Login
Register
E-alert
2026 Vol. 56, No. 2
Display Method:
2026, 56(2): 1-7.
doi: 10.3724/j.gyjzG26012811
Abstract:
To study the mechanical properties of the stainless steel rod-shaped connectors， three pull-out tests and twelve push-off tests were conducted. The research parameters included the thickness of the insulation layer （50 mm and 70 mm） and whether the insulation layer was present during testing. The test results showed that the tensile specimens experienced concrete cone failure， and the pull-out load-displacement curve was approximately linear before peak load. The average tensile bearing capacity was 8.52 kN， and the peak slip between concrete wythes ranged from 1.49 mm to 1.61 mm. In the push-off tests， the connectors underwent bending followed by pull-out， but no concrete cone was pulled out. During the early loading stage， the push-off load-slip curve was approximately linear. After the connector experienced bending， the load-slip curve exhibited a distinct nonlinear relationship. The average shear bearing capacity of a single connector ranged from 2.48 kN to 6.45 kN， with corresponding slips between wythes ranging from 1.3 mm to 5.4 mm. The shear bearing capacity decreased as the insulation layer thickness increased. The shear bearing capacity of the connectors decreased as the thickness of the insulation layer increased. When the insulation layer thickness increased from 50 mm to 70 mm， the shear bearing capacity of the specimens without the insulation layer decreased by 79.8%， while that of the specimens with the insulation layer decreased by 8.4%. The presence of the insulation layer had a significant effect on the shear bearing capacity of the connectors， and the shear bearing capacity of the specimens with the insulation layer was 1.4 to 2.4 times that of the specimens without it.
To study the mechanical properties of the stainless steel rod-shaped connectors， three pull-out tests and twelve push-off tests were conducted. The research parameters included the thickness of the insulation layer （50 mm and 70 mm） and whether the insulation layer was present during testing. The test results showed that the tensile specimens experienced concrete cone failure， and the pull-out load-displacement curve was approximately linear before peak load. The average tensile bearing capacity was 8.52 kN， and the peak slip between concrete wythes ranged from 1.49 mm to 1.61 mm. In the push-off tests， the connectors underwent bending followed by pull-out， but no concrete cone was pulled out. During the early loading stage， the push-off load-slip curve was approximately linear. After the connector experienced bending， the load-slip curve exhibited a distinct nonlinear relationship. The average shear bearing capacity of a single connector ranged from 2.48 kN to 6.45 kN， with corresponding slips between wythes ranging from 1.3 mm to 5.4 mm. The shear bearing capacity decreased as the insulation layer thickness increased. The shear bearing capacity of the connectors decreased as the thickness of the insulation layer increased. When the insulation layer thickness increased from 50 mm to 70 mm， the shear bearing capacity of the specimens without the insulation layer decreased by 79.8%， while that of the specimens with the insulation layer decreased by 8.4%. The presence of the insulation layer had a significant effect on the shear bearing capacity of the connectors， and the shear bearing capacity of the specimens with the insulation layer was 1.4 to 2.4 times that of the specimens without it.
2026, 56(2): 8-15.
doi: 10.3724/j.gyjzG25103101
Abstract:
The sandwich insulation wall panel is a prefabricated exterior wall component of the prefabricated shear wall structure. It consists of three layers： an inner leaf plate， an outer leaf plate and a middle insulation board. Connectors pass through the insulation board to join the inner and outer leaf plates together. As ultra-low energy buildings are being promoted， their insulation layers have become thicker， and the combined tension-shear effect of the connectors has become increasingly prominent. However， there is a lack of experimental research on the mechanical properties of connectors under combined tension-shear loading. In this paper， a test device for simulating the combined tension-shear combined force on connectors was designed， and combined tension-shear loading tests were conducted on GFRP connectors with a "+" cross-section. Four structural combinations were set with the connector embedment depth of 30 mm and 50 mm， and the insulation layer thickness of 100 mm and 200 mm， respectively. In addition to the pull-out and shear tests， this study also included tests under six different tension-shear ratios. The bearing capacity， failure modes and other mechanical properties of the connectors under four structural combinations and eight different tension-shear ratios were obtained. Furthermore， by normalizing the applied forces， the failure criteria for the connectors under combined tension-shear loading were summarized.
