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2025 Vol. 55, No. 11
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2025, 55(11): 1-10.
doi: 10.3724/j.gyjzG23111302
Abstract:
It is important to explore the development process and main trends of healthy campus evaluation systems in order to guide the construction of healthy campuses and support the healthy growth of students. By reviewing and comparing healthy campus evaluation systems in China and other countries， this study focuses on the progress in terms of evaluation targets， content， and outcomes. It summarizes three trends in the development of healthy campus evaluation systems： the differentiation of evaluation targets， the diversification of evaluation content， and the variation in evaluation outcomes. Furthermore， it offers insights for China's healthy campus evaluation system， including considering people from different educational stages， constructing a systematic evaluation index system， and strengthening the implementation of evaluation systems.
It is important to explore the development process and main trends of healthy campus evaluation systems in order to guide the construction of healthy campuses and support the healthy growth of students. By reviewing and comparing healthy campus evaluation systems in China and other countries， this study focuses on the progress in terms of evaluation targets， content， and outcomes. It summarizes three trends in the development of healthy campus evaluation systems： the differentiation of evaluation targets， the diversification of evaluation content， and the variation in evaluation outcomes. Furthermore， it offers insights for China's healthy campus evaluation system， including considering people from different educational stages， constructing a systematic evaluation index system， and strengthening the implementation of evaluation systems.
2025, 55(11): 11-18.
doi: 10.3724/j.gyjzG22102303
Abstract:
In recent years， research on K-type eccentrically braced steel frames has often neglected the influence of floor slabs. By integrating a steel frame with floor slabs to form a K-type eccentrically braced steel frame with composite beams， this study derived formulas for the initial stiffness and ultimate bearing capacity of the steel frames with shear links under the influence of floor slabs. Additionally， the ABAQRS software was used to establish 17 models to analyze its performance under unidirectional loading. The results showed that the combination of floor slabs improved the overall performance of the steel frame and enhanced the transmission of horizontal forces in the structure， thereby significantly improving its seismic performance. The calculation results based on the deduced formula for the K-type eccentrically braced steel frame with shear links under floor slab action were compared with the ABAQUS simulation results. The error of the derived formula was found to be within 15%， showing good agreement. This provides some formula references for calculating and analyzing the bearing capacity and stiffness of K-type eccentrically braced steel frames with shear links and floor slabs.
In recent years， research on K-type eccentrically braced steel frames has often neglected the influence of floor slabs. By integrating a steel frame with floor slabs to form a K-type eccentrically braced steel frame with composite beams， this study derived formulas for the initial stiffness and ultimate bearing capacity of the steel frames with shear links under the influence of floor slabs. Additionally， the ABAQRS software was used to establish 17 models to analyze its performance under unidirectional loading. The results showed that the combination of floor slabs improved the overall performance of the steel frame and enhanced the transmission of horizontal forces in the structure， thereby significantly improving its seismic performance. The calculation results based on the deduced formula for the K-type eccentrically braced steel frame with shear links under floor slab action were compared with the ABAQUS simulation results. The error of the derived formula was found to be within 15%， showing good agreement. This provides some formula references for calculating and analyzing the bearing capacity and stiffness of K-type eccentrically braced steel frames with shear links and floor slabs.
2025, 55(11): 19-27.
doi: 10.3724/j.gyjzG23032309
Abstract:
The localization of blind bolt production has promoted the application of square steel tube members with excellent mechanical properties in steel structure engineering. A new type of prefabricated steel frame structure is formed by connecting H-shaped steel beams and square steel tube columns using T-stubs and blind bolt connection technology. In order to study the seismic performance of this type of structure， a single-layer single-span steel frame connected by T-stubs and blind bolts was designed and subjected to quasi-static testing.. At the same time， a refined finite element model was established for nonlinear analysis， and the model was verified based on the test results. The hysteresis performance and failure modes of the steel frame connected with blind bolts were obtained， and the plastic development characteristics， lateral stiffness degradation law， and ductility deformation capacity of the steel frame were analyzed. The research results showed that the steel frame connected with blind bolts exhibited good seismic performance and could withstand certain seismic effects. The results provide a certain reference and reference value for the application of prefabricated steel structures.
The localization of blind bolt production has promoted the application of square steel tube members with excellent mechanical properties in steel structure engineering. A new type of prefabricated steel frame structure is formed by connecting H-shaped steel beams and square steel tube columns using T-stubs and blind bolt connection technology. In order to study the seismic performance of this type of structure， a single-layer single-span steel frame connected by T-stubs and blind bolts was designed and subjected to quasi-static testing.. At the same time， a refined finite element model was established for nonlinear analysis， and the model was verified based on the test results. The hysteresis performance and failure modes of the steel frame connected with blind bolts were obtained， and the plastic development characteristics， lateral stiffness degradation law， and ductility deformation capacity of the steel frame were analyzed. The research results showed that the steel frame connected with blind bolts exhibited good seismic performance and could withstand certain seismic effects. The results provide a certain reference and reference value for the application of prefabricated steel structures.
2025, 55(11): 28-35.
doi: 10.3724/j.gyjzG23082406
Abstract:
In order to reduce the residual deformation of traditional building structures after an earthquake， a novel self-centering energy dissipation damper is proposed. Theoretical analysis and structural design of the damper were carried out. The damper resets itself through the combination of a spiral compression spring and a shape memory alloy （SMA）， with energy dissipation achieved through the tensile process of the SMA rod and the sliding friction between other components. The force relationship between each component is clear， and the overall structure is simple and easy to install. The effects of the initial pretension of the SMA rod， the initial pre-pressure of the helical compression spring， and the friction coefficient between the components on the bearing capacity， energy dissipation capacity， and resetting capacity of the damper were comprehensively investigated by means of finite element simulation. The mechanical properties of steel frame beam-column joints equipped with the dampers were further analyzed. The results showed that the novel self-centering energy dissipation damper exhibited strong stability and excellent self-centering energy dissipation effect in both tension and compression processes， characterized by a "flag-shaped" hysteretic curve. When the self-centering energy dissipation damper was installed in the steel frame beam-column joint， it dissipated a large amount of energy and effectively controlled the residual deformation of the joint.
In order to reduce the residual deformation of traditional building structures after an earthquake， a novel self-centering energy dissipation damper is proposed. Theoretical analysis and structural design of the damper were carried out. The damper resets itself through the combination of a spiral compression spring and a shape memory alloy （SMA）， with energy dissipation achieved through the tensile process of the SMA rod and the sliding friction between other components. The force relationship between each component is clear， and the overall structure is simple and easy to install. The effects of the initial pretension of the SMA rod， the initial pre-pressure of the helical compression spring， and the friction coefficient between the components on the bearing capacity， energy dissipation capacity， and resetting capacity of the damper were comprehensively investigated by means of finite element simulation. The mechanical properties of steel frame beam-column joints equipped with the dampers were further analyzed. The results showed that the novel self-centering energy dissipation damper exhibited strong stability and excellent self-centering energy dissipation effect in both tension and compression processes， characterized by a "flag-shaped" hysteretic curve. When the self-centering energy dissipation damper was installed in the steel frame beam-column joint， it dissipated a large amount of energy and effectively controlled the residual deformation of the joint.
2025, 55(11): 36-44.
doi: 10.3724/j.gyjzG22110709
Abstract:
This study investigates the influence of ambient temperature on the static and dynamic properties of a continuously welded stainless steel roofing system. First， five specimens were designed and fabricated based on the system used in the terminal of Qingdao Jiaodong International Airport. Then， satic tests were conducted under cyclic temperatures， and dynamic tests under stable temperatures.Finally， ABAQUS software was used to establish a more accurate finite element model.According to the relevant basic theories， the initial model was modified using a Support Vector Machine （SVM） model optimized by the Moth-Flame Optimization （MFO） algorithm. Taking specimen WG5 as an example， a detailed comparison was made between the experimental and finite element analysis results. The results showed that the structural stress was positively correlated with temperature， exhibiting an approximately linear trend， while the structural frequency was negatively correlated， with a rate of change between 0.7% and 1.3%. After modifying the MFO-SVM model， the fundamental frequency error decreased from approximately 13% to less than 5%， and the error in the extreme stress between the numerical simulation and the measured results ranged from approximately 4% to 16%. This indicates that the modified model can better reflect the real structural response.
