Login
Register
E-alert
2025 Vol. 55, No. 1
Display Method:
2025, 55(1): 1-12.
doi: 10.3724/j.gyjzG24090603
Abstract:
With the rapid development of wind power industry and the continuous upsizing of wind blades, the research needs of a test bench for the wind turbine blade with higher bearing capacity, which are suitable for larger wind turbine blades testing, have become increasingly urgent. In this context, the applicability of reinforced concrete structures with double inclined loading surface for the test bench for large wind turbine blades was analyzed based on the research of the test bench and the performance requirements of large wind turbine blade test, and the relevant design reference indexes were proposed from engineering experience. Secondly, on the basis of the engineering design, the finite element simulations were carried out on the mode of vibration and the stress characteristics under different loading conditions of the main structure of the test bench for large wind turbine blades, indicating that the control factor of the bearing capacity was the maximum principal tensile stress of the concrete. Finally, the influence of the design parameters such as wall thickness, flange size, reinforcement and material on the force of the main structure of the test bench was analyzed, leading to the proposal of optimization methods for the structural design.
With the rapid development of wind power industry and the continuous upsizing of wind blades, the research needs of a test bench for the wind turbine blade with higher bearing capacity, which are suitable for larger wind turbine blades testing, have become increasingly urgent. In this context, the applicability of reinforced concrete structures with double inclined loading surface for the test bench for large wind turbine blades was analyzed based on the research of the test bench and the performance requirements of large wind turbine blade test, and the relevant design reference indexes were proposed from engineering experience. Secondly, on the basis of the engineering design, the finite element simulations were carried out on the mode of vibration and the stress characteristics under different loading conditions of the main structure of the test bench for large wind turbine blades, indicating that the control factor of the bearing capacity was the maximum principal tensile stress of the concrete. Finally, the influence of the design parameters such as wall thickness, flange size, reinforcement and material on the force of the main structure of the test bench was analyzed, leading to the proposal of optimization methods for the structural design.
2025, 55(1): 13-19.
doi: 10.3724/j.gyjzG23121403
Abstract:
In order to explore the dynamic performance of prefabricated shear wall structures in the service operation and maintenance stage, and ensure the safety of structures in the service operation and maintenance stage of buildings, based on the prefabricated experimental building structure in Dingfuzhuang, Beijing, on-site dynamic and static in-situ tests were carried out. The structure was loaded to failure by combining tests and calculation. After each failure, vibration pickers and acquisition instruments were used to measure dynamic indicators and obtain vibration response data of the structure under different states, thus improving the reliability and accuracy of the data. Then, the stochastic subspace identification and stability diagram were used to process the obtained vibration response data, and the modal parameters of the building structure in different failure conditions were obtained, and the dynamic and static performance of the building structure was studied. The influence of cracking damage of shear wall structure components on dynamic performance was studied and evaluated, and the temperature effect of structural dynamic performance was considered. The test results showed that the effect of structural cracking damage on dynamic performance was lower than that of temperature effect in service stage, and had little effect on shear wall structure.
In order to explore the dynamic performance of prefabricated shear wall structures in the service operation and maintenance stage, and ensure the safety of structures in the service operation and maintenance stage of buildings, based on the prefabricated experimental building structure in Dingfuzhuang, Beijing, on-site dynamic and static in-situ tests were carried out. The structure was loaded to failure by combining tests and calculation. After each failure, vibration pickers and acquisition instruments were used to measure dynamic indicators and obtain vibration response data of the structure under different states, thus improving the reliability and accuracy of the data. Then, the stochastic subspace identification and stability diagram were used to process the obtained vibration response data, and the modal parameters of the building structure in different failure conditions were obtained, and the dynamic and static performance of the building structure was studied. The influence of cracking damage of shear wall structure components on dynamic performance was studied and evaluated, and the temperature effect of structural dynamic performance was considered. The test results showed that the effect of structural cracking damage on dynamic performance was lower than that of temperature effect in service stage, and had little effect on shear wall structure.
2025, 55(1): 20-26.
doi: 10.3724/j.gyjzG24061705
Abstract:
The development of new industrialized structures and connections adapted to intelligent construction is currently a hot topic. A novel mortise-tenon type connector was proposed for prefabricated concrete column-column. Experimental studies were conducted on the key component, the mortise-tenon connector, to evaluate the influence of tenon dimensions on bearing capacity, deformation with stiffness. The experimental results indicated that the load-displacement curves of the specimens had no distinct yield plateau. The tensile stiffness exceedsed the initial tensile stiffness but was less than the compressive stiffness. Failure modes include shear failure at the bottom of the hole and tensile failure of the tensile bars on both sides of the hole, which were related to the shear height at the bottom of the tenon and the width of the tensile bars on both sides. The effects of monotonic loading and cyclic loading on tensile bearing capacity, deformation, and failure modes were found to be insignificant. Furthermore, the peak load and residual deformation under the force control loading stage of the specimens met the standards for Class I connection joints specified in the Technical Specification for Mechanical Splicing of Steel Reinforcing Bars (JGJ 107—2016).
The development of new industrialized structures and connections adapted to intelligent construction is currently a hot topic. A novel mortise-tenon type connector was proposed for prefabricated concrete column-column. Experimental studies were conducted on the key component, the mortise-tenon connector, to evaluate the influence of tenon dimensions on bearing capacity, deformation with stiffness. The experimental results indicated that the load-displacement curves of the specimens had no distinct yield plateau. The tensile stiffness exceedsed the initial tensile stiffness but was less than the compressive stiffness. Failure modes include shear failure at the bottom of the hole and tensile failure of the tensile bars on both sides of the hole, which were related to the shear height at the bottom of the tenon and the width of the tensile bars on both sides. The effects of monotonic loading and cyclic loading on tensile bearing capacity, deformation, and failure modes were found to be insignificant. Furthermore, the peak load and residual deformation under the force control loading stage of the specimens met the standards for Class I connection joints specified in the Technical Specification for Mechanical Splicing of Steel Reinforcing Bars (JGJ 107—2016).