The sandwich insulation wall panel is a prefabricated exterior wall component of the prefabricated shear wall structure. It consists of three layers： an inner leaf plate， an outer leaf plate and a middle insulation board. Connectors pass through the insulation board to join the inner and outer leaf plates together. As ultra-low energy buildings are being promoted， their insulation layers have become thicker， and the combined tension-shear effect of the connectors has become increasingly prominent. However， there is a lack of experimental research on the mechanical properties of connectors under combined tension-shear loading. In this paper， a test device for simulating the combined tension-shear combined force on connectors was designed， and combined tension-shear loading tests were conducted on GFRP connectors with a "+" cross-section. Four structural combinations were set with the connector embedment depth of 30 mm and 50 mm， and the insulation layer thickness of 100 mm and 200 mm， respectively. In addition to the pull-out and shear tests， this study also included tests under six different tension-shear ratios. The bearing capacity， failure modes and other mechanical properties of the connectors under four structural combinations and eight different tension-shear ratios were obtained. Furthermore， by normalizing the applied forces， the failure criteria for the connectors under combined tension-shear loading were summarized.
2026, 56(2): 16-20.
doi: 10.3724/j.gyjzG26012810
Abstract:
To investigate the pull-out performance of FRP bar connectors during the construction stage， this study designed and conducted pull-out tests on four groups with a total of twelve FRP bar connectors， with concrete strength （C25， C15） and insulation layer thickness （50 mm， 70 mm） as the research parameters. The failure modes， pull-out bearing capacity， load-slip curves， and load-connector strain curves were systematically analyzed. The experimental results indicated that all specimens failed due to concrete anchorage failure at the connector end. Concrete strength grade had a significant influence on the pull-out bearing capacity of the connectors. When the concrete strength increased from C15 to C25， the pull-out bearing capacity of specimens with insulation layer thicknesses of 50 mm and 70 mm improved by 18.1% and 21.0%， respectively. In contrast， insulation layer thickness had a relatively minor effect on the pull-out bearing capacity. When the insulation layer thickness increased from 50 mm to 70 mm， the pull-out bearing capacity of specimens with concrete strength grades of C15 and C25 increased by 3.3% and 7.4%， respectively. At failure， the strain of the connectors along the pull-out direction remained well below the ultimate tensile strain of the FRP material， and no damage was observed in any of the connectors.
To investigate the pull-out performance of FRP bar connectors during the construction stage， this study designed and conducted pull-out tests on four groups with a total of twelve FRP bar connectors， with concrete strength （C25， C15） and insulation layer thickness （50 mm， 70 mm） as the research parameters. The failure modes， pull-out bearing capacity， load-slip curves， and load-connector strain curves were systematically analyzed. The experimental results indicated that all specimens failed due to concrete anchorage failure at the connector end. Concrete strength grade had a significant influence on the pull-out bearing capacity of the connectors. When the concrete strength increased from C15 to C25， the pull-out bearing capacity of specimens with insulation layer thicknesses of 50 mm and 70 mm improved by 18.1% and 21.0%， respectively. In contrast， insulation layer thickness had a relatively minor effect on the pull-out bearing capacity. When the insulation layer thickness increased from 50 mm to 70 mm， the pull-out bearing capacity of specimens with concrete strength grades of C15 and C25 increased by 3.3% and 7.4%， respectively. At failure， the strain of the connectors along the pull-out direction remained well below the ultimate tensile strain of the FRP material， and no damage was observed in any of the connectors.
2026, 56(2): 21-28.
doi: 10.3724/j.gyjzG26012809
Abstract:
To investigate the out-of-plane flexural behavior and the influence of key design parameters of prefabricated sandwich insulated wall panels incorporating FRP plate connectors， a full-scale specimen was designed and tested under monotonic static loading. A refined nonlinear finite element （FE） model was developed using the ABAQUS platform. The accuracy of the FE model was validated by comparing the failure modes， load-displacement responses， and crack propagation processes with experimental observations. On this basis， a parametric study was conducted to evaluate the effects of insulation layer thickness， connector spacing， and concrete strength on the structural performance. The results indicated that the proposed FE model accurately reproduced the “X”-shaped yield line failure pattern and the overall load-bearing mechanism of the wall panel. Increasing the insulation layer thickness significantly reduced structural stiffness； an increase from 100 mm to 200 mm resulted in a 26.4% decrease in bearing capacity. Connector spacing had a pronounced impact on bearing capacity： as the spacing increased from 400 mm to 600 mm， the composite action between layers weakened substantially， leading to an ultimate bearing capacity reduction to 219.21 kN. Furthermore， increasing the concrete strength effectively improved both the stiffness and bearing capacity.
