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2020 Vol. 50, No. 12
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2020, 50(12): 1-7.
doi: 10.13204/j.gyjzG19092502
Abstract:
Microbial mineralized geotechnical materials are new kinds of rock-like green materials, which matrix particles are cemented and pores are filled with calcium carbonate precipitation induced by mineralization properties of microbial metabolism. The curves of pore-size distribution for the material after enduring drying-wetting cycles and corroded by different salt solutions were obtained by NMR, the relationships between the pore size and porosity were analyzed, and the change rule of the micro-pore structure for the material was studied. The results showed that under the combined action of corrosion and dry-wet cycling, the material would be destroyed sooner, which was characterized by spalling and loss of particles, and the damage would be aggravated under the condition of compound salt. During the process of salt corrosion and dry-wet cycling, the porosity of materials was related to the degree of material damage and exfoliation, and the pore-size distribution of different pores in the materials changed continuously with the increase of cycles. The pore-size distribution of macropores (100 to 1 000 μm) was the most and increasing with the increase of cycles. The cumulative changes of micropores (<1 μm) were significantly correlated with the porosity which characterized the degree of material damage. The research results could provide references to the engineering practices of the materials in the salt environment from the perspective of micro-pore structure changes.
Microbial mineralized geotechnical materials are new kinds of rock-like green materials, which matrix particles are cemented and pores are filled with calcium carbonate precipitation induced by mineralization properties of microbial metabolism. The curves of pore-size distribution for the material after enduring drying-wetting cycles and corroded by different salt solutions were obtained by NMR, the relationships between the pore size and porosity were analyzed, and the change rule of the micro-pore structure for the material was studied. The results showed that under the combined action of corrosion and dry-wet cycling, the material would be destroyed sooner, which was characterized by spalling and loss of particles, and the damage would be aggravated under the condition of compound salt. During the process of salt corrosion and dry-wet cycling, the porosity of materials was related to the degree of material damage and exfoliation, and the pore-size distribution of different pores in the materials changed continuously with the increase of cycles. The pore-size distribution of macropores (100 to 1 000 μm) was the most and increasing with the increase of cycles. The cumulative changes of micropores (<1 μm) were significantly correlated with the porosity which characterized the degree of material damage. The research results could provide references to the engineering practices of the materials in the salt environment from the perspective of micro-pore structure changes.
2020, 50(12): 8-14,7.
doi: 10.13204/j.gyjzG20062207
Abstract:
Microbial-induced calcite precipitation (MICP) can effectively improve the strength of sand, while rubber-particle sand compacted with sandy soil is of low densities, strong elastic deformation capacity, high energy dissipation capacity and low elastic modulus than that of pure sand. Therefore, a method of improving soil combined with rubber particles and the MICP tachnique was proposed. The influence of rubber-particle contents on microbial induced calcium carbonate precipitation was analyzed. Based on the resonant-column test, the effects of rubber contents and confining pressure on dynamic shear modulus and equivalent damping ratios of the mixed soil were compared. The unconfined compressive strength of the mixed soil could be improved when the contents of rubber particles were in a cartain range (about 3%). The confining pressure and the contents of rubber particles were the main factors affecting the dynamic moduli and damping ratios of the soil. The higher the confining pressure, the greater the dynamic modulus and the slower the attenuation of damping ratios, and the smaller the damping ratios; under the constant confining pressure, the higher the rubber contents, the slower the attenuation of the dynamic modulus, and the larger the damping ratios.
Microbial-induced calcite precipitation (MICP) can effectively improve the strength of sand, while rubber-particle sand compacted with sandy soil is of low densities, strong elastic deformation capacity, high energy dissipation capacity and low elastic modulus than that of pure sand. Therefore, a method of improving soil combined with rubber particles and the MICP tachnique was proposed. The influence of rubber-particle contents on microbial induced calcium carbonate precipitation was analyzed. Based on the resonant-column test, the effects of rubber contents and confining pressure on dynamic shear modulus and equivalent damping ratios of the mixed soil were compared. The unconfined compressive strength of the mixed soil could be improved when the contents of rubber particles were in a cartain range (about 3%). The confining pressure and the contents of rubber particles were the main factors affecting the dynamic moduli and damping ratios of the soil. The higher the confining pressure, the greater the dynamic modulus and the slower the attenuation of damping ratios, and the smaller the damping ratios; under the constant confining pressure, the higher the rubber contents, the slower the attenuation of the dynamic modulus, and the larger the damping ratios.
2020, 50(12): 15-18,49.
doi: 10.13204/j.gyjzG20052521
Abstract:
MICP is a research hotspot in soil improvement in recent years. However, the mechanical properties of sand cemented by MICP and conventional improvement with cement have not been sufficiently compared. To further clarify the mechanical properties of sand columns cemented by MICP and sand columns cemented with cement, sand columns comented by MICP or with cement were made, and the tests of unconfined compressive strength and splitting-tensile strength were performed. The test results showed that: the unconfined strength values of sand columns cemented by MICP with calcium carbonate contents of 7.1% and 10.4% were 221% and 117% of that cemented with cement of contents 7.14% and 10%, its splitting tensile strength were 609% and 228% of that cemented with cement. In a word, when the calcium carbonate content was as similar as the cement content, the unconfined compressive strength and splitting-tensile strength of sand columns cemented by MICP were higher than those of cement mortar.
MICP is a research hotspot in soil improvement in recent years. However, the mechanical properties of sand cemented by MICP and conventional improvement with cement have not been sufficiently compared. To further clarify the mechanical properties of sand columns cemented by MICP and sand columns cemented with cement, sand columns comented by MICP or with cement were made, and the tests of unconfined compressive strength and splitting-tensile strength were performed. The test results showed that: the unconfined strength values of sand columns cemented by MICP with calcium carbonate contents of 7.1% and 10.4% were 221% and 117% of that cemented with cement of contents 7.14% and 10%, its splitting tensile strength were 609% and 228% of that cemented with cement. In a word, when the calcium carbonate content was as similar as the cement content, the unconfined compressive strength and splitting-tensile strength of sand columns cemented by MICP were higher than those of cement mortar.