This study investigates the influence of ambient temperature on the static and dynamic properties of a continuously welded stainless steel roofing system. First， five specimens were designed and fabricated based on the system used in the terminal of Qingdao Jiaodong International Airport. Then， satic tests were conducted under cyclic temperatures， and dynamic tests under stable temperatures.Finally， ABAQUS software was used to establish a more accurate finite element model.According to the relevant basic theories， the initial model was modified using a Support Vector Machine （SVM） model optimized by the Moth-Flame Optimization （MFO） algorithm. Taking specimen WG5 as an example， a detailed comparison was made between the experimental and finite element analysis results. The results showed that the structural stress was positively correlated with temperature， exhibiting an approximately linear trend， while the structural frequency was negatively correlated， with a rate of change between 0.7% and 1.3%. After modifying the MFO-SVM model， the fundamental frequency error decreased from approximately 13% to less than 5%， and the error in the extreme stress between the numerical simulation and the measured results ranged from approximately 4% to 16%. This indicates that the modified model can better reflect the real structural response.
2025, 55(11): 45-51.
doi: 10.3724/j.gyjzG23112228
Abstract:
The cable-membrane connection of the double-layer orthogonal cable system adopts an aluminum interlocking connection， and the interlocking connection exerts a clamping effect on the folded membrane through the assembled interlocking components. In order to explore the failure mode and mechanical properties of the cable-membrane interlocking connection， a static loading test was carried out. Four groups of comparative tests were designed to investigate the failure mode and bearing capacity of the connection. Factors such as the membrane folding angle and the ridge membrane protection measures were respectively considered. The failure mode and bearing capacity of the connection were obtained， and the stress distribution of the connection was analyzed using the finite element software. The experimental results indicated that when the strength of the membrane was insufficient， the membrane would tear along the edge of the end of the profile. When the strength of the membrane was sufficient， the penetrating rope would fall off and cause the connection to fail. The increase of the membrane folding angle would be beneficial to the deformation of the interlocking components. The weak positions of the interlocking connection were located at the middle of the interlocked side and the end of the interlocking side， respectively. At a 120° membrane folding angle， the bearing capacity of the connection with the protective membrane increased by 19.3%. At a 140° membrane folding angle， the protective membrane had little effect on the bearing capacity of the connection.
The cable-membrane connection of the double-layer orthogonal cable system adopts an aluminum interlocking connection， and the interlocking connection exerts a clamping effect on the folded membrane through the assembled interlocking components. In order to explore the failure mode and mechanical properties of the cable-membrane interlocking connection， a static loading test was carried out. Four groups of comparative tests were designed to investigate the failure mode and bearing capacity of the connection. Factors such as the membrane folding angle and the ridge membrane protection measures were respectively considered. The failure mode and bearing capacity of the connection were obtained， and the stress distribution of the connection was analyzed using the finite element software. The experimental results indicated that when the strength of the membrane was insufficient， the membrane would tear along the edge of the end of the profile. When the strength of the membrane was sufficient， the penetrating rope would fall off and cause the connection to fail. The increase of the membrane folding angle would be beneficial to the deformation of the interlocking components. The weak positions of the interlocking connection were located at the middle of the interlocked side and the end of the interlocking side， respectively. At a 120° membrane folding angle， the bearing capacity of the connection with the protective membrane increased by 19.3%. At a 140° membrane folding angle， the protective membrane had little effect on the bearing capacity of the connection.
2025, 55(11): 52-59.
doi: 10.3724/j.gyjzG23061504
Abstract:
Composite sandwich exterior wall panels have broad application prospects in engineering practice. However， they might often be subjected to accidental impact during their service life， making it essential to investigate their impact performance. This study conducted impact performance tests and numerical simulations on these wall panels. Two specimens with different spans were fabricated and tested under impact loading to investigate the dynamic responses and failure mechanisms. Subsequently， a numerical model considering the strength improvement at various strain rates was established and verified against the test results. Furthermore， a parametric analysis was conducted to evaluate the influence of six parameters， including the drop height， the mass and stiffness of the impactor， and the boundary conditions， on the impact performance of the composite sandwich exterior wall panels. Within a certain range， there is a positive correlation among the drop height， weight， stiffness， and impact force. As the boundary conditions intensify， the impact response time shortens.
Composite sandwich exterior wall panels have broad application prospects in engineering practice. However， they might often be subjected to accidental impact during their service life， making it essential to investigate their impact performance. This study conducted impact performance tests and numerical simulations on these wall panels. Two specimens with different spans were fabricated and tested under impact loading to investigate the dynamic responses and failure mechanisms. Subsequently， a numerical model considering the strength improvement at various strain rates was established and verified against the test results. Furthermore， a parametric analysis was conducted to evaluate the influence of six parameters， including the drop height， the mass and stiffness of the impactor， and the boundary conditions， on the impact performance of the composite sandwich exterior wall panels. Within a certain range， there is a positive correlation among the drop height， weight， stiffness， and impact force. As the boundary conditions intensify， the impact response time shortens.
2025, 55(11): 60-67.
doi: 10.3724/j.gyjzG24040305
Abstract:
Determining sealant joint width is the key issue during the design of precast concrete facade panels， which is related to seismic， wind-resistant， waterproof， airtight， and fireproof performance of building facade panels system， and a reasonable sealant joint width is very important for the in-plane adaptability of the panels to the story drift of main structures and the displacement ability of the sealant. Based on the displacement ability of the sealant， the nominal shear deformation rate was put forward in this paper， and then calibrated， which can be directly used to calculate sealant joint size. The calculation method of sealant joint width was given by considering the influence factors of thermal movement， seismic movement， wind load movement， construction tolerances and sealant movement capacity， and the movement check computation of sealant joint width was suggested for the story drift of the main structure during fortification earthquake and rare earthquake. Finally， through a specific project example， it analyzed the impact of the connection mode of precast concrete facade panels and the main structure on the width of the joints， and gave the value of the joint width for different facade panel heights and connection modes， which can provide a reference for similar projects.
Determining sealant joint width is the key issue during the design of precast concrete facade panels， which is related to seismic， wind-resistant， waterproof， airtight， and fireproof performance of building facade panels system， and a reasonable sealant joint width is very important for the in-plane adaptability of the panels to the story drift of main structures and the displacement ability of the sealant. Based on the displacement ability of the sealant， the nominal shear deformation rate was put forward in this paper， and then calibrated， which can be directly used to calculate sealant joint size. The calculation method of sealant joint width was given by considering the influence factors of thermal movement， seismic movement， wind load movement， construction tolerances and sealant movement capacity， and the movement check computation of sealant joint width was suggested for the story drift of the main structure during fortification earthquake and rare earthquake. Finally， through a specific project example， it analyzed the impact of the connection mode of precast concrete facade panels and the main structure on the width of the joints， and gave the value of the joint width for different facade panel heights and connection modes， which can provide a reference for similar projects.
2025, 55(11): 68-79.
doi: 10.3724/j.gyjzG25031308
Abstract:
Ultra-high toughness cementitious composites （UHTCC） are fiber-reinforced， cement-based materials known for their exceptional toughness， crack resistance， and tensile strain hardening. These properties ensure that UHTCC resists cracking under normal conditions and effectively prevents the intrusion of chloride ions and water， thereby enhancing structural durability and energy dissipation. As a result， UHTCC holds significant potential for use in critical projects and key infrastructure. This study introduces a UHTCC-encased circular steel tube composite column， offering advantages such as lightweight construction， ease of assembly， high bearing capacity， and superior durability. The axial compressive performance and steel tube buckling behavior of the proposed composite column， which incorporates both stud and PBL shear connectors， were investigated using a combined approach of theoretical and finite element analysis.A detailed finite element model of the composite column was developed and validated against experimental data， with an error range of 1.2%–2.3%. The finite element parameter analysis showed that as the number of PBLs increased from 4 to 12， the bearing capacity of the composite column with width-to-thickness ratios of 25 and 150 increased by 15% and 10%， respectively. Finally， theoretical calculations were performed to determine the steel tube’s critical buckling load， from which the composite column’s axial compressive capacity was derived.
