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2025, Volume 55, Issue 10
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2025,
55(10):
1-14.
doi: 10.3724/j.gyjzG25042503
Abstract:
Fiber-reinforced polymer （FRP） composites are high-performance materials characterized by their high strength， lightweight， corrosion resistance， and excellent fatigue resistance， making them highly promising for prestressed structural applications. However， FRPs are typically orthotropic materials， exhibiting significantly lower strength and modulus perpendicular to the fiber direction compared to the longitudinal direction， posing challenges for the application of FRP tendons/cables. Existing research findings remain insufficient to support the standardized use of FRP tendons/cables in prestressed structures. Based on recent experimental studies and theoretical analyses of FRP tendons/cables， this paper summarizes the testing methods， failure modes， mechanical characteristics， and other relevant conclusions under different loading conditions. It systematically examines the influence of various factors—such as fiber type and content， tendon/cable diameter， manufacturing processes， and testing methods—on the short- and long-term mechanical properties of FRP tendons/cables. Furthermore， future research and development directions for FRP tendons/cables are outlined， providing valuable insights for both academic research and practical engineering applications.
Fiber-reinforced polymer （FRP） composites are high-performance materials characterized by their high strength， lightweight， corrosion resistance， and excellent fatigue resistance， making them highly promising for prestressed structural applications. However， FRPs are typically orthotropic materials， exhibiting significantly lower strength and modulus perpendicular to the fiber direction compared to the longitudinal direction， posing challenges for the application of FRP tendons/cables. Existing research findings remain insufficient to support the standardized use of FRP tendons/cables in prestressed structures. Based on recent experimental studies and theoretical analyses of FRP tendons/cables， this paper summarizes the testing methods， failure modes， mechanical characteristics， and other relevant conclusions under different loading conditions. It systematically examines the influence of various factors—such as fiber type and content， tendon/cable diameter， manufacturing processes， and testing methods—on the short- and long-term mechanical properties of FRP tendons/cables. Furthermore， future research and development directions for FRP tendons/cables are outlined， providing valuable insights for both academic research and practical engineering applications.
2025,
55(10):
15-25.
doi: 10.3724/j.gyjzG25081907
Abstract:
Fiber-reinforced polymer （FRP） composites are lightweight， high-strength， and corrosion-resistant materials. Confining concrete columns by externally wrapping FRP in the hoop direction can significantly enhance their structural performance and durability. While extensive research exists on circular FRP-confined concrete columns， the systematic study of rectangular FRP-confined concrete columns remains comparatively less developed. Therefore， this paper focuses on rectangular FRP-confined concrete columns， presenting a comprehensive review of their axial compressive behavior from both experimental and theoretical modeling perspectives. Regarding experimental research， a database compiling 227 specimens was established. This database was used to investigate the influence mechanism of key parameters， including sectional aspect ratio， corner radius， concrete strength， FRP confinement level， and column size on the mechanical properties of the confined concrete. Valid ranges for these critical design parameters were identified. Regarding theoretical models， three categories of stress-strain relationship models for rectangular FRP-confined concrete （namely single-segment， two-segment， and three-segment models） and corresponding equations for ultimate states were reviewed. The calculation model for the FRP strain efficiency factor was also discussed. The findings of this study offer valuable references for the rational design of rectangular FRP-confined concrete columns.
Fiber-reinforced polymer （FRP） composites are lightweight， high-strength， and corrosion-resistant materials. Confining concrete columns by externally wrapping FRP in the hoop direction can significantly enhance their structural performance and durability. While extensive research exists on circular FRP-confined concrete columns， the systematic study of rectangular FRP-confined concrete columns remains comparatively less developed. Therefore， this paper focuses on rectangular FRP-confined concrete columns， presenting a comprehensive review of their axial compressive behavior from both experimental and theoretical modeling perspectives. Regarding experimental research， a database compiling 227 specimens was established. This database was used to investigate the influence mechanism of key parameters， including sectional aspect ratio， corner radius， concrete strength， FRP confinement level， and column size on the mechanical properties of the confined concrete. Valid ranges for these critical design parameters were identified. Regarding theoretical models， three categories of stress-strain relationship models for rectangular FRP-confined concrete （namely single-segment， two-segment， and three-segment models） and corresponding equations for ultimate states were reviewed. The calculation model for the FRP strain efficiency factor was also discussed. The findings of this study offer valuable references for the rational design of rectangular FRP-confined concrete columns.
2025,
55(10):
26-34.
doi: 10.3724/j.gyjzG25080803
Abstract:
To address durability issues in concrete structures caused by steel corrosion， this study proposed replacing steel reinforcement with carbon fiber-reinforced polymer （CFRP） tendons and systematically investigated the seismic performance of CFRP-reinforced concrete columns. Through low-cycle reversed loading tests on three full-scale specimens and OpenSEES numerical simulations， the influence mechanisms of key design parameters—including axial compression ratio （ν）， concrete strength， shear span ratio （λ）， longitudinal reinforcement ratio （ρ）， and stirrup ratio （ρs）—were elucidated. The results demonstrated that a threshold effect of axial compression ratio （ν）， beyond which the risk of reinforcement yielding surged and seismic performance deteriorated abruptly； unlike strength degradation induced by excessive ν， enhanced concrete strength significantly improved load-bearing capacity and energy dissipation but exacerbated brittle failure； increased shear span ratio （λ） shifed failure modes toward flexural dominance， reducing load capacity while the linear-elastic constitutive behavior of CFRP tendons limited energy dissipation enhancement； higher longitudinal reinforcement ratio （ρ） boost load capacity， delayed yielding initiation and stiffness degradation， and improved energy dissipation； stirrup ratio （ρs） exerted negligible effects on lateral stiffness but maintained post-yield strength stability through enhanced core concrete confinement at elevated ratios.
To address durability issues in concrete structures caused by steel corrosion， this study proposed replacing steel reinforcement with carbon fiber-reinforced polymer （CFRP） tendons and systematically investigated the seismic performance of CFRP-reinforced concrete columns. Through low-cycle reversed loading tests on three full-scale specimens and OpenSEES numerical simulations， the influence mechanisms of key design parameters—including axial compression ratio （ν）， concrete strength， shear span ratio （λ）， longitudinal reinforcement ratio （ρ）， and stirrup ratio （ρs）—were elucidated. The results demonstrated that a threshold effect of axial compression ratio （ν）， beyond which the risk of reinforcement yielding surged and seismic performance deteriorated abruptly； unlike strength degradation induced by excessive ν， enhanced concrete strength significantly improved load-bearing capacity and energy dissipation but exacerbated brittle failure； increased shear span ratio （λ） shifed failure modes toward flexural dominance， reducing load capacity while the linear-elastic constitutive behavior of CFRP tendons limited energy dissipation enhancement； higher longitudinal reinforcement ratio （ρ） boost load capacity， delayed yielding initiation and stiffness degradation， and improved energy dissipation； stirrup ratio （ρs） exerted negligible effects on lateral stiffness but maintained post-yield strength stability through enhanced core concrete confinement at elevated ratios.
