prototype，considering geometry of the adjacent building located in one side of the excavation，the characteristics of the supporting system deformation were analyzed due to variation of the overload depth． The results showed that as the deformation for supporting system far away from the building，existence of the adjacent building was favorable and the deformation almost kept unchanged with variation of the overload depth and the overload distance from the deep excavation． For the deformation of the deep excavation near side from the building，there was a critical overload depth，and if the overload depth was less than it，existence of the building would be unfavorable; otherwise，the building was favorable． The critical depth had a decreasing tendency with reduction of the overload magnitude and increase of the overload distance from the excavation． Characteristics of the near side deformation due to variation of the distance between the building and the excavation for different overload depth were analyzed． Furthermore，mechanism of the deformation of the support system under different overload depth of adjacent buildings was also discussed．
Some of literatures have investigated the influence on deformation of deep excavations adjacent to buildings，but most of them regarded the adjacent building as a kind of uniform load directly instead of the geometry of the building，and ignored the overload depth． Therefore，taking a typical deep excavation in Qingdao supported by pile-inner bracing structures in soil-rock mixed area as a prototype，considering geometry of the adjacent building located in one side of the excavation，the characteristics of the supporting system deformation were analyzed due to variation of the overload depth． The results showed that as the deformation for supporting system far away from the building，existence of the adjacent building was favorable and the deformation almost kept unchanged with variation of the overload depth and the overload distance from the deep excavation． For the deformation of the deep excavation near side from the building，there was a critical overload depth，and if the overload depth was less than it，existence of the building would be unfavorable; otherwise，the building was favorable． The critical depth had a decreasing tendency with reduction of the overload magnitude and increase of the overload distance from the excavation． Characteristics of the near side deformation due to variation of the distance between the building and the excavation for different overload depth were analyzed． Furthermore，mechanism of the deformation of the support system under different overload depth of adjacent buildings was also discussed．
2015, 45(4): 113-116.
doi: 10.13204/j.gyjz201504021
Abstract:
There is a great difference between the calculated collapse under overburden pressure and the measured collapse，it is one of the main reasons for the difference that the method indoor for determining coefficient of collapsibility under overburden pressure has theory deficiency，it has become an urgent requirement how to correctly evaluate loess foundation improving the theory and method for determining coefficient of collapsibility under overburden pressure． An improved method for determining coefficient of collapsibility under overburden pressure was established in the literature No. 10，based on which taking dry density，moisture content，interparticle force and natural weight pressure as factors，the problems of determining coefficient of collapsibility under overburden earth pressure were studied by experiment． The rationality of the improved method was analyzed，and the influencing rule of each factor on the difference between the two determination results was explored by comparison of Rc and 0 ，Rc was the ratio of coefficient of collapsibility under overburden pressure determined by the improved method and current method，0 was the correction coefficient varied with the soil．Research showed that the overburden pressure，dry density，water content and interpartical force had different effects on Rc ，dry density was the most important factor， water content and overberden pressure were the less ones，and the interpartical force was the minimum． The improved method had general applicability and theoretic rationality，which could reduce the effects of soil disturbance on coefficient of self-weight collapsibility．
There is a great difference between the calculated collapse under overburden pressure and the measured collapse，it is one of the main reasons for the difference that the method indoor for determining coefficient of collapsibility under overburden pressure has theory deficiency，it has become an urgent requirement how to correctly evaluate loess foundation improving the theory and method for determining coefficient of collapsibility under overburden pressure． An improved method for determining coefficient of collapsibility under overburden pressure was established in the literature No. 10，based on which taking dry density，moisture content，interparticle force and natural weight pressure as factors，the problems of determining coefficient of collapsibility under overburden earth pressure were studied by experiment． The rationality of the improved method was analyzed，and the influencing rule of each factor on the difference between the two determination results was explored by comparison of Rc and 0 ，Rc was the ratio of coefficient of collapsibility under overburden pressure determined by the improved method and current method，0 was the correction coefficient varied with the soil．Research showed that the overburden pressure，dry density，water content and interpartical force had different effects on Rc ，dry density was the most important factor， water content and overberden pressure were the less ones，and the interpartical force was the minimum． The improved method had general applicability and theoretic rationality，which could reduce the effects of soil disturbance on coefficient of self-weight collapsibility．
2015, 45(4): 117-119.