Ultra-high toughness cementitious composites （UHTCC） are fiber-reinforced， cement-based materials known for their exceptional toughness， crack resistance， and tensile strain hardening. These properties ensure that UHTCC resists cracking under normal conditions and effectively prevents the intrusion of chloride ions and water， thereby enhancing structural durability and energy dissipation. As a result， UHTCC holds significant potential for use in critical projects and key infrastructure. This study introduces a UHTCC-encased circular steel tube composite column， offering advantages such as lightweight construction， ease of assembly， high bearing capacity， and superior durability. The axial compressive performance and steel tube buckling behavior of the proposed composite column， which incorporates both stud and PBL shear connectors， were investigated using a combined approach of theoretical and finite element analysis.A detailed finite element model of the composite column was developed and validated against experimental data， with an error range of 1.2%–2.3%. The finite element parameter analysis showed that as the number of PBLs increased from 4 to 12， the bearing capacity of the composite column with width-to-thickness ratios of 25 and 150 increased by 15% and 10%， respectively. Finally， theoretical calculations were performed to determine the steel tube’s critical buckling load， from which the composite column’s axial compressive capacity was derived.
2025, 55(11): 80-88.
doi: 10. 3724/j. gyjzG23112206
Abstract:
To further investigate the stability of high-strength steel （HSS） welded box-section axiallycompressed columns with different strength grades，the overall buckling strength of HSS welded box-section columns was analyzed using the numerical fiber model method. The results were then used to verify the appli-cability of the column curves specified in the current code. A fiber model was established，taking into account the effects of residual stress and geometric imperfections. The overall bearing capacities of the HSS welded box-section specimens were calculated，and the accuracy of the fiber model was verified by comparing the results with experimental data. Based on the fiber model，the overall bearing capacities of 480 specimens were analyzed，including five nominal yield strengths ranging from 460 MPa to 960 MPa，eight box-section dimensions，and twelve slenderness ratios for each section. The parametric analysis results were compared with the design curves of the current steel structure design code，and the design curves suitable for HSS axially-compressed members were updated It is recommended that the stability coefficient of 460-550 MPa steel members and 690-960 MPa steel members should be designed with b-type columns and a-type columns respectively. Additionally，the coefficients in the column curve formula of the code were modified，and a new calculation formula suitable for HSS with different yield strengths was proposed.
To further investigate the stability of high-strength steel （HSS） welded box-section axiallycompressed columns with different strength grades，the overall buckling strength of HSS welded box-section columns was analyzed using the numerical fiber model method. The results were then used to verify the appli-cability of the column curves specified in the current code. A fiber model was established，taking into account the effects of residual stress and geometric imperfections. The overall bearing capacities of the HSS welded box-section specimens were calculated，and the accuracy of the fiber model was verified by comparing the results with experimental data. Based on the fiber model，the overall bearing capacities of 480 specimens were analyzed，including five nominal yield strengths ranging from 460 MPa to 960 MPa，eight box-section dimensions，and twelve slenderness ratios for each section. The parametric analysis results were compared with the design curves of the current steel structure design code，and the design curves suitable for HSS axially-compressed members were updated It is recommended that the stability coefficient of 460-550 MPa steel members and 690-960 MPa steel members should be designed with b-type columns and a-type columns respectively. Additionally，the coefficients in the column curve formula of the code were modified，and a new calculation formula suitable for HSS with different yield strengths was proposed.
2025, 55(11): 89-96.
doi: 10.3724/j.gyjzG23101921
Abstract:
Composite box girder bridges with corrugated steel webs have been widely used in bridge construction due to their light weight， aesthetic appearance， and rational structural behavior. However， due to the thin web， significant torsional effects occur under eccentric loads， which may compromise structural safety. To gain a comprehensive understanding of the torsional performance of such girders， this paper reviews research progress in four aspects： calculation theory， numerical simulations， model tests， and torsional capacity. Results show that it is feasible to apply Umansky’s second theory to calculate torsional stresses in composite box girders with corrugated steel webs. The elastoplastic theoretical model can predict the complete force curves of such girders under pure torsion； however， its computational efficiency and stability require further improvement. Although some studies have been conducted on concrete diaphragms， lining concrete， and web inclination， a unified calculation formula and design method are still lacking. Moreover， existing formulas for torsional capacity do not adequately account for dimensional parameters， structural configurations， and failure modes， indicating a need for further research.
Composite box girder bridges with corrugated steel webs have been widely used in bridge construction due to their light weight， aesthetic appearance， and rational structural behavior. However， due to the thin web， significant torsional effects occur under eccentric loads， which may compromise structural safety. To gain a comprehensive understanding of the torsional performance of such girders， this paper reviews research progress in four aspects： calculation theory， numerical simulations， model tests， and torsional capacity. Results show that it is feasible to apply Umansky’s second theory to calculate torsional stresses in composite box girders with corrugated steel webs. The elastoplastic theoretical model can predict the complete force curves of such girders under pure torsion； however， its computational efficiency and stability require further improvement. Although some studies have been conducted on concrete diaphragms， lining concrete， and web inclination， a unified calculation formula and design method are still lacking. Moreover， existing formulas for torsional capacity do not adequately account for dimensional parameters， structural configurations， and failure modes， indicating a need for further research.
2025, 55(11): 97-105.
doi: 10.3724/j.gyjzG23110215
Abstract:
Experiments under monotonic and cyclic loading conditions， along with simulations， were conducted to investigate the mechanical properties of steel square tube columns with standard flange connections. The constraint stiffness， failure mode， bearing capacity， hysteretic performance， and stiffness degradation of the steel square tube columns under different design strengths were studied. The results showed that the design strength of the flange connection significantly affected the mechanical properties of the steel square tube column. The constraint effect of the flange connection on the column could be adjusted by changing the design strength multiplier of the flange connection. When the connection strength multiplier was small （0.25-0.85）， the flange’s constraint effect on the column behaved as a semi-rigid connection. Under such connection conditions， the column rapidly lost its bearing capacity. The bearing capacity of the specimen was linearly and positively correlated with the with design strength multiplier of the connection in this range. When the connection strength multiplier was large （1-1.6）， the flange’s constraint effect on the column was that of a rigid connection， which allowed full utilization of the bending performance of the square tube column. In this case， the bearing capacity of the specimen remained almost unchanged with an increase in the connection strength parameter. As the flange connection strength increased， the cyclic stiffness degradation of the specimen showed a decreasing trend.
Experiments under monotonic and cyclic loading conditions， along with simulations， were conducted to investigate the mechanical properties of steel square tube columns with standard flange connections. The constraint stiffness， failure mode， bearing capacity， hysteretic performance， and stiffness degradation of the steel square tube columns under different design strengths were studied. The results showed that the design strength of the flange connection significantly affected the mechanical properties of the steel square tube column. The constraint effect of the flange connection on the column could be adjusted by changing the design strength multiplier of the flange connection. When the connection strength multiplier was small （0.25-0.85）， the flange’s constraint effect on the column behaved as a semi-rigid connection. Under such connection conditions， the column rapidly lost its bearing capacity. The bearing capacity of the specimen was linearly and positively correlated with the with design strength multiplier of the connection in this range. When the connection strength multiplier was large （1-1.6）， the flange’s constraint effect on the column was that of a rigid connection， which allowed full utilization of the bending performance of the square tube column. In this case， the bearing capacity of the specimen remained almost unchanged with an increase in the connection strength parameter. As the flange connection strength increased， the cyclic stiffness degradation of the specimen showed a decreasing trend.