2025, 55(1): 27-39.
doi: 10.3724/j.gyjzG24083006
Abstract:
In response to the lack of design data for explosive charges greater than 100 kg trinitrotoluene (TNT) in the current Design Code for Blast-Resistant Structures (GB 50907—2013), the study utilized the explicit finite element software LS-DYNA to simulate the dynamic responses of blast-resistant chambers under large-equivalent explosion scenarios. A parametric analysis was conducted on various design parameters to investigate their impacts on the structural performance of the blast-resistant chamber, and design recommendations were proposed.Firstly, the accuracy of the simulation model was verified by comparing the finite element results with existing blast test data, showing errors of 4.7%, 12.9%, and 2.3% for panels P2-1, P2-2, and P2-3, respectively. Secondly, the study analyzed the stress variations in the blast-resistant chamber under the equivalent of 100-200 kg TNT, revealing that when the TNT equivalent reached 160 kg, the wall reinforcement entered the plastic deformation stage. Based on this, further analysis was carried out to assess the effects of different design parameters on the load-bearing capacity of the blast-resistant chamber at the 160 kg TNT equivalent. The results indicated that within the range of 100 kg to 200 kg TNT, plastic zones initially formed in the tensile region at the base of the sidewalls and gradually expanded outward. The wall panel connections emerged as the primary areas of stress concentration.Based on the analysis, it was recommended that the wall thickness of the blast-resistant chamber should be between 600 mm and 900 mm, with the concrete strength not lower than C50, the rebar yield strength not less than 300 MPa, and the rebar diameter not smaller than 22 mm. The reinforcement ratio for the walls should exceed 0.3%, and haunched diagonal rebars at the wall panel connections should be chosen at 4/5 of the main rebar diameter.
In response to the lack of design data for explosive charges greater than 100 kg trinitrotoluene (TNT) in the current Design Code for Blast-Resistant Structures (GB 50907—2013), the study utilized the explicit finite element software LS-DYNA to simulate the dynamic responses of blast-resistant chambers under large-equivalent explosion scenarios. A parametric analysis was conducted on various design parameters to investigate their impacts on the structural performance of the blast-resistant chamber, and design recommendations were proposed.Firstly, the accuracy of the simulation model was verified by comparing the finite element results with existing blast test data, showing errors of 4.7%, 12.9%, and 2.3% for panels P2-1, P2-2, and P2-3, respectively. Secondly, the study analyzed the stress variations in the blast-resistant chamber under the equivalent of 100-200 kg TNT, revealing that when the TNT equivalent reached 160 kg, the wall reinforcement entered the plastic deformation stage. Based on this, further analysis was carried out to assess the effects of different design parameters on the load-bearing capacity of the blast-resistant chamber at the 160 kg TNT equivalent. The results indicated that within the range of 100 kg to 200 kg TNT, plastic zones initially formed in the tensile region at the base of the sidewalls and gradually expanded outward. The wall panel connections emerged as the primary areas of stress concentration.Based on the analysis, it was recommended that the wall thickness of the blast-resistant chamber should be between 600 mm and 900 mm, with the concrete strength not lower than C50, the rebar yield strength not less than 300 MPa, and the rebar diameter not smaller than 22 mm. The reinforcement ratio for the walls should exceed 0.3%, and haunched diagonal rebars at the wall panel connections should be chosen at 4/5 of the main rebar diameter.
2025, 55(1): 40-51.
doi: 10.3724/j.gyjzG24112602
Abstract:
From the perspective of structural engineering, seismic design methods can generally be divided into two categories: the performance-based approach and the capacity-based approach. Most countries’ seismic codes are based on the performance-based approach. The paper focused on steel frame structures and systematically discussed the key techniques of ductile seismic design methods for such structures. It first introduced the core concepts of the performance-based approach and the essence of ductility development in steel components. Then, it discussed the similarities and differences in ductile design concepts for steel frames in various major seismic codes. Special emphasis was placed on the evolution of the ductile seismic design concepts throughout the historical versions of the Code for Seismic Design of Buildings(GB 50011). On the other hand, by comparing the differences in seismic coefficients between Chinese and major international codes, the paper identified the shortcomings of the current Chinese code regarding performance coefficients, applicable heights, width-to-thickness ratios of steel components, and damping ratios for steel frame structures. It also provided suggestions for revisions.
From the perspective of structural engineering, seismic design methods can generally be divided into two categories: the performance-based approach and the capacity-based approach. Most countries’ seismic codes are based on the performance-based approach. The paper focused on steel frame structures and systematically discussed the key techniques of ductile seismic design methods for such structures. It first introduced the core concepts of the performance-based approach and the essence of ductility development in steel components. Then, it discussed the similarities and differences in ductile design concepts for steel frames in various major seismic codes. Special emphasis was placed on the evolution of the ductile seismic design concepts throughout the historical versions of the Code for Seismic Design of Buildings(GB 50011). On the other hand, by comparing the differences in seismic coefficients between Chinese and major international codes, the paper identified the shortcomings of the current Chinese code regarding performance coefficients, applicable heights, width-to-thickness ratios of steel components, and damping ratios for steel frame structures. It also provided suggestions for revisions.
2025, 55(1): 52-57.
doi: 10.3724/j.gyjzG24082604
Abstract:
Based on the actual project of the Xi’an Metro Line 10 combined road-rail bridge crossing the Weihe River,the mechanical properties of a double-layer steel truss bridge with arched stiffening chords were investigated by using the ABAQUS finite element analysis software, a model focusing on the middle three spans with arched stiffening chords was established considering boundary conditions. Vertical load simulations were compared with the results from scaled model tests. The comparisons showed that the load-displacement and load-strain curves in the elastic stage matched well, confirming the reliability of the simulation method. A parametric analysis was then conducted to examine the effects of the number and arrangement of vertical rods on the vertical bearing performance of the bridge. The results indicated that adjusting the vertical rod arrangement had minimal impact on mid-span displacements and web member strains above the supports, but slightly increased the stress in the top chord at the supports and significantly increased stress in the stiffening chord members at the highest point. Arranging one vertical rod above each joint under the stiffening chord increased the steel consumption, but it could effectively control the structural deformation and member strain, and provide a uniform and aesthetically pleasing design. This arrangement is therefore recommended.