doi: 10.13204/j.gyjz201504022
Abstract:
The formula of acting force on pile top of foundation with asymmetric piles was deduced． Analysis showed that the formula of Technical Code for Building Pile Foundations ( JGJ 942008) was a special case，which was only applicative with the situation of symmetric arrangeing piles and selecting the origin of coordinates should be careful when the formula was used，centroid of pile group instead of centroid of cushion cap should be selected as the origin of coordinates． Meanwhile，through analysis results of the formula， larger calculation error appeared on the asymmetric piles using the formula of JGJ 942008． When calculating acting force on pile top，designer should choose the reasonable formula according to real situation．
The formula of acting force on pile top of foundation with asymmetric piles was deduced． Analysis showed that the formula of Technical Code for Building Pile Foundations ( JGJ 942008) was a special case，which was only applicative with the situation of symmetric arrangeing piles and selecting the origin of coordinates should be careful when the formula was used，centroid of pile group instead of centroid of cushion cap should be selected as the origin of coordinates． Meanwhile，through analysis results of the formula， larger calculation error appeared on the asymmetric piles using the formula of JGJ 942008． When calculating acting force on pile top，designer should choose the reasonable formula according to real situation．
2015, 45(4): 120-126.
doi: 10.13204/j.gyjz201504023
Abstract:
Engineered cementitious composite ( ECC) can significantly improve the anti-cracking performance and damage resistance ability of concrete structure due to its pseudo strain hardening and multiple cracking performances． Specimens of 9 groups with different mix of engineered cementitious composite were designed and their compressive properties were tested． By comparing with concrete and mortar matrix，the following conclusions were drawn: 1) engineered cementitious composite showed good compressive resilience in the compression failure，which was markedly different from ordinary concrete and mortar matrix; 2) on the secondary loading，the fiber of the fractured cross-section carried most of the tension and multiple cracks occurred within the specimens，which made energy releasing during damage of the material; 3) on the condition of full dispersion of fiber and liquidity of mixture，the lower the water-binder ratio，the higher the compressive strength，and the increase of fly ash could improve interface property and ductility of the material; 4) the secondary compression strength of engineered cementitious composite was close to its first compression strength and its strength continued to grow to some extent even after damaged， so its ability of resistance to damage is significantly better than that of ordinary concrete．
Engineered cementitious composite ( ECC) can significantly improve the anti-cracking performance and damage resistance ability of concrete structure due to its pseudo strain hardening and multiple cracking performances． Specimens of 9 groups with different mix of engineered cementitious composite were designed and their compressive properties were tested． By comparing with concrete and mortar matrix，the following conclusions were drawn: 1) engineered cementitious composite showed good compressive resilience in the compression failure，which was markedly different from ordinary concrete and mortar matrix; 2) on the secondary loading，the fiber of the fractured cross-section carried most of the tension and multiple cracks occurred within the specimens，which made energy releasing during damage of the material; 3) on the condition of full dispersion of fiber and liquidity of mixture，the lower the water-binder ratio，the higher the compressive strength，and the increase of fly ash could improve interface property and ductility of the material; 4) the secondary compression strength of engineered cementitious composite was close to its first compression strength and its strength continued to grow to some extent even after damaged， so its ability of resistance to damage is significantly better than that of ordinary concrete．
2015, 45(4): 127-131.
doi: 10.13204/j.gyjz201504024
Abstract:
To investigate the effect of different environment and stress levels on creep of glass fiber reinforced polymer composite ( GFRP) ，its creeps under the effect of atmospheric and chloride ion environment during different test periods were measured． The results showed that the rate of creep increases fast initially and slower in late period． The property of GFRP was influenced by environment and stress level， in the same environment， the higher stress level， the more increment of creep; in the same stress level，the increment of creep of GFRP in chloride ion was higher than that in atmosphere; water absorption and diffusion in the resin resulted in a volumetric expansion leading to microcracks， and then decreased the properties of it's viscoelasticity． There was a chemical reaction of the resin with the water molecules， and the chemical agents were easily leached out，which led to the occurrence of pits， then the bonding between the fiber and the matrix broke． The creep prediction model of GFRP and its applicability were proposed， based on the standard linear solid model theory by Kelvin，considering various environment and stress range．
To investigate the effect of different environment and stress levels on creep of glass fiber reinforced polymer composite ( GFRP) ，its creeps under the effect of atmospheric and chloride ion environment during different test periods were measured． The results showed that the rate of creep increases fast initially and slower in late period． The property of GFRP was influenced by environment and stress level， in the same environment， the higher stress level， the more increment of creep; in the same stress level，the increment of creep of GFRP in chloride ion was higher than that in atmosphere; water absorption and diffusion in the resin resulted in a volumetric expansion leading to microcracks， and then decreased the properties of it's viscoelasticity． There was a chemical reaction of the resin with the water molecules， and the chemical agents were easily leached out，which led to the occurrence of pits， then the bonding between the fiber and the matrix broke． The creep prediction model of GFRP and its applicability were proposed， based on the standard linear solid model theory by Kelvin，considering various environment and stress range．
2015, 45(4): 132-135.