2025, 55(11): 106-114.
doi: 10.3724/j.gyjzG23101609
Abstract:
To study the bearing capacity of spatial TT-joints reinforced with collar plates under axial compression， experimental tests were conducted on one unreinforced spatial TT-joint and one collar plate-reinforced spatial TT-joint， respectively. The failure mode and the bearing capacity were studied； based on this， finite element models of spatial TT-joints reinforced with collar plates were established， and then a parametric analysis was conducted. The research showed that reinforcing with collar plates improved the bearing capacity of spatial TT-joints； the length of the collar plate had no effect on the bearing capacity of the joints； the main influencing factors of bearing capacity in spatial TT-joints included the brace-to-chord diameter ratio β， the chord diameter-to-twice chord wall thickness ratio γ， the brace wall thickness-to-chord wall thickness ratio τ， and the collar plate thickness-to-chord wall thickness ratio τc； the parameter τ affected the failure modes of the joints. The calculation formula for the bearing capacity of spatial TT-joints reinforced with collar plates under chord plastic failure was proposed using the multiple linear regression method.
To study the bearing capacity of spatial TT-joints reinforced with collar plates under axial compression， experimental tests were conducted on one unreinforced spatial TT-joint and one collar plate-reinforced spatial TT-joint， respectively. The failure mode and the bearing capacity were studied； based on this， finite element models of spatial TT-joints reinforced with collar plates were established， and then a parametric analysis was conducted. The research showed that reinforcing with collar plates improved the bearing capacity of spatial TT-joints； the length of the collar plate had no effect on the bearing capacity of the joints； the main influencing factors of bearing capacity in spatial TT-joints included the brace-to-chord diameter ratio β， the chord diameter-to-twice chord wall thickness ratio γ， the brace wall thickness-to-chord wall thickness ratio τ， and the collar plate thickness-to-chord wall thickness ratio τc； the parameter τ affected the failure modes of the joints. The calculation formula for the bearing capacity of spatial TT-joints reinforced with collar plates under chord plastic failure was proposed using the multiple linear regression method.
2025, 55(11): 115-123.
doi: 10.3724/j.gyjzG23120504
Abstract:
Torsional stiffness is crucial for the stability and service performance of half-through truss bridges. To study the torsional characteristics of the main girder of a half-through truss bridge， the half-through truss is equated to an open-section thin-walled member， and the calculation formula for the free torsional moment of inertia of the main girder is derived. Since the main truss of the half-through truss bridge resists warping deformation through bending， it contributes significantly to the torsional stiffness of the main girder. Based on the vertical bending behavior of the main truss， the correction formula for the torsional moment of inertia of the main girder is derived. Taking a half-through truss pedestrian bridge as an example， the torsional moment of inertia of the bridge under different width-span ratios was calculated using theoretical and finite element analysis. The results showed that when calculating the torsional moment of inertia of the main girder of a half-through truss bridge， the free torsional moment of inertia calculated using the equivalent open-section differed significantly from the actual torsional stiffness， and the bending correction of the main truss must be considered. The contribution of the main truss to torsional resistance through bending increased rapidly with the increase in the width-span ratio. The theoretical solution， after incorporating the correction， showed good agreement with the finite element results. The theoretical formula can be used to explain the torsional mechanism of this type of bridge. However， since the theoretical calculation did not account for the beneficial effect of the transverse bending resistance of the bottom chord， the theoretical solution gradually became smaller than the finite element solution as the bridge width increased. Based on the mechanism study， a method of adding X-shaped longitudinal bracing between the upper transverse beams to improve the torsional stiffness was proposed. The addition of X-shaped longitudinal bracing not only preserves the dimensions of the half-through truss bridge but also significantly enhances the torsional stiffness and stability of the structure.
Torsional stiffness is crucial for the stability and service performance of half-through truss bridges. To study the torsional characteristics of the main girder of a half-through truss bridge， the half-through truss is equated to an open-section thin-walled member， and the calculation formula for the free torsional moment of inertia of the main girder is derived. Since the main truss of the half-through truss bridge resists warping deformation through bending， it contributes significantly to the torsional stiffness of the main girder. Based on the vertical bending behavior of the main truss， the correction formula for the torsional moment of inertia of the main girder is derived. Taking a half-through truss pedestrian bridge as an example， the torsional moment of inertia of the bridge under different width-span ratios was calculated using theoretical and finite element analysis. The results showed that when calculating the torsional moment of inertia of the main girder of a half-through truss bridge， the free torsional moment of inertia calculated using the equivalent open-section differed significantly from the actual torsional stiffness， and the bending correction of the main truss must be considered. The contribution of the main truss to torsional resistance through bending increased rapidly with the increase in the width-span ratio. The theoretical solution， after incorporating the correction， showed good agreement with the finite element results. The theoretical formula can be used to explain the torsional mechanism of this type of bridge. However， since the theoretical calculation did not account for the beneficial effect of the transverse bending resistance of the bottom chord， the theoretical solution gradually became smaller than the finite element solution as the bridge width increased. Based on the mechanism study， a method of adding X-shaped longitudinal bracing between the upper transverse beams to improve the torsional stiffness was proposed. The addition of X-shaped longitudinal bracing not only preserves the dimensions of the half-through truss bridge but also significantly enhances the torsional stiffness and stability of the structure.
2025, 55(11): 124-132.
doi: 10.3724/j.gyjzG25072501
Abstract:
This paper takes a complex high-rise building as the background and aims to study the mechanical behavior of its "weakly-correlated" structural form under special construction techniques. By establishing a refined finite element model， the construction process of the overall lifting of suspended floors was simulated using the equivalent load method， taking into account the influence of time-varying factors such as concrete shrinkage and creep， as well as the timing of construction loads. Based on this model， numerical simulations were conducted for the entire construction process， revealing the vertical deformation accumulation law of the suspended floors during the installation process from top to bottom layer by layer. The deformation of the suspended floors showed a significant non-uniform spatial distribution and was concentrated at the corners of the structure. At the same time， the deformation gradually increased with the decrease of floor levels， without exhibiting the layer-by-layer stacking effect of strongly-correlated structures. The analysis results indicate that the time-varying effect cannot be ignored in the deformation of the vertical components of the core tube， and reasonable construction adjustment measures can effectively optimize the internal forces of the components.
This paper takes a complex high-rise building as the background and aims to study the mechanical behavior of its "weakly-correlated" structural form under special construction techniques. By establishing a refined finite element model， the construction process of the overall lifting of suspended floors was simulated using the equivalent load method， taking into account the influence of time-varying factors such as concrete shrinkage and creep， as well as the timing of construction loads. Based on this model， numerical simulations were conducted for the entire construction process， revealing the vertical deformation accumulation law of the suspended floors during the installation process from top to bottom layer by layer. The deformation of the suspended floors showed a significant non-uniform spatial distribution and was concentrated at the corners of the structure. At the same time， the deformation gradually increased with the decrease of floor levels， without exhibiting the layer-by-layer stacking effect of strongly-correlated structures. The analysis results indicate that the time-varying effect cannot be ignored in the deformation of the vertical components of the core tube， and reasonable construction adjustment measures can effectively optimize the internal forces of the components.
2025, 55(11): 133-140.
doi: 10.3724/j.gyjzG23110612
Abstract:
In order to evaluate the impact of mining-induced surface deformation on the safety of transmission towers with high and low legs， this study investigates a typical 220 kV tower. Finite element models of the tower were established for both equal-leg and high-low leg configurations （with a 2 m leg height difference）. The influence of types and directions of horizontal surface deformation on the force variation characteristics of the tower structure was studied and analyzed， and the capacity of the tower to resist surface horizontal deformation was obtained. The results indicate that buckling of the primary or secondary X-bracings or diaphragms is the primary failure indicator under horizontal surface deformation. The tower's resistance to deformation in oblique directions （30°， 45°， 60°） is significantly lower than in the 0° or 90° directions， with the 60° direction exhibiting the poorest deformation resistance， only 21.8%-29.9% in the 0° direction and 18.1%-31.4% in the 90° direction. Furthermore， the tower's resistance to tensile deformation is lower than its resistance to compressive deformation. The high-low leg tower exhibits significantly lower resistance to surface horizontal deformation than the equal-leg tower under the same conditions， with a maximum difference of 40.0%. Therefore， when constructing high-low leg transmission towers in mining areas， the direction of surface deformation must be considered， and the anti-surface-deformation performance， particularly in oblique directions， requires specific evaluation.