Based on the actual project of the Xi’an Metro Line 10 combined road-rail bridge crossing the Weihe River,the mechanical properties of a double-layer steel truss bridge with arched stiffening chords were investigated by using the ABAQUS finite element analysis software, a model focusing on the middle three spans with arched stiffening chords was established considering boundary conditions. Vertical load simulations were compared with the results from scaled model tests. The comparisons showed that the load-displacement and load-strain curves in the elastic stage matched well, confirming the reliability of the simulation method. A parametric analysis was then conducted to examine the effects of the number and arrangement of vertical rods on the vertical bearing performance of the bridge. The results indicated that adjusting the vertical rod arrangement had minimal impact on mid-span displacements and web member strains above the supports, but slightly increased the stress in the top chord at the supports and significantly increased stress in the stiffening chord members at the highest point. Arranging one vertical rod above each joint under the stiffening chord increased the steel consumption, but it could effectively control the structural deformation and member strain, and provide a uniform and aesthetically pleasing design. This arrangement is therefore recommended.
2025, 55(1): 58-64.
doi: 10.3724/j.gyjzG24060705
Abstract:
To study the influence of geometric parameters on flexural capacity and stiffness of beam-column connections using stain-steel S31608 and get the key influence parameters, on the basis of test data, using the finite element analysis software ABAQUS, parameter analysis on three main geometrical parameters of flexural capacity and stiffness of stain-steel beam-column connections was conducted. The analysis results showed that when thickness of steel beam flange of bolted-welded beam-to-column joints in stainless steel structure increased, bearing capacity and initial stiffness of the joints increased with large amplitude; when slipping coefficient increased, bearing capacity and initial stiffness of the joints increased with small amplitude; when weld access hole changed, bearing capacity increased and initial stiffness increased with small amplitude, but could decrease stress concentrate phenomenon; when "Dog-bone" was used, the position of plastic hinge appearance would out-shift, but bearing capacity and initial stiffness decreased with large amplitude. Using the weld access hole of FEMA350 and increasing the flange thickness of I-shaped bars is a good way to improve the static behavior of stain-steel beam-column connections.
To study the influence of geometric parameters on flexural capacity and stiffness of beam-column connections using stain-steel S31608 and get the key influence parameters, on the basis of test data, using the finite element analysis software ABAQUS, parameter analysis on three main geometrical parameters of flexural capacity and stiffness of stain-steel beam-column connections was conducted. The analysis results showed that when thickness of steel beam flange of bolted-welded beam-to-column joints in stainless steel structure increased, bearing capacity and initial stiffness of the joints increased with large amplitude; when slipping coefficient increased, bearing capacity and initial stiffness of the joints increased with small amplitude; when weld access hole changed, bearing capacity increased and initial stiffness increased with small amplitude, but could decrease stress concentrate phenomenon; when "Dog-bone" was used, the position of plastic hinge appearance would out-shift, but bearing capacity and initial stiffness decreased with large amplitude. Using the weld access hole of FEMA350 and increasing the flange thickness of I-shaped bars is a good way to improve the static behavior of stain-steel beam-column connections.
2025, 55(1): 65-74.
doi: 10.3724/j.gyjzG23021614
Abstract:
A new type of prefabricated beam-column joint with buckling constraints is proposed, which has better energy dissipation capacity and is easy to repair after earthquakes. The joint consists of a steel tube column with cantilever beam and an intermediate beam. The cantilever beam and the intermediate beam are connected by a buckling constraint connection device, which can effectively improve the ductility of the structure while ensuring the plastic damage control. The quasi-static analysis of eight cases with different parameters was carried out by finite element simulations to study the influence of different parameters on the mechanical properties and failure modes of the joint, and then the key parameters affecting the bearing energy dissipation capacity and buckling constraint effects of the joint were determined. The results showed that the bearing energy dissipation capacity of the joint increased significantly with the increase of the thickness and strength of the flange cover plate. As the stiffening height of the outer flange cover plate increased, the spacing between the inner flange cover plate and the web connector decreased and the stiffening degree of the web connector increased, the buckling constraint effect of the joint could be significantly enhanced. Too few high-strength bolts would cause premature slip of the flange cover plate, which would affect the bearing energy dissipation capacity of the joint.
A new type of prefabricated beam-column joint with buckling constraints is proposed, which has better energy dissipation capacity and is easy to repair after earthquakes. The joint consists of a steel tube column with cantilever beam and an intermediate beam. The cantilever beam and the intermediate beam are connected by a buckling constraint connection device, which can effectively improve the ductility of the structure while ensuring the plastic damage control. The quasi-static analysis of eight cases with different parameters was carried out by finite element simulations to study the influence of different parameters on the mechanical properties and failure modes of the joint, and then the key parameters affecting the bearing energy dissipation capacity and buckling constraint effects of the joint were determined. The results showed that the bearing energy dissipation capacity of the joint increased significantly with the increase of the thickness and strength of the flange cover plate. As the stiffening height of the outer flange cover plate increased, the spacing between the inner flange cover plate and the web connector decreased and the stiffening degree of the web connector increased, the buckling constraint effect of the joint could be significantly enhanced. Too few high-strength bolts would cause premature slip of the flange cover plate, which would affect the bearing energy dissipation capacity of the joint.