2025,
55(10):
35-46.
doi: 10.3724/j.gyjzG25081603
Abstract:
To investigate the feasibility of replacing traditional epoxy resin with magnesium phosphate inorganic adhesive （MPIA） for carbon fiber reinforced polymer （CFRP） sheet-strengthened reinforced concrete （RC） columns， axial compression tests were conducted on eleven RC square columns. The experimental variables included adhesive type， the number of CFRP sheet layers， and the amount of transverse reinforcement， in order to evaluate load–vertical strain curves， transverse strain development， and the displacement ductility factor. The study examined the damage evolution and failure mechanisms of the CFRP sheet-strengthened columns， revealed the synergistic mechanism between the CFRP sheets and MPIA， and analyzed the enhancement effect of MPIA-bonded CFRP sheets on axial compressive performance. Test results indicated that both MPIA and epoxy resin effectively confined the core concrete， with MPIA-strengthened columns exhibiting a greater improvement in bearing capacity. In addition， CFRP sheet-strengthened specimens using MPIA exhibited lower ductility than those using epoxy resin， but performed better than other inorganic adhesive systems. Furthermore， based on design codes and literature research， this study modified existing predictive models and proposed a method for calculating the axial compressive capacity of CFRP sheet-strengthened RC square columns using MPIA as the adhesive.
To investigate the feasibility of replacing traditional epoxy resin with magnesium phosphate inorganic adhesive （MPIA） for carbon fiber reinforced polymer （CFRP） sheet-strengthened reinforced concrete （RC） columns， axial compression tests were conducted on eleven RC square columns. The experimental variables included adhesive type， the number of CFRP sheet layers， and the amount of transverse reinforcement， in order to evaluate load–vertical strain curves， transverse strain development， and the displacement ductility factor. The study examined the damage evolution and failure mechanisms of the CFRP sheet-strengthened columns， revealed the synergistic mechanism between the CFRP sheets and MPIA， and analyzed the enhancement effect of MPIA-bonded CFRP sheets on axial compressive performance. Test results indicated that both MPIA and epoxy resin effectively confined the core concrete， with MPIA-strengthened columns exhibiting a greater improvement in bearing capacity. In addition， CFRP sheet-strengthened specimens using MPIA exhibited lower ductility than those using epoxy resin， but performed better than other inorganic adhesive systems. Furthermore， based on design codes and literature research， this study modified existing predictive models and proposed a method for calculating the axial compressive capacity of CFRP sheet-strengthened RC square columns using MPIA as the adhesive.
2025,
55(10):
47-54.
doi: 10.3724/j.gyjzG25062604
Abstract:
In order to solve the problems of reduced bearing capacity and large deformation of concrete composite slabs without protruding rebars， reinforcement methods such as setting grooves at the edges of the prefabricated bottom slabs and pasting fiber-reinforced composites at the cross-seam positions of the slab bottom are proposed. Through the static load tests of one monolithic cast slab and eight concrete composite floor slabs without protruding rebars， a comparative analysis was carried out on the flexural characteristics， failure modes， bearing characteristics， and deformation capacities of the specimens.The results showed that the bearing capacity， stiffness， and ductility of the closely spliced composite slab specimens were significantly smaller than those of the monolithic cast slab. Through the strengthening measures such as grooving at the edge of the slab and pasting fiber composites across the cracks at the bottom of the slab， the stress transfer and integrity at the bottom of the composite slab were enhanced to a certain extent， and the mechanical properties of the composite slab were improved. The reinforcement ratio and anchorage length of the additional rebars set at the composite surface of the splicing joint had a significant impact on the mechanical properties of the composite slab. The specimens with increased groove depth exhibited relatively outstanding bearing capacity and deformation performance， with good ductility. During the loading process， the restraining effect of the fiber composite materials on the bottom of the slab increased the cracking load of the composite slab， enhanced the stress transfer on both sides of the splicing joint at the bottom of the slab， reduced the degree of "deformation concentration" at the slab joint， and improved the stiffness and ductility of the composite slab．
In order to solve the problems of reduced bearing capacity and large deformation of concrete composite slabs without protruding rebars， reinforcement methods such as setting grooves at the edges of the prefabricated bottom slabs and pasting fiber-reinforced composites at the cross-seam positions of the slab bottom are proposed. Through the static load tests of one monolithic cast slab and eight concrete composite floor slabs without protruding rebars， a comparative analysis was carried out on the flexural characteristics， failure modes， bearing characteristics， and deformation capacities of the specimens.The results showed that the bearing capacity， stiffness， and ductility of the closely spliced composite slab specimens were significantly smaller than those of the monolithic cast slab. Through the strengthening measures such as grooving at the edge of the slab and pasting fiber composites across the cracks at the bottom of the slab， the stress transfer and integrity at the bottom of the composite slab were enhanced to a certain extent， and the mechanical properties of the composite slab were improved. The reinforcement ratio and anchorage length of the additional rebars set at the composite surface of the splicing joint had a significant impact on the mechanical properties of the composite slab. The specimens with increased groove depth exhibited relatively outstanding bearing capacity and deformation performance， with good ductility. During the loading process， the restraining effect of the fiber composite materials on the bottom of the slab increased the cracking load of the composite slab， enhanced the stress transfer on both sides of the splicing joint at the bottom of the slab， reduced the degree of "deformation concentration" at the slab joint， and improved the stiffness and ductility of the composite slab．
2025,
55(10):
55-64.
doi: 10.3724/j.gyjzG25082902
Abstract:
To address issues such as construction congestion， concrete casting defects， and shear-induced brittle failure in the core region of traditional concrete beam–column joints under severe earthquakes， this study proposes a novel joint system incorporating glass fiber-reinforced polymer （GFRP） tubes combined with high-ductility hybrid fiber-reinforced engineered cementitious composite （HECC）. This system is designed to replace stirrups in the joint core and improve interfacial bonding performance. Four exterior beam-column joint specimens were designed， with the core material （normal concrete （NC） or HECC） and GFRP tube fiber orientation （±45° or ±60°） as the main test variables. Quasi-static cyclic loading tests were conducted to evaluate and compare the seismic performance of the joints， including bearing capacity， ductility， energy dissipation， and stiffness degradation. The results demonstrated that the confinement provided by the GFRP tubes significantly enhanced joint ductility. Specimens with ±45° fiber-oriented tubes exhibited a 9.3% improvement in energy dissipation compared to those with ±60° tubes. Moreover， due to the lateral confinement provided by the GFRP tubes， which helps resist diagonal principal tensile/compressive stresses， and the improved reinforcement-to-matrix bond and crack propagation inhibition offered by the HECC， the joint combining GFRP tubes and HECC in the core region showed comparable ductility and stiffness retention to the conventional concrete joint， along with a 1.3% increase in bearing capacity and an 8.8% improvement in energy dissipation.Compared with traditional concrete joints， the proposed composite joint significantly reduces stirrup usage and construction difficulty， thus offering a viable solution for designing high-performance beam-column joints with minimal transverse reinforcement.