doi: 10.13204/j.gyjz201504025
Abstract:
To investigate the effects of silica fume on the mechanical properties of Reactive Powder Concrete( RPC) ， the compression strength，split tensile strength and flexural tensile strength of RPC with five different silica fume volumetric contents were researched by the compressive，split tensile and flexural tensile tests of RPC cubic and beam specimens． It was shown that the increasing content of silica fume could improve the mechanical properties of RPC effectively，but there existed an optimum content of silica． In order to meet the requirements of the high performance， good workability and economy simultaneously，the volumetric content of silica fume being 12% could obtain the good performance RPC200． In addition，the relationships between the measured strengths and the volumetric contents of silica fume were empirically formulated．
To investigate the effects of silica fume on the mechanical properties of Reactive Powder Concrete( RPC) ， the compression strength，split tensile strength and flexural tensile strength of RPC with five different silica fume volumetric contents were researched by the compressive，split tensile and flexural tensile tests of RPC cubic and beam specimens． It was shown that the increasing content of silica fume could improve the mechanical properties of RPC effectively，but there existed an optimum content of silica． In order to meet the requirements of the high performance， good workability and economy simultaneously，the volumetric content of silica fume being 12% could obtain the good performance RPC200． In addition，the relationships between the measured strengths and the volumetric contents of silica fume were empirically formulated．
2015, 45(4): 136-142.
doi: 10.13204/j.gyjz201504026
Abstract:
To meet the needs of the new structure construction，a new kind of cantilever support system is brought forward． Based on the system，it was built a finite element model taking account of the joint semi-rigid connection and generalized initial imperfections，whose correctness，practicability，security were analyzed and verified． In order to predict and treat the emergency in the construction of the system，its stress and strain were monitored and a further optimization of the new cantilever support system was also conducted． By the contrastive analysis of the finite element and the test results， the correctness of the finite element model and necessity of thinking about the influence of the joint semi-rigid connection and generalized initial imperfections were verified，which provided important reference and basis for the design and application of the cantilever support system．
To meet the needs of the new structure construction，a new kind of cantilever support system is brought forward． Based on the system，it was built a finite element model taking account of the joint semi-rigid connection and generalized initial imperfections，whose correctness，practicability，security were analyzed and verified． In order to predict and treat the emergency in the construction of the system，its stress and strain were monitored and a further optimization of the new cantilever support system was also conducted． By the contrastive analysis of the finite element and the test results， the correctness of the finite element model and necessity of thinking about the influence of the joint semi-rigid connection and generalized initial imperfections were verified，which provided important reference and basis for the design and application of the cantilever support system．
2015, 45(4): 143-146.
doi: 10.13204/j.gyjz201504027
Abstract:
The spatial steel pipe truss and radiation beam horizontal supporting structures with the same diameter of 30 m were selected for comparison，the two models were applied with 0，800，1 600，2 400 kN loads and analyzed by the ANSYS software under different loads． The results showed that the displacement of the two finite models as the load increased． Under the same load，vertical displacement of the radiation beam support system and the spatial steel truss was not so far different． With the rod force in the elastic range，the maximum vertical displacement of two structure systems displayed a significant linear relationship as the load changed． Hence，the steel truss support system had a higher ability to withstand the load than the radiation beam support system．
The spatial steel pipe truss and radiation beam horizontal supporting structures with the same diameter of 30 m were selected for comparison，the two models were applied with 0，800，1 600，2 400 kN loads and analyzed by the ANSYS software under different loads． The results showed that the displacement of the two finite models as the load increased． Under the same load，vertical displacement of the radiation beam support system and the spatial steel truss was not so far different． With the rod force in the elastic range，the maximum vertical displacement of two structure systems displayed a significant linear relationship as the load changed． Hence，the steel truss support system had a higher ability to withstand the load than the radiation beam support system．
2015, 45(4): 151-155.