2025, 55(1): 75-85.
doi: 10.3724/j.gyjzG24071501
Abstract:
The chimney of the towering steel structure is often connected by bolted flange joints, which are prone to fatigue cracks under wind loads. Firstly, an 80 m self-standing steel chimney girder-solid multi-scale finite element model was established based on ABAQUS. The wind field was simulated by MATLAB, and the fatigue life of the bolt was calculated based on the rainflow counting method and the Miner cumulative damage criterion. The influence of bolt preload on the fatigue life was discussed, and the relation curve between bolt preload and fatigue life was fitted. The fatigue life of bolted flange joints under the action of typhoons of different intensities was compared and analyzed. Tuned Liquid Damper (TLD) was designed and installed, and the effects of TLD damping on the fatigue life of steel chimneys were analyzed. The results showed that under the action of wind loads, the life of the bolted joint at the variable section was the lowest, and the life of the bolted joint at the bottom of the steel chimney of the project was the second. The fatigue life of bolted flange joints significantly decreased with the decrease of bolt preload.When the preload was lost by 40%, the fatigue life of bolts at the variable section under normal climate wind would be lower than the design service life of 50 years. The TLD damping design installed a total of 48 circular water tanks with 6 layers, which could effectively prolong the fatigue life of bolts. Under ordinary typhoons, after installing TLD, the fatigue life of bolt joints at the variable section of the steel chimney could be extended from 32 years to 54 years. When the bolt preload was lost to different degrees under typhoons, the fatigue life of bolts could increase by 50% after installing TLD.
The chimney of the towering steel structure is often connected by bolted flange joints, which are prone to fatigue cracks under wind loads. Firstly, an 80 m self-standing steel chimney girder-solid multi-scale finite element model was established based on ABAQUS. The wind field was simulated by MATLAB, and the fatigue life of the bolt was calculated based on the rainflow counting method and the Miner cumulative damage criterion. The influence of bolt preload on the fatigue life was discussed, and the relation curve between bolt preload and fatigue life was fitted. The fatigue life of bolted flange joints under the action of typhoons of different intensities was compared and analyzed. Tuned Liquid Damper (TLD) was designed and installed, and the effects of TLD damping on the fatigue life of steel chimneys were analyzed. The results showed that under the action of wind loads, the life of the bolted joint at the variable section was the lowest, and the life of the bolted joint at the bottom of the steel chimney of the project was the second. The fatigue life of bolted flange joints significantly decreased with the decrease of bolt preload.When the preload was lost by 40%, the fatigue life of bolts at the variable section under normal climate wind would be lower than the design service life of 50 years. The TLD damping design installed a total of 48 circular water tanks with 6 layers, which could effectively prolong the fatigue life of bolts. Under ordinary typhoons, after installing TLD, the fatigue life of bolt joints at the variable section of the steel chimney could be extended from 32 years to 54 years. When the bolt preload was lost to different degrees under typhoons, the fatigue life of bolts could increase by 50% after installing TLD.
2025, 55(1): 86-94.
doi: 10.3724/j.gyjzG24091306
Abstract:
The Xi’an Tree Project is located in Qujiang New District, Xi’an City, on the urban axis of the millennium-old ancient capital Chang’an. The project adopts large and complex curved stainless steel building skins, and its complex geometric features as well as installation methods pose new challenges to the construction process of the building skin. In order to reduce the adverse effects on the building skin, the construction sequence of "pre-loading of the main structure-installation of skins-partial unloading-reloading" is adopted during construction. Therefore, it is necessary to simulate the entire construction process of building skins, and to study their relative deformation and stress situation with the main steel structure. This paper mainly focued on the effects of different unloading schemes of multiple blade on the unloading deformation between the main steel structure and the building skins after the installation of the building skins with the main structure being preloaded firstly, providing a valuable reference for the construction of this project. The SAP 2000 software was applied herein, and the unloading situations of two blades unloaded simultaneously, three blades unloaded simultaneously as well as the partial middle platform blades unloaded simultaneously at different positions were considered, in which the unloading deformations of key nodes of the blades were extracted and analyzed. It was indicated that in case of two blades unloaded simultaneously, its adverse effects were the minimal with a deformation displacement of less than 1.0 mm, and it was suggested to be prioritised; In case of simultaneous interval unloading for three blades, it was suggested to be adopted in the ST layer where the overall displacements of the blades were small; In case of partial middle platform blades unloaded simultaneously, it had a maximum deformation displacement of 25.9 mm, which needed to be carefully considered in conjunction with specific conditions.
The Xi’an Tree Project is located in Qujiang New District, Xi’an City, on the urban axis of the millennium-old ancient capital Chang’an. The project adopts large and complex curved stainless steel building skins, and its complex geometric features as well as installation methods pose new challenges to the construction process of the building skin. In order to reduce the adverse effects on the building skin, the construction sequence of "pre-loading of the main structure-installation of skins-partial unloading-reloading" is adopted during construction. Therefore, it is necessary to simulate the entire construction process of building skins, and to study their relative deformation and stress situation with the main steel structure. This paper mainly focued on the effects of different unloading schemes of multiple blade on the unloading deformation between the main steel structure and the building skins after the installation of the building skins with the main structure being preloaded firstly, providing a valuable reference for the construction of this project. The SAP 2000 software was applied herein, and the unloading situations of two blades unloaded simultaneously, three blades unloaded simultaneously as well as the partial middle platform blades unloaded simultaneously at different positions were considered, in which the unloading deformations of key nodes of the blades were extracted and analyzed. It was indicated that in case of two blades unloaded simultaneously, its adverse effects were the minimal with a deformation displacement of less than 1.0 mm, and it was suggested to be prioritised; In case of simultaneous interval unloading for three blades, it was suggested to be adopted in the ST layer where the overall displacements of the blades were small; In case of partial middle platform blades unloaded simultaneously, it had a maximum deformation displacement of 25.9 mm, which needed to be carefully considered in conjunction with specific conditions.
2025, 55(1): 95-102.
doi: 10.3724/j.gyjzG24080108
Abstract:
To conduct further research on the calculated length coefficients of columns with variable sections, the existing calculation methods of the calculation length factors of columns with variable sections were verified through numerical simulations. Taking the Shenzhen Dayun Transportation Hub as the engineering background, numerical simulations of buckling of variable-section compression members in the overall structure and individual members were conducted. The calculation length coefficients of three compression members in the project were calculated, and the constraints conditions were obtained for reference in actual engineering. Based on this, the parameter analysis was conducted under the boundary conditions of one end fixed and the other end hinged, and one end fixed and the other end free, and the empirical calculation formula for the calculation length coefficient of the members under these two boundary conditions was obtained. The results showed that as the ratio of the inertia moment of the upper and lower ends decreased, the calculation length coefficients of the variable-section compression member was smaller than that of the equal-section compression member, indicating that the buckling of the member was constrained, and the material properties was fully utilized.