To address issues such as construction congestion， concrete casting defects， and shear-induced brittle failure in the core region of traditional concrete beam–column joints under severe earthquakes， this study proposes a novel joint system incorporating glass fiber-reinforced polymer （GFRP） tubes combined with high-ductility hybrid fiber-reinforced engineered cementitious composite （HECC）. This system is designed to replace stirrups in the joint core and improve interfacial bonding performance. Four exterior beam-column joint specimens were designed， with the core material （normal concrete （NC） or HECC） and GFRP tube fiber orientation （±45° or ±60°） as the main test variables. Quasi-static cyclic loading tests were conducted to evaluate and compare the seismic performance of the joints， including bearing capacity， ductility， energy dissipation， and stiffness degradation. The results demonstrated that the confinement provided by the GFRP tubes significantly enhanced joint ductility. Specimens with ±45° fiber-oriented tubes exhibited a 9.3% improvement in energy dissipation compared to those with ±60° tubes. Moreover， due to the lateral confinement provided by the GFRP tubes， which helps resist diagonal principal tensile/compressive stresses， and the improved reinforcement-to-matrix bond and crack propagation inhibition offered by the HECC， the joint combining GFRP tubes and HECC in the core region showed comparable ductility and stiffness retention to the conventional concrete joint， along with a 1.3% increase in bearing capacity and an 8.8% improvement in energy dissipation.Compared with traditional concrete joints， the proposed composite joint significantly reduces stirrup usage and construction difficulty， thus offering a viable solution for designing high-performance beam-column joints with minimal transverse reinforcement.
2025,
55(10):
65-72.
doi: 10.3724/j.gyjzG25081702
Abstract:
Carbon fiber reinforced polymer （CFRP） has the advantages of low weight， high tensile strength， corrosion resistance， and fatigue resistance， which makes it suitable for cable domes. To study the feasibility of applying CFRP cables in cable dome structures， some steel cables and single-type cables in an open cable dome structure with a span of 120 meters were replaced with CFRP cables using different methods. The static performance finite element analysis of the cable dome structure after the replacement of CFRP cables was carried out. The simulation results showed that， compared with the cable dome using steel cables， when some steel cables were replaced with CFRP cables by the equal area method， the stress of the cables in the replaced cable dome structure was reduced， and the stress of each group of cables was reduced by less than 8%. The maximum vertical displacement of the joints varied within 10%. When all single-type cables were replaced with CFRP cables by the equal strength method， the stress of the cables and the maximum vertical displacement of the joints changed significantly. Replacing all single-type cables with CFRP cables by the equal stiffness method had a relatively small impact on the stress of the cables and the maximum vertical displacement of the joints. For this open cable dome structure， all steel ridge cables can be replaced with CFRP cables. This research demonstrates that through reasonable design， it is feasible to use CFRP cables to replace steel cables in such structures.
Carbon fiber reinforced polymer （CFRP） has the advantages of low weight， high tensile strength， corrosion resistance， and fatigue resistance， which makes it suitable for cable domes. To study the feasibility of applying CFRP cables in cable dome structures， some steel cables and single-type cables in an open cable dome structure with a span of 120 meters were replaced with CFRP cables using different methods. The static performance finite element analysis of the cable dome structure after the replacement of CFRP cables was carried out. The simulation results showed that， compared with the cable dome using steel cables， when some steel cables were replaced with CFRP cables by the equal area method， the stress of the cables in the replaced cable dome structure was reduced， and the stress of each group of cables was reduced by less than 8%. The maximum vertical displacement of the joints varied within 10%. When all single-type cables were replaced with CFRP cables by the equal strength method， the stress of the cables and the maximum vertical displacement of the joints changed significantly. Replacing all single-type cables with CFRP cables by the equal stiffness method had a relatively small impact on the stress of the cables and the maximum vertical displacement of the joints. For this open cable dome structure， all steel ridge cables can be replaced with CFRP cables. This research demonstrates that through reasonable design， it is feasible to use CFRP cables to replace steel cables in such structures.
2025,
55(10):
73-85.
doi: 10.3724/j.gyjzG25061306
Abstract:
Freeze-thaw （F-T） resistance tests were conducted on eight groups of steel fiber-reinforced concrete （SFRC） with different strength grades. The effects of concrete strength and the number of F-T cycles on the compressive strength， mass loss rate， relative dynamic elastic modulus （RDEM）， and microstructural evolution of SFRC were investigated. An F-T damage model based on RDEM was established， and the service life of SFRC in typical cold regions was predicted. The results indicated that low-strength SFRC （C30， C40） exhibited significant F-T damage， with pronounced surface spalling， exposed aggregates， and through-thickness microcracking. After 125 F-T cycles， the compressive strength loss rates reached 35.02% and 31.65%， respectively. In contrast， high-strength SFRC （C50， C60） maintained better integrity， with strength loss rates below 9.61%. Mass loss and RDEM degradation increased progressively with F-T cycles， while high-strength SFRC demonstrated superior F-T resistance. Scanning electron microscopy revealed denser matrix structures in high-strength SFRC compared to low-strength specimens. The RDEM-based damage model achieved a coefficient of determination （R²） exceeding 0.994， accurately capturing the evolution of mechanical properties in SFRC under F-T cycles. Service life predictions suggest that C60 SFRC can achieve a maximum service life of up to 19.7 years in cold regions.
Freeze-thaw （F-T） resistance tests were conducted on eight groups of steel fiber-reinforced concrete （SFRC） with different strength grades. The effects of concrete strength and the number of F-T cycles on the compressive strength， mass loss rate， relative dynamic elastic modulus （RDEM）， and microstructural evolution of SFRC were investigated. An F-T damage model based on RDEM was established， and the service life of SFRC in typical cold regions was predicted. The results indicated that low-strength SFRC （C30， C40） exhibited significant F-T damage， with pronounced surface spalling， exposed aggregates， and through-thickness microcracking. After 125 F-T cycles， the compressive strength loss rates reached 35.02% and 31.65%， respectively. In contrast， high-strength SFRC （C50， C60） maintained better integrity， with strength loss rates below 9.61%. Mass loss and RDEM degradation increased progressively with F-T cycles， while high-strength SFRC demonstrated superior F-T resistance. Scanning electron microscopy revealed denser matrix structures in high-strength SFRC compared to low-strength specimens. The RDEM-based damage model achieved a coefficient of determination （R²） exceeding 0.994， accurately capturing the evolution of mechanical properties in SFRC under F-T cycles. Service life predictions suggest that C60 SFRC can achieve a maximum service life of up to 19.7 years in cold regions.
2025,
55(10):
86-93.
doi: 10.3724/j.gyjzG25073102
Abstract:
Coal gangue， a solid byproduct continuously generated during mining operations， can be utilized to replace natural aggregates in concrete， forming coal gangue aggregate concrete （CGAC）. This application addresses the environmental pollution caused by gangue stockpiling and mitigates the scarcity of natural aggregates. To compensate for the reduction in the mechanical properties of concrete resulting from replacing conventional aggregates with coal gangue， fiber-reinforced polymer （FRP） confinement can be employed to enhance the axial compressive strength of CGAC. In this study， the effects of three parameters were investigated： the coal gangue replacement ratio by volume （0% and 50%）， the FRP fabric type （glass fiber and carbon fiber）， and the number of FRP confinement layers （1 to 6 layers）. A total of eighteen specimens were tested under axial compression to compare the stress-strain relationships of CGAC confined with different types of FRP. Experimental results indicated that FRP-confined CGAC exhibited characteristics similar to those of FRP-confined conventional concrete. Under sufficient confinement， the load-displacement response demonstrated a distinct two-stage ascending behavior. However， the enhancement effect on the axial compressive strength gradually diminished as the confinement stiffness increased significantly. Finally， based on the experimental findings， an analytical model for FRP-confined CGAC was developed using a three-dimensional graphical representation approach.