In order to evaluate the impact of mining-induced surface deformation on the safety of transmission towers with high and low legs， this study investigates a typical 220 kV tower. Finite element models of the tower were established for both equal-leg and high-low leg configurations （with a 2 m leg height difference）. The influence of types and directions of horizontal surface deformation on the force variation characteristics of the tower structure was studied and analyzed， and the capacity of the tower to resist surface horizontal deformation was obtained. The results indicate that buckling of the primary or secondary X-bracings or diaphragms is the primary failure indicator under horizontal surface deformation. The tower's resistance to deformation in oblique directions （30°， 45°， 60°） is significantly lower than in the 0° or 90° directions， with the 60° direction exhibiting the poorest deformation resistance， only 21.8%-29.9% in the 0° direction and 18.1%-31.4% in the 90° direction. Furthermore， the tower's resistance to tensile deformation is lower than its resistance to compressive deformation. The high-low leg tower exhibits significantly lower resistance to surface horizontal deformation than the equal-leg tower under the same conditions， with a maximum difference of 40.0%. Therefore， when constructing high-low leg transmission towers in mining areas， the direction of surface deformation must be considered， and the anti-surface-deformation performance， particularly in oblique directions， requires specific evaluation.
2025, 55(11): 141-148.
doi: 10.3724/j.gyjzG23091804
Abstract:
Carbon fiber composite materials （CFRP） have the advantages of light weight， high strength， corrosion resistance， and fatigue resistance. Among them， CFRP rod cables are more advantageous in bridge structures and long-span space structures. The surface treatment process of the CFRP cable anchoring area is the key to affecting the bearing capacity performance of the anchoring system. This article studies the surface treatment process of the CFRP cable base material and compares the improvement effect of the CFRP rod cable anchoring performance under different surface treatment processes. The results show that polishing the surface of CFRP rod cables with 16-grit sandpaper and bonding 26 to 40 mesh quartz sand can improve the load-bearing performance of anchor nodes by 361.1% compared with smooth rod cables. The research results can provide an important basis for the production of improved CFRP rod and cable anchor systems.
Carbon fiber composite materials （CFRP） have the advantages of light weight， high strength， corrosion resistance， and fatigue resistance. Among them， CFRP rod cables are more advantageous in bridge structures and long-span space structures. The surface treatment process of the CFRP cable anchoring area is the key to affecting the bearing capacity performance of the anchoring system. This article studies the surface treatment process of the CFRP cable base material and compares the improvement effect of the CFRP rod cable anchoring performance under different surface treatment processes. The results show that polishing the surface of CFRP rod cables with 16-grit sandpaper and bonding 26 to 40 mesh quartz sand can improve the load-bearing performance of anchor nodes by 361.1% compared with smooth rod cables. The research results can provide an important basis for the production of improved CFRP rod and cable anchor systems.
2025, 55(11): 149-156.
doi: 10.3724/j.gyjzG23122507
Abstract:
Offshore wind power， as a key field of renewable energy in China， is of great strategic significance. Currently， two primary methods are used in the design phase： integrated analysis and traditional iterative analysis. Given the high cost of offshore wind power units， selecting an appropriate design method is crucial. In this paper， the fatigue loads and dynamic responses of the monopile foundation and the jacket foundation for a 5 MW offshore wind turbine were compared using both the integrated and traditional iterative analysis methods. The results showed that integrated analysis effectively reduced fatigue damage in both the monopile foundation and the jacket foundation， thereby decreasing their steel material consumption. Differences in the bottom bending moment of the monopile foundation and the base shear of jacket foundation legs between the integrated and traditional iterative analyses were compared. The results indicated that the discrepancies between the integrated and traditional iterative analyses were mainly attributable to the interaction of wind loads and wave loads.
Offshore wind power， as a key field of renewable energy in China， is of great strategic significance. Currently， two primary methods are used in the design phase： integrated analysis and traditional iterative analysis. Given the high cost of offshore wind power units， selecting an appropriate design method is crucial. In this paper， the fatigue loads and dynamic responses of the monopile foundation and the jacket foundation for a 5 MW offshore wind turbine were compared using both the integrated and traditional iterative analysis methods. The results showed that integrated analysis effectively reduced fatigue damage in both the monopile foundation and the jacket foundation， thereby decreasing their steel material consumption. Differences in the bottom bending moment of the monopile foundation and the base shear of jacket foundation legs between the integrated and traditional iterative analyses were compared. The results indicated that the discrepancies between the integrated and traditional iterative analyses were mainly attributable to the interaction of wind loads and wave loads.
2025, 55(11): 157-163.
doi: 10.3724/j.gyjzG23112213
Abstract:
By using the hollow cylinder torsional shear test system， this study investigated the dynamic deformation characteristics of rubber-sand mixtures with varying rubber contents， particle size ratios， and consolidation ratios. The effects and underlying mechanisms of these three factors on the dynamic deformation characteristics were explored. The test results showed that under isotropic consolidation， the specimens with higher rubber content required more vibration cycles to fail under cyclic torsional shear loading. As the particle size ratio increased， the specimens' deformation resistance was enhanced， thereby reducing the damage induced by the cyclic load. The dynamic shear modulus decreased with the rubber content but increased with the particle size ratio. The specimens with 5% rubber content exhibited the highest cumulative energy dissipation， which decreased as the rubber content increased. Furthermore， the damping ratio at 5% rubber content was significantly higher than that at 10% and 15%， and it decreased as the particle size ratio increased. Under anisotropic consolidation， the shear strain of the specimens decreased obviously， and a greater shear stress was required to induce failure. The influence of both rubber content and particle size ratio on the dynamic deformation of the specimens was relatively reduced， the attenuation rate of the dynamic shear modulus accelerated， and the sensitivity of the damping ratio to changes in both rubber content and particle size ratio decreased.
By using the hollow cylinder torsional shear test system， this study investigated the dynamic deformation characteristics of rubber-sand mixtures with varying rubber contents， particle size ratios， and consolidation ratios. The effects and underlying mechanisms of these three factors on the dynamic deformation characteristics were explored. The test results showed that under isotropic consolidation， the specimens with higher rubber content required more vibration cycles to fail under cyclic torsional shear loading. As the particle size ratio increased， the specimens' deformation resistance was enhanced， thereby reducing the damage induced by the cyclic load. The dynamic shear modulus decreased with the rubber content but increased with the particle size ratio. The specimens with 5% rubber content exhibited the highest cumulative energy dissipation， which decreased as the rubber content increased. Furthermore， the damping ratio at 5% rubber content was significantly higher than that at 10% and 15%， and it decreased as the particle size ratio increased. Under anisotropic consolidation， the shear strain of the specimens decreased obviously， and a greater shear stress was required to induce failure. The influence of both rubber content and particle size ratio on the dynamic deformation of the specimens was relatively reduced， the attenuation rate of the dynamic shear modulus accelerated， and the sensitivity of the damping ratio to changes in both rubber content and particle size ratio decreased.
2025, 55(11): 164-170.
doi: 10.3724/j.gyjzG23050402
Abstract:
Based on the Cangrong Xunjiang Bridge project， relevant research was conducted on the design and stress characteristics of the large-diameter pile-wall composite anchor foundation. By analyzing the anchor foundation scheme of Cangrong Xunjiang Bridge， the overall layout of the bridge， anchor foundation， anchor cable system， and other design schemes were elucidated. Combined with the geological conditions of the anchor foundation， the displacement and internal force of the pile-wall composite anchor foundation on the south side of Cangrong Xunjiang Bridge were analyzed. The impact of pile-wall connection types on the bearing capacity of the anchor foundation was analyzed， and a comparative study was conducted on four types of pile-wall connection types： fully connected pile-wall， fully separated pile-wall， interface-connected pile-wall， and pure pile foundation. The research results indicate that the deformation and internal force of the pile-wall composite foundation meet the requirements under construction and cable-hoisting operation conditions. The fully connected pile-wall is the ideal optimal form， whereas the pure pile foundation is the least effective form. Despite this， both are capable of meeting the requirements and possess a bearing capacity over 2.0 times the cable force. Upon completion of the pile-wall composite anchor foundation， the overall structure is in a good state of stress.