To conduct further research on the calculated length coefficients of columns with variable sections, the existing calculation methods of the calculation length factors of columns with variable sections were verified through numerical simulations. Taking the Shenzhen Dayun Transportation Hub as the engineering background, numerical simulations of buckling of variable-section compression members in the overall structure and individual members were conducted. The calculation length coefficients of three compression members in the project were calculated, and the constraints conditions were obtained for reference in actual engineering. Based on this, the parameter analysis was conducted under the boundary conditions of one end fixed and the other end hinged, and one end fixed and the other end free, and the empirical calculation formula for the calculation length coefficient of the members under these two boundary conditions was obtained. The results showed that as the ratio of the inertia moment of the upper and lower ends decreased, the calculation length coefficients of the variable-section compression member was smaller than that of the equal-section compression member, indicating that the buckling of the member was constrained, and the material properties was fully utilized.
2025, 55(1): 103-109.
doi: 10.3724/j.gyjzG23030403
Abstract:
A new type of laminated timber joint connected with prestressed steel strips and self-tapping screws is proposed to address the problem of bending and splitting of half-lapped beams in the laminated wood joint. An experimental study on the bending resistance of the joint under axial compression load was conducted, and the crack propagation and failure modes of the specimen were obtained. The mechanical properties of the new type of joints were analyzed based on the bending moment-deflection curve. The test results showed that the failure modes of the joint were mainly the pull-out failure of the horizontally oblique self-tapping screw, and the cracks at the shoulder angle were significantly restricted. The bearing capacity of the new type of joints was 72.5% of that of the intact laminated timber beams, compared to the glued laminated timber joint beams without horizontal inclined self-tapping screws, their bending load-bearing capacity has increased by 11.3%.To address the problem of complex and inefficient computation of the solid model of the self-tapping screw, a combination of solid and simplified models was proposed in the paper. The model’s validity was verified based on the test results, and a fully simplified modeling method was proposed to further improve the calculation efficiency.
A new type of laminated timber joint connected with prestressed steel strips and self-tapping screws is proposed to address the problem of bending and splitting of half-lapped beams in the laminated wood joint. An experimental study on the bending resistance of the joint under axial compression load was conducted, and the crack propagation and failure modes of the specimen were obtained. The mechanical properties of the new type of joints were analyzed based on the bending moment-deflection curve. The test results showed that the failure modes of the joint were mainly the pull-out failure of the horizontally oblique self-tapping screw, and the cracks at the shoulder angle were significantly restricted. The bearing capacity of the new type of joints was 72.5% of that of the intact laminated timber beams, compared to the glued laminated timber joint beams without horizontal inclined self-tapping screws, their bending load-bearing capacity has increased by 11.3%.To address the problem of complex and inefficient computation of the solid model of the self-tapping screw, a combination of solid and simplified models was proposed in the paper. The model’s validity was verified based on the test results, and a fully simplified modeling method was proposed to further improve the calculation efficiency.
2025, 55(1): 110-119.
doi: 10.3724/j.gyjzG24080306
Abstract:
In order to explore the long-term performance of steel-tube-confined concrete-filled steel tube (TCFST) short columns under axial compression, 10 specimens of TCFST short columns and 2 specimens of concrete-filled steel tube (CFST) short columns were designed and loaded under sustained axial compression for 850 days. The main research parameters include the stress ratio of core concrete (0.35,0.50 and 0.65), the ratio between inner and outer steel tubes (0.30,1.25 and 2.23), and the temperature (20,45 and 55 ℃). The effects of various parameters on the long-term deformation performance of specimens were compared and analysed. Axial compression tests were performed on 6 load-bearing specimens at room temperature, 6 load-bearing specimens subjected to the temperature action, as well as 4 load-free specimens for comparison, to investigate the influence of long-term loads and temperature effect on the axial compression bearing capacity. The results showed that the larger ratio between inner and outer steel tubes, the smaller stress ratio of core concrete, and the smaller temperature led to a long-term deformation of the TCFST. The combined effects of long-term loading and temperature had no significant effect on the initial stiffness and axial bearing capacity of the TCFST.
In order to explore the long-term performance of steel-tube-confined concrete-filled steel tube (TCFST) short columns under axial compression, 10 specimens of TCFST short columns and 2 specimens of concrete-filled steel tube (CFST) short columns were designed and loaded under sustained axial compression for 850 days. The main research parameters include the stress ratio of core concrete (0.35,0.50 and 0.65), the ratio between inner and outer steel tubes (0.30,1.25 and 2.23), and the temperature (20,45 and 55 ℃). The effects of various parameters on the long-term deformation performance of specimens were compared and analysed. Axial compression tests were performed on 6 load-bearing specimens at room temperature, 6 load-bearing specimens subjected to the temperature action, as well as 4 load-free specimens for comparison, to investigate the influence of long-term loads and temperature effect on the axial compression bearing capacity. The results showed that the larger ratio between inner and outer steel tubes, the smaller stress ratio of core concrete, and the smaller temperature led to a long-term deformation of the TCFST. The combined effects of long-term loading and temperature had no significant effect on the initial stiffness and axial bearing capacity of the TCFST.