Coal gangue， a solid byproduct continuously generated during mining operations， can be utilized to replace natural aggregates in concrete， forming coal gangue aggregate concrete （CGAC）. This application addresses the environmental pollution caused by gangue stockpiling and mitigates the scarcity of natural aggregates. To compensate for the reduction in the mechanical properties of concrete resulting from replacing conventional aggregates with coal gangue， fiber-reinforced polymer （FRP） confinement can be employed to enhance the axial compressive strength of CGAC. In this study， the effects of three parameters were investigated： the coal gangue replacement ratio by volume （0% and 50%）， the FRP fabric type （glass fiber and carbon fiber）， and the number of FRP confinement layers （1 to 6 layers）. A total of eighteen specimens were tested under axial compression to compare the stress-strain relationships of CGAC confined with different types of FRP. Experimental results indicated that FRP-confined CGAC exhibited characteristics similar to those of FRP-confined conventional concrete. Under sufficient confinement， the load-displacement response demonstrated a distinct two-stage ascending behavior. However， the enhancement effect on the axial compressive strength gradually diminished as the confinement stiffness increased significantly. Finally， based on the experimental findings， an analytical model for FRP-confined CGAC was developed using a three-dimensional graphical representation approach.
2025,
55(10):
94-101.
doi: 10.3724/j.gyjzG25081304
Abstract:
In marine environments， clarifying both the durability of CFRP and its galvanic behavior when coupled with carbon steel is critical for engineering practice. Galvanic interaction accelerates steel corrosion， and CFRP’s long-term performance hinges on the stability of its barrier and interfacial adhesion. In this study， specimens with original surface （OS）， bare surface （BS）， and peel-ply （PPS） surface， as well as cross-sections， underwent water immersion and cyclic-corrosion accelerated ageing. Electrochemical characterization quantified CFRP durability evolution and galvanic acceleration on steel. The results showed that aged CFRP exhibited only mild degradation while retaining a barrier function. Specifically， low-frequency impedance and interfacial charge-transfer resistance decreased without spanning an order of magnitude， whereas the constant-phase element increased and the phase angle decreased； cyclic corrosion was more detrimental than water immersion. An open-circuit potential difference of approximately 800 to 900 mV between steel and CFRP provided a strong driving force for galvanic corrosion. Polarization curves and mixed-potential analysis indicatd that galvanic coupling increased the steel corrosion rate by about 4.6~23.3 times. By reducing fiber exposure and electrical connectivity while preserving a resin-rich layer， PPS surface treatment effectively suppressed galvanic corrosion and enhanced interfacial adhesion， whereas the cross-section was the most vulnerable region to galvanic acceleration.
In marine environments， clarifying both the durability of CFRP and its galvanic behavior when coupled with carbon steel is critical for engineering practice. Galvanic interaction accelerates steel corrosion， and CFRP’s long-term performance hinges on the stability of its barrier and interfacial adhesion. In this study， specimens with original surface （OS）， bare surface （BS）， and peel-ply （PPS） surface， as well as cross-sections， underwent water immersion and cyclic-corrosion accelerated ageing. Electrochemical characterization quantified CFRP durability evolution and galvanic acceleration on steel. The results showed that aged CFRP exhibited only mild degradation while retaining a barrier function. Specifically， low-frequency impedance and interfacial charge-transfer resistance decreased without spanning an order of magnitude， whereas the constant-phase element increased and the phase angle decreased； cyclic corrosion was more detrimental than water immersion. An open-circuit potential difference of approximately 800 to 900 mV between steel and CFRP provided a strong driving force for galvanic corrosion. Polarization curves and mixed-potential analysis indicatd that galvanic coupling increased the steel corrosion rate by about 4.6~23.3 times. By reducing fiber exposure and electrical connectivity while preserving a resin-rich layer， PPS surface treatment effectively suppressed galvanic corrosion and enhanced interfacial adhesion， whereas the cross-section was the most vulnerable region to galvanic acceleration.
2025,
55(10):
102-114.
doi: 10.3724/j.gyjzG25080202
Abstract:
This study investigates the bond strength between fiber-reinforced polymer （FRP） bars and concrete. A database was constructed by integrating 487 pull-out test data points from 16 literature sources， featuring 12 input variables such as fiber type， forming process， and surface characteristics. Seven machine learning algorithms， such as RF， XGBoost， and LightGBM， were employed for prediction. The influence mechanisms of the 12 variables on the bond strength were analyzed and compared. The prediction results indicated the compressive strength of concrete， along with the tensile strength and elastic modulus of the FRP bars， as the key factors affecting the bond strength. Among them， tree models showed superior performance to non-tree models， with the LightGBM algorithm exhibiting high accuracy and efficiency. SHAP value evaluation revealed that forming processes （e.g.， the RB process） had a greater influence on the bond strength than fiber type did. Furthermore， the significance of all involved variables was quantitatively ranked using the LightGBM algorithm， showing that the mechanical properties of the materials and the surface characteristics of the FRP bars had a more significant effect on the bond strength.
This study investigates the bond strength between fiber-reinforced polymer （FRP） bars and concrete. A database was constructed by integrating 487 pull-out test data points from 16 literature sources， featuring 12 input variables such as fiber type， forming process， and surface characteristics. Seven machine learning algorithms， such as RF， XGBoost， and LightGBM， were employed for prediction. The influence mechanisms of the 12 variables on the bond strength were analyzed and compared. The prediction results indicated the compressive strength of concrete， along with the tensile strength and elastic modulus of the FRP bars， as the key factors affecting the bond strength. Among them， tree models showed superior performance to non-tree models， with the LightGBM algorithm exhibiting high accuracy and efficiency. SHAP value evaluation revealed that forming processes （e.g.， the RB process） had a greater influence on the bond strength than fiber type did. Furthermore， the significance of all involved variables was quantitatively ranked using the LightGBM algorithm， showing that the mechanical properties of the materials and the surface characteristics of the FRP bars had a more significant effect on the bond strength.
2025,
55(10):
115-123.
doi: 10.3724/j.gyjzG25073107
Abstract:
Carbon fiber reinforced polymer （CFRP） composites， owing to their exceptional material properties， offer a novel solution for cable components in long-span spatial structures. Therefore， a CFRP spoke-type tensegrity structure was implemented in the roof system of an airport， utilizing CFRP cables as the primary load-bearing elements. To better understand the structural responses during different construction stages， cable tensioning schemes were developed based on structural characteristics. A full-process simulation of CFRP cable tensioning was conducted using an improved tension compensation method， presenting key response parameters such as cable forces， structural deformations， and internal forces at each construction step. The numerical simulation of the entire tensioning process validated the rationality of the structural design and the feasibility of the construction procedure， thereby providing a theoretical foundation for the actual construction implementation.
Carbon fiber reinforced polymer （CFRP） composites， owing to their exceptional material properties， offer a novel solution for cable components in long-span spatial structures. Therefore， a CFRP spoke-type tensegrity structure was implemented in the roof system of an airport， utilizing CFRP cables as the primary load-bearing elements. To better understand the structural responses during different construction stages， cable tensioning schemes were developed based on structural characteristics. A full-process simulation of CFRP cable tensioning was conducted using an improved tension compensation method， presenting key response parameters such as cable forces， structural deformations， and internal forces at each construction step. The numerical simulation of the entire tensioning process validated the rationality of the structural design and the feasibility of the construction procedure， thereby providing a theoretical foundation for the actual construction implementation.