2020, 50(12): 19-24,118.
doi: 10.13204/j.gyjzG20021404
Abstract:
In the light of the increasingly serious dust pollution, the technique of soybean urease induced calcium carbonate deposition (EICP) was used to control the dust of exposed silt in the flood area of the Yellow River. The reaction solution of soybean urease extracted by centrifugation and urea-calcium chloride was used to cement the silt in the flood area of the Yellow River,and the indoor wind resistance test, calcium carbonate production test and surface strength test were conducted. The results showed that the technique of soybean urease induced carbonate precipitation could form a crust in the surface of silty soil, which made the surface soil particles cement together and have the characteristics of wind erosion resistance. In order to further reveal the effectiveness of EICP in the treatment of dust, the effects of different concentrations of reaction solution, mass concentrations of soybean powder and sprayed amounts on cementing effect of silt were studied. The results showed that the mass loss of soil specimens decreased with the increase of the concentration of reaction solution, the mass concentration of the soybean powder and the amounts of being sprayed, when the reaction solution concentration was 0.08 mol/L, the mass concentration of soybean powder was 40 g/L and the volume of treatment solution was 4 L/m2, the mass loss of EICP cemented specimens was zero, the specimens were of good wind erosion resistance characteristics.
In the light of the increasingly serious dust pollution, the technique of soybean urease induced calcium carbonate deposition (EICP) was used to control the dust of exposed silt in the flood area of the Yellow River. The reaction solution of soybean urease extracted by centrifugation and urea-calcium chloride was used to cement the silt in the flood area of the Yellow River,and the indoor wind resistance test, calcium carbonate production test and surface strength test were conducted. The results showed that the technique of soybean urease induced carbonate precipitation could form a crust in the surface of silty soil, which made the surface soil particles cement together and have the characteristics of wind erosion resistance. In order to further reveal the effectiveness of EICP in the treatment of dust, the effects of different concentrations of reaction solution, mass concentrations of soybean powder and sprayed amounts on cementing effect of silt were studied. The results showed that the mass loss of soil specimens decreased with the increase of the concentration of reaction solution, the mass concentration of the soybean powder and the amounts of being sprayed, when the reaction solution concentration was 0.08 mol/L, the mass concentration of soybean powder was 40 g/L and the volume of treatment solution was 4 L/m2, the mass loss of EICP cemented specimens was zero, the specimens were of good wind erosion resistance characteristics.
2020, 50(12): 25-31,179.
doi: 10.13204/j.gyjzG20062910
Abstract:
In the context of rural revitalization, the study of transformation for rural spaces has dual significances of continuing the agricultural tradition and maintaining the harmonious development of rural social structure. From the perspective of spatial syntax, taking Peicheng Village in Henan as an example, a quantitative research model was established before and after the rural dynamic renewal. By quantitative comparisons of spatial integration, comprehensibility, and street network density before and after village renewal, the change laws in rural space accessibility, spatial structure, and village centers were concluded, which could provide references to quantitative analysis on formulation of planning in rural protection and development, study on the impact of local renewal on the overall spatial structure of rural areas, and choice of sites for rural renewal practice.
In the context of rural revitalization, the study of transformation for rural spaces has dual significances of continuing the agricultural tradition and maintaining the harmonious development of rural social structure. From the perspective of spatial syntax, taking Peicheng Village in Henan as an example, a quantitative research model was established before and after the rural dynamic renewal. By quantitative comparisons of spatial integration, comprehensibility, and street network density before and after village renewal, the change laws in rural space accessibility, spatial structure, and village centers were concluded, which could provide references to quantitative analysis on formulation of planning in rural protection and development, study on the impact of local renewal on the overall spatial structure of rural areas, and choice of sites for rural renewal practice.
2020, 50(12): 32-41.
doi: 10.13204/j.gyjzG19112606
Abstract:
In the offshore atmospheric environment, the corrosion of steel bars will lead to the seismic behavior of shear wall structures degenerated. It is necessary to establish the seismic fragility model of corroded RC shear wall structures. The typical shear wall structure was taken as the research object. Based on PERFORM-3D, the corrosion of steel bars in the offshore atmosphere was mainly considered by the principle of material degradation, and the numerical models of RC shear wall structures were established by fiber model. Taking PGA as the intensity index of ground motion, 22 seismic waves were amplitude modulated, and the demand model parameters of typical structures corresponding to different layers with different ages were obtained. The performance index limit of multi-aged RC shear wall structures was defined, and the seismic fragility analysis of typical shear wall structures of different layers with different ages under the condition of seismic fortification intensity 8 was carried out respectively. The results showed that with the increase of age, the probability of exceeding limit state of typical shear wall structures with different layers increased.
In the offshore atmospheric environment, the corrosion of steel bars will lead to the seismic behavior of shear wall structures degenerated. It is necessary to establish the seismic fragility model of corroded RC shear wall structures. The typical shear wall structure was taken as the research object. Based on PERFORM-3D, the corrosion of steel bars in the offshore atmosphere was mainly considered by the principle of material degradation, and the numerical models of RC shear wall structures were established by fiber model. Taking PGA as the intensity index of ground motion, 22 seismic waves were amplitude modulated, and the demand model parameters of typical structures corresponding to different layers with different ages were obtained. The performance index limit of multi-aged RC shear wall structures was defined, and the seismic fragility analysis of typical shear wall structures of different layers with different ages under the condition of seismic fortification intensity 8 was carried out respectively. The results showed that with the increase of age, the probability of exceeding limit state of typical shear wall structures with different layers increased.
2020, 50(12): 42-49.
doi: 10.13204/j.gyjz201907080013
Abstract:
To promote the research and application of recycled concrete and study the mechanical properties of fiber-reinforced recycled concrete(FRC) precast composite wallboard, two FRC prefabricated composite wall specimens and one ordinary concrete prefabricated composite wall specimen were designed and tested. The experiment aimed to study the failure phenomenon, failure mechanism and hysteresis characteristics of FRC prefabricated composite walls, and to explore the influence of different precast wallboard materials on stiffness degradation, strength degradation, deformation curve, energy dissipation capacity and residual deformation rate of the wall. The test results showed that FRC prefabricated composite walls showed an obvious bending-shear failure mode, and the stiffness degradation was gentle, which was consistent with the degradation law of ordinary concrete specimen; different materials mainly affected the stiffness on the yield point, and had almost no influence on the later stiffness; the strength degradation law of the three specimens was similar, while the strength degradation of FRC specimens was more stable than that of the ordinary concrete specimen after peak load. Compared with the ordinary concrete specimen, the peak load of two FRC specimens decreased by 2.1% and 2.6% respectively, and the ductility coefficient increased by 28.0% and 27.4% respectively. The FEC walls showed a good comprehensive performance and could be applied to 12-storey prefabricated composite wall structure based on effective design.