To investigate the out-of-plane flexural behavior and the influence of key design parameters of prefabricated sandwich insulated wall panels incorporating FRP plate connectors， a full-scale specimen was designed and tested under monotonic static loading. A refined nonlinear finite element （FE） model was developed using the ABAQUS platform. The accuracy of the FE model was validated by comparing the failure modes， load-displacement responses， and crack propagation processes with experimental observations. On this basis， a parametric study was conducted to evaluate the effects of insulation layer thickness， connector spacing， and concrete strength on the structural performance. The results indicated that the proposed FE model accurately reproduced the “X”-shaped yield line failure pattern and the overall load-bearing mechanism of the wall panel. Increasing the insulation layer thickness significantly reduced structural stiffness； an increase from 100 mm to 200 mm resulted in a 26.4% decrease in bearing capacity. Connector spacing had a pronounced impact on bearing capacity： as the spacing increased from 400 mm to 600 mm， the composite action between layers weakened substantially， leading to an ultimate bearing capacity reduction to 219.21 kN. Furthermore， increasing the concrete strength effectively improved both the stiffness and bearing capacity.
2026, 56(2): 29-37.
doi: 10.3724/j.gyjzG25093004
Abstract:
This paper proposes a novel ultra-high performance concrete （UHPC） panel-steel keel composite wallboard. Designed with steel keels as the primary load-bearing components， the wallboard utilizes UHPC for its exterior panels to enhance impermeability and durability. Glass fiber-reinforced polymer （GFRP） connectors are employed to reduce heat conduction and improve structural integrity between the UHPC panels and the steel keel framework. This design meets the requirements for external wallboards in frame structures of ultra-low energy consumption buildings. A full-scale composite wallboard was fabricated and subjected to an out-of-plane bending test under a uniformly distributed load with four-point supports， complemented by finite element simulation.The results showed that the GFRP connectors had a significant impact on the integrity of the composite wallboard， resulting in a 30% increase in bending stiffness and a 30% reduction in both the mid-span deflection and the steel keel’s mid-span bending moment. When the load reached 14 kN/m2， the steel keel of the test wallboard reached the yield stress， and fine cracks with widths not exceeding 0.1 mm appeared on the UHPC panels. At the load of 25 kN/m2， the supports failed； the slope of the load-deflection curve decreased to 29% of its initial value， but it had not yet entered the descending section. A limited number of through-thickness cracks were observed in the UHPC panels near the four corner supports and at the mid-span of each edge. Except for some irreversible lateral deformation in the corner GFRP connectors， all other components remained intact. These findings indicate that the proposed UHPC panel-steel keel composite wallboard can meet the mechanical requirements for prefabricated exterior wallboards in frame structures.
This paper proposes a novel ultra-high performance concrete （UHPC） panel-steel keel composite wallboard. Designed with steel keels as the primary load-bearing components， the wallboard utilizes UHPC for its exterior panels to enhance impermeability and durability. Glass fiber-reinforced polymer （GFRP） connectors are employed to reduce heat conduction and improve structural integrity between the UHPC panels and the steel keel framework. This design meets the requirements for external wallboards in frame structures of ultra-low energy consumption buildings. A full-scale composite wallboard was fabricated and subjected to an out-of-plane bending test under a uniformly distributed load with four-point supports， complemented by finite element simulation.The results showed that the GFRP connectors had a significant impact on the integrity of the composite wallboard， resulting in a 30% increase in bending stiffness and a 30% reduction in both the mid-span deflection and the steel keel’s mid-span bending moment. When the load reached 14 kN/m2， the steel keel of the test wallboard reached the yield stress， and fine cracks with widths not exceeding 0.1 mm appeared on the UHPC panels. At the load of 25 kN/m2， the supports failed； the slope of the load-deflection curve decreased to 29% of its initial value， but it had not yet entered the descending section. A limited number of through-thickness cracks were observed in the UHPC panels near the four corner supports and at the mid-span of each edge. Except for some irreversible lateral deformation in the corner GFRP connectors， all other components remained intact. These findings indicate that the proposed UHPC panel-steel keel composite wallboard can meet the mechanical requirements for prefabricated exterior wallboards in frame structures.
2026, 56(2): 38-45.
doi: 10.3724/j.gyjzG26012802
Abstract:
Ultra-High-Performance Concrete （UHPC） demonstrates significant application potential in civil engineering due to its excellent mechanical properties and durability. However， the synergistic mechanisms between fiber type and member size—key influencing factors for its flexural performance—are not yet fully understood. Existing research often focuses on single variables， lacking systematic investigation into the interactive effects of slab thickness and different fiber types. This paper presents a comparative experimental study on a total of six slabs， with research parameters including fiber type ［steel fiber， glass fiber， polyoxymethylene （POM） fiber］ and slab thickness （30 mm， 50 mm）. The test results indicated that slab thickness had a significant influence on flexural performance. Increasing the thickness from 30 mm to 50 mm enhanced the cracking load and ultimate bearing capacity by 3 to 4 times. Under the same thickness conditions， the reinforcement effects of different fibers varied markedly： specimens with steel fibers exhibited the highest bearing capacity， followed by those with glass fibers， while POM fiber specimens showed the lowest capacity. When the slab thickness increased from 30 mm to 50 mm， the ductility of the steel-fiber， glass-fiber， and POM-fiber specimens improved by 37.4%， 3.4%， and 13.0%， respectively. Strain analysis revealed that the plane-section assumption held before cracking and up to approximately 60% of the peak load. Beyond this threshold， nonlinear characteristics emerged， varying with fiber type and slab thickness.