2025,
55(10):
124-129.
doi: 10.3724/j.gyjzG25081505
Abstract:
Addressing the cracking issue caused by concrete drying shrinkage stress in the cast-in-place surface layer of high-piled wharfs in seaports， technical measures were studied through theoretical analysis， laboratory tests， and numerical simulations. These measures involve adding thermoplastic Glassfiber-Reinforced Polymer （GFRP） rebars to the design based on the conventional single-layer steel reinforcement to disperse concentrated stress， thereby transforming harmful cracks into harmless ones. These measures were applied in the concrete construction of the berth surface layer in Kemen， Fujian Province. The results showed that after soaking in a simulated saline-alkali solution （pH≈13.4） at 60 ℃ for 90 days， the strength retention rate of the reinforcement material could still reach 76.3%. Using thermoplastic GFRP rebars with a diameter of 12 mm and a spacing of 10 cm， placed 2 cm away from the concrete protective layer， effectively reduced the maximum tensile stress on the concrete surface. Combined with construction quality control measures for thermoplastic GFRP rebars and concrete， the maximum shrinkage strain on the concrete surface could be controlled within 120×10⁻⁶ under strong wind and intense sunlight conditions. After six months of continuous monitoring， the appearance quality remained good， the cracking area was effectively reduced， and no harmful cracks were observed.
Addressing the cracking issue caused by concrete drying shrinkage stress in the cast-in-place surface layer of high-piled wharfs in seaports， technical measures were studied through theoretical analysis， laboratory tests， and numerical simulations. These measures involve adding thermoplastic Glassfiber-Reinforced Polymer （GFRP） rebars to the design based on the conventional single-layer steel reinforcement to disperse concentrated stress， thereby transforming harmful cracks into harmless ones. These measures were applied in the concrete construction of the berth surface layer in Kemen， Fujian Province. The results showed that after soaking in a simulated saline-alkali solution （pH≈13.4） at 60 ℃ for 90 days， the strength retention rate of the reinforcement material could still reach 76.3%. Using thermoplastic GFRP rebars with a diameter of 12 mm and a spacing of 10 cm， placed 2 cm away from the concrete protective layer， effectively reduced the maximum tensile stress on the concrete surface. Combined with construction quality control measures for thermoplastic GFRP rebars and concrete， the maximum shrinkage strain on the concrete surface could be controlled within 120×10⁻⁶ under strong wind and intense sunlight conditions. After six months of continuous monitoring， the appearance quality remained good， the cracking area was effectively reduced， and no harmful cracks were observed.
2025,
55(10):
130-135.
doi: 10.3724/j.gyjzG23091507
Abstract:
The differences in social forms between China and the West have led to significant differences in mainstream cultures. The concept of “New Orientalism” originated from the rise of artistic subjectivity in China. It was first applied in the expression of film art and later extended to other fields， often being utilized in the design and creation of modern architectural landscapes. Starting from the defining characteristics of “New Orientalism”， this paper compared and analyzed typical cases influenced by “New Orientalism” thinking. It summarized the influence of “New Orientalism” aesthetics on modern architectural landscape design and creation into the following three aspects： spatial construction of landscapes， material application， and emotional expression in landscape design. Furthermore， the development trends of architectural landscapes led by “New Orientalism” in the future were also predicted.
The differences in social forms between China and the West have led to significant differences in mainstream cultures. The concept of “New Orientalism” originated from the rise of artistic subjectivity in China. It was first applied in the expression of film art and later extended to other fields， often being utilized in the design and creation of modern architectural landscapes. Starting from the defining characteristics of “New Orientalism”， this paper compared and analyzed typical cases influenced by “New Orientalism” thinking. It summarized the influence of “New Orientalism” aesthetics on modern architectural landscape design and creation into the following three aspects： spatial construction of landscapes， material application， and emotional expression in landscape design. Furthermore， the development trends of architectural landscapes led by “New Orientalism” in the future were also predicted.
2025,
55(10):
136-145.
doi: 10.3724/j.gyjzG23090910
Abstract:
As the core of the military system constructed by the Ming Dynasty to stabilize the southwest⁃ern border area， the garrison town settlements possess distinctive characteristics of Han immigrant cul⁃ture and military defense， giving them with high recognizability and cultural landscape value.This study took Pu’an Fortress， a key military garrison town at the junction of three southwestern provinces during the Ming Dynasty， as an example. Using spatial gene theory and related technologies， it constructed a research path for identify⁃ing， extracting， analyzing， and inheriting the spatial genes of Pu’an Fortress. Following this path， the study identified spatial elements in multiple spatial layers and categories at key historical stages， employing methods such as historical map deciphering， literature review， and qualitative analysis. The characteris⁃tics and inner development mechanisms of the spatial genes of garrison towns were then extracted and analyzed. Finally， these spatial genes were translated into new development structures and functions，providing a reference for the conservation， sustainable development， and regional urban design of tradi⁃tional settlements in Southwest China.
As the core of the military system constructed by the Ming Dynasty to stabilize the southwest⁃ern border area， the garrison town settlements possess distinctive characteristics of Han immigrant cul⁃ture and military defense， giving them with high recognizability and cultural landscape value.This study took Pu’an Fortress， a key military garrison town at the junction of three southwestern provinces during the Ming Dynasty， as an example. Using spatial gene theory and related technologies， it constructed a research path for identify⁃ing， extracting， analyzing， and inheriting the spatial genes of Pu’an Fortress. Following this path， the study identified spatial elements in multiple spatial layers and categories at key historical stages， employing methods such as historical map deciphering， literature review， and qualitative analysis. The characteris⁃tics and inner development mechanisms of the spatial genes of garrison towns were then extracted and analyzed. Finally， these spatial genes were translated into new development structures and functions，providing a reference for the conservation， sustainable development， and regional urban design of tradi⁃tional settlements in Southwest China.
2025,
55(10):
146-154.
doi: 10.3724/j.gyjzG24081311
Abstract:
To effectively address the issue of excessive weight in traditional concrete power cover slabs， this paper proposes a new type of lightweight composite power cover slab. Four types of composite cover slabs were designed and subjected to vertical load-bearing failure tests. The failure modes， ultimate bearing capacity， and strain variation patterns of the slabs were obtained. The results showed that， compared with traditional steel fiber-reinforced concrete cover slabs， the weight of the new composite cover slabs was reduced by over 70%. The ultimate bearing capacities were 135 kN， 143.59 kN， 260.31 kN， and 550.65 kN， respectively， all meeting the requirements of Steel Fiber Reinforced Concrete Manhole Cover（GB/T 26537-2011）. Additionally， the composite slabs exhibited good deformability. The failure mode of the composite cover slabs was characterized by concrete compression-induced cracking and slab buckling in the area 1/4 of the slab length from the end. No slippage occurred between the concrete and the steel structure， indicating good overall integrity. To ensure effective collaboration between the two materials， it is recommended that the concrete thickness should not exceed 25% of the slab height. Finally， based on the experimental results and equilibrium theory， a method for calculating the ultimate bearing capacity was proposed.