To promote the research and application of recycled concrete and study the mechanical properties of fiber-reinforced recycled concrete(FRC) precast composite wallboard, two FRC prefabricated composite wall specimens and one ordinary concrete prefabricated composite wall specimen were designed and tested. The experiment aimed to study the failure phenomenon, failure mechanism and hysteresis characteristics of FRC prefabricated composite walls, and to explore the influence of different precast wallboard materials on stiffness degradation, strength degradation, deformation curve, energy dissipation capacity and residual deformation rate of the wall. The test results showed that FRC prefabricated composite walls showed an obvious bending-shear failure mode, and the stiffness degradation was gentle, which was consistent with the degradation law of ordinary concrete specimen; different materials mainly affected the stiffness on the yield point, and had almost no influence on the later stiffness; the strength degradation law of the three specimens was similar, while the strength degradation of FRC specimens was more stable than that of the ordinary concrete specimen after peak load. Compared with the ordinary concrete specimen, the peak load of two FRC specimens decreased by 2.1% and 2.6% respectively, and the ductility coefficient increased by 28.0% and 27.4% respectively. The FEC walls showed a good comprehensive performance and could be applied to 12-storey prefabricated composite wall structure based on effective design.
2020, 50(12): 50-54,68.
doi: 10.13204/j.gyjzG19113014
Abstract:
In order to reasonably evaluate the residual bending capacity of existing corroded reinforced concrete beams and establish a reasonable and scientific calculation model for the flexural capacity of corroded reinforced concrete beams, considering the degradation of mechanical properties and section damage of sulfuric acid corrosion concrete, the degradation of mechanical properties of corrosion reinforcement and the influence of reinforcement strength utilization coefficient, a calculation method of flexural bearing capacity of reinforced concrete beams after sulfuric acid corrosion was proposed. Calcalated results were in good agreement with experimental ones. The results showed that with the decrease of pH value, the influence of sulfuric acid corrosion on the flexural capacity of beams increased; the higher the strength grade of concrete, the faster the bearing capacity of beams decreased; when the reinforcement was not corroded, the bearing capacity of beams decreased with the increase of the thickness of concrete corrosion layer.
In order to reasonably evaluate the residual bending capacity of existing corroded reinforced concrete beams and establish a reasonable and scientific calculation model for the flexural capacity of corroded reinforced concrete beams, considering the degradation of mechanical properties and section damage of sulfuric acid corrosion concrete, the degradation of mechanical properties of corrosion reinforcement and the influence of reinforcement strength utilization coefficient, a calculation method of flexural bearing capacity of reinforced concrete beams after sulfuric acid corrosion was proposed. Calcalated results were in good agreement with experimental ones. The results showed that with the decrease of pH value, the influence of sulfuric acid corrosion on the flexural capacity of beams increased; the higher the strength grade of concrete, the faster the bearing capacity of beams decreased; when the reinforcement was not corroded, the bearing capacity of beams decreased with the increase of the thickness of concrete corrosion layer.
2020, 50(12): 55-63.
doi: 10.13204/j.gyjz201907170003
Abstract:
Standard for Seismic Design of Industrial Buildings is being compiled, in which the structural categories are divided into three categories: plastic structure, elastic-plastic structure and elastic structure. Moreover, the structural performance coefficient q used in all kinds of types is proposed to adjust the seismic effect combination. For elastic structures, it is proposed that the performance coefficient q=2.0 and qh=2.5 can be used for seismic calculation. In this study, the existing single-story single-span and multi-span bent structure were taken as examples and considered as elastic structure, the plane calculation model was established by using the improved PKPM software. The seismic effect was calculated under different fortification intensities. Under the intensity when the stress ratio of the column exceeded 1.0 for the first time, the elastic-plastic time history analysis of large earthquakes was carried out. It was clarified that the single-story industrial factory building would not collapse in large earthquakes on the premise of meeting the requirements of elastic structure design.
Standard for Seismic Design of Industrial Buildings is being compiled, in which the structural categories are divided into three categories: plastic structure, elastic-plastic structure and elastic structure. Moreover, the structural performance coefficient q used in all kinds of types is proposed to adjust the seismic effect combination. For elastic structures, it is proposed that the performance coefficient q=2.0 and qh=2.5 can be used for seismic calculation. In this study, the existing single-story single-span and multi-span bent structure were taken as examples and considered as elastic structure, the plane calculation model was established by using the improved PKPM software. The seismic effect was calculated under different fortification intensities. Under the intensity when the stress ratio of the column exceeded 1.0 for the first time, the elastic-plastic time history analysis of large earthquakes was carried out. It was clarified that the single-story industrial factory building would not collapse in large earthquakes on the premise of meeting the requirements of elastic structure design.
2020, 50(12): 64-68.
doi: 10.13204/j.gyjzG201906280004
Abstract:
The long-span stadium is a wind-sensitive structure. Due to the difficulty in designing and manufacturing the aeroelastic model, there is still little wind tunnel test of such structure. In this paper, an aeroelastic model of a long-span stadium was manufactured and tested in wind tunnel. The effects of wind speed and wind direction on the displacement response were analyzed. In addition, wind pressure of the aeroelastic model were also measured to make a comparison with that of rigid model. The results showed that the maximum displacement of the roof structure occured at the position perpendicular to the wind direction. The displacement response increased with wind speed, the higher the wind speed, the higher the growth rate. It was also found that there was little difference in mean wind pressures between aeroelastic model and rigid model, while the fluctuating wind pressures of aeroelastic model were larger than that of rigid model.
The long-span stadium is a wind-sensitive structure. Due to the difficulty in designing and manufacturing the aeroelastic model, there is still little wind tunnel test of such structure. In this paper, an aeroelastic model of a long-span stadium was manufactured and tested in wind tunnel. The effects of wind speed and wind direction on the displacement response were analyzed. In addition, wind pressure of the aeroelastic model were also measured to make a comparison with that of rigid model. The results showed that the maximum displacement of the roof structure occured at the position perpendicular to the wind direction. The displacement response increased with wind speed, the higher the wind speed, the higher the growth rate. It was also found that there was little difference in mean wind pressures between aeroelastic model and rigid model, while the fluctuating wind pressures of aeroelastic model were larger than that of rigid model.
2020, 50(12): 69-75.
doi: 10.13204/j.gyjzG19111006
Abstract:
Accelerated corrosion testing on concrete specimens was carried out under the action of dry-wet cycle and constant-current power with using the mass fraction of 5% NaCl solution to investigate the degradation law of mechanical properties of concrete in chloride environment. The concrete specimens damaged by chloride erosion and coupling of chlorine-rebar corrosion were obtained, and then the compressive strength of concrete specimens was studied. The results showed that under the action of single factor for chloride erosion, the compressive strength of concrete increased first and then decreased with the increase of time of dry-wet cycle, with a maximum increase of 16.6%; under chlorine-rebar corrosion coupling, the compressive strength of concrete generally decreased with the corrosion rate of reinforcement increases, and the decrease in the early stage was faster than that in the later stage. When the corrosion rate reached 6.3%, the compressive strength was 19.4% lower than the initial undamaged strength; when the corrosion rate reached 14.9%, the compressive strength of concrete decreased by 24.5%. Corrosion damage was the main reason of the decrease of concrete strength, the corrosion rate and the corrosion-induced crack width were selected as the strength damage variables respectively to analyze regressively the test data, and consequently established the calculation models on compressive strength deterioration of concrete damaged by chlorine-corrosion coupling.
