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2013 Vol. 43, No. 6
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2013, 43(6): 1-4.
doi: 10.13204/j.gyjz201306001
Abstract:
The tensile mechanical properties of single carbon fibers produced in China were tested.The Weibull distribution function was used to analyze the testing results.It is found that the tensile strength of the domestic carbon fibers is much lower than that of Toray T700 and TC36S carbon fibers.Scanning electron microscope(SEM) analysis shows that the surface of Toray T700 carbon fiber is smooth, and there are shallow grooves on the surface of TC36S carbon fiber;whereas there are wider and deeper groover on the surface of domestic carbon fiber.Which may be responsible for relatively lower tensile strengths.
The tensile mechanical properties of single carbon fibers produced in China were tested.The Weibull distribution function was used to analyze the testing results.It is found that the tensile strength of the domestic carbon fibers is much lower than that of Toray T700 and TC36S carbon fibers.Scanning electron microscope(SEM) analysis shows that the surface of Toray T700 carbon fiber is smooth, and there are shallow grooves on the surface of TC36S carbon fiber;whereas there are wider and deeper groover on the surface of domestic carbon fiber.Which may be responsible for relatively lower tensile strengths.
2013, 43(6): 5-8,35.
doi: 10.13204/j.gyjz201306002
Abstract:
According to the provisions in Fiber Reinforced Composite Bars for Structural Engineeing(GB/T 267432011), mechanical property tests of CFRP bars with different diameters are made to determine some mechanical properties such as tensile strength, elastic modulus and elongation rate.The experimental process, method and failure state are introduced in detail.The results show that stress-strain curves are straight lines and the failure mechanism has brittle fracture characteristics.From the point of view of detection method, it is recommended that sand-gluing treatment should be done for the anchor end to ensure that the adhesive anchor does not fail when testing bars in accordance with anchorage of resin sleeve in national standard.Unilateral anchoring length is suggested to be 200mm when the adhering sand with a diameter of less than 7 mm is firm.
According to the provisions in Fiber Reinforced Composite Bars for Structural Engineeing(GB/T 267432011), mechanical property tests of CFRP bars with different diameters are made to determine some mechanical properties such as tensile strength, elastic modulus and elongation rate.The experimental process, method and failure state are introduced in detail.The results show that stress-strain curves are straight lines and the failure mechanism has brittle fracture characteristics.From the point of view of detection method, it is recommended that sand-gluing treatment should be done for the anchor end to ensure that the adhesive anchor does not fail when testing bars in accordance with anchorage of resin sleeve in national standard.Unilateral anchoring length is suggested to be 200mm when the adhering sand with a diameter of less than 7 mm is firm.
2013, 43(6): 9-13,26.
doi: 10.13204/j.gyjz201306003
Abstract:
The pultrusion process parameters having influence on the mechanical properties of CFRP plates based on Taguchi method and the optimal pultrusion process parameters for producing CFRP plates with high mechanical properties are studied.The results show that fiber content, epoxy resin types, draw rate and mold temperature are the main factors influencing the mechanical properties of CFRP plates, post-curing temperature and fiber tension have less influence, the influence of glue tank temperature can be neglected.
The pultrusion process parameters having influence on the mechanical properties of CFRP plates based on Taguchi method and the optimal pultrusion process parameters for producing CFRP plates with high mechanical properties are studied.The results show that fiber content, epoxy resin types, draw rate and mold temperature are the main factors influencing the mechanical properties of CFRP plates, post-curing temperature and fiber tension have less influence, the influence of glue tank temperature can be neglected.
2013, 43(6): 14-17.
doi: 10.13204/j.gyjz201306004
Abstract:
An experimental study on two kinds of FRP bars in two high temperature solutions was conducted to investigate their corrosion resistant performance.Furthermore, it was also studied the mechanical properties degradation of BFRP bars within indoor concrete environment.Meanwhile, the water uptake and mass loss performance of BFRP bars in two temperatures and two solutions were studied.The results showed that the increase of temperature aggravated the degradation degree of the tensile strength of FRP bars;the corrosion degree of BFRP bar in alkali solution was much more severe than in water, and the indoor concrete environment would not damage BFRP bar.There was almost no degradation in two corrosive solutions for tensile strength of CFRP bars, but their elastic modulus degraded greater than BFRP tendons.The higher the temperature, the greater the moisture absorption rate of reinforcement, the one in alkali solution was greater than that in water;mass loss rate could characterize the degradation of FRP bars well.
An experimental study on two kinds of FRP bars in two high temperature solutions was conducted to investigate their corrosion resistant performance.Furthermore, it was also studied the mechanical properties degradation of BFRP bars within indoor concrete environment.Meanwhile, the water uptake and mass loss performance of BFRP bars in two temperatures and two solutions were studied.The results showed that the increase of temperature aggravated the degradation degree of the tensile strength of FRP bars;the corrosion degree of BFRP bar in alkali solution was much more severe than in water, and the indoor concrete environment would not damage BFRP bar.There was almost no degradation in two corrosive solutions for tensile strength of CFRP bars, but their elastic modulus degraded greater than BFRP tendons.The higher the temperature, the greater the moisture absorption rate of reinforcement, the one in alkali solution was greater than that in water;mass loss rate could characterize the degradation of FRP bars well.