To effectively address the issue of excessive weight in traditional concrete power cover slabs， this paper proposes a new type of lightweight composite power cover slab. Four types of composite cover slabs were designed and subjected to vertical load-bearing failure tests. The failure modes， ultimate bearing capacity， and strain variation patterns of the slabs were obtained. The results showed that， compared with traditional steel fiber-reinforced concrete cover slabs， the weight of the new composite cover slabs was reduced by over 70%. The ultimate bearing capacities were 135 kN， 143.59 kN， 260.31 kN， and 550.65 kN， respectively， all meeting the requirements of Steel Fiber Reinforced Concrete Manhole Cover（GB/T 26537-2011）. Additionally， the composite slabs exhibited good deformability. The failure mode of the composite cover slabs was characterized by concrete compression-induced cracking and slab buckling in the area 1/4 of the slab length from the end. No slippage occurred between the concrete and the steel structure， indicating good overall integrity. To ensure effective collaboration between the two materials， it is recommended that the concrete thickness should not exceed 25% of the slab height. Finally， based on the experimental results and equilibrium theory， a method for calculating the ultimate bearing capacity was proposed.
2025,
55(10):
155-162.
doi: 10.3724/j.gyjzG24091602
Abstract:
In order to develop unified calculation methods for the bearing capacities of multi-cell L-shaped concrete-filled steel tubular （ML-CFST） columns under different loading conditions， a finite element analysis was conducted using ABAQUS. The effects of different parameters on the behavior of the ML-CFST columns were analyzed under uniaxial bending， bending at any angle， and eccentric compression. The study results demonstrated that the steel yield strength， steel tube thickness， and height of the web limb had a great influence on the flexural capacity. The flexural capacities M0° and M180° were found to be lower than those at other angles due to the minimal bending stiffness in these directions. The shape of the Mx0/Mπ/4-My0/M3π/4 curve was similar to an ellipse. The steel yield strength and concrete compressive strength had a minor influence on the curve shape. The normalized interaction curve for biaxial eccentric compression expanded outward as the axial compression ratio increased. Based on theoretical and regression analyses of the numerical results， design methods for the bearing capacity of ML-CFST members under uniaxial bending， bending at any angle， and eccentric compression were proposed.
In order to develop unified calculation methods for the bearing capacities of multi-cell L-shaped concrete-filled steel tubular （ML-CFST） columns under different loading conditions， a finite element analysis was conducted using ABAQUS. The effects of different parameters on the behavior of the ML-CFST columns were analyzed under uniaxial bending， bending at any angle， and eccentric compression. The study results demonstrated that the steel yield strength， steel tube thickness， and height of the web limb had a great influence on the flexural capacity. The flexural capacities M0° and M180° were found to be lower than those at other angles due to the minimal bending stiffness in these directions. The shape of the Mx0/Mπ/4-My0/M3π/4 curve was similar to an ellipse. The steel yield strength and concrete compressive strength had a minor influence on the curve shape. The normalized interaction curve for biaxial eccentric compression expanded outward as the axial compression ratio increased. Based on theoretical and regression analyses of the numerical results， design methods for the bearing capacity of ML-CFST members under uniaxial bending， bending at any angle， and eccentric compression were proposed.
2025,
55(10):
163-170.
doi: 10.3724/j.gyjzG24022710
Abstract:
For concrete-filled steel tube （CFST） columns with a large diameter， the cracking problems caused by the early-age hydration heat in the internal mass concrete urgently need to be studied. The temperature and strain in the concrete of the tower leg （a 2.1 m diameter CFST member） after pouring were measured. The tower leg is part of the world’s highest transmission tower， which stands 385 meters tall.The results showed that due to the early-age hydration of concrete， the temperature in its core region reached 97.0 ℃， with a maximum temperature difference of up to 30.6 ℃ compared to the steel wall surface. The tensile strain at the core region of the concrete reached 400×10-6 after 30 hours of pouring， leading to early-age cracking in the concrete. Additionally， to investigate the impact of size on the early-age behavior of CFST members， eight CFST specimens with different diameters were manufactured and measured for temperature and strain. Based on the “hydration-thermal-mechanical” constitutive model， a refined finite element model for CFST members was developed and validated against experimental results. Finally， an early-age hydration heat database considering the diameter of CFST members， ambient temperature， and concrete mix proportions was established. Based on a BP neural network， the early-age behavior of CFST members was predicted. The BP neural network enables accurate prediction of early-age hydration heat in CFST members， thereby helping to reduce the risk of early-age cracking.
For concrete-filled steel tube （CFST） columns with a large diameter， the cracking problems caused by the early-age hydration heat in the internal mass concrete urgently need to be studied. The temperature and strain in the concrete of the tower leg （a 2.1 m diameter CFST member） after pouring were measured. The tower leg is part of the world’s highest transmission tower， which stands 385 meters tall.The results showed that due to the early-age hydration of concrete， the temperature in its core region reached 97.0 ℃， with a maximum temperature difference of up to 30.6 ℃ compared to the steel wall surface. The tensile strain at the core region of the concrete reached 400×10-6 after 30 hours of pouring， leading to early-age cracking in the concrete. Additionally， to investigate the impact of size on the early-age behavior of CFST members， eight CFST specimens with different diameters were manufactured and measured for temperature and strain. Based on the “hydration-thermal-mechanical” constitutive model， a refined finite element model for CFST members was developed and validated against experimental results. Finally， an early-age hydration heat database considering the diameter of CFST members， ambient temperature， and concrete mix proportions was established. Based on a BP neural network， the early-age behavior of CFST members was predicted. The BP neural network enables accurate prediction of early-age hydration heat in CFST members， thereby helping to reduce the risk of early-age cracking.
2025,
55(10):
171-183.
doi: 10.3724/j.gyjzG23061101
Abstract:
In order to study the mechanical properties of large-opening saddle-shaped orthogonal cable network structures， a 1∶10 scale model was designed based on the Xi’an International Football Center. Bearing capacity tests were carried out on the large-opening saddle-shaped orthogonal cable network structure. The testing process， which included full-span， upper half-span， and right half-span loading of the cable net， was simulated using the general finite element software ANSYS. The results showed that under the three loading modes， the axial force in the upper load-bearing cables gradually decreased from the edges toward the center of the cable network， while the axial force in the upper stable cables decreased from the central axis toward the edges along the long span. Both the cable internal forces and the vertical deformation of the cable network exhibited an approximately linear trend with increasing load. Additionally， the cable network underwent only minor in-plane deformation. Under full-span loading， the opening expanded slightly outward in the short-axis direction and contracted slightly inward in the long-axis direction.
In order to study the mechanical properties of large-opening saddle-shaped orthogonal cable network structures， a 1∶10 scale model was designed based on the Xi’an International Football Center. Bearing capacity tests were carried out on the large-opening saddle-shaped orthogonal cable network structure. The testing process， which included full-span， upper half-span， and right half-span loading of the cable net， was simulated using the general finite element software ANSYS. The results showed that under the three loading modes， the axial force in the upper load-bearing cables gradually decreased from the edges toward the center of the cable network， while the axial force in the upper stable cables decreased from the central axis toward the edges along the long span. Both the cable internal forces and the vertical deformation of the cable network exhibited an approximately linear trend with increasing load. Additionally， the cable network underwent only minor in-plane deformation. Under full-span loading， the opening expanded slightly outward in the short-axis direction and contracted slightly inward in the long-axis direction.