Based on the Cangrong Xunjiang Bridge project， relevant research was conducted on the design and stress characteristics of the large-diameter pile-wall composite anchor foundation. By analyzing the anchor foundation scheme of Cangrong Xunjiang Bridge， the overall layout of the bridge， anchor foundation， anchor cable system， and other design schemes were elucidated. Combined with the geological conditions of the anchor foundation， the displacement and internal force of the pile-wall composite anchor foundation on the south side of Cangrong Xunjiang Bridge were analyzed. The impact of pile-wall connection types on the bearing capacity of the anchor foundation was analyzed， and a comparative study was conducted on four types of pile-wall connection types： fully connected pile-wall， fully separated pile-wall， interface-connected pile-wall， and pure pile foundation. The research results indicate that the deformation and internal force of the pile-wall composite foundation meet the requirements under construction and cable-hoisting operation conditions. The fully connected pile-wall is the ideal optimal form， whereas the pure pile foundation is the least effective form. Despite this， both are capable of meeting the requirements and possess a bearing capacity over 2.0 times the cable force. Upon completion of the pile-wall composite anchor foundation， the overall structure is in a good state of stress.
2025, 55(11): 171-176.
doi: 10.3724/j.gyjzG23051704
Abstract:
Based on the Guangdong Shiziyang Bridge project， the reasonable bearing capacity of the foundation bearing layer was determined for the anchorage foundation of the super long-span suspension bridge. The double-walled bored cast-in-place pile technology was adopted to construct the load-transfer piles for the deep loading plate test. The inner steel cage was wrapped in a 0.8 m diameter steel casing that served as the inner wall， thereby minimizing the pile side friction and ensuring the full transfer of the applied load to the pile tip. For the outer layer， a 1.2 m steel casing was used for borehole wall protection， with gravel filled between the inner and outer walls to ensure the stability of both the load-transfer pile and the borehole wall. In addition， the sediment removal process at the pile tip was optimized by tightening the control standards for slurry density and ensuring a seamless transition between the commencement of the initial concreting and the completion of the second-stage hole cleaning. The test Q-s curve was obtained through methods employing pre-embedded rebar gauges on the pile body to monitor tip stress and pre-installed settlement monitoring rebars to measure tip settlement. The bearing capacity characteristic values of the bearing layer were then determined through analysis. The test results demonstrated that the characteristic value of the bearing capacity for the moderately weathered bearing layer was recommended to be 2461 kPa， and confirmed the effectiveness and feasibility of the deep loading plate test method using the double-walled bored pile technology.
Based on the Guangdong Shiziyang Bridge project， the reasonable bearing capacity of the foundation bearing layer was determined for the anchorage foundation of the super long-span suspension bridge. The double-walled bored cast-in-place pile technology was adopted to construct the load-transfer piles for the deep loading plate test. The inner steel cage was wrapped in a 0.8 m diameter steel casing that served as the inner wall， thereby minimizing the pile side friction and ensuring the full transfer of the applied load to the pile tip. For the outer layer， a 1.2 m steel casing was used for borehole wall protection， with gravel filled between the inner and outer walls to ensure the stability of both the load-transfer pile and the borehole wall. In addition， the sediment removal process at the pile tip was optimized by tightening the control standards for slurry density and ensuring a seamless transition between the commencement of the initial concreting and the completion of the second-stage hole cleaning. The test Q-s curve was obtained through methods employing pre-embedded rebar gauges on the pile body to monitor tip stress and pre-installed settlement monitoring rebars to measure tip settlement. The bearing capacity characteristic values of the bearing layer were then determined through analysis. The test results demonstrated that the characteristic value of the bearing capacity for the moderately weathered bearing layer was recommended to be 2461 kPa， and confirmed the effectiveness and feasibility of the deep loading plate test method using the double-walled bored pile technology.
2025, 55(11): 177-186.
doi: 10.3724/j.gyjzG23090203
Abstract:
Based on the three-bore parallel rectangular pipe jacking project at Mingxiulu Station of the Nanning Metro， the construction control measures for small-spacing three-bore parallel pipe jacking were proposed. The investigation into ground settlement and pipe deformation was conducted using numerical simulation and field monitoring. The numerical analysis showed that the ground settlement curve presented a three-peak "wave" pattern， with the greatest settlement occurring at the axis of the middle pipe. The maximum ground settlements with and without implementing control measures were 16.65 mm and 5.46 mm， respectively， indicating that the measures effectively reduced settlement. The range of ground disturbance caused by construction was approximately three times the pipe width when control measures were implemented. Field monitoring results showed a ground settlement ranging from 1.02 mm to 6.12 mm， with larger settlements observed at the launch and reception ends. Key measures， including construction axis control and deflection correction， synchronous grouting， optimization of the construction sequence， channel steel reinforcement， and soil conditioning， were taken during the construction. These measures successfully controlled ground settlement.
Based on the three-bore parallel rectangular pipe jacking project at Mingxiulu Station of the Nanning Metro， the construction control measures for small-spacing three-bore parallel pipe jacking were proposed. The investigation into ground settlement and pipe deformation was conducted using numerical simulation and field monitoring. The numerical analysis showed that the ground settlement curve presented a three-peak "wave" pattern， with the greatest settlement occurring at the axis of the middle pipe. The maximum ground settlements with and without implementing control measures were 16.65 mm and 5.46 mm， respectively， indicating that the measures effectively reduced settlement. The range of ground disturbance caused by construction was approximately three times the pipe width when control measures were implemented. Field monitoring results showed a ground settlement ranging from 1.02 mm to 6.12 mm， with larger settlements observed at the launch and reception ends. Key measures， including construction axis control and deflection correction， synchronous grouting， optimization of the construction sequence， channel steel reinforcement， and soil conditioning， were taken during the construction. These measures successfully controlled ground settlement.
2025, 55(11): 187-194.
doi: 10.3724/j.gyjzG23091705
Abstract:
Biological enzyme soil stabilizers are a new type of soil solidification material fermented from organic matter. Their construction process is simple and adaptable， improving construction efficiency. Compared to traditional soil stabilizers， they demonstrates significant advantages in both solidification effectiveness and environmental friendliness. In recent years， researchers have mainly focused on the solidification mechanism of biological enzyme soil stabilizers and their effects on soil properties. By combining microscopic and macroscopic approaches and improving the mix ratio， while fully leveraging the advantages of biological enzyme soil stabilizers， they can be better applied in actual engineering. This paper summarized the basic properties， reinforcement mechanism， solidification performance， and application in practical engineering of biological enzyme soil stabilizers. Based on this， some research suggestions were proposed to provide a reference for the preparation and research of subsequent biological enzyme soil stabilizers.
Biological enzyme soil stabilizers are a new type of soil solidification material fermented from organic matter. Their construction process is simple and adaptable， improving construction efficiency. Compared to traditional soil stabilizers， they demonstrates significant advantages in both solidification effectiveness and environmental friendliness. In recent years， researchers have mainly focused on the solidification mechanism of biological enzyme soil stabilizers and their effects on soil properties. By combining microscopic and macroscopic approaches and improving the mix ratio， while fully leveraging the advantages of biological enzyme soil stabilizers， they can be better applied in actual engineering. This paper summarized the basic properties， reinforcement mechanism， solidification performance， and application in practical engineering of biological enzyme soil stabilizers. Based on this， some research suggestions were proposed to provide a reference for the preparation and research of subsequent biological enzyme soil stabilizers.
2025, 55(11): 195-203.
doi: 10.3724/j.gyjzG23062103
Abstract:
To clarify the deformation laws of excavation and support of super deep foundation pits on both sides of existing tunnel turning areas in loess areas. Based on the third phase expansion project of Xi’an Xianyang International Airport， this paper conducts a numerical simulation analysis of the whole process of foundation pit excavation， and deeply explores the influence of the excavation of super deep foundation pit in the loess area on the foundation pit side wall， the existing turning tunnel and the surface deformation. Through research， it was found that： 1） the horizontal and vertical displacements of the lining structure exhibit the characteristics of “large front and small rear”， and the deformation of the lining structure in the bending direction is relatively large； 2） the deformation of the side wall of the foundation pit diffuses radially from the top of the far corner to the connection direction of the slurry wall； 3） as the distance along the tunnel increases， the deformation curve of the upper surface of the lining structure changes from a “U” shape to a “W” shape. 4） during the construction process， it is important to focus on monitoring the lining structure in the bending direction， the deformation of the far end top of the corner， and the difference in surface deformation near the foundation pit.