2025, 55(1): 120-128.
doi: 10.3724/j.gyjzG24052303
Abstract:
The concrete-filled double-steel-plate composite cable tower displays many advantages such as high compression-bending stiffness, high load-bearing capacity, and convenient construction, and has a broad application prospect in long-span suspension bridges. Four full-scale bending beam tests on local configuration of the tower wall were carried out, to study the synergistic working performance of steel plates and concrete in the composite cable tower using C80 high-strength concrete, and to examine the impact of connection types and stiffener spacing. The experimental results showed that the perfobond connectors and stud bolts jointly ensured the synergistic work between the steel plates and concrete. Bearing capacity, stiffness, and synergistic working effect of the pure stud bolt specimens without reinforcement were slightly lower than those of the reinforced specimens. Transverse stiffener spacing of the tower wall was more appropriate at 1 200 mm. Based on the experimental results, a calculation formula for the bending bearing capacity of the cross-section of the double-steel-plate concrete composite structure was further analyzed and established, which matched well with the experimental results.
The concrete-filled double-steel-plate composite cable tower displays many advantages such as high compression-bending stiffness, high load-bearing capacity, and convenient construction, and has a broad application prospect in long-span suspension bridges. Four full-scale bending beam tests on local configuration of the tower wall were carried out, to study the synergistic working performance of steel plates and concrete in the composite cable tower using C80 high-strength concrete, and to examine the impact of connection types and stiffener spacing. The experimental results showed that the perfobond connectors and stud bolts jointly ensured the synergistic work between the steel plates and concrete. Bearing capacity, stiffness, and synergistic working effect of the pure stud bolt specimens without reinforcement were slightly lower than those of the reinforced specimens. Transverse stiffener spacing of the tower wall was more appropriate at 1 200 mm. Based on the experimental results, a calculation formula for the bending bearing capacity of the cross-section of the double-steel-plate concrete composite structure was further analyzed and established, which matched well with the experimental results.
2025, 55(1): 129-136.
doi: 10.3724/j.gyjzG24092611
Abstract:
The multi-ribbed composite wall is a new type of seismic wall formed by concrete ribbed beams and ribbed columns, and filled with light weight materials in the grid. It has the advantages of light weight, good seismic performance, convenient construction and low cost; hence, having a promising future in multi-level buildings. The concrete-filled steel tube frame-multi-ribbed reinforced concrete shear wall structure system is formed by combining multi-ribbed composite walls with the concrete-filled steel tube frame structure system, which makes the seismic performance of the structure system better and saves the construction cost. However, there is no modeling method for concrete-filled steel tube frame-reinforced concrete multi-ribbed shear wall structure system for designers, which restricts the practical application of this kind of structure system. Because of this, the experiments on two multi-ribbed composite walls under lateral monotonic loading were carried out. The force-lateral deformation curves of the walls were obtained. Based on the test results, two equivalent modeling methods were compared, and an equivalent modeling method for multi-ribbed composite wall was proposed. Based on the equivalent modeling method, the comparative studies were conducted for concrete-filled steel tube frame-multi-ribbed composite wall structure system with different methods. The effects of the equivalent modeling method on the mechanical properties were investigated.
The multi-ribbed composite wall is a new type of seismic wall formed by concrete ribbed beams and ribbed columns, and filled with light weight materials in the grid. It has the advantages of light weight, good seismic performance, convenient construction and low cost; hence, having a promising future in multi-level buildings. The concrete-filled steel tube frame-multi-ribbed reinforced concrete shear wall structure system is formed by combining multi-ribbed composite walls with the concrete-filled steel tube frame structure system, which makes the seismic performance of the structure system better and saves the construction cost. However, there is no modeling method for concrete-filled steel tube frame-reinforced concrete multi-ribbed shear wall structure system for designers, which restricts the practical application of this kind of structure system. Because of this, the experiments on two multi-ribbed composite walls under lateral monotonic loading were carried out. The force-lateral deformation curves of the walls were obtained. Based on the test results, two equivalent modeling methods were compared, and an equivalent modeling method for multi-ribbed composite wall was proposed. Based on the equivalent modeling method, the comparative studies were conducted for concrete-filled steel tube frame-multi-ribbed composite wall structure system with different methods. The effects of the equivalent modeling method on the mechanical properties were investigated.
2025, 55(1): 137-144.
doi: 10.3724/j.gyjzG24092902
Abstract:
The T-shaped steel-concrete filled steel tube (CFST) composite special-shaped column is a kind of space grid structure formed by T-shaped steel and CFST. It has the outstanding advantages of non-protruding walls, excellent seismic performance, ease of construction, and convenient connection. This type of component not only retains the advantages of CFST and T-shaped steel, but also addresses issues like difficulties in connecting CFST columns with walls and steel beams, the weak flexural capacity of long columns, and the protrusion of components from the wall surface. However, there is no modeling method available for T-shaped steel-CFST composite columns that can be utilized by designers, which significantly limits the engineering demonstration and application of these innovative components. Therefore, the study aimed to conduct horizontal monotonic loading tests and investigate modeling methods of software for T-shaped steel-CFST composite columns. Based on validated modeling methods, the study explored the impact of different modeling methods on the mechanical properties of the T-shaped steel-CFST composite column structural system and provide design recommendations.
The T-shaped steel-concrete filled steel tube (CFST) composite special-shaped column is a kind of space grid structure formed by T-shaped steel and CFST. It has the outstanding advantages of non-protruding walls, excellent seismic performance, ease of construction, and convenient connection. This type of component not only retains the advantages of CFST and T-shaped steel, but also addresses issues like difficulties in connecting CFST columns with walls and steel beams, the weak flexural capacity of long columns, and the protrusion of components from the wall surface. However, there is no modeling method available for T-shaped steel-CFST composite columns that can be utilized by designers, which significantly limits the engineering demonstration and application of these innovative components. Therefore, the study aimed to conduct horizontal monotonic loading tests and investigate modeling methods of software for T-shaped steel-CFST composite columns. Based on validated modeling methods, the study explored the impact of different modeling methods on the mechanical properties of the T-shaped steel-CFST composite column structural system and provide design recommendations.