2013, 43(6): 18-22,31.
doi: 10.13204/j.gyjz201306005
Abstract:
The bearing capacity, peak strain, stress-strain relation of circular concrete columns confined by CFRP, BFRP, GFRP and hybrid FRP were analyzed under axial compressive load.The confinement effects of hybrid FRP on concrete columns were analyzed.A strength simulation model and a stress-strain whole process simulation model of hybrid FRP confined concrete columns were presented.The new stress-strain whole process simulation model has good simulation accuracy and does not need piecewise fitting compared with single FRP model provided by Teng et al.The new simulation model is also suitable for single FRP confinement cases.
The bearing capacity, peak strain, stress-strain relation of circular concrete columns confined by CFRP, BFRP, GFRP and hybrid FRP were analyzed under axial compressive load.The confinement effects of hybrid FRP on concrete columns were analyzed.A strength simulation model and a stress-strain whole process simulation model of hybrid FRP confined concrete columns were presented.The new stress-strain whole process simulation model has good simulation accuracy and does not need piecewise fitting compared with single FRP model provided by Teng et al.The new simulation model is also suitable for single FRP confinement cases.
2013, 43(6): 23-26.
doi: 10.13204/j.gyjz201306006
Abstract:
The flexural behaviors of pre-stressed C/BFRP-concrete composite beams were experimentally studied, wherein C/BFRP is carbon basalt fibers reinforced polymer.The effects of hybrid modes and prestress levels on the bending behaviors of the composite beams were investigated.The load carrying capacity, stiffness, deflection and ductility of the beams were also discussed.The experimental results show that prestressed C/BFRP can effectively improve the bending behaviors of the composite beams, delay the initiation of the cracks and improve the ductility of the beams.The composite beams also have higher secondary stiffness after the yielding of steel reinforcing bars.
The flexural behaviors of pre-stressed C/BFRP-concrete composite beams were experimentally studied, wherein C/BFRP is carbon basalt fibers reinforced polymer.The effects of hybrid modes and prestress levels on the bending behaviors of the composite beams were investigated.The load carrying capacity, stiffness, deflection and ductility of the beams were also discussed.The experimental results show that prestressed C/BFRP can effectively improve the bending behaviors of the composite beams, delay the initiation of the cracks and improve the ductility of the beams.The composite beams also have higher secondary stiffness after the yielding of steel reinforcing bars.
2013, 43(6): 27-31.
doi: 10.13204/j.gyjz201306007
Abstract:
In order to study seismic performance of FRP confined RC hollow section bridge pier, quasi-static test was carried out for CFRP confined RC rectangular hollow section bridge pier with shear-span ration of 4 and 8 under horizontal unidirectional and bidirectional loads.Failure mode, hysteretic curves, lateral force and displacement of tested pier columns were analyzed respectively.The results show that through confining plastic hinge region of tested hollow bridge pier by CFRP, the failure location and damage degree are reduced, and the failure mode of tested bridge piers with lower shear-span ratio is changed;the hysteretic performance and ductility of tested bridge piers with bigger shear-span ratio are improved, however, horizontal force is only increased by less than 20%.
In order to study seismic performance of FRP confined RC hollow section bridge pier, quasi-static test was carried out for CFRP confined RC rectangular hollow section bridge pier with shear-span ration of 4 and 8 under horizontal unidirectional and bidirectional loads.Failure mode, hysteretic curves, lateral force and displacement of tested pier columns were analyzed respectively.The results show that through confining plastic hinge region of tested hollow bridge pier by CFRP, the failure location and damage degree are reduced, and the failure mode of tested bridge piers with lower shear-span ratio is changed;the hysteretic performance and ductility of tested bridge piers with bigger shear-span ratio are improved, however, horizontal force is only increased by less than 20%.
2013, 43(6): 32-35.
doi: 10.13204/j.gyjz201306008
Abstract:
Aimed at the low joint efficiency arising from the unidirectional pultruded fiber composites application to civil and transportation field, it was put forward a new type of joint of FRP composite:binding-adhesive joints.Experiments were conducted on three types of joints, including binding-adhesive joints, bolt joints and adhesive joints.The experimental results proved that binding-adhesive joints had a high joint efficiency factor;the bearing capacity was 3.8 times of the bolt joints, 3.5 times of the adhesive joints.Based on the load-displacement curve obtained from experiments, a comparative analysis of stiffness and ductility of the three types of joints was made.According to the experimental phenomena and results, the analysis of the working mechanism of binding-adhesive joints was made.
Aimed at the low joint efficiency arising from the unidirectional pultruded fiber composites application to civil and transportation field, it was put forward a new type of joint of FRP composite:binding-adhesive joints.Experiments were conducted on three types of joints, including binding-adhesive joints, bolt joints and adhesive joints.The experimental results proved that binding-adhesive joints had a high joint efficiency factor;the bearing capacity was 3.8 times of the bolt joints, 3.5 times of the adhesive joints.Based on the load-displacement curve obtained from experiments, a comparative analysis of stiffness and ductility of the three types of joints was made.According to the experimental phenomena and results, the analysis of the working mechanism of binding-adhesive joints was made.