2025,
55(10):
184-192.
doi: 10.3724/j.gyjzG23120614
Abstract:
This project involves an out-of-code high-rise long-span complex steel frame structure. It is characterized by a local upper-suspended and lower-bracing structural system， and incorporates a damping technology that integrates a toggle-brace displacement amplification mechanism with a friction-type displacement damper. This paper presents the selection of the load-bearing and lateral resistance systems for the structure， with a focus on analyzing the stress and deformation characteristics of this special structural type， the design of the suspension system， damper damping technology， as well as stress analysis and control of long-span truss floor slabs. Analyses for progressive collapse resistance and comfort of the long-span truss were carried out， along with a construction simulation analysis of the entire structure. The structural system also includes different types of force-transfer components such as landing columns， transfer columns， and suspended columns. It belongs to a special type of high-rise building that is not specified in current codes and has multi-directional force transfer paths. Corresponding performance-based design objectives have been formulated， and stress ratio control standards for steel members under different performance levels have been proposed. Through comprehensive theoretical calculations and appropriate structural measures， the structural system can be ensured to be reasonable and safe.
This project involves an out-of-code high-rise long-span complex steel frame structure. It is characterized by a local upper-suspended and lower-bracing structural system， and incorporates a damping technology that integrates a toggle-brace displacement amplification mechanism with a friction-type displacement damper. This paper presents the selection of the load-bearing and lateral resistance systems for the structure， with a focus on analyzing the stress and deformation characteristics of this special structural type， the design of the suspension system， damper damping technology， as well as stress analysis and control of long-span truss floor slabs. Analyses for progressive collapse resistance and comfort of the long-span truss were carried out， along with a construction simulation analysis of the entire structure. The structural system also includes different types of force-transfer components such as landing columns， transfer columns， and suspended columns. It belongs to a special type of high-rise building that is not specified in current codes and has multi-directional force transfer paths. Corresponding performance-based design objectives have been formulated， and stress ratio control standards for steel members under different performance levels have been proposed. Through comprehensive theoretical calculations and appropriate structural measures， the structural system can be ensured to be reasonable and safe.
2025,
55(10):
193-202.
doi: 10.3724/j.gyjzG23052306
Abstract:
In order to meet the application requirements of super-long-span spatial grid structures for large-diameter bolted spherical joints， M90×6 to M120×6 large-diameter bolts were designed. Uniaxial tensile tests were conducted on ten full-scale M100×6 specimens and nine machined M120×6 specimens. The test results showed that their mechanical property indicators all met the requirements. The corresponding tapered heads for M90×6 to M120×6 large-diameter bolts were also designed， and their tensile and stress properties were investigated using ABAQUS. The simulation results validated the rationality of the tapered head design. Based on the above research and development outcomes， the standard for M90×6 to M120×6 large-diameter bolts was successfully applied for project approval and compiled.
In order to meet the application requirements of super-long-span spatial grid structures for large-diameter bolted spherical joints， M90×6 to M120×6 large-diameter bolts were designed. Uniaxial tensile tests were conducted on ten full-scale M100×6 specimens and nine machined M120×6 specimens. The test results showed that their mechanical property indicators all met the requirements. The corresponding tapered heads for M90×6 to M120×6 large-diameter bolts were also designed， and their tensile and stress properties were investigated using ABAQUS. The simulation results validated the rationality of the tapered head design. Based on the above research and development outcomes， the standard for M90×6 to M120×6 large-diameter bolts was successfully applied for project approval and compiled.
2025,
55(10):
203-211.
doi: 10.3724/j.gyjzG25082604
Abstract:
This paper conducted axial compression tests on six concrete-filled square stainless steel tube （CFSSST） columns and two hollow square stainless steel tube （HSSST） columns under different temperature conditions （ranging from -30 ℃ to 20 ℃）， to investigate the effects of low temperature and slenderness ratio on their failure modes， bearing capacity， and ductility. The results indicated that when the environmental temperature decreased to -30 ℃， the bearing capacity and initial stiffness of CFSSST columns increased significantly， while their ductility decreased. Low temperatures yielded negligible improvement in the bearing capacity of HSSST columns. As the slenderness ratio increased， the failure mode of CFSSST columns gradually shifted from being dominated by section failure to being dominated by buckling failure. The bearing capacity of CFSSST columns primarily originated from the outer stainless steel tubes， with the core concrete effectively preventing buckling failure due to inward collapse during service. When the test results were compared with domestic and international standards， Eurocode 4， AISC 360-16， and the Chinese standards were all found to yield conservative predictions for the axial bearing capacity of CFSSST columns. Finally， considering the strain hardening characteristics of stainless steel， this paper proposed a theoretical model for stainless steel tube-concrete composite columns. The computational results agreed well with the experimental data. Based on this， axial compression data for stainless steel tube-concrete columns from domestic and international sources were collected， and the theoretical model was shown to accurately predict the experimental results.
This paper conducted axial compression tests on six concrete-filled square stainless steel tube （CFSSST） columns and two hollow square stainless steel tube （HSSST） columns under different temperature conditions （ranging from -30 ℃ to 20 ℃）， to investigate the effects of low temperature and slenderness ratio on their failure modes， bearing capacity， and ductility. The results indicated that when the environmental temperature decreased to -30 ℃， the bearing capacity and initial stiffness of CFSSST columns increased significantly， while their ductility decreased. Low temperatures yielded negligible improvement in the bearing capacity of HSSST columns. As the slenderness ratio increased， the failure mode of CFSSST columns gradually shifted from being dominated by section failure to being dominated by buckling failure. The bearing capacity of CFSSST columns primarily originated from the outer stainless steel tubes， with the core concrete effectively preventing buckling failure due to inward collapse during service. When the test results were compared with domestic and international standards， Eurocode 4， AISC 360-16， and the Chinese standards were all found to yield conservative predictions for the axial bearing capacity of CFSSST columns. Finally， considering the strain hardening characteristics of stainless steel， this paper proposed a theoretical model for stainless steel tube-concrete composite columns. The computational results agreed well with the experimental data. Based on this， axial compression data for stainless steel tube-concrete columns from domestic and international sources were collected， and the theoretical model was shown to accurately predict the experimental results.
2025,
55(10):
212-218.
doi: 10.3724/j.gyjzG25012002
Abstract:
To investigate the seismic performance of T-stub connected beam-column joints， quasi-static loading tests were conducted on two T-stub joint specimens. Key mechanical indicators， including hysteretic curves， skeleton curves， and failure modes， were obtained. Based on the shape characteristics of the skeleton curves， a simplified skeleton curve model was proposed for this joint type. The mechanical parameter calculation method for the simplified model was established through mechanism analysis and the small deformation superposition principle. By performing regression analysis on experimental data from this study and joint test data from existing literature， the hysteretic rule expression was fitted and the restoring force model for such joints was developed. The validity of the proposed model was verified through a comparative analysis between theoretical calculations and experimental results. Research findings demonstrate that T-stub connected beam-column joints exhibited typical semi-rigid connection behavior with favorable seismic performance. The established restoring force model demonstrated high computational accuracy， making it suitable for seismic performance analysis and evaluation of this type of joint.
To investigate the seismic performance of T-stub connected beam-column joints， quasi-static loading tests were conducted on two T-stub joint specimens. Key mechanical indicators， including hysteretic curves， skeleton curves， and failure modes， were obtained. Based on the shape characteristics of the skeleton curves， a simplified skeleton curve model was proposed for this joint type. The mechanical parameter calculation method for the simplified model was established through mechanism analysis and the small deformation superposition principle. By performing regression analysis on experimental data from this study and joint test data from existing literature， the hysteretic rule expression was fitted and the restoring force model for such joints was developed. The validity of the proposed model was verified through a comparative analysis between theoretical calculations and experimental results. Research findings demonstrate that T-stub connected beam-column joints exhibited typical semi-rigid connection behavior with favorable seismic performance. The established restoring force model demonstrated high computational accuracy， making it suitable for seismic performance analysis and evaluation of this type of joint.