To clarify the deformation laws of excavation and support of super deep foundation pits on both sides of existing tunnel turning areas in loess areas. Based on the third phase expansion project of Xi’an Xianyang International Airport， this paper conducts a numerical simulation analysis of the whole process of foundation pit excavation， and deeply explores the influence of the excavation of super deep foundation pit in the loess area on the foundation pit side wall， the existing turning tunnel and the surface deformation. Through research， it was found that： 1） the horizontal and vertical displacements of the lining structure exhibit the characteristics of “large front and small rear”， and the deformation of the lining structure in the bending direction is relatively large； 2） the deformation of the side wall of the foundation pit diffuses radially from the top of the far corner to the connection direction of the slurry wall； 3） as the distance along the tunnel increases， the deformation curve of the upper surface of the lining structure changes from a “U” shape to a “W” shape. 4） during the construction process， it is important to focus on monitoring the lining structure in the bending direction， the deformation of the far end top of the corner， and the difference in surface deformation near the foundation pit.
2025, 55(11): 204-211.
doi: 10.3724/j.gyjzG23092006
Abstract:
To investigate the excavation stability of horseshoe tunnels through different jointed rock body inclinations， a section of Qingdao Metro Line 8 was selected as the study object， and the FLAC3D elastic-plastic model of joints was employed for simulation， to analyze the displacement of the tunnel's surrounding rock， the construction of the step method， and the law of shear stress. The findings of the research demonstrated that in geology with dense joint development， the displacement of the tunnel surrounding rock increased at the joint intersections. When joint tendencies were perpendicular to the horseshoe tunnel excavation direction， joint inclination angles ranging from 0° to 30°， the deformation was reduced by 16.1%； and joint inclination angles ranging from 30° to 90°， the deformation was reduced by 8.5%. The step method was more effective than the full-section method in maintaining the stability of the palm face and the surrounding rock in the broken rock layer. For joint inclination angles ranging from 0° to 30°， the shear stress rose diagram of the tunnel's surrounding rock was assumed to have a "butterfly" shape； as the joint inclination angle increased， the shear stress of the surrounding rock decreased.
To investigate the excavation stability of horseshoe tunnels through different jointed rock body inclinations， a section of Qingdao Metro Line 8 was selected as the study object， and the FLAC3D elastic-plastic model of joints was employed for simulation， to analyze the displacement of the tunnel's surrounding rock， the construction of the step method， and the law of shear stress. The findings of the research demonstrated that in geology with dense joint development， the displacement of the tunnel surrounding rock increased at the joint intersections. When joint tendencies were perpendicular to the horseshoe tunnel excavation direction， joint inclination angles ranging from 0° to 30°， the deformation was reduced by 16.1%； and joint inclination angles ranging from 30° to 90°， the deformation was reduced by 8.5%. The step method was more effective than the full-section method in maintaining the stability of the palm face and the surrounding rock in the broken rock layer. For joint inclination angles ranging from 0° to 30°， the shear stress rose diagram of the tunnel's surrounding rock was assumed to have a "butterfly" shape； as the joint inclination angle increased， the shear stress of the surrounding rock decreased.
2025, 55(11): 212-218.
doi: 10.3724/j.gyjzG23051601
Abstract:
When using the "m-method" to design and calculate the foundation pit support structure or other support structures subjected to horizontal loads， it is essential to first determine the proportional coefficient m of the foundation’s horizontal reaction force coefficient as a key parameter. The accuracy of the m value directly affects the rationality and safety of the engineering design. This paper summarized several common methods for determining the proportional coefficient m in the design and calculation of support structures or retaining structures. It also put forward a calculation method for the proportional coefficient m under the assumption of equivalent horizontal reaction force in layered soil foundations for foundation pit support projects. Combined with the practice of a specific foundation pit project， axial force monitoring data from the automatic monitoring platform of the support system were used to establish the correlation between the increment of axial force in the support system caused by temperature changes and the proportional coefficient m of the foundation's horizontal reaction force coefficient， under specific support arrangement conditions. This enables the inversion of the m value. Simultaneously， a mechanical model was established for this foundation pit project， and Plaxis software was employed to determine the m value by numerical simulations. Finally， the results obtained from field measurements and numerical simulations in this project were compared with both the method of equivalent horizontal reaction force proposed in this paper and the conventional method of average thickness of foundation soil layer， thereby verifying the feasibility of the formula proposed for the equivalent horizontal reaction force method.
When using the "m-method" to design and calculate the foundation pit support structure or other support structures subjected to horizontal loads， it is essential to first determine the proportional coefficient m of the foundation’s horizontal reaction force coefficient as a key parameter. The accuracy of the m value directly affects the rationality and safety of the engineering design. This paper summarized several common methods for determining the proportional coefficient m in the design and calculation of support structures or retaining structures. It also put forward a calculation method for the proportional coefficient m under the assumption of equivalent horizontal reaction force in layered soil foundations for foundation pit support projects. Combined with the practice of a specific foundation pit project， axial force monitoring data from the automatic monitoring platform of the support system were used to establish the correlation between the increment of axial force in the support system caused by temperature changes and the proportional coefficient m of the foundation's horizontal reaction force coefficient， under specific support arrangement conditions. This enables the inversion of the m value. Simultaneously， a mechanical model was established for this foundation pit project， and Plaxis software was employed to determine the m value by numerical simulations. Finally， the results obtained from field measurements and numerical simulations in this project were compared with both the method of equivalent horizontal reaction force proposed in this paper and the conventional method of average thickness of foundation soil layer， thereby verifying the feasibility of the formula proposed for the equivalent horizontal reaction force method.
2025, 55(11): 219-229.
doi: 10.3724/j.gyjzG24022306
Abstract:
Compared with the traditional constant-diameter fully-bonded bolt with single friction resistance， the end-expanded bolt provides resistance by the combined action of support and friction resistance， which greatly improves the force transmission mechanism of the bolt under load， and the pull-out bearing capacity of the bolt can be significantly increased. The main feature of the expanded-body bolt is that the cement grouting is carried out in the capsule， which can make most of the volume of cement soil formed by high-pressure jetting into the expanded-body anchoring section be squeezed around by the bag filled with cement slurry. Because the strength of the cement-stone body is much greater than that of the cement-soil body in the expansion section of the high-pressure jetting technology， compared with the ordinary rotary jetting expansion head anchor. The capsule expansion anchor can not only significantly improve the friction strength of the expansion section and the surrounding soil， but also improve the friction strength of the expansion section and the surrounding soil. The supporting force of the extended head in contact with the formation can be ensured. Therefore， as one of the main anchoring components in the anti-floating structure design， the bolting with expanded capsule is increasingly favored by engineers and technicians. Based on the theoretical analysis and the field test results， the paper introduces the load-transfer mechanism and deformation characteristics of the expansion bolting which can significantly improve the pullout bearing capacity when the anchorage body is limited in length， through the analysis of the mechanical properties of the basic test results， the feasibility of not applying prestressing based on ensuring the anchoring effect is discussed， to reduce the difficulty of waterproof node and reduce the cost of the project.