2013, 43(6): 36-41.
doi: 10.13204/j.gyjz201306009
Abstract:
Mao Yisheng Public Bridge in Chongqing is the first all FRP truss bridge made of pultruded profiles in China, with a span of 20 m and width of 2.0 m.Based on which, the behavior of pultruded profiles, some connection methods and structural system of the bridge were introduced.The static and dynamic behavior of the FRP pultruded bridge were studied.The bridge has been tested twice when it was pre-installed in the factory and 174 d after it opened.A dynamic behavior test was conducted also.All test cases were simulated using FEA program SAP 2000.The results show that the FRP truss bridge has a higher stiffness and load bearing capacity.It has a 2.09 mm deformation under 45% of design load, and the first vertical natural frequency is about 10.8 Hz.The results from FEA match the test results very well, showing that it is reasonable to consider the FRP truss members as the linear-elastic link elements.
Mao Yisheng Public Bridge in Chongqing is the first all FRP truss bridge made of pultruded profiles in China, with a span of 20 m and width of 2.0 m.Based on which, the behavior of pultruded profiles, some connection methods and structural system of the bridge were introduced.The static and dynamic behavior of the FRP pultruded bridge were studied.The bridge has been tested twice when it was pre-installed in the factory and 174 d after it opened.A dynamic behavior test was conducted also.All test cases were simulated using FEA program SAP 2000.The results show that the FRP truss bridge has a higher stiffness and load bearing capacity.It has a 2.09 mm deformation under 45% of design load, and the first vertical natural frequency is about 10.8 Hz.The results from FEA match the test results very well, showing that it is reasonable to consider the FRP truss members as the linear-elastic link elements.
2013, 43(6): 42-46,51.
doi: 10.13204/j.gyjz201306010
Abstract:
It was analysed the features of industrialized construction ways, building system and building component of the solar decathlon Europe in 2010 cases.It was proposed that a new design method of the path of building system, the design elements, integrated technology of industrialized architecture design and component design, and an example was also given in this paper.
It was analysed the features of industrialized construction ways, building system and building component of the solar decathlon Europe in 2010 cases.It was proposed that a new design method of the path of building system, the design elements, integrated technology of industrialized architecture design and component design, and an example was also given in this paper.
2013, 43(6): 47-51.
doi: 10.13204/j.gyjz201306011
Abstract:
The mega-frame structure system is a new type of structural system to adapt to the development of high-rise and super high-rise buildings.However, there is less study on the mega-frame structure currently.In order to study the seismic performance of the mega-frame better, according to Chinese Engineering Design Standard, a 55 layer 39 m36 m201 m super high-level reinforced concrete mega-frame structure was designed in a region with 7 seismic fortification and Ⅱ site.Which was used as the scaled integral structure model of shaking table test for earthquake simulation.In order to study the seismic performance of the mega-frame better, it was described the choosing of materials for the test model, the design of the dynamic correlation coefficient and the design of the test program, which provided a reference for future related experimental design.
The mega-frame structure system is a new type of structural system to adapt to the development of high-rise and super high-rise buildings.However, there is less study on the mega-frame structure currently.In order to study the seismic performance of the mega-frame better, according to Chinese Engineering Design Standard, a 55 layer 39 m36 m201 m super high-level reinforced concrete mega-frame structure was designed in a region with 7 seismic fortification and Ⅱ site.Which was used as the scaled integral structure model of shaking table test for earthquake simulation.In order to study the seismic performance of the mega-frame better, it was described the choosing of materials for the test model, the design of the dynamic correlation coefficient and the design of the test program, which provided a reference for future related experimental design.
2013, 43(6): 52-55.
doi: 10.13204/j.gyjz201306012
Abstract:
For the effect of stirrup ratios on damage characteristic, hysteretic characteristic, rigidity degradation, ductility performance, energy dissipation capacity of T-shaped and L-shaped columns, through quasi-static test method, four concrete specially shaped columns, high strength steel bars were tested under low cyclic loading.The component failure characteristics and ductility performance were analyzed, hysteresis curves and stiffness degradation curves and equivalent viscous damping coefficient curves were also plotted.The results show that descending parts of the hysteresis loops of specially shaped columns, high strength steel bars and concrete are steeper and the ductility was also worse.The damage characteristic and the hysteretic characteristic of specimens were improved with the increase of stirrup ratios.The energy dissipation capacity of T-shaped column and L-shaped column were also enhanced with the increase of stirrup ratios.
For the effect of stirrup ratios on damage characteristic, hysteretic characteristic, rigidity degradation, ductility performance, energy dissipation capacity of T-shaped and L-shaped columns, through quasi-static test method, four concrete specially shaped columns, high strength steel bars were tested under low cyclic loading.The component failure characteristics and ductility performance were analyzed, hysteresis curves and stiffness degradation curves and equivalent viscous damping coefficient curves were also plotted.The results show that descending parts of the hysteresis loops of specially shaped columns, high strength steel bars and concrete are steeper and the ductility was also worse.The damage characteristic and the hysteretic characteristic of specimens were improved with the increase of stirrup ratios.The energy dissipation capacity of T-shaped column and L-shaped column were also enhanced with the increase of stirrup ratios.