Ultra-High-Performance Concrete （UHPC） demonstrates significant application potential in civil engineering due to its excellent mechanical properties and durability. However， the synergistic mechanisms between fiber type and member size—key influencing factors for its flexural performance—are not yet fully understood. Existing research often focuses on single variables， lacking systematic investigation into the interactive effects of slab thickness and different fiber types. This paper presents a comparative experimental study on a total of six slabs， with research parameters including fiber type ［steel fiber， glass fiber， polyoxymethylene （POM） fiber］ and slab thickness （30 mm， 50 mm）. The test results indicated that slab thickness had a significant influence on flexural performance. Increasing the thickness from 30 mm to 50 mm enhanced the cracking load and ultimate bearing capacity by 3 to 4 times. Under the same thickness conditions， the reinforcement effects of different fibers varied markedly： specimens with steel fibers exhibited the highest bearing capacity， followed by those with glass fibers， while POM fiber specimens showed the lowest capacity. When the slab thickness increased from 30 mm to 50 mm， the ductility of the steel-fiber， glass-fiber， and POM-fiber specimens improved by 37.4%， 3.4%， and 13.0%， respectively. Strain analysis revealed that the plane-section assumption held before cracking and up to approximately 60% of the peak load. Beyond this threshold， nonlinear characteristics emerged， varying with fiber type and slab thickness.
2026, 56(2): 46-55.
doi: 10.3724/j.gyjzG26013003
Abstract:
Ultra-high performance concrete （UHPC）， with its exceptional tensile strength and strain-hardening characteristics， offers the possibility of designing non-reinforced lightweight structures. However， current design codes often underestimate its tensile contribution， and traditional analytical methods struggle to accurately quantify the complex influence of different fibers on the flexural capacity of members. During the casting of thin-walled elements or narrow cross-sections， the mold boundaries impose significant constraints on fiber orientation—a phenomenon known as the “wall effect”—leading to anisotropic fiber distribution and consequently a substantial impact on the flexural performance of the element. In this study， flexural performance tests were conducted on three non-reinforced UHPC slabs and compared with prior experimental results. The findings revealed that as the cross-sectional size decreased， the influence of the wall effect on fiber orientation intensified， significantly enhancing the nominal flexural strength of the element. Particularly for narrow and deep cross-sections， the side-wall effect increased the effective tensile strength by more than 30% compared to that of the matrix. Building on this， the ultimate flexural mechanism of non-reinforced UHPC simply-supported slabs was systematically investigated. By introducing an equivalent rectangular stress block model， a calculation method for the flexural capacity of UHPC simply-supported slabs with three fiber types was proposed. The theoretical model presented in this paper can effectively predict the ultimate bearing capacity of UHPC slabs across various geometric dimensions.
Ultra-high performance concrete （UHPC）， with its exceptional tensile strength and strain-hardening characteristics， offers the possibility of designing non-reinforced lightweight structures. However， current design codes often underestimate its tensile contribution， and traditional analytical methods struggle to accurately quantify the complex influence of different fibers on the flexural capacity of members. During the casting of thin-walled elements or narrow cross-sections， the mold boundaries impose significant constraints on fiber orientation—a phenomenon known as the “wall effect”—leading to anisotropic fiber distribution and consequently a substantial impact on the flexural performance of the element. In this study， flexural performance tests were conducted on three non-reinforced UHPC slabs and compared with prior experimental results. The findings revealed that as the cross-sectional size decreased， the influence of the wall effect on fiber orientation intensified， significantly enhancing the nominal flexural strength of the element. Particularly for narrow and deep cross-sections， the side-wall effect increased the effective tensile strength by more than 30% compared to that of the matrix. Building on this， the ultimate flexural mechanism of non-reinforced UHPC simply-supported slabs was systematically investigated. By introducing an equivalent rectangular stress block model， a calculation method for the flexural capacity of UHPC simply-supported slabs with three fiber types was proposed. The theoretical model presented in this paper can effectively predict the ultimate bearing capacity of UHPC slabs across various geometric dimensions.