Accelerated corrosion testing on concrete specimens was carried out under the action of dry-wet cycle and constant-current power with using the mass fraction of 5% NaCl solution to investigate the degradation law of mechanical properties of concrete in chloride environment. The concrete specimens damaged by chloride erosion and coupling of chlorine-rebar corrosion were obtained, and then the compressive strength of concrete specimens was studied. The results showed that under the action of single factor for chloride erosion, the compressive strength of concrete increased first and then decreased with the increase of time of dry-wet cycle, with a maximum increase of 16.6%; under chlorine-rebar corrosion coupling, the compressive strength of concrete generally decreased with the corrosion rate of reinforcement increases, and the decrease in the early stage was faster than that in the later stage. When the corrosion rate reached 6.3%, the compressive strength was 19.4% lower than the initial undamaged strength; when the corrosion rate reached 14.9%, the compressive strength of concrete decreased by 24.5%. Corrosion damage was the main reason of the decrease of concrete strength, the corrosion rate and the corrosion-induced crack width were selected as the strength damage variables respectively to analyze regressively the test data, and consequently established the calculation models on compressive strength deterioration of concrete damaged by chlorine-corrosion coupling.
2020, 50(12): 76-81,111.
doi: 10.13204/j.gyjz201906040002
Abstract:
Concrete structures serving in cold regions are inevitably affected by freeze-thaw cycles. In this paper, the compressive constitutive relationship of self-compacting concrete after 0, 50, 100, 150, 200, 250 and 300 freeze-thaw cycles was investigated. The results showed that with the increasing freeze-thaw cycles, the mass loss of specimens increased, and the relative dynamic elastic modulus decreased. The self-compacting concrete could achieve the level of F300. The elastic modulus and peak stress of the specimen remained stable in the early stage of freeze-thaw test, and decreased significantly after 150 freeze-thaw cycles. As the number of freeze-thaw cycles increased, the peak strain decreased first and then increased, and the lateral deformation coefficient decreased. Based on the test results, the normalized compressive constitutive model of self-compacting concrete after freeze-thaw cycles was established, which was in good agreement with the experimental results.
Concrete structures serving in cold regions are inevitably affected by freeze-thaw cycles. In this paper, the compressive constitutive relationship of self-compacting concrete after 0, 50, 100, 150, 200, 250 and 300 freeze-thaw cycles was investigated. The results showed that with the increasing freeze-thaw cycles, the mass loss of specimens increased, and the relative dynamic elastic modulus decreased. The self-compacting concrete could achieve the level of F300. The elastic modulus and peak stress of the specimen remained stable in the early stage of freeze-thaw test, and decreased significantly after 150 freeze-thaw cycles. As the number of freeze-thaw cycles increased, the peak strain decreased first and then increased, and the lateral deformation coefficient decreased. Based on the test results, the normalized compressive constitutive model of self-compacting concrete after freeze-thaw cycles was established, which was in good agreement with the experimental results.
2020, 50(12): 82-87.
doi: 10.13204/j.gyjzG20011014
Abstract:
Through the double-sided shear test and four-point bending test of PVA reinforced cement-based composite, the double-characteristic indexes of toughness ratio and toughness index were used to evaluate the shear toughness and bending toughness, and the effects of different fiber content and water binder ratio on the shear toughness and bending toughness were observed. The test results showed that the ductility and energy absorption capacity of PVA reinforced tailing sand cement-based composite were significantly improved compared with those without fiber, and the shear toughness and bending toughness of the composite with fiber were better, the effect of the toughening degree of the sample was significant, and the toughness quality was greatly increased. In this test, when the water binder ratio was 0.25 to 0.3 to 0.35, the toughness ratio and toughness index increased correspondingly. When the water binder ratio was 0.35, the toughness ratio and toughness index increased obviously.
Through the double-sided shear test and four-point bending test of PVA reinforced cement-based composite, the double-characteristic indexes of toughness ratio and toughness index were used to evaluate the shear toughness and bending toughness, and the effects of different fiber content and water binder ratio on the shear toughness and bending toughness were observed. The test results showed that the ductility and energy absorption capacity of PVA reinforced tailing sand cement-based composite were significantly improved compared with those without fiber, and the shear toughness and bending toughness of the composite with fiber were better, the effect of the toughening degree of the sample was significant, and the toughness quality was greatly increased. In this test, when the water binder ratio was 0.25 to 0.3 to 0.35, the toughness ratio and toughness index increased correspondingly. When the water binder ratio was 0.35, the toughness ratio and toughness index increased obviously.
2020, 50(12): 88-92,159.
doi: 10.13204/j.gyjzG19100806
Abstract:
The waste fiber extracted from the scrap tire was used as the additional material in the concrete. The shear test of 76 pieces of 150 mm×150 mm×300 mm industrial waste fiber reinforced cement matrix composite under shear load was designed to study the effects of aspect ratio, fiber content and fiber type on the shear strength of fiber reinforced cementitious composites. The results showed that the shear capacity of fiber reinforced cementitions composited increased remarkably with the increase of fiber volume of industrial waste fiber reinforced cementitions composites, and the best effect was achieved at 1.5% volume. The shear strength of straight industrial waste fiber reinforced cementitions composites increased with the increase of aspect ratio. At the same time, the finite element analysis software ABAQUS was used for numerical simulation, and the calculated results were consistent with the test results.
The waste fiber extracted from the scrap tire was used as the additional material in the concrete. The shear test of 76 pieces of 150 mm×150 mm×300 mm industrial waste fiber reinforced cement matrix composite under shear load was designed to study the effects of aspect ratio, fiber content and fiber type on the shear strength of fiber reinforced cementitious composites. The results showed that the shear capacity of fiber reinforced cementitions composited increased remarkably with the increase of fiber volume of industrial waste fiber reinforced cementitions composites, and the best effect was achieved at 1.5% volume. The shear strength of straight industrial waste fiber reinforced cementitions composites increased with the increase of aspect ratio. At the same time, the finite element analysis software ABAQUS was used for numerical simulation, and the calculated results were consistent with the test results.