Compared with the traditional constant-diameter fully-bonded bolt with single friction resistance， the end-expanded bolt provides resistance by the combined action of support and friction resistance， which greatly improves the force transmission mechanism of the bolt under load， and the pull-out bearing capacity of the bolt can be significantly increased. The main feature of the expanded-body bolt is that the cement grouting is carried out in the capsule， which can make most of the volume of cement soil formed by high-pressure jetting into the expanded-body anchoring section be squeezed around by the bag filled with cement slurry. Because the strength of the cement-stone body is much greater than that of the cement-soil body in the expansion section of the high-pressure jetting technology， compared with the ordinary rotary jetting expansion head anchor. The capsule expansion anchor can not only significantly improve the friction strength of the expansion section and the surrounding soil， but also improve the friction strength of the expansion section and the surrounding soil. The supporting force of the extended head in contact with the formation can be ensured. Therefore， as one of the main anchoring components in the anti-floating structure design， the bolting with expanded capsule is increasingly favored by engineers and technicians. Based on the theoretical analysis and the field test results， the paper introduces the load-transfer mechanism and deformation characteristics of the expansion bolting which can significantly improve the pullout bearing capacity when the anchorage body is limited in length， through the analysis of the mechanical properties of the basic test results， the feasibility of not applying prestressing based on ensuring the anchoring effect is discussed， to reduce the difficulty of waterproof node and reduce the cost of the project.
2025, 55(11): 230-236.
doi: 10.3724/j.gyjzG25101603
Abstract:
Prefabricated bridge piers have been widely used in bridge construction across seas， urban municipal areas， and mountainous regions. Large-diameter threaded rebars， serving as crucial connecting and load-bearing components in prefabricated modules， have been extensively implemented in practical engineering projects. Due to their manufacturing characteristics， these threaded rebars inherently exhibit stress concentration and initial defects at thread roots， with relatively limited research available on their mechanical properties. This study focuses on large-diameter high-strength cold-rolled threaded rebars， investigating the impact of stress concentration effects at thread roots on their service performance. Using finite element methods， the research examined how different thread geometric parameters influence stress concentration and fatigue performance， revealing the relations between thread parameters and mechanical properties， while identifying key influential parameters. Furthermore， the coupled effects of stress concentration and initial defects on fatigue performance were explored. The results demonstrated that the stress concentration factor Kt at thread roots increased with thread base width l and thread angle α. When the fillet radius r was increased from 0.5 mm to 2.5 mm， Kt decreased by approximately 35%. The initial crack inclination angle β did not affect crack propagation direction but significantly influence fatigue life： reducing β from 90° to 45° decreased fatigue life by 28%.
Prefabricated bridge piers have been widely used in bridge construction across seas， urban municipal areas， and mountainous regions. Large-diameter threaded rebars， serving as crucial connecting and load-bearing components in prefabricated modules， have been extensively implemented in practical engineering projects. Due to their manufacturing characteristics， these threaded rebars inherently exhibit stress concentration and initial defects at thread roots， with relatively limited research available on their mechanical properties. This study focuses on large-diameter high-strength cold-rolled threaded rebars， investigating the impact of stress concentration effects at thread roots on their service performance. Using finite element methods， the research examined how different thread geometric parameters influence stress concentration and fatigue performance， revealing the relations between thread parameters and mechanical properties， while identifying key influential parameters. Furthermore， the coupled effects of stress concentration and initial defects on fatigue performance were explored. The results demonstrated that the stress concentration factor Kt at thread roots increased with thread base width l and thread angle α. When the fillet radius r was increased from 0.5 mm to 2.5 mm， Kt decreased by approximately 35%. The initial crack inclination angle β did not affect crack propagation direction but significantly influence fatigue life： reducing β from 90° to 45° decreased fatigue life by 28%.
2025, 55(11): 237-244.
doi: 10.3724/j.gyjzG24112803
Abstract:
To investigate the evolution mechanism and evaluation method of compressive damage in rubber concrete under various influencing factors， compression tests were conducted on rubber concrete specimens， with simultaneous monitoring using acoustic emission technology. This study considered variables such as rubber content， rubber particle size， and loading method. The results indicate that the damage evolution process can be divided into four stages according to the trend of stress development. As the rubber content increased， the fragile area within the specimens expanded， and the corresponding acoustic emission characteristic parameters also increased. With the decrease in rubber particle size， the fragile area first increased and then decreased， and the acoustic emission characteristic parameters exhibited a similar trend of initial increase followed by decrease. Based on the theory of rate process and damage mechanics， a damage constitutive model for rubber concrete was proposed， and a mathematical model of damage evolution using acoustic emission characteristic parameters was established. Finally， a method and criteria for damage evaluation of rubber concrete materials under compression were proposed.
To investigate the evolution mechanism and evaluation method of compressive damage in rubber concrete under various influencing factors， compression tests were conducted on rubber concrete specimens， with simultaneous monitoring using acoustic emission technology. This study considered variables such as rubber content， rubber particle size， and loading method. The results indicate that the damage evolution process can be divided into four stages according to the trend of stress development. As the rubber content increased， the fragile area within the specimens expanded， and the corresponding acoustic emission characteristic parameters also increased. With the decrease in rubber particle size， the fragile area first increased and then decreased， and the acoustic emission characteristic parameters exhibited a similar trend of initial increase followed by decrease. Based on the theory of rate process and damage mechanics， a damage constitutive model for rubber concrete was proposed， and a mathematical model of damage evolution using acoustic emission characteristic parameters was established. Finally， a method and criteria for damage evaluation of rubber concrete materials under compression were proposed.
2025, 55(11): 245-252.
doi: 10.3724/j.gyjzG23091417
Abstract:
The steel box girders for the non-navigable bridge sections in the Contract Section CB03 of the Hong Kong-Zhuhai-Macao Bridge's deep-water zone， along with those of the Yacheng 13-1 gas-field pipeline bridge， comprise a total of 68 spans. All of these were constructed using an integrated lifting scheme. Among these， 66 spans were individually lifted using a 4000 t floating crane. The other two spans， which are large segments of the Yacheng gas-field pipeline （with lengths of 152.6 m and 151.15 m， respectively）， were lifted using a combination of 4000 t and 2600 t floating cranes. To minimize the frequency of assembly and disassembly of the equipment， and to meet the lifting requirements for steel box girders of various specifications， a specially designed lifting rig was developed. This rig features a single-layer， straight-truss beam structure and is capable of lifting all types of non-navigable bridge girders. Prior to hoisting， computational analysis was performed on the box girder reinforcement at the pier-top adjustment locations and the bull leg adjustment points. During the actual lifting process， the maximum stress observed in the steel box girder was 231 MPa， resulting from localized stress concentration. This value remained below the allowable stress limit of 250 MPa. Internal reinforcements within the girder also satisfied the construction technical requirements. The positioning and adjustment of the steel box girder during hoisting were achieved using an initial alignment system， a pier-top adjustment system， and a corbel adjustment system. The achieved alignment accuracy reached 2 mm horizontally and 1 mm vertically， meeting the stringent installation precision requirements for the steel box girders of the Hong Kong-Zhuhai-Macao Bridge.
The steel box girders for the non-navigable bridge sections in the Contract Section CB03 of the Hong Kong-Zhuhai-Macao Bridge's deep-water zone， along with those of the Yacheng 13-1 gas-field pipeline bridge， comprise a total of 68 spans. All of these were constructed using an integrated lifting scheme. Among these， 66 spans were individually lifted using a 4000 t floating crane. The other two spans， which are large segments of the Yacheng gas-field pipeline （with lengths of 152.6 m and 151.15 m， respectively）， were lifted using a combination of 4000 t and 2600 t floating cranes. To minimize the frequency of assembly and disassembly of the equipment， and to meet the lifting requirements for steel box girders of various specifications， a specially designed lifting rig was developed. This rig features a single-layer， straight-truss beam structure and is capable of lifting all types of non-navigable bridge girders. Prior to hoisting， computational analysis was performed on the box girder reinforcement at the pier-top adjustment locations and the bull leg adjustment points. During the actual lifting process， the maximum stress observed in the steel box girder was 231 MPa， resulting from localized stress concentration. This value remained below the allowable stress limit of 250 MPa. Internal reinforcements within the girder also satisfied the construction technical requirements. The positioning and adjustment of the steel box girder during hoisting were achieved using an initial alignment system， a pier-top adjustment system， and a corbel adjustment system. The achieved alignment accuracy reached 2 mm horizontally and 1 mm vertically， meeting the stringent installation precision requirements for the steel box girders of the Hong Kong-Zhuhai-Macao Bridge.