2026, 56(2): 56-61.
doi: 10.3724/j.gyjzG25062201
Abstract:
In this paper， a truss-type curtain wall connection was proposed， which used embedded steel bar trusses to connect the insulated sandwich wall panels and curtain wall systems. Considering different steel truss web member diameters （8， 10，12 mm）， spacing of welding joints on the inner truss chord member （100，130 mm）， and insulation layer thickness （80，120 mm）， tensile mechanical performance tests were conducted on five curtain wall connection specimens to study the failure process， load-displacement relationships， tensile strength and deformation capabilities of the connection specimens. The experimental results indicated that the tensile failure modes of the embedded truss-type curtain wall connections included the cracking and spalling of local concrete on the inner side of the anchor plate， flexural yielding of the anchor plate， and fracture failure of welding joints on the outer truss chord member. During the tests， no anchorage failure occurred between the inner leaf plate and the embedded steel trusses. All connection specimens exhibited comparable yield strength， with tensile strength not only satisfying the design load requirements but also exhibiting substantial safety margins. Increasing the steel truss web member diameter can increase both the tensile strength and plastic deformation capability of the curtain wall connection， while the spacing of welding joints on the inner truss chord member and the thickness of the insulation layer showed little influence on these mechanical properties.
In this paper， a truss-type curtain wall connection was proposed， which used embedded steel bar trusses to connect the insulated sandwich wall panels and curtain wall systems. Considering different steel truss web member diameters （8， 10，12 mm）， spacing of welding joints on the inner truss chord member （100，130 mm）， and insulation layer thickness （80，120 mm）， tensile mechanical performance tests were conducted on five curtain wall connection specimens to study the failure process， load-displacement relationships， tensile strength and deformation capabilities of the connection specimens. The experimental results indicated that the tensile failure modes of the embedded truss-type curtain wall connections included the cracking and spalling of local concrete on the inner side of the anchor plate， flexural yielding of the anchor plate， and fracture failure of welding joints on the outer truss chord member. During the tests， no anchorage failure occurred between the inner leaf plate and the embedded steel trusses. All connection specimens exhibited comparable yield strength， with tensile strength not only satisfying the design load requirements but also exhibiting substantial safety margins. Increasing the steel truss web member diameter can increase both the tensile strength and plastic deformation capability of the curtain wall connection， while the spacing of welding joints on the inner truss chord member and the thickness of the insulation layer showed little influence on these mechanical properties.
2026, 56(2): 62-69.
doi: 10.3724/j.gyjzG26010804
Abstract:
Concrete ribs， serving as crucial load-bearing components， inherently face thermal bridging issues that have become a core challenge in the energy-efficient design of such envelope systems. This study focuses on high-performance concrete ribbed sandwich insulation walls， employing three-dimensional steady-state heat transfer simulations to quantify the local thermal characteristics along the tangential （x）， normal （y）， and vertical （z） directions. The results indicated that the heat flux densities in the three directions exhibited an approximately proportional distribution. Structural geometric parameters primarily governed the proportional allocation of heat flow in each direction， while the thermophysical properties of materials determined the magnitude of increase. Based on this heat transfer behavior， a thermal bridge mitigation strategy was proposed， involving the differentiated wrapping of the ribs with aerogel felts in different directions. Optimal thermal performance was achieved when the ribs were wrapped with 16-mm-thick aerogel felts in the x and z directions， reducing the wall’s average thermal transmittance by 6.35% compared to the unwrapped condition. Under the same thickness of aerogel felts， this method reduced the wall’s average thermal transmittance by up to 20.28% compared to embedded local treatment， providing an effective approach for optimizing the thermal performance of concrete ribbed sandwich insulation walls.
Concrete ribs， serving as crucial load-bearing components， inherently face thermal bridging issues that have become a core challenge in the energy-efficient design of such envelope systems. This study focuses on high-performance concrete ribbed sandwich insulation walls， employing three-dimensional steady-state heat transfer simulations to quantify the local thermal characteristics along the tangential （x）， normal （y）， and vertical （z） directions. The results indicated that the heat flux densities in the three directions exhibited an approximately proportional distribution. Structural geometric parameters primarily governed the proportional allocation of heat flow in each direction， while the thermophysical properties of materials determined the magnitude of increase. Based on this heat transfer behavior， a thermal bridge mitigation strategy was proposed， involving the differentiated wrapping of the ribs with aerogel felts in different directions. Optimal thermal performance was achieved when the ribs were wrapped with 16-mm-thick aerogel felts in the x and z directions， reducing the wall’s average thermal transmittance by 6.35% compared to the unwrapped condition. Under the same thickness of aerogel felts， this method reduced the wall’s average thermal transmittance by up to 20.28% compared to embedded local treatment， providing an effective approach for optimizing the thermal performance of concrete ribbed sandwich insulation walls.