2013, 43(6): 56-59,89.
doi: 10.13204/j.gyjz201306013
Abstract:
In this paper, by using a simplified mechanical model on subarea in tension and compression, the analytical solution of bimodular simply supported beams under uniformly distributed loads was derived without the assumption of plane section.Based on the numerical iteration technique from bimodular finite element method, the shear modulus used for accelerating convergence was introduced and the numerical iterative program for the same problem was rebuilt.Using this program, bimodular beams in the cases of different ratios of elastic moduli in tension and compression, including from shallow beams to deep ones, are computed.The numerical result shows that different ratios of elastic moduli has great influences on the bending stresses and the vertical deflection of bimodular beams.By contrasting the numerical results with the analytical solutions, the applicable range of the analytical solutions presented in this paper was determined.
In this paper, by using a simplified mechanical model on subarea in tension and compression, the analytical solution of bimodular simply supported beams under uniformly distributed loads was derived without the assumption of plane section.Based on the numerical iteration technique from bimodular finite element method, the shear modulus used for accelerating convergence was introduced and the numerical iterative program for the same problem was rebuilt.Using this program, bimodular beams in the cases of different ratios of elastic moduli in tension and compression, including from shallow beams to deep ones, are computed.The numerical result shows that different ratios of elastic moduli has great influences on the bending stresses and the vertical deflection of bimodular beams.By contrasting the numerical results with the analytical solutions, the applicable range of the analytical solutions presented in this paper was determined.
2013, 43(6): 60-66.
doi: 10.13204/j.gyjz201306014
Abstract:
Based on 30 sets of acceleration records of near-fault earthquake, the influence of vertical effect of near-fault earthquake on displacement demand of structures was studied.Using each set of near-fault acceleration records, a set of dynamic time-history analyses was carried out to determine the displacement responses of 6 story and 10 story frames, the statistical results show that the vertical effect of near-fault earthquake will remarkably amplify the floor displacement and the inter-story drift demands of frame structures, to which much attention should be paid by the researchers and designers in the field of earthquake engineering.
Based on 30 sets of acceleration records of near-fault earthquake, the influence of vertical effect of near-fault earthquake on displacement demand of structures was studied.Using each set of near-fault acceleration records, a set of dynamic time-history analyses was carried out to determine the displacement responses of 6 story and 10 story frames, the statistical results show that the vertical effect of near-fault earthquake will remarkably amplify the floor displacement and the inter-story drift demands of frame structures, to which much attention should be paid by the researchers and designers in the field of earthquake engineering.
2013, 43(6): 67-70,104.
doi: 10.13204/j.gyjz201306015
Abstract:
The analysis of dynamic responses of a reinforced concrete pier with eccentricity based on fiber unit model under strong earthquake was carried out.Through the analysis of damage status of section, residual deformation, the time history of deformation and the strain time history of concrete, the characteristic of the eccentric pier was discussed, when very large one-way deformation and residual deformation occurred in the direction of beam cantilever.It was pointed out that the direction should be considered even if the unidirectional seismic wave was inputted while analyzing the earthquake response of eccentric piers, the input of bidirectional earthquake wave had a great influence on residual deformation.
The analysis of dynamic responses of a reinforced concrete pier with eccentricity based on fiber unit model under strong earthquake was carried out.Through the analysis of damage status of section, residual deformation, the time history of deformation and the strain time history of concrete, the characteristic of the eccentric pier was discussed, when very large one-way deformation and residual deformation occurred in the direction of beam cantilever.It was pointed out that the direction should be considered even if the unidirectional seismic wave was inputted while analyzing the earthquake response of eccentric piers, the input of bidirectional earthquake wave had a great influence on residual deformation.
2013, 43(6): 71-75.
doi: 10.13204/j.gyjz201306016
Abstract:
To study the effects of surface deformation on hydraulic structure due to coal mining subsidence, an experiment system for soil hydraulic structure interface was developed to investigate the interface behavior under water.A series of soil-structure shear tests using the orthogonal experiment method were performed by that system.The influence of initial porosity ratio, initial saturation and surface roughness on mechanical behavior of soil-hydraulic structure interface.The test results showed that the system of the interface could study well the main mechanical behaviors of the interface under water and could realize the function of common direct shear apparatus.By means of range analysis and variance analysis, the results showed the initial porosity ratio designed had little impact on the shear strength.The initial saturation had a significant impact on the shear strength, which was affected by the method under water in saturated condition.Surface roughness had an impact on the shear strength, but more research was needed to study the influence rule.
To study the effects of surface deformation on hydraulic structure due to coal mining subsidence, an experiment system for soil hydraulic structure interface was developed to investigate the interface behavior under water.A series of soil-structure shear tests using the orthogonal experiment method were performed by that system.The influence of initial porosity ratio, initial saturation and surface roughness on mechanical behavior of soil-hydraulic structure interface.The test results showed that the system of the interface could study well the main mechanical behaviors of the interface under water and could realize the function of common direct shear apparatus.By means of range analysis and variance analysis, the results showed the initial porosity ratio designed had little impact on the shear strength.The initial saturation had a significant impact on the shear strength, which was affected by the method under water in saturated condition.Surface roughness had an impact on the shear strength, but more research was needed to study the influence rule.