2025,
55(10):
219-227.
doi: 10.3724/j.gyjzG24040812
Abstract:
The technology of the steel-concrete composite reinforcement method has developed rapidly in recent years. This method has emerged as one of the best choices for reinforcement， as it saves both time and space. At the same time， research on this method continues to progress. This study takes the third section of the north-to-east ramp of Chegongmiao Interchange in Shenzhen as the research object. A composite reinforcement scheme is proposed for the single-column pier of this curved bridge， with a focus on the interfacial performance between new and existing concrete after reinforcement， which has not been sufficiently investigated under this configuration. Nine sets of comparative experiments were conducted to analyze the key issue of shear resistance at the interface between new and existing concrete in the composite reinforcement scheme. It was found that under the circumferential reinforcement structure proposed in this paper， both ductility and failure bearing capacity were improved due to the Poisson effect in the later stage of the interface treatment component. At the same time， by applying the calculation formulas provided in existing reinforcement codes， the shear strength parameters for the new “serrated groove” configuration were introduced and evaluated.
The technology of the steel-concrete composite reinforcement method has developed rapidly in recent years. This method has emerged as one of the best choices for reinforcement， as it saves both time and space. At the same time， research on this method continues to progress. This study takes the third section of the north-to-east ramp of Chegongmiao Interchange in Shenzhen as the research object. A composite reinforcement scheme is proposed for the single-column pier of this curved bridge， with a focus on the interfacial performance between new and existing concrete after reinforcement， which has not been sufficiently investigated under this configuration. Nine sets of comparative experiments were conducted to analyze the key issue of shear resistance at the interface between new and existing concrete in the composite reinforcement scheme. It was found that under the circumferential reinforcement structure proposed in this paper， both ductility and failure bearing capacity were improved due to the Poisson effect in the later stage of the interface treatment component. At the same time， by applying the calculation formulas provided in existing reinforcement codes， the shear strength parameters for the new “serrated groove” configuration were introduced and evaluated.
2025,
55(10):
228-233.
doi: 10.3724/j.gyjzG25033104
Abstract:
The wind power industry aligns with the strategic needs of low-carbon development and serves as a significant driving force for the global green economic transformation. To adapt to the higher capacity of new-generation wind turbines， improve power generation efficiency， and prolong service life， it is essential to retrofit the foundation of wind turbines. The structural foundation of a wind turbine was upgraded by incorporating rock anchor cables in an actual project. This study employed ANSYS software to establish a three-dimensional model for analyzing and calculating the principal stress and deformation of the concrete foundation， as well as the stresses in anchor bolts and anchor cables， and steel anchor plates of the prestressed anchor cable foundation. The analysis was conducted under three conditions： prestressing， normal operation， and extreme loading. The results indicated that the vertical deformation at the center and the overall rotational angle of the prestressed anchor cable foundation under extreme loading complied with the relevant code requirements. This finding demonstrated the feasibility of applying prestressed anchor cable foundations in the structural retrofitting of wind turbine foundations.
The wind power industry aligns with the strategic needs of low-carbon development and serves as a significant driving force for the global green economic transformation. To adapt to the higher capacity of new-generation wind turbines， improve power generation efficiency， and prolong service life， it is essential to retrofit the foundation of wind turbines. The structural foundation of a wind turbine was upgraded by incorporating rock anchor cables in an actual project. This study employed ANSYS software to establish a three-dimensional model for analyzing and calculating the principal stress and deformation of the concrete foundation， as well as the stresses in anchor bolts and anchor cables， and steel anchor plates of the prestressed anchor cable foundation. The analysis was conducted under three conditions： prestressing， normal operation， and extreme loading. The results indicated that the vertical deformation at the center and the overall rotational angle of the prestressed anchor cable foundation under extreme loading complied with the relevant code requirements. This finding demonstrated the feasibility of applying prestressed anchor cable foundations in the structural retrofitting of wind turbine foundations.
2025,
55(10):
234-247.
doi: 10.3724/j.gyjzG24051601
Abstract:
The rich internal pore structure of calcareous sand allows fine particles and sand particles in the foundation to mix easily with each other during hydraulic transport during hydraulic filling and site leveling in later construction. The addition of fine particles can change the particle composition of calcareous sand， thereby affecting its mechanical properties. To analyze the influence of calcareous fine content on the static characteristics of calcareous sand， multiple sets of consolidated undrained triaxial tests were conducted under varied confining pressures on calcareous fine-sand mixtures with fine contents of 0%， 10%， 40%， 70%， and 100%. Changes in shear strength and pore pressure were investigated， and the impact of calcareous fine content on the breakage of calcareous sand particles was analyzed. The experimental results showed that as the fine content increased， the peak stresses of the calcareous fine-sand mixtures first decreased and then increased， while the peak pore pressures and peak internal friction angles first increased and then decreased. In this experiment， the turning points of these changes all occurred in the mixture samples with a fine content of 10%. As the confining pressure increased， the peak internal friction angles of the calcareous fine-sand mixtures decreased， and the relative breakage index increased. In addition， the relative particle breakage index of calcareous sand showed a strong linear relationship with both confining pressure and fine content. Based on the results of this study， the relative particle breakage index of calcareous sand can be expressed by a polynomial function of confining stress and fine content.
The rich internal pore structure of calcareous sand allows fine particles and sand particles in the foundation to mix easily with each other during hydraulic transport during hydraulic filling and site leveling in later construction. The addition of fine particles can change the particle composition of calcareous sand， thereby affecting its mechanical properties. To analyze the influence of calcareous fine content on the static characteristics of calcareous sand， multiple sets of consolidated undrained triaxial tests were conducted under varied confining pressures on calcareous fine-sand mixtures with fine contents of 0%， 10%， 40%， 70%， and 100%. Changes in shear strength and pore pressure were investigated， and the impact of calcareous fine content on the breakage of calcareous sand particles was analyzed. The experimental results showed that as the fine content increased， the peak stresses of the calcareous fine-sand mixtures first decreased and then increased， while the peak pore pressures and peak internal friction angles first increased and then decreased. In this experiment， the turning points of these changes all occurred in the mixture samples with a fine content of 10%. As the confining pressure increased， the peak internal friction angles of the calcareous fine-sand mixtures decreased， and the relative breakage index increased. In addition， the relative particle breakage index of calcareous sand showed a strong linear relationship with both confining pressure and fine content. Based on the results of this study， the relative particle breakage index of calcareous sand can be expressed by a polynomial function of confining stress and fine content.
2025,
55(10):
248-253.
doi: 10.3724/j.gyjzG23102516
Abstract:
The cover system is one of the most important engineering barriers in the closure of near-surface disposal facilities. Based on the site characteristics of a near-surface disposal facility in Southwest China， this paper proposes the basic principles and safety functions for its cover system. Furthermore， a conceptual study on the cover is presented， including seepage control measures， drainage measures， and robustness. This study could provide a technical reference for the closure of near-surface disposal facilities.
The cover system is one of the most important engineering barriers in the closure of near-surface disposal facilities. Based on the site characteristics of a near-surface disposal facility in Southwest China， this paper proposes the basic principles and safety functions for its cover system. Furthermore， a conceptual study on the cover is presented， including seepage control measures， drainage measures， and robustness. This study could provide a technical reference for the closure of near-surface disposal facilities.