2026, 56(2): 70-76.
doi: 10.3724/j.gyjzG26012601
Abstract:
Prefabricated concrete modular construction represents the highest level of integration in industrialized prefabricated building systems. Owing to its exceptional degree of standardization， it possesses inherent advantages in industrialized production， automated assembly， and digital operation and maintenance. It serves as a crucial pathway for advancing "intelligent construction" and facilitating the green， low-carbon transformation of the building industry. This paper focuses on a novel prefabricated concrete modular structural system. Using ANSYS software， a finite element analysis was conducted to evaluate the thermal performance of the exterior walls in a modular unit. This study revealed the influence of factors such as dry connectors and external insulation layers on the wall's thermal performance. It also analyzed the local thermal bridges induced by dry connectors under various external insulation configurations and investigated applicable calculation methods for the average thermal transmittance （U-value） of the modular unit's exterior wall. The results indicated that under cold climate conditions， box-type connectors create local thermal bridges， increasing the average U-value at the structural frame sections by 3.4%. As the thickness of the external insulation layer increased， the thermal bridge effect was gradually mitigated. The relative error between the one-dimensional area-weighted method and the three-dimensional simulation for calculating the average wall U-value decreased progressively. When the insulation thickness exceeded 30 mm， the error fell below 3%. When the external insulation thickness reached 70 mm， the average U-value of the exterior wall is 0.42 W/（m2·K），complying with the specified limit for the thermal transmittance of the external wall， as stipulated for buildings with more than 3 storeys in Design Standard for Energy Efficiency of Residential Buildings（DB 61/T 5033—2022）.
Prefabricated concrete modular construction represents the highest level of integration in industrialized prefabricated building systems. Owing to its exceptional degree of standardization， it possesses inherent advantages in industrialized production， automated assembly， and digital operation and maintenance. It serves as a crucial pathway for advancing "intelligent construction" and facilitating the green， low-carbon transformation of the building industry. This paper focuses on a novel prefabricated concrete modular structural system. Using ANSYS software， a finite element analysis was conducted to evaluate the thermal performance of the exterior walls in a modular unit. This study revealed the influence of factors such as dry connectors and external insulation layers on the wall's thermal performance. It also analyzed the local thermal bridges induced by dry connectors under various external insulation configurations and investigated applicable calculation methods for the average thermal transmittance （U-value） of the modular unit's exterior wall. The results indicated that under cold climate conditions， box-type connectors create local thermal bridges， increasing the average U-value at the structural frame sections by 3.4%. As the thickness of the external insulation layer increased， the thermal bridge effect was gradually mitigated. The relative error between the one-dimensional area-weighted method and the three-dimensional simulation for calculating the average wall U-value decreased progressively. When the insulation thickness exceeded 30 mm， the error fell below 3%. When the external insulation thickness reached 70 mm， the average U-value of the exterior wall is 0.42 W/（m2·K），complying with the specified limit for the thermal transmittance of the external wall， as stipulated for buildings with more than 3 storeys in Design Standard for Energy Efficiency of Residential Buildings（DB 61/T 5033—2022）.
2026, 56(2): 77-87.
doi: 10.3724/j.gyjzG25060908
Abstract:
The application of insulated precast concrete sandwich walls in external envelope systems has characteristics such as outstanding thermal insulation， high durability， and rapid installation. However， the flammability and thermal conductivity of insulation layers exacerbate risks of structural damage and fire spread under the influence of high-temperature smoke during fires. Therefore， it is necessary to research the fire resistance performance of seaming joints between panels and window opening joints. Firstly， this paper investigated the structural design requirements of the seaming joints between panels and window opening joints in the current specifications. Based on the characteristics of ultra-low energy buildings， applicable fire-resistant joint design methods were proposed. Experimental studies on the fire resistance performance of seaming joints between panels and window opening joints were conducted. The fire behavior of the specimens， temperature variation， and fire-affected area were investigated as the key indicators. Based on the test result， optimized joint design methods considering fire resistance performance were proposed to prevent fire spread and protect building structures.
The application of insulated precast concrete sandwich walls in external envelope systems has characteristics such as outstanding thermal insulation， high durability， and rapid installation. However， the flammability and thermal conductivity of insulation layers exacerbate risks of structural damage and fire spread under the influence of high-temperature smoke during fires. Therefore， it is necessary to research the fire resistance performance of seaming joints between panels and window opening joints. Firstly， this paper investigated the structural design requirements of the seaming joints between panels and window opening joints in the current specifications. Based on the characteristics of ultra-low energy buildings， applicable fire-resistant joint design methods were proposed. Experimental studies on the fire resistance performance of seaming joints between panels and window opening joints were conducted. The fire behavior of the specimens， temperature variation， and fire-affected area were investigated as the key indicators. Based on the test result， optimized joint design methods considering fire resistance performance were proposed to prevent fire spread and protect building structures.