2013, 43(6): 76-83.
doi: 10.13204/j.gyjz201306017
Abstract:
One-dimensional electroosmotic laboratory test was conducted in saturated soft clay under one dimensional electroosmotic consolidation test device, by monitoring current, voltage, potentials, the amount of drainage in the process of electroosmosis, and initial and final moisture content and shear strength, electrical permeability coefficient, electric migration coefficient, energy consumption coefficient were used to study electroosmotic drainage condition under the way of different power output.The test results showed that compared to stabilized output way of voltage, the cumulative amount of drainage was smaller and drainage rate was more slowly, change amplitude of effective potential utilization rate was slight, electric coefficient of permeability and electric migration coefficient decay were faster, and the overall decline value of the moisture content and normalized shear strength were slightly larger in the mode of the voltage and current.Compared to the mode of constant-current output, cumulative displacement was larger and drainage rate was faster, change amplitude of effective potential utilization rate was small, electric coefficient of permeability and electric migration coefficient attenuation were more slowly, and the overall decline value of the moisture content and normalized shear strength were larger in the mode of current and voltage.By contrasting to energy consumption coefficient under the different way of hybrid power output, drawing the electroosmosis condition in the mode of current and voltage was more economic and reasonable.
One-dimensional electroosmotic laboratory test was conducted in saturated soft clay under one dimensional electroosmotic consolidation test device, by monitoring current, voltage, potentials, the amount of drainage in the process of electroosmosis, and initial and final moisture content and shear strength, electrical permeability coefficient, electric migration coefficient, energy consumption coefficient were used to study electroosmotic drainage condition under the way of different power output.The test results showed that compared to stabilized output way of voltage, the cumulative amount of drainage was smaller and drainage rate was more slowly, change amplitude of effective potential utilization rate was slight, electric coefficient of permeability and electric migration coefficient decay were faster, and the overall decline value of the moisture content and normalized shear strength were slightly larger in the mode of the voltage and current.Compared to the mode of constant-current output, cumulative displacement was larger and drainage rate was faster, change amplitude of effective potential utilization rate was small, electric coefficient of permeability and electric migration coefficient attenuation were more slowly, and the overall decline value of the moisture content and normalized shear strength were larger in the mode of current and voltage.By contrasting to energy consumption coefficient under the different way of hybrid power output, drawing the electroosmosis condition in the mode of current and voltage was more economic and reasonable.
2013, 43(6): 84-89.
doi: 10.13204/j.gyjz201306018
Abstract:
Base stress distribution characteristics and the deformation characteristics of immersed tube tunnel in excavation and backfilling process of tunnel engineering occupy an important position.Taking one cross-section of the natural foundation in Hong Kong-Zhuhai-Macao immersed tube tunnel as research object, centrifugal model test and finite element simulation of the whole construction process with different cushion layer thickness were carried out.When excavation rebound and backfilling compression in the immersed tube tunnel, stress distribution and deformation characters of natural foundation, the strain characteristics of immersed tube structure and the influence of cushion layer thickness were revealed, which provided the design basis for the construction of immersed tube tunnel and scheme of ground treatment.The results showed that excavation unloading made basement produce arch distribution rebound.Basal stress distribution was the shape of a saddle after backfill, and only the stress in the middle of base was increasing with time and silting.The strain distribution of immersed tube plate was the shape of a saddle and strain had little change after construction.The thinning of the cushion layer thickness led to a poor smoothing effect on basal stress distribution, and recompression quantity and foundation settlement after construction become large.
Base stress distribution characteristics and the deformation characteristics of immersed tube tunnel in excavation and backfilling process of tunnel engineering occupy an important position.Taking one cross-section of the natural foundation in Hong Kong-Zhuhai-Macao immersed tube tunnel as research object, centrifugal model test and finite element simulation of the whole construction process with different cushion layer thickness were carried out.When excavation rebound and backfilling compression in the immersed tube tunnel, stress distribution and deformation characters of natural foundation, the strain characteristics of immersed tube structure and the influence of cushion layer thickness were revealed, which provided the design basis for the construction of immersed tube tunnel and scheme of ground treatment.The results showed that excavation unloading made basement produce arch distribution rebound.Basal stress distribution was the shape of a saddle after backfill, and only the stress in the middle of base was increasing with time and silting.The strain distribution of immersed tube plate was the shape of a saddle and strain had little change after construction.The thinning of the cushion layer thickness led to a poor smoothing effect on basal stress distribution, and recompression quantity and foundation settlement after construction become large.
2013, 43(6): 90-94,116.
doi: 10.13204/j.gyjz201306019
Abstract:
The effective compressive stress and prestress loss in manufacture and curing of larger-diameter prestressed high concrete(PHC) pipe piles were studied by a field experiment performanced for two pipes of PHC with 1 400 mm diameter and different lengths.Pasting the strain gauges on prestresed steel bars directly was used for testing the prestress for the first time, and the designed prestress and the distribution of different section in different manufacture stage were compared with the experimental results.The results showed that tensile stress of prestressed steel bar was a linear decreasing trend form tension section to anchor section after forming by centrifugal technics;the effective tensile stress of prestressed steel bar and the effective compressive stress of concrete in two pipes were much lower than the theoretical data.The loss of prestress of PHC pipe piles was much greater during releasing tension than during other process.the prestress distribution of each section was not uniform but the midsection was much better which had a increasing trend with time growth.