2025, 55(1): 145-152.
doi: 10.3724/j.gyjzG24092302
Abstract:
Coal combustion of industrial production will release large amounts of SO2 and CO2 gases. High concentrations of acidic gases will accelerate the deterioration of concrete corrosion, leading to premature failure or damage to structures. To investigate the corrosion behavior of concrete structures exposed to industrial coal-fired flue gas for 12 years, this paper tested the concrete’s macro-mechanical properties, pore structure characteristics, and micro-properties by in-situ and laboratory tests along the height and depth. The test results indicated that the concrete exhibited significant uneven corrosion along the height of the structure. In the severely attacked region (28.6-39.1 m), the neutralization depth in the concrete was 1.4 times greater than that in the slightly attacked region (0-6.6 m), and the porosity was 5 times higher. Different corrosion mechanisms were occurred inside the concrete along the corrosion depth direction. In the shallow concrete zone (0-8 mm), sulfation was predominant, with gypsum (Gyp) as the primary product. The pH was below 8.0, and the sulfate ion (SO2-4) concentration at the exposure surface reached up to 5.5%. In the coexistence concrete zone (8-14 mm), both sulfation and carbonation were presented, with the pH increasing from 8.0 to 11.0. Above 14 mm, SO2-4 and Gyp were no longer detected. At 10 mm, calcium carbonate (CaCO3) was found, and its content gradually increased. In the deep concrete zone (14-18 mm), carbonation was the dominant process, with CaCO3 as the main product.
Coal combustion of industrial production will release large amounts of SO2 and CO2 gases. High concentrations of acidic gases will accelerate the deterioration of concrete corrosion, leading to premature failure or damage to structures. To investigate the corrosion behavior of concrete structures exposed to industrial coal-fired flue gas for 12 years, this paper tested the concrete’s macro-mechanical properties, pore structure characteristics, and micro-properties by in-situ and laboratory tests along the height and depth. The test results indicated that the concrete exhibited significant uneven corrosion along the height of the structure. In the severely attacked region (28.6-39.1 m), the neutralization depth in the concrete was 1.4 times greater than that in the slightly attacked region (0-6.6 m), and the porosity was 5 times higher. Different corrosion mechanisms were occurred inside the concrete along the corrosion depth direction. In the shallow concrete zone (0-8 mm), sulfation was predominant, with gypsum (Gyp) as the primary product. The pH was below 8.0, and the sulfate ion (SO2-4) concentration at the exposure surface reached up to 5.5%. In the coexistence concrete zone (8-14 mm), both sulfation and carbonation were presented, with the pH increasing from 8.0 to 11.0. Above 14 mm, SO2-4 and Gyp were no longer detected. At 10 mm, calcium carbonate (CaCO3) was found, and its content gradually increased. In the deep concrete zone (14-18 mm), carbonation was the dominant process, with CaCO3 as the main product.
2025, 55(1): 153-160.
doi: 10.3724/j.gyjzG24100602
Abstract:
The neutralization model of concrete corroded by CO2 and SO2 coupling was established. The model considered the dissolution process of solid calcium in concrete and the expansion damage caused by sulfation products. The influence of different water-cement ratios (0.37, 0.47, 0.57) on the neutralization process of concrete was studied. The changes of neutralization degree, gas diffusion coefficient, porosity, CaCO3 content and CaSO4 content of corroded concrete were analyzed. The results showed that with the increase of water-cement ratio, the diffusion range of CO2 gas in concrete gradually increased, while the diffusion range of SO2 was almost the same. After 28 days of corrosion, with the decrease of the water-cement ratio of concrete, the decrease in porosity of concrete increased gradually, and the expansion damage in concrete with different water-cement ratios was almost the same. In the area of increasing porosity, the change trends of concrete porosity were similar. With the increase of the water-cement ratio, the length of the complete sulfation area of concrete increased, the length of the partial sulfation area decreased, and the length of the partial carbonation area of concrete gradually increased.
The neutralization model of concrete corroded by CO2 and SO2 coupling was established. The model considered the dissolution process of solid calcium in concrete and the expansion damage caused by sulfation products. The influence of different water-cement ratios (0.37, 0.47, 0.57) on the neutralization process of concrete was studied. The changes of neutralization degree, gas diffusion coefficient, porosity, CaCO3 content and CaSO4 content of corroded concrete were analyzed. The results showed that with the increase of water-cement ratio, the diffusion range of CO2 gas in concrete gradually increased, while the diffusion range of SO2 was almost the same. After 28 days of corrosion, with the decrease of the water-cement ratio of concrete, the decrease in porosity of concrete increased gradually, and the expansion damage in concrete with different water-cement ratios was almost the same. In the area of increasing porosity, the change trends of concrete porosity were similar. With the increase of the water-cement ratio, the length of the complete sulfation area of concrete increased, the length of the partial sulfation area decreased, and the length of the partial carbonation area of concrete gradually increased.
2025, 55(1): 161-168.
doi: 10.3724/j.gyjzG24061105
Abstract:
A device for pressure forming concrete-filled steel tubes (CFST) was designed, which can apply a certain amount of mechanical pressure on fresh concrete for a certain period of time. Using this device, 7 sets of compressed concrete specimens with different compressing times and pressure levels were fabricated and subjected to axial compression failure tests. The influence of compressing conditions on concrete strength, brittleness, and stress-strain relation was studied, and a strength fitting formula for compressed concrete was proposed. The collaborative mechanism between the steel tube and core concrete in pressure formed components was analyzed through numerical simulations. The results showed that after compressing, the strength of concrete could be increased by 12%-42%, and the strength of concrete increased with the increase of compressing time and pressure magnitude; the effect of compressing time on the strength of compressed concrete was more significant; the proposed formula for compressed concrete strength could fit the test results well, with most specimens having an error of less than 3% and some specimens having an error of less than 15%.The pressure forming technique mainly improved the axial compression performance of pressure formed components by improving the strength of the core concrete. The growth rate of the component’s axial compression strength caused by the initial circumferential stress was less than 5%.