2020, 50(12): 93-97,87.
doi: 10.13204/j.gyjzG19121204
Abstract:
In order to study the bearing capacity of double-curvature cold-formed single glass, cold forming and loading tests of 8 single tempered glass plates supported by two long frames were carried out, the distribution law of internal stress in glass plate during cold forming was analyzed, the bearing capacity of cold bending glass under the coupling effect of cold-formed stress and negative load was studied through the ultimate bearing capacity test. The test results showed that the maximum cold-formed principal tensile stress increased linearly with the increase of torsional curvature and appears in the corner area of short side which adjacent to the cold forming corner. The bearing capacity decreased linearly with the increase of distortion rate. And the position of maximum stress after the coupling changed with the increase of load. Conclusion could be made that in the design of cold-formed glass, the key of bearing capacity design was to find the maximum point of cold-formed stress and the maximum point of cold-formed coupling stress, the thickness of glass plate should be designed according to the coupling of cold forming rate and external load.
In order to study the bearing capacity of double-curvature cold-formed single glass, cold forming and loading tests of 8 single tempered glass plates supported by two long frames were carried out, the distribution law of internal stress in glass plate during cold forming was analyzed, the bearing capacity of cold bending glass under the coupling effect of cold-formed stress and negative load was studied through the ultimate bearing capacity test. The test results showed that the maximum cold-formed principal tensile stress increased linearly with the increase of torsional curvature and appears in the corner area of short side which adjacent to the cold forming corner. The bearing capacity decreased linearly with the increase of distortion rate. And the position of maximum stress after the coupling changed with the increase of load. Conclusion could be made that in the design of cold-formed glass, the key of bearing capacity design was to find the maximum point of cold-formed stress and the maximum point of cold-formed coupling stress, the thickness of glass plate should be designed according to the coupling of cold forming rate and external load.
2020, 50(12): 98-101,75.
doi: 10.13204/j.gyjz201902180009
Abstract:
In order to study the influence of the support system of inclined column in the whole construction process of ancient site protection building and ensure the construction safety of Dongduo building in Luoyang Yingtianmen site, a three-dimensional finite element model of Dongduo building was established by MIDAS Gen. Considering the earth pressure, deadweight and construction load, according to the order of design and construction, the simulation analysis of the whole construction process was carried out, and the variation law of stress and deformation of inclined column bracing system during construction was studied. The analysis of the measured and calculated results showed that the influence of the original soil load on the site could not be ignored, the model considering its effect was relatively reasonable, the simulation results were close to the measured results, and the stress and deformation trends of the inclined column bracing system were basically the same. It was suggested to optimize the analysis procedure of pile-soil interaction.
In order to study the influence of the support system of inclined column in the whole construction process of ancient site protection building and ensure the construction safety of Dongduo building in Luoyang Yingtianmen site, a three-dimensional finite element model of Dongduo building was established by MIDAS Gen. Considering the earth pressure, deadweight and construction load, according to the order of design and construction, the simulation analysis of the whole construction process was carried out, and the variation law of stress and deformation of inclined column bracing system during construction was studied. The analysis of the measured and calculated results showed that the influence of the original soil load on the site could not be ignored, the model considering its effect was relatively reasonable, the simulation results were close to the measured results, and the stress and deformation trends of the inclined column bracing system were basically the same. It was suggested to optimize the analysis procedure of pile-soil interaction.
2020, 50(12): 102-111.
doi: 10.13204/j.gyjz20041001
Abstract:
The technology of fiber reinforced polymer (FRP) strengthened reinforced concrete structures has many advantages compared to the traditional strengthening technology, and it has been widely used in many practical engineering in recent years. The strengthening method mainly consists of externally bonded FRP sheets, near-surface mounted FRP bars and FRP grids strengthening. When FRP is used for strengthening buildings, it must meet the requirements of fire resistance standard of buildings. Thus understanding the fire resistance of reinforced concrete beams strengthened with FRP is an important precondition for using this technology into structural strengthening of buildings. This paper presented a state-of-the-art review on the relevant research results at home and abroad, which includes the basic mechanical properties of FRP at high temperature, the bond performance of FRP to concrete at high temperature, the fire tests of FRP strengthened RC beams, the finite element simulation of fire performance of FRP strengthened RC beams, the residual strength of FRP strengthened RC beams, and the fire resistance design of FRP strengthened RC beams. The fire resistance of RC beams strengthened by FRP was systematically illustrated.
The technology of fiber reinforced polymer (FRP) strengthened reinforced concrete structures has many advantages compared to the traditional strengthening technology, and it has been widely used in many practical engineering in recent years. The strengthening method mainly consists of externally bonded FRP sheets, near-surface mounted FRP bars and FRP grids strengthening. When FRP is used for strengthening buildings, it must meet the requirements of fire resistance standard of buildings. Thus understanding the fire resistance of reinforced concrete beams strengthened with FRP is an important precondition for using this technology into structural strengthening of buildings. This paper presented a state-of-the-art review on the relevant research results at home and abroad, which includes the basic mechanical properties of FRP at high temperature, the bond performance of FRP to concrete at high temperature, the fire tests of FRP strengthened RC beams, the finite element simulation of fire performance of FRP strengthened RC beams, the residual strength of FRP strengthened RC beams, and the fire resistance design of FRP strengthened RC beams. The fire resistance of RC beams strengthened by FRP was systematically illustrated.
2020, 50(12): 112-118.
doi: 10.13204/j.gyjzG19100804
Abstract:
Quasi-static loading tests of three SRC columns were conducted to compare the seismic behavior of SRC columns under different loading systems. The results showed that under the far-field loading system, the damage degree of specimen deepened, the bearing capacity of specimen decreased and the energy dissipation capacity of specimen enhanced with the increase of equal displacement cycle number; the cycle number had little effect on seismic behavior as the drift ratio was less than 1/50, and had significant effect on seismic behavior at the drift ratio 1/40; the ultimate deformation,one-cycle hysteresis energy dissipation and equivalent viscous damping coefficient reaching ultimate displace of specimen were small, the ductility and ultimate energy dissipation capacity of specimen were poor. Under the near-field loading system, the crack number of specimen was small and the concrete crushing area of specimen was large, the bearing capacity of specimen was reduced greatly after enduring the initial ultimate displacement loading, and the energy dissipation capacity of specimen was developed fully; the ultimate deformation,one-cycle hysteresis energy dissipation and equivalent viscous damping coefficient reaching ultimate displace of specimen were large, the ductility and ultimate energy dissipation capacity of specimen were strong; when loading against with increasing displacement, the bearing capacity and energy dissipation capacity of specimen had little change as the drift ratio was less than 1/50, and the bearing capacity of decreased sharply and the energy dissipation capacity increased rapidly at the drift ratio 1/40.