doi: 10.13204/j.gyjz201504029
Abstract:
For the purpose of improving seismic performance of steel reinforced concrete ( SRC) columns with high axial compression ratio，SRC columns with cross-shaped steel along diagonal line were put forward，whose bearing capacity calculation could not adopt the related formulas of current codes directly． The strength superposition method and limit equilibrium method were employed to calculate normal section bearing capacity of proposed SRC columns on this background． The bearing capacity of confined concrete，steel flange and steel web were calculated respectively first，and then the maximum axial force and ultimate moment were obtained according to superposition principle of the strength superposition method． From the thought of material mechanics，the simplified calculation formulas of normal section bearing capacity were deduced through regressing numerical simulation results of a large number of SRC columns with cross-shaped steel subjected to biaxial eccentric compression of limit equilibrium method． Three experimental specimens and sixteen finite element simulated columns with the same sections were calculated using the above formulas and the theoretical results agreed well with practical bearing capacity of the columns，which verified the correctness and applicability of the proposed formulas．
For the purpose of improving seismic performance of steel reinforced concrete ( SRC) columns with high axial compression ratio，SRC columns with cross-shaped steel along diagonal line were put forward，whose bearing capacity calculation could not adopt the related formulas of current codes directly． The strength superposition method and limit equilibrium method were employed to calculate normal section bearing capacity of proposed SRC columns on this background． The bearing capacity of confined concrete，steel flange and steel web were calculated respectively first，and then the maximum axial force and ultimate moment were obtained according to superposition principle of the strength superposition method． From the thought of material mechanics，the simplified calculation formulas of normal section bearing capacity were deduced through regressing numerical simulation results of a large number of SRC columns with cross-shaped steel subjected to biaxial eccentric compression of limit equilibrium method． Three experimental specimens and sixteen finite element simulated columns with the same sections were calculated using the above formulas and the theoretical results agreed well with practical bearing capacity of the columns，which verified the correctness and applicability of the proposed formulas．
2015, 45(4): 156-160.
doi: 10.13204/j.gyjz201504030
Abstract:
With the consideration of the second order effect of the structure，the calculated internal forces and displacement are both larger than the results obtained from the first order analysis． While dealing with the same load and the same geometric conditions of a structure，if the first order analysis method is used to calculate the structure drift，the result would meet the allowable drift values in Code for Design of Steel Structure ( GB 500172003) ，but if the second order analysis is used，the structure drift may not meet the allowable values． So it is necessary to add relevant content for drift limits considering second-order effect． This paper researched the reasonable peak drift limits of steel frame considering the second-order effect，the second-order peak drift limits of steel frames was given by using reliability theory and the analysis method used in present standard． Which would provide a reference for revision of the code and engineering uses．
With the consideration of the second order effect of the structure，the calculated internal forces and displacement are both larger than the results obtained from the first order analysis． While dealing with the same load and the same geometric conditions of a structure，if the first order analysis method is used to calculate the structure drift，the result would meet the allowable drift values in Code for Design of Steel Structure ( GB 500172003) ，but if the second order analysis is used，the structure drift may not meet the allowable values． So it is necessary to add relevant content for drift limits considering second-order effect． This paper researched the reasonable peak drift limits of steel frame considering the second-order effect，the second-order peak drift limits of steel frames was given by using reliability theory and the analysis method used in present standard． Which would provide a reference for revision of the code and engineering uses．
2015, 45(4): 161-167.