The effective compressive stress and prestress loss in manufacture and curing of larger-diameter prestressed high concrete(PHC) pipe piles were studied by a field experiment performanced for two pipes of PHC with 1 400 mm diameter and different lengths.Pasting the strain gauges on prestresed steel bars directly was used for testing the prestress for the first time, and the designed prestress and the distribution of different section in different manufacture stage were compared with the experimental results.The results showed that tensile stress of prestressed steel bar was a linear decreasing trend form tension section to anchor section after forming by centrifugal technics;the effective tensile stress of prestressed steel bar and the effective compressive stress of concrete in two pipes were much lower than the theoretical data.The loss of prestress of PHC pipe piles was much greater during releasing tension than during other process.the prestress distribution of each section was not uniform but the midsection was much better which had a increasing trend with time growth.
2013, 43(6): 95-99.
doi: 10.13204/j.gyjz201306020
Abstract:
In actual projects, there are many factors which may influence the ultimate bearing capacity of ground anchors.Some problems like defects in calculation method and constuction process would result in discrepancy between theorical an chorage force and actual force.Some investigation tests of pre-stressed cables were done to obtain the relationships between the axial force and the axial displacement of the prestressed cables;and to acquire how the fixed length affects the bond stress.It was also proposed some problems that easily happened in actual projects.
In actual projects, there are many factors which may influence the ultimate bearing capacity of ground anchors.Some problems like defects in calculation method and constuction process would result in discrepancy between theorical an chorage force and actual force.Some investigation tests of pre-stressed cables were done to obtain the relationships between the axial force and the axial displacement of the prestressed cables;and to acquire how the fixed length affects the bond stress.It was also proposed some problems that easily happened in actual projects.
2013, 43(6): 100-104.
doi: 10.13204/j.gyjz201306021
Abstract:
Taking the typical concrete buildings in Xi'an and Xianyang and their periphery county cities as research objects, more than 1 000 structures were investigated.The concrete strength, reinforcing bar properties and component dimension parameters were statistically analyzed.The influence of some factors such as preparation process, stirring method and construction level on material properties and dimension parameters were analyzed.The results show that the strength mean of commercial concrete is close to strength mean of self-mixing concrete, but the strength variation of commercial concrete is smaller.In addition to the concrete strength of floor is higher, the concrete strengths of other elements are basically the same.The higher the building company's qualification, the higher is the concrete strength and the smaller is the strength variation.Reinforcing bar properties are good and their performance difference of different manufacturers is not big.The control level of dominant geometric parameter is better, but the control level of hidden geometric parameter is poor and its variation is large.
Taking the typical concrete buildings in Xi'an and Xianyang and their periphery county cities as research objects, more than 1 000 structures were investigated.The concrete strength, reinforcing bar properties and component dimension parameters were statistically analyzed.The influence of some factors such as preparation process, stirring method and construction level on material properties and dimension parameters were analyzed.The results show that the strength mean of commercial concrete is close to strength mean of self-mixing concrete, but the strength variation of commercial concrete is smaller.In addition to the concrete strength of floor is higher, the concrete strengths of other elements are basically the same.The higher the building company's qualification, the higher is the concrete strength and the smaller is the strength variation.Reinforcing bar properties are good and their performance difference of different manufacturers is not big.The control level of dominant geometric parameter is better, but the control level of hidden geometric parameter is poor and its variation is large.
2013, 43(6): 105-116.
doi: 10.13204/j.gyjz201306022
Abstract:
In the paper, the seismic analysis methods, fine theoretical model, and structural vibration control were summarized to illustrate the advance on seismic analysis theory of spatial structure over last thirty years in China.Meanwhile, the typical achievements on seismic analysis and design for spatial structures were listed as well.In addition, the further development of seismic analysis and design method for spatial structures which related to complexity analysis theory and performancebased seismic design method were discussed at last.
In the paper, the seismic analysis methods, fine theoretical model, and structural vibration control were summarized to illustrate the advance on seismic analysis theory of spatial structure over last thirty years in China.Meanwhile, the typical achievements on seismic analysis and design for spatial structures were listed as well.In addition, the further development of seismic analysis and design method for spatial structures which related to complexity analysis theory and performancebased seismic design method were discussed at last.
2013, 43(6): 117-119,66.
doi: 10.13204/j.gyjz201306023
Abstract:
The bearing capacity of pulling and compression on single angle steel with local deformation was tested:local deformation could low down the bearing capacity of single angle steel, and low down more with the deformation getting bigger.Local deformation had greater influences on compression bearing capacity than pulling, but the influence of the mode of inside and outside deformation was very small.
The bearing capacity of pulling and compression on single angle steel with local deformation was tested:local deformation could low down the bearing capacity of single angle steel, and low down more with the deformation getting bigger.Local deformation had greater influences on compression bearing capacity than pulling, but the influence of the mode of inside and outside deformation was very small.
2013, 43(6): 120-123.
doi: 10.13204/j.gyjz201306024
Abstract:
Distortional buckling is one of the most important buckling modes for cold-formed lipped channel sections as well as local buckling and global buckling may change mechanical properties and decrease the ultimate load of members.It was reviewed the researches on distortional buckling and compared the existed design methods according to five national(regional) codes and the latest research achievements.Based on the comparison between five calculated data and test results, it was shown that the direct strength method of North American specification has widespread application and relative high accuracy.