Quasi-static loading tests of three SRC columns were conducted to compare the seismic behavior of SRC columns under different loading systems. The results showed that under the far-field loading system, the damage degree of specimen deepened, the bearing capacity of specimen decreased and the energy dissipation capacity of specimen enhanced with the increase of equal displacement cycle number; the cycle number had little effect on seismic behavior as the drift ratio was less than 1/50, and had significant effect on seismic behavior at the drift ratio 1/40; the ultimate deformation,one-cycle hysteresis energy dissipation and equivalent viscous damping coefficient reaching ultimate displace of specimen were small, the ductility and ultimate energy dissipation capacity of specimen were poor. Under the near-field loading system, the crack number of specimen was small and the concrete crushing area of specimen was large, the bearing capacity of specimen was reduced greatly after enduring the initial ultimate displacement loading, and the energy dissipation capacity of specimen was developed fully; the ultimate deformation,one-cycle hysteresis energy dissipation and equivalent viscous damping coefficient reaching ultimate displace of specimen were large, the ductility and ultimate energy dissipation capacity of specimen were strong; when loading against with increasing displacement, the bearing capacity and energy dissipation capacity of specimen had little change as the drift ratio was less than 1/50, and the bearing capacity of decreased sharply and the energy dissipation capacity increased rapidly at the drift ratio 1/40.
2020, 50(12): 119-125.
doi: 10.13204/j.gyjzG19120603
Abstract:
Cyclic test was conducted on six high-strength concrete filled high-strength square steel tube (HCFHST) beam-columns to study their hysteretic behaviors in this paper. The main parameter was the axial load ratio. The failure modes, the load versus displacement hysteretic curves, the load versus displacement envelope curves and the ductility of the beam-columns were studied. Additionally, numerical model was established by the numerical analysis software ABAQUS to study the influence of the parameters on the bearing capacity of the HCFHST beam-columns with different steel yield strengths, concrete compression strengths, steel ratio, axial load ratios and slenderness ratios. Test results indicated that increasing the steel yield strength and steel ratio could increase the bearing capacity. The bearing capacity decreased with the increase of slenderness ratio. Additionally, the changing of concrete compressive strength and axial load ratio had no obvious effect on the bearing capacity.
Cyclic test was conducted on six high-strength concrete filled high-strength square steel tube (HCFHST) beam-columns to study their hysteretic behaviors in this paper. The main parameter was the axial load ratio. The failure modes, the load versus displacement hysteretic curves, the load versus displacement envelope curves and the ductility of the beam-columns were studied. Additionally, numerical model was established by the numerical analysis software ABAQUS to study the influence of the parameters on the bearing capacity of the HCFHST beam-columns with different steel yield strengths, concrete compression strengths, steel ratio, axial load ratios and slenderness ratios. Test results indicated that increasing the steel yield strength and steel ratio could increase the bearing capacity. The bearing capacity decreased with the increase of slenderness ratio. Additionally, the changing of concrete compressive strength and axial load ratio had no obvious effect on the bearing capacity.
2020, 50(12): 126-134.
doi: 10.13204/j.gyjzG20051107
Abstract:
A new type of connection between hollow floor slab and steel beam for assembled staggered truss structure was proposed, and a finite element model based on ABAQUS was established to study its mechanical properties. Based on the finite element model of 17 beam and slab connections, the influence of the parameters such as the height, strength and embedding depth of the T-type connecting steel plate, bolt strength, the diameter of penetrating steel bar, whether there is penetrating steel bar or not, and the strength of post-cast concrete on the bearing capacity of the beam and slab joints was studied. The results showed that: setting T-type connecting steel plate would affect the failure position of post-cast concrete, which would cause the phenomenon of stress concentration; with the increase of the height of T-type connecting steel plate, the stiffness of beam slab joint was also increasing, but it had little effect on the ultimate bearing capacity; the embedding depth of T-type connecting steel plate was the key factor that affected the bearing capacity of beam slab joints, the greater the embedment depth, the greater the bearing capacity; the strength of T-type connecting steel plate, bolt strength and diameter of through reinforcement had little influence on the bearing capacity, while the strength of post cast concrete had a certain influence on the bearing capacity of beam slab joints, the greater the strength, the greater the bearing capacity; the shear capacity of the beam slab joint increased with the increase of the diameter of the shear reinforcement, when the diameter of the reinforcement was larger than 20 mm, the increase of the bearing capacity was limited, and the maximum shear stress could meet the needs of the actual project.
A new type of connection between hollow floor slab and steel beam for assembled staggered truss structure was proposed, and a finite element model based on ABAQUS was established to study its mechanical properties. Based on the finite element model of 17 beam and slab connections, the influence of the parameters such as the height, strength and embedding depth of the T-type connecting steel plate, bolt strength, the diameter of penetrating steel bar, whether there is penetrating steel bar or not, and the strength of post-cast concrete on the bearing capacity of the beam and slab joints was studied. The results showed that: setting T-type connecting steel plate would affect the failure position of post-cast concrete, which would cause the phenomenon of stress concentration; with the increase of the height of T-type connecting steel plate, the stiffness of beam slab joint was also increasing, but it had little effect on the ultimate bearing capacity; the embedding depth of T-type connecting steel plate was the key factor that affected the bearing capacity of beam slab joints, the greater the embedment depth, the greater the bearing capacity; the strength of T-type connecting steel plate, bolt strength and diameter of through reinforcement had little influence on the bearing capacity, while the strength of post cast concrete had a certain influence on the bearing capacity of beam slab joints, the greater the strength, the greater the bearing capacity; the shear capacity of the beam slab joint increased with the increase of the diameter of the shear reinforcement, when the diameter of the reinforcement was larger than 20 mm, the increase of the bearing capacity was limited, and the maximum shear stress could meet the needs of the actual project.
2020, 50(12): 135-143,134.
doi: 10.13204/j.gyjzG19122306
Abstract:
In order to reveal the bond-slip behavior between steel tube and core concrete after fire sprinkler cooling, 23 concrete-filled square steel tube (CFSST) specimens were designed and manufactured, and the variation parameters included the maximum temperature, the anchorage length of concrete, the concrete strength and the cooling mode. Through the push-out test, the failure modes of the specimens were observed, the whole load-slip curve and characteristic parameters were obtained,the influence of different parameters on the bond strength of the interface was analyzed, the calculation formula was put forward and the load-slip constitutive relationship model was constructed.The results showed that the shape of load-slip curve at the loading end was similar to that at the free end, and the free end sliped later.With the increase of maximum temperature, the interfacial bond strength increased first and then decreased, and reached its peak at 600 ℃. At the same time, the anchorage length had a significant effect on the interfacial bond strength and the relationship between them was inverse. The interfacial bond strength of the specimens cooled by fire sprinkler was lower than that of the natural cooling specimens.The decreasing range was gradually increased with the increase of temperature.