doi: 10.13204/j.gyjz201504031
Abstract:
An optimizing idea was produced for the design of the top beam in electrostatic precipitator casing: the insulation layer and the original short-span top beam of casing could constitute a long-span truss beam system，then the overall cross section of the truss beam was heightened，which enabled its bending bearing capacity to be much greater than the original short-span beam，thus，the span of beam system could be enlarged． The original double short-span beams could be transformed into a long-span truss beam system and the original separating wall could be dismantled． Consequently，the steel consumption was reduced． By the method of one-dimensional beam-link structural analysis and the finite element method of shell element，the design and internal force evaluation method for the long-span truss beam system were investigated． Besides，the load bearing performance of bottom chord with box section was emphatically investigated by the shell finite element method． The preliminary design method of constituting members，the optimum configuration and the internal force evaluation method for the beam system were proposed． For the bottom chord，the load bearing evaluation method of end face of supporting stiffener，the sensitive local buckling mode and the most unfavorable initial geometrical imperfection mode were obtained． Besides，the optimizing suggestion was also produced for the size design of transversal stiffener and the height position of axial stiffener．
An optimizing idea was produced for the design of the top beam in electrostatic precipitator casing: the insulation layer and the original short-span top beam of casing could constitute a long-span truss beam system，then the overall cross section of the truss beam was heightened，which enabled its bending bearing capacity to be much greater than the original short-span beam，thus，the span of beam system could be enlarged． The original double short-span beams could be transformed into a long-span truss beam system and the original separating wall could be dismantled． Consequently，the steel consumption was reduced． By the method of one-dimensional beam-link structural analysis and the finite element method of shell element，the design and internal force evaluation method for the long-span truss beam system were investigated． Besides，the load bearing performance of bottom chord with box section was emphatically investigated by the shell finite element method． The preliminary design method of constituting members，the optimum configuration and the internal force evaluation method for the beam system were proposed． For the bottom chord，the load bearing evaluation method of end face of supporting stiffener，the sensitive local buckling mode and the most unfavorable initial geometrical imperfection mode were obtained． Besides，the optimizing suggestion was also produced for the size design of transversal stiffener and the height position of axial stiffener．
2015, 45(4): 168-172.
doi: 10.13204/j.gyjz201504032
Abstract:
A new seismic retrofitting technology of using post-tensioning tendons to retrofit brick wall structures is presented．To verify the validity of the retrofitting technology，MSC.MARC was used to set up the models of one unreinforced brick wall and the other retrofitted with post-tensioned tendons，which were simulated under lateral lowcyclic reversed load，whose results were compared with those of the test． Numerical results showed that this new retrofitting technology could significantly improve the cracking capacity and shear bearing capacity，and the seismic behaviors of the brick wall retrofitted using post-tensioned tendons could be significantly improved．
A new seismic retrofitting technology of using post-tensioning tendons to retrofit brick wall structures is presented．To verify the validity of the retrofitting technology，MSC.MARC was used to set up the models of one unreinforced brick wall and the other retrofitted with post-tensioned tendons，which were simulated under lateral lowcyclic reversed load，whose results were compared with those of the test． Numerical results showed that this new retrofitting technology could significantly improve the cracking capacity and shear bearing capacity，and the seismic behaviors of the brick wall retrofitted using post-tensioned tendons could be significantly improved．
2015, 45(4): 173-176.
doi: 10.13204/j.gyjz201504033
Abstract:
Through the case introduction of sino-singapore Tianjin eco-city heat supply plant industrial building design，starting fromgreen industrial buildingsdesign concept，and by combining with the heat source plant project in site selection，function demand and structure，this paper investigated the heat source plant green industrial building design，particularly in terms of energy conservation and environmental protection design in order to advocate the application of green industrial building design and form a new pattern of the industrial building design that would be helpful to the development of modern and future society gradually．
Through the case introduction of sino-singapore Tianjin eco-city heat supply plant industrial building design，starting fromgreen industrial buildingsdesign concept，and by combining with the heat source plant project in site selection，function demand and structure，this paper investigated the heat source plant green industrial building design，particularly in terms of energy conservation and environmental protection design in order to advocate the application of green industrial building design and form a new pattern of the industrial building design that would be helpful to the development of modern and future society gradually．
2015, 45(4): 177-180.
doi: 10.13204/j.gyjz201504034
Abstract:
The paper introduced and analyzed the process of building design of Bozhou grand theatre and radio ＆ television center，and discussed the architectural features of large stadium and gym which reflect the culture foundation of a city，with which the local culture elements and symbols could be extracted so as to strive to show the city's classic architecture through modern design methods; at the same time，by combining the pattern of natural water system with the pattern of the green space in the field，the relationship of the surrounding environment could be coordinated to realize an organic integration of architectural function with natural environment．
The paper introduced and analyzed the process of building design of Bozhou grand theatre and radio ＆ television center，and discussed the architectural features of large stadium and gym which reflect the culture foundation of a city，with which the local culture elements and symbols could be extracted so as to strive to show the city's classic architecture through modern design methods; at the same time，by combining the pattern of natural water system with the pattern of the green space in the field，the relationship of the surrounding environment could be coordinated to realize an organic integration of architectural function with natural environment．