Distortional buckling is one of the most important buckling modes for cold-formed lipped channel sections as well as local buckling and global buckling may change mechanical properties and decrease the ultimate load of members.It was reviewed the researches on distortional buckling and compared the existed design methods according to five national(regional) codes and the latest research achievements.Based on the comparison between five calculated data and test results, it was shown that the direct strength method of North American specification has widespread application and relative high accuracy.
2013, 43(6): 124-128.
doi: 10.13204/j.gyjz201306025
Abstract:
It was presented a new light-weight energy-saving composite floor slab, which composed of light-gauge shaped steel, thermal insulation core material and thin panel.The light-weight energy-saving composite floor slab integrates the functions of enclosure, separation, heat-insulation and load-bearing.The paper presented the test of six floor slab specimens in full-scale under concentrated load.According to the damage process and test data, it was studied damage pattern and forced featurse of the floor slab.It was put forward that suggestions on creating calculation formula of bending capacity, and the test data provided a basis for working out relevant codes in the future.
It was presented a new light-weight energy-saving composite floor slab, which composed of light-gauge shaped steel, thermal insulation core material and thin panel.The light-weight energy-saving composite floor slab integrates the functions of enclosure, separation, heat-insulation and load-bearing.The paper presented the test of six floor slab specimens in full-scale under concentrated load.According to the damage process and test data, it was studied damage pattern and forced featurse of the floor slab.It was put forward that suggestions on creating calculation formula of bending capacity, and the test data provided a basis for working out relevant codes in the future.
2013, 43(6): 129-133,137.
doi: 10.13204/j.gyjz201306026
Abstract:
In order to know the effect of embedded wallboard on the mechanical behavior of steel frame and the spatial mechanical behavior of steel frame with wallboard, ANSYS was used to establish the strong axis and weak axis plane framework with wallboard to analyze the effect of the wallboard on empty frame.On this basis, a single span two-layer space frame model was established to analyze the spatial mechanical behavior of steel frame with different disposal of wallboard.The result shows that the longitudinal framework with wallboard can make the bearing capacity of horizontal empty framework increase by more than 20%.It can be designed the steel frame with walls by setting the spring unit in each story of the empty frame.This way was verified by analyzing the six-story frame structure.
In order to know the effect of embedded wallboard on the mechanical behavior of steel frame and the spatial mechanical behavior of steel frame with wallboard, ANSYS was used to establish the strong axis and weak axis plane framework with wallboard to analyze the effect of the wallboard on empty frame.On this basis, a single span two-layer space frame model was established to analyze the spatial mechanical behavior of steel frame with different disposal of wallboard.The result shows that the longitudinal framework with wallboard can make the bearing capacity of horizontal empty framework increase by more than 20%.It can be designed the steel frame with walls by setting the spring unit in each story of the empty frame.This way was verified by analyzing the six-story frame structure.
2013, 43(6): 134-137.
doi: 10.13204/j.gyjz201306027
Abstract:
During the design and calculation of bolt connection of main and secondary girder, the force arm of additional moment usually takes the value which is the distance from the centroid of the bolt group in secondary girder to central line of the main girder web, the calculation method of additional moment caused by the eccentricity is not accurate with the actual stressing state.Monotonic static tests were conducted on the steel beam-and-girder bolt nodes, and yield load, ultimate bearing capacity and ultimate deformability of bolt connection of main and secondary girder were explored.Meanwhile, the finite element software ANSYS was employed to simulate the models of bolt connection of main and secondary girder, and comparison was made between the results of test, finite element calculation and routine analysis method.Finally, a method for the value of eccentricity of bearing capacity calculation of bolts in connection of main and secondary girder was proposed, the result was accord well with the test and finite element analysis ones.
During the design and calculation of bolt connection of main and secondary girder, the force arm of additional moment usually takes the value which is the distance from the centroid of the bolt group in secondary girder to central line of the main girder web, the calculation method of additional moment caused by the eccentricity is not accurate with the actual stressing state.Monotonic static tests were conducted on the steel beam-and-girder bolt nodes, and yield load, ultimate bearing capacity and ultimate deformability of bolt connection of main and secondary girder were explored.Meanwhile, the finite element software ANSYS was employed to simulate the models of bolt connection of main and secondary girder, and comparison was made between the results of test, finite element calculation and routine analysis method.Finally, a method for the value of eccentricity of bearing capacity calculation of bolts in connection of main and secondary girder was proposed, the result was accord well with the test and finite element analysis ones.
2013, 43(6): 138-140,156.
doi: 10.13204/j.gyjz201306028
Abstract:
Current energy consumption situations of 83 existing public buildings of cold regions in Jiangsu were investigated.Based on the accurate information collected during the survey, energy-consumption conditions of different kinds of public buildings were analyzed.Combining energy-efficient reconstruction project and simulation analysis comparison using software, energy-efficient reconstruction suggestions on existing public buildings in this area were also put forward, which could be seclected in practice.
Current energy consumption situations of 83 existing public buildings of cold regions in Jiangsu were investigated.Based on the accurate information collected during the survey, energy-consumption conditions of different kinds of public buildings were analyzed.Combining energy-efficient reconstruction project and simulation analysis comparison using software, energy-efficient reconstruction suggestions on existing public buildings in this area were also put forward, which could be seclected in practice.