In order to reveal the bond-slip behavior between steel tube and core concrete after fire sprinkler cooling, 23 concrete-filled square steel tube (CFSST) specimens were designed and manufactured, and the variation parameters included the maximum temperature, the anchorage length of concrete, the concrete strength and the cooling mode. Through the push-out test, the failure modes of the specimens were observed, the whole load-slip curve and characteristic parameters were obtained,the influence of different parameters on the bond strength of the interface was analyzed, the calculation formula was put forward and the load-slip constitutive relationship model was constructed.The results showed that the shape of load-slip curve at the loading end was similar to that at the free end, and the free end sliped later.With the increase of maximum temperature, the interfacial bond strength increased first and then decreased, and reached its peak at 600 ℃. At the same time, the anchorage length had a significant effect on the interfacial bond strength and the relationship between them was inverse. The interfacial bond strength of the specimens cooled by fire sprinkler was lower than that of the natural cooling specimens.The decreasing range was gradually increased with the increase of temperature.
2020, 50(12): 144-149,185.
doi: 10.13204/j.gyjzG1904020007
Abstract:
This paper investigated the whole shear loading process and the influence of weld shapes on the shear bearing capacity of stud by push-out tests and finite element parameter studies. The results showed that the failure mode of specimen was the fracture of stud. The specimen had experienced a significant elastic and plastic process before fracture. The shear bearing capacity of the stud was significantly improved by weld seam, and the test value was 1.59 times of the value calculated by design code. When the weld size was controlled within a reasonable range, the shear bearing capacity increased linearly with the weld height for studs with fillet weld. The ratio of weld height h to diameter D was recommended smaller than 0.42 for studs formed by porcelain ring. Within this limit, the shear bearing capacity of stud increased linearly with the weld height and diameter. The weld shape should be considered in finite element simulations, otherwise the shear bearing capacity of studs would be reduced.
This paper investigated the whole shear loading process and the influence of weld shapes on the shear bearing capacity of stud by push-out tests and finite element parameter studies. The results showed that the failure mode of specimen was the fracture of stud. The specimen had experienced a significant elastic and plastic process before fracture. The shear bearing capacity of the stud was significantly improved by weld seam, and the test value was 1.59 times of the value calculated by design code. When the weld size was controlled within a reasonable range, the shear bearing capacity increased linearly with the weld height for studs with fillet weld. The ratio of weld height h to diameter D was recommended smaller than 0.42 for studs formed by porcelain ring. Within this limit, the shear bearing capacity of stud increased linearly with the weld height and diameter. The weld shape should be considered in finite element simulations, otherwise the shear bearing capacity of studs would be reduced.
2020, 50(12): 150-159.
doi: 10.13204/j.gyjzG19120105
Abstract:
In order to study the influence of non load action on super high-rise buildings, this paper analyzed the monitoring data and ANSYS numerical simulation. Firstly, for CFST columns, ASHREA clear sky model and CEB-FIP (90) prediction model were used to analyze the temperature effect and concrete creep effect respectively. The results showed that the horizontal deformation of the component was affected by the non-uniform temperature field, which decreased with the increase of the cross-section, tended to be gentle when it was larger than 900 mm, and increased rapidly with the increase of the column length. For the analysis of structural level, this paper proposed a simplified calculation method, which was based on the simulation analysis of Building 9 of Jinwan square. It was considered that the influence of non-uniform temperature field of components was only limited to local stress, which had little effect on the whole structure; the temperature and stress monitoring results of Building 9 of Jinwan square were analyzed to verify the above-mentioned finite element simulation results. Through further parameter analysis, it was considered that the construction progress of thick coating fire retardant coating reached more than half of the total height when the structure was capped, and the temperature effect could be properly ignored in the design.
In order to study the influence of non load action on super high-rise buildings, this paper analyzed the monitoring data and ANSYS numerical simulation. Firstly, for CFST columns, ASHREA clear sky model and CEB-FIP (90) prediction model were used to analyze the temperature effect and concrete creep effect respectively. The results showed that the horizontal deformation of the component was affected by the non-uniform temperature field, which decreased with the increase of the cross-section, tended to be gentle when it was larger than 900 mm, and increased rapidly with the increase of the column length. For the analysis of structural level, this paper proposed a simplified calculation method, which was based on the simulation analysis of Building 9 of Jinwan square. It was considered that the influence of non-uniform temperature field of components was only limited to local stress, which had little effect on the whole structure; the temperature and stress monitoring results of Building 9 of Jinwan square were analyzed to verify the above-mentioned finite element simulation results. Through further parameter analysis, it was considered that the construction progress of thick coating fire retardant coating reached more than half of the total height when the structure was capped, and the temperature effect could be properly ignored in the design.
2020, 50(12): 160-165.
doi: 10.13204/j.gyjzG19122806
Abstract:
The bonding behavior between CFRP and concrete is one of the main factors affecting the mechanical properties of CFRP reinforced concrete structures. In order to study the factors affecting the bonding performance of CFRP-concrete, the double shear tests of CFRP-concrete interface bond properties were carried out according to different CFRP weight per square metre, CFRP layer number and concrete strength grade. Under different CFRP weight per square metre, different CFRP layer number and different concrete strength grade, the failure characteristics of the bond interface between CFRP and concrete were analyzed. Combined with its load-displacement curve, the failure mechanism of CFRP-concrete bonding interface was analyzed. The bond-slip curve was obtained by strain stacking, the slip amount and the maximum shear stress under different factors were analyzed, and the influence law of the slip amount and the maximum shear stress under a single factor were obtained. The test results showed that the failure of the specimens occurred between the concrete surface layer; and the strength grade of the carbon fiber cloth could increase the ultimate bearing capacity and the maximum shear stress of the interface, but different CFRP weight per square metre had little effect on the ultimate bearing capacity and the maximum shear stress of the interface; the relative slip of CFRP decreased with the increase of CFRP mass per unit area, CFRP layers and the strength grade of concrete.
The bonding behavior between CFRP and concrete is one of the main factors affecting the mechanical properties of CFRP reinforced concrete structures. In order to study the factors affecting the bonding performance of CFRP-concrete, the double shear tests of CFRP-concrete interface bond properties were carried out according to different CFRP weight per square metre, CFRP layer number and concrete strength grade. Under different CFRP weight per square metre, different CFRP layer number and different concrete strength grade, the failure characteristics of the bond interface between CFRP and concrete were analyzed. Combined with its load-displacement curve, the failure mechanism of CFRP-concrete bonding interface was analyzed. The bond-slip curve was obtained by strain stacking, the slip amount and the maximum shear stress under different factors were analyzed, and the influence law of the slip amount and the maximum shear stress under a single factor were obtained. The test results showed that the failure of the specimens occurred between the concrete surface layer; and the strength grade of the carbon fiber cloth could increase the ultimate bearing capacity and the maximum shear stress of the interface, but different CFRP weight per square metre had little effect on the ultimate bearing capacity and the maximum shear stress of the interface; the relative slip of CFRP decreased with the increase of CFRP mass per unit area, CFRP layers and the strength grade of concrete.