2026, 56(2): 88-98.
doi: 10.3724/j.gyjzG26012901
Abstract:
To investigate the influence of the inorganic insulation mortar layer on the fire resistance of precast concrete sandwich panels（PCSPs） with fiber-reinforced polymer （FRP） connectors， a coupled temperature-displacement finite element model was developed using the finite element software ABAQUS by considering the effects of high temperature on concrete， rebars， and FRP materials. Finite element analyses were conducted under standard fire conditions， and the results were validated against fire resistance tests on two PCSPs with FRP connectors. Subsequently， parametric analyses were performed to examine the effects of out-of-plane loading and fire exposure duration. The results showed that the inorganic mortar increased thermal resistance and flexural stiffness but reduced heat convection within the panel. The FRP connectors were slightly damaged while still capable of providing shear capacity， and the glass transition temperature was found to be a conservative indicator of their failure. Although out-of-plane loading led to larger panel deflections， it had no appreciable effect on the temperature distribution. Compared to the 60-minute fire exposure， the FRP connectors were more prone to anchorage failure after 180 minutes of fire exposure.
To investigate the influence of the inorganic insulation mortar layer on the fire resistance of precast concrete sandwich panels（PCSPs） with fiber-reinforced polymer （FRP） connectors， a coupled temperature-displacement finite element model was developed using the finite element software ABAQUS by considering the effects of high temperature on concrete， rebars， and FRP materials. Finite element analyses were conducted under standard fire conditions， and the results were validated against fire resistance tests on two PCSPs with FRP connectors. Subsequently， parametric analyses were performed to examine the effects of out-of-plane loading and fire exposure duration. The results showed that the inorganic mortar increased thermal resistance and flexural stiffness but reduced heat convection within the panel. The FRP connectors were slightly damaged while still capable of providing shear capacity， and the glass transition temperature was found to be a conservative indicator of their failure. Although out-of-plane loading led to larger panel deflections， it had no appreciable effect on the temperature distribution. Compared to the 60-minute fire exposure， the FRP connectors were more prone to anchorage failure after 180 minutes of fire exposure.
2026, 56(2): 99-105.
doi: 10.3724/j.gyjzG25060904
Abstract:
Precast facade panels highly integrate multiple functions such as decoration， thermal insulation， fire resistance， structural performance， and waterproofing， representing an important technical route for achieving industrialized construction， longevity， and quality enhancement of the envelope system. Traditional linear-supporting connections for facade panels tend to form linear thermal bridges， which can weaken the thermal performance of the envelope system. To address this， a centralized connection that balances structural safety and thermal performance has been proposed. Experiment and finite element analysis have been conducted on its out-of-plane mechanical performance and thermal performance. The results indicate that the rotation ratio of the facade panel at the peak and ultimate status of the specimens are 1/32 and 1/20， respectively. The connection with concrete punching shear failure still exhibits good deformation capacity， necessitating enhanced punching shear resistance design in the connection. The thermal bridge effect of the centralized connection is only 17.4% of that of a traditional linear-supporting connection， thereby achieving thermal bridge mitigation near the connection. The proposed centralized connection can be applied to achieve coordinated improvement of both structural and thermal performances of the linear-supporting connection between the facade panel and the main structure．
Precast facade panels highly integrate multiple functions such as decoration， thermal insulation， fire resistance， structural performance， and waterproofing， representing an important technical route for achieving industrialized construction， longevity， and quality enhancement of the envelope system. Traditional linear-supporting connections for facade panels tend to form linear thermal bridges， which can weaken the thermal performance of the envelope system. To address this， a centralized connection that balances structural safety and thermal performance has been proposed. Experiment and finite element analysis have been conducted on its out-of-plane mechanical performance and thermal performance. The results indicate that the rotation ratio of the facade panel at the peak and ultimate status of the specimens are 1/32 and 1/20， respectively. The connection with concrete punching shear failure still exhibits good deformation capacity， necessitating enhanced punching shear resistance design in the connection. The thermal bridge effect of the centralized connection is only 17.4% of that of a traditional linear-supporting connection， thereby achieving thermal bridge mitigation near the connection. The proposed centralized connection can be applied to achieve coordinated improvement of both structural and thermal performances of the linear-supporting connection between the facade panel and the main structure．
2026, 56(2): 106-118.
doi: 10.3724/j.gyjzG25060905
Abstract:
The precast concrete sandwich wall panel， an envelope structure integrated with decorative， insulation， and structural functions， is widely used in prefabricated buildings. Its design requires comprehensive coordination of multiple objectives， including thermal and mechanical performance， economic feasibility， and ease of processing. Based on the characteristics of typical climate zones， this paper systematically examines the structural parameters of PC sandwich wall panels. By carrying out computational simulations and practical investigations， this paper established the quantitative relationships between panel parameters and their performance. To address the conflicts of multi-objective performance and the lack of decision-making mechanisms in existing design algorithms， this paper proposes an innovative optimization design method based on dynamic weight assignment， which collaboratively achieves optimization of multiple performance and provides scientific guidance for multi-objective optimization design of envelope wall panel.