A device for pressure forming concrete-filled steel tubes (CFST) was designed, which can apply a certain amount of mechanical pressure on fresh concrete for a certain period of time. Using this device, 7 sets of compressed concrete specimens with different compressing times and pressure levels were fabricated and subjected to axial compression failure tests. The influence of compressing conditions on concrete strength, brittleness, and stress-strain relation was studied, and a strength fitting formula for compressed concrete was proposed. The collaborative mechanism between the steel tube and core concrete in pressure formed components was analyzed through numerical simulations. The results showed that after compressing, the strength of concrete could be increased by 12%-42%, and the strength of concrete increased with the increase of compressing time and pressure magnitude; the effect of compressing time on the strength of compressed concrete was more significant; the proposed formula for compressed concrete strength could fit the test results well, with most specimens having an error of less than 3% and some specimens having an error of less than 15%.The pressure forming technique mainly improved the axial compression performance of pressure formed components by improving the strength of the core concrete. The growth rate of the component’s axial compression strength caused by the initial circumferential stress was less than 5%.
2025, 55(1): 169-175.
doi: 10.3724/j.gyjzG24080902
Abstract:
Steel structures that have been in service in the harsh environment for many years, often suffer from macroscopic cracks and surface corrosion damage at the same time. In order to properly evaluate the reduction degree of crack initiation threshold of existing crack defects in corroded steel structures, the paper studied the crack initiation criteria for existing crack defects in corroded steels. Through the tensile tests of cracked corroded steel plates, and the fracture analysis based on microscopic mechanism, the fracture initiation criterion for existed crack defects in corroded steels was established.The results showed that surface corrosion greatly reduced the critical loads of the existing cracks in the steel structure. According to the micro fracture mechanism of hole initiation and deformation in the crack tip region of the corroded steel plates, the crack initiation criteria for the existing crack defects of the corroded steel plates could be established, and the fracture loads of the corroded steel plates with cracks could be better calculated.
Steel structures that have been in service in the harsh environment for many years, often suffer from macroscopic cracks and surface corrosion damage at the same time. In order to properly evaluate the reduction degree of crack initiation threshold of existing crack defects in corroded steel structures, the paper studied the crack initiation criteria for existing crack defects in corroded steels. Through the tensile tests of cracked corroded steel plates, and the fracture analysis based on microscopic mechanism, the fracture initiation criterion for existed crack defects in corroded steels was established.The results showed that surface corrosion greatly reduced the critical loads of the existing cracks in the steel structure. According to the micro fracture mechanism of hole initiation and deformation in the crack tip region of the corroded steel plates, the crack initiation criteria for the existing crack defects of the corroded steel plates could be established, and the fracture loads of the corroded steel plates with cracks could be better calculated.
2025, 55(1): 176-181.
doi: 10.3724/j.gyjzG24110702
Abstract:
The core objective of human lunar exploration has shifted from "understanding the moon" to a dual focus on "understanding and utilization." In order to meet the requirements for lunar in-situ construction research, a specific method for the preparation and evaluation of simulated lunar regolith was proposed. Using the Chang’e 5 lunar samples as a reference, the study developed a simulated lunar regolith, TC-1C (Tsinghua-China Building Materials Academy-type1 for Construction), and assessed its similarity in four key parameters: phase composition, particle size distribution, particle morphology, and density. The results indicated that the similarity of TC-1C to the actual Chang’e 5 lunar regolith exceeded 0.94.
The core objective of human lunar exploration has shifted from "understanding the moon" to a dual focus on "understanding and utilization." In order to meet the requirements for lunar in-situ construction research, a specific method for the preparation and evaluation of simulated lunar regolith was proposed. Using the Chang’e 5 lunar samples as a reference, the study developed a simulated lunar regolith, TC-1C (Tsinghua-China Building Materials Academy-type1 for Construction), and assessed its similarity in four key parameters: phase composition, particle size distribution, particle morphology, and density. The results indicated that the similarity of TC-1C to the actual Chang’e 5 lunar regolith exceeded 0.94.
2025, 55(1): 182-187.
doi: 10.3724/j.gyjzG24041001
Abstract:
The mass reinforced concrete in the raft foundation of nuclear power plant reactors has the characteristics of large area, large thickness, high strength, large cement dosage, and increased adiabatic temperature during construction, so the measures to prevent and control cracks are the top priorities. The internal stress is mainly the comprehensive stress caused by temperatures, hydration shrinkage and its constraints during construction. The temperature stress formula shows that the temperature field mainly varies along the radial direction, maximum temperature stress is horizontally hooped at the raft edge, independent of the temperature values and radius. Experimental data showed that the shrinkage stress was tensioned at the center and compressed at the edges, as opposed to the temperature stress. Based on this, the dynamic curing method was proposed, the temperature distribution was changed by continuously changing the insulation measures of the surface covering, and then the temperature deformation was used to neutralize the shrinkage deformation, the total deformation was tested by the elastic deformation device, and the cracks were controlled according to the third failure criterion, thus, and the total internal stress was controlled within a certain range. The crack control method is safe, economical, effective and low investment, and has been successfully applied in dozens of nuclear power foundation construction, which greatly shortens the foundation construction time.
The mass reinforced concrete in the raft foundation of nuclear power plant reactors has the characteristics of large area, large thickness, high strength, large cement dosage, and increased adiabatic temperature during construction, so the measures to prevent and control cracks are the top priorities. The internal stress is mainly the comprehensive stress caused by temperatures, hydration shrinkage and its constraints during construction. The temperature stress formula shows that the temperature field mainly varies along the radial direction, maximum temperature stress is horizontally hooped at the raft edge, independent of the temperature values and radius. Experimental data showed that the shrinkage stress was tensioned at the center and compressed at the edges, as opposed to the temperature stress. Based on this, the dynamic curing method was proposed, the temperature distribution was changed by continuously changing the insulation measures of the surface covering, and then the temperature deformation was used to neutralize the shrinkage deformation, the total deformation was tested by the elastic deformation device, and the cracks were controlled according to the third failure criterion, thus, and the total internal stress was controlled within a certain range. The crack control method is safe, economical, effective and low investment, and has been successfully applied in dozens of nuclear power foundation construction, which greatly shortens the foundation construction time.