2013, 43(6): 141-145.
doi: 10.13204/j.gyjz201306029
Abstract:
The in-patient building of a hospital is a structure with three layers of brick and concrete, built in 1976, class B building.There are cracks on the upper wall by the uneven subsidence due to foundation flooding, and the seismic design of the original structure was not fully realized, the seismic capacity is low.According to the status of the building the static pressing pile was used, concrete structural columns and beam were added to stabilize the foundation of structure, and strengthen the constraints of the upper structure, so as to raise its integrity and seismic ability obviously, and a good seismic reinforcement effect was got to guarantee the safe use of the structure within its follow-up life of 20 years.
The in-patient building of a hospital is a structure with three layers of brick and concrete, built in 1976, class B building.There are cracks on the upper wall by the uneven subsidence due to foundation flooding, and the seismic design of the original structure was not fully realized, the seismic capacity is low.According to the status of the building the static pressing pile was used, concrete structural columns and beam were added to stabilize the foundation of structure, and strengthen the constraints of the upper structure, so as to raise its integrity and seismic ability obviously, and a good seismic reinforcement effect was got to guarantee the safe use of the structure within its follow-up life of 20 years.
2013, 43(6): 146-149.
doi: 10.13204/j.gyjz201306030
Abstract:
In the concrete structure, the stress may change with load and tempercture etc.For crack depth testing by NDT methods, the stress condition of crack surface must be considered, especially for deep crack.In this paper, the results by large concrete block test were got.It was compared the difference between several representative nondestructive testing methods at the different stress conditions.The results show that the tested crack depth may be underestimated seriously by phase inversion methodand propagation time method, and the surface wave method performs better when the compressive stress on the crack surface is equal to, or less than 5 MPa.
In the concrete structure, the stress may change with load and tempercture etc.For crack depth testing by NDT methods, the stress condition of crack surface must be considered, especially for deep crack.In this paper, the results by large concrete block test were got.It was compared the difference between several representative nondestructive testing methods at the different stress conditions.The results show that the tested crack depth may be underestimated seriously by phase inversion methodand propagation time method, and the surface wave method performs better when the compressive stress on the crack surface is equal to, or less than 5 MPa.
2013, 43(6): 150-156.
doi: 10.13204/j.gyjz201306031
Abstract:
Metal roofing has been widely used in building projects in China, but there were many problems in application.It was introduced the main problems such as structure, fire protection, waterproofing and thermal performance etc of current metal roofings, and the main reasons for these problems were analyzed and summarized.In order to improve the quality of metal roofing projects, it is necessary to improve the technical level and strengthen the industry management.
Metal roofing has been widely used in building projects in China, but there were many problems in application.It was introduced the main problems such as structure, fire protection, waterproofing and thermal performance etc of current metal roofings, and the main reasons for these problems were analyzed and summarized.In order to improve the quality of metal roofing projects, it is necessary to improve the technical level and strengthen the industry management.
2013, 43(6): 157-159.
doi: 10.13204/j.gyjz201306032
Abstract:
In the numerous and complicated trends in architecture, BIG's idea and works are unique.With analyzing BIG's experimental works, this paper talks about their resolution on people's lifestyle and emotional experience, and explores their special understanding and persistent architectural ideal.In a way of showing free and kind form and abundant experiences, their works endow the architecture with a strong appeal.In addition, they demonstrate the value of human and society.
In the numerous and complicated trends in architecture, BIG's idea and works are unique.With analyzing BIG's experimental works, this paper talks about their resolution on people's lifestyle and emotional experience, and explores their special understanding and persistent architectural ideal.In a way of showing free and kind form and abundant experiences, their works endow the architecture with a strong appeal.In addition, they demonstrate the value of human and society.
2013, 43(6): 160-162.
doi: 10.13204/j.gyjz201306033
Abstract:
Industrial building is a sign to reflect the architectural culture in an era, industrial building renovation is also a trend of architectural development in modern history.Under the current architectural history, it is one of the important steps to research the process of renewing and reproducing the materials of building surface to study industrial building renovation and utilization in Qingdao.The dissertation will study renewing and reproducing the materials of building surface through a part of practical case study in Qingdao, summarizing the characteristics and methods of implementation and renovation, in order to offer some reference and guidance to reuse of old industrial buildings.
Industrial building is a sign to reflect the architectural culture in an era, industrial building renovation is also a trend of architectural development in modern history.Under the current architectural history, it is one of the important steps to research the process of renewing and reproducing the materials of building surface to study industrial building renovation and utilization in Qingdao.The dissertation will study renewing and reproducing the materials of building surface through a part of practical case study in Qingdao, summarizing the characteristics and methods of implementation and renovation, in order to offer some reference and guidance to reuse of old industrial buildings.
2013, 43(6): 163-166,159.
doi: 10.13204/j.gyjz201306034
Abstract:
Through the contrast of two dimensional comprehensive pipeline design and three dimensional comprehensive pipeline design based on BIM technology, combined with the operation and analysis of specific engineering practice, it is pointed out that the application of three dimensional comprehensive pipeline design based on BIM technology in the subway station is groundbreaking and significant.
Through the contrast of two dimensional comprehensive pipeline design and three dimensional comprehensive pipeline design based on BIM technology, combined with the operation and analysis of specific engineering practice, it is pointed out that the application of three dimensional comprehensive pipeline design based on BIM technology in the subway station is groundbreaking and significant.