2020, 50(12): 166-171.
doi: 10.13204/j.gyjzGYJZ2019013004
Abstract:
In order to greatly improve the flexural capacity of the existing reinforced concrete beams andavoidwet concrete operation, a method of strengthening rigid concrete beams with double-sided channel steel is proposed. The effectiveness of the method was analyzed by comparing reinforced specimens with five different connecting methods and one specimen without strengthing. The bending bearing capacity, ductility and failure morphology of each specimen were tested. Different calculation methods were analysed to compare the accuracy of calculating the flexural bearing capacity of the specimen. The results showed that: 1) after the reinforced concrete frame beam was strengthened with bolted double-sided channel steel, the flexural bearing capacity of the frame beam wass greatly improved; 2) the reinforced concrete beam specimen was strengthened with bolted double-sided channel steel and the flexural capacity was 73%~78% of the flexural capacity calculated according to the steel and concrete composite beam design method in Design Standards for Steel Structures (GB 50017—2017); 3) the flexural bearing capacity of the reinforced concrete beam specimens strengthened with bolted double-sided channel steel was 1.21~1.28 times of the flexural bearing capacity calculated according to the superposition method in Technical Specification for Steel Reinforced Concrete Structures (YB 9082—2006); 4) the measured flexural bearing capacity of the reinforced concrete beam specimens reinforced with side channel steel was 0.96~1.01 times of the flexural bearing capacity calculated according to Design Code for Composite Structures (JGJ 138—2016) after considering the influence of the stress distribution of the built-in steel frame, and this was quite reasonable.
In order to greatly improve the flexural capacity of the existing reinforced concrete beams andavoidwet concrete operation, a method of strengthening rigid concrete beams with double-sided channel steel is proposed. The effectiveness of the method was analyzed by comparing reinforced specimens with five different connecting methods and one specimen without strengthing. The bending bearing capacity, ductility and failure morphology of each specimen were tested. Different calculation methods were analysed to compare the accuracy of calculating the flexural bearing capacity of the specimen. The results showed that: 1) after the reinforced concrete frame beam was strengthened with bolted double-sided channel steel, the flexural bearing capacity of the frame beam wass greatly improved; 2) the reinforced concrete beam specimen was strengthened with bolted double-sided channel steel and the flexural capacity was 73%~78% of the flexural capacity calculated according to the steel and concrete composite beam design method in Design Standards for Steel Structures (GB 50017—2017); 3) the flexural bearing capacity of the reinforced concrete beam specimens strengthened with bolted double-sided channel steel was 1.21~1.28 times of the flexural bearing capacity calculated according to the superposition method in Technical Specification for Steel Reinforced Concrete Structures (YB 9082—2006); 4) the measured flexural bearing capacity of the reinforced concrete beam specimens reinforced with side channel steel was 0.96~1.01 times of the flexural bearing capacity calculated according to Design Code for Composite Structures (JGJ 138—2016) after considering the influence of the stress distribution of the built-in steel frame, and this was quite reasonable.
2020, 50(12): 172-179.
doi: 10.13204/j.gyjzG20051507
Abstract:
The construction of underground subway stations often has to underpass the existing building structures. However, there is less relevant construction experience underneath the existing tunnel bridges. As smooth traffic needs to be ensured in the existing tunnel bridges, it is very important to ensure the safety of tunnel bridges and quickly restore traffic while constructing subway stations.Taking the construction of Harbin Metro Line 3 Haping Road Station underpassing the Tunnel Bridge of Health Road as an example, the underpinning reinforcement construction technique of the underpass above the station passage was introduced in detail. To examine the reliability of the construction technology, the whole process of the construction of the passage underpassing through the existing tunnel bridge was numerically stimulated to analyze the deformation settlement of the underpinning reinforced tunnel bridge during the excavation construction at the lower station.The analysis results showed that the maximum vertical deformation of the underpinning reinforced tunnel bridge was only 2.35 mm. The maximum stress was 0.210 MPa, which was much smaller than its tensile deformation and strength design value. This proved the reliability of the underpinning reinforcement scheme adopted for the tunnel bridge.
The construction of underground subway stations often has to underpass the existing building structures. However, there is less relevant construction experience underneath the existing tunnel bridges. As smooth traffic needs to be ensured in the existing tunnel bridges, it is very important to ensure the safety of tunnel bridges and quickly restore traffic while constructing subway stations.Taking the construction of Harbin Metro Line 3 Haping Road Station underpassing the Tunnel Bridge of Health Road as an example, the underpinning reinforcement construction technique of the underpass above the station passage was introduced in detail. To examine the reliability of the construction technology, the whole process of the construction of the passage underpassing through the existing tunnel bridge was numerically stimulated to analyze the deformation settlement of the underpinning reinforced tunnel bridge during the excavation construction at the lower station.The analysis results showed that the maximum vertical deformation of the underpinning reinforced tunnel bridge was only 2.35 mm. The maximum stress was 0.210 MPa, which was much smaller than its tensile deformation and strength design value. This proved the reliability of the underpinning reinforcement scheme adopted for the tunnel bridge.
2020, 50(12): 180-185.
doi: 10.13204/j.gyjzG20073101
Abstract:
TANK Shanghai is the world’s first oil tank renovation space case, is also a model of domestic industrial heritage renovation projects. As the first non-profit art institutions in China, TANK Shanghai has a high social visibility. TANK Shanghai has been transformed from a group of discarded aviation oil storage tanks and ancillary facilities. The paper mainly explored the renovation methods of the oil tank art center from four aspects: design concept, space layout, function orientation and surface reconstruction, and expounded the operational social effect and economic significance after the transformation. Through the renovation of the abandoned oil tank, the Green Park and art exhibition, landscape and architectural space, industrial heritage and innovative future were skillfully integrated and integrated into the city life, realized from the abandoned industrial heritage to the city open park transformation.
TANK Shanghai is the world’s first oil tank renovation space case, is also a model of domestic industrial heritage renovation projects. As the first non-profit art institutions in China, TANK Shanghai has a high social visibility. TANK Shanghai has been transformed from a group of discarded aviation oil storage tanks and ancillary facilities. The paper mainly explored the renovation methods of the oil tank art center from four aspects: design concept, space layout, function orientation and surface reconstruction, and expounded the operational social effect and economic significance after the transformation. Through the renovation of the abandoned oil tank, the Green Park and art exhibition, landscape and architectural space, industrial heritage and innovative future were skillfully integrated and integrated into the city life, realized from the abandoned industrial heritage to the city open park transformation.