The precast concrete sandwich wall panel， an envelope structure integrated with decorative， insulation， and structural functions， is widely used in prefabricated buildings. Its design requires comprehensive coordination of multiple objectives， including thermal and mechanical performance， economic feasibility， and ease of processing. Based on the characteristics of typical climate zones， this paper systematically examines the structural parameters of PC sandwich wall panels. By carrying out computational simulations and practical investigations， this paper established the quantitative relationships between panel parameters and their performance. To address the conflicts of multi-objective performance and the lack of decision-making mechanisms in existing design algorithms， this paper proposes an innovative optimization design method based on dynamic weight assignment， which collaboratively achieves optimization of multiple performance and provides scientific guidance for multi-objective optimization design of envelope wall panel.
2026, 56(2): 119-126.
doi: 10.3724/j.gyjzG25120403
Abstract:
With the development of modern building floor structures towards lighteweight， large-span， and prefabricated construction， the comfort of floor systems has become increasingly prominent. To evaluate the comfort performance of a novel prefabricated steel-framed composite panel， a periodic dynamic loading test was conducted using an eccentric vibration exciter based on the resonance principle. Dynamic characteristics， including natural frequency， peak acceleration， and damping ratio， were measured for the panel in both undamaged and damaged states. The experimental results showed that the comfort level of the panel met the requirements of relevant specifications. Finally， a finite element model was established to analyze the panel’s vibration behavior. The calculated natural frequencies from the model showed good agreement with the measured values， providing a basis and reference for the promotion and application of this composite panel.
With the development of modern building floor structures towards lighteweight， large-span， and prefabricated construction， the comfort of floor systems has become increasingly prominent. To evaluate the comfort performance of a novel prefabricated steel-framed composite panel， a periodic dynamic loading test was conducted using an eccentric vibration exciter based on the resonance principle. Dynamic characteristics， including natural frequency， peak acceleration， and damping ratio， were measured for the panel in both undamaged and damaged states. The experimental results showed that the comfort level of the panel met the requirements of relevant specifications. Finally， a finite element model was established to analyze the panel’s vibration behavior. The calculated natural frequencies from the model showed good agreement with the measured values， providing a basis and reference for the promotion and application of this composite panel.
2026, 56(2): 127-135.
doi: 10.3724/j.gyjzG25082104
Abstract:
With the advancement of prefabricated buildings and green construction， Ultra-High Performance Concrete （UHPC） Light-Gauge Steel Framing （LGSF） sandwich insulation wall panels have emerged as a key focus in developing new building enclosures， owing to their superior mechanical properties， thermal insulation performance， and construction efficiency. However， the manufacturing of such panels involves complex processes， multiple stages， and significant variations in takt time， making traditional scheduling methods inadequate for meeting the demands of high-efficiency and energy-synergized production. To address this， focusing on a typical wall panel production line and targeting issues such as unbalanced operation takt and irrational resource allocation， this study developed a Mixed-Integer Nonlinear Programming （MINLP） model aimed at maximizing the line-balancing rate. Furthermore， an intelligent optimization method was designed by hybridizing a genetic algorithm with simulated annealing and dynamic mutation control， thereby solving the scheduling challenges arising from uneven operation durations and discrete resource allocation. Validation through field data and simulations demonstrated that the optimized solution significantly enhanced line takt balance and resource utilization， indicating good engineering adaptability and promotion value.
With the advancement of prefabricated buildings and green construction， Ultra-High Performance Concrete （UHPC） Light-Gauge Steel Framing （LGSF） sandwich insulation wall panels have emerged as a key focus in developing new building enclosures， owing to their superior mechanical properties， thermal insulation performance， and construction efficiency. However， the manufacturing of such panels involves complex processes， multiple stages， and significant variations in takt time， making traditional scheduling methods inadequate for meeting the demands of high-efficiency and energy-synergized production. To address this， focusing on a typical wall panel production line and targeting issues such as unbalanced operation takt and irrational resource allocation， this study developed a Mixed-Integer Nonlinear Programming （MINLP） model aimed at maximizing the line-balancing rate. Furthermore， an intelligent optimization method was designed by hybridizing a genetic algorithm with simulated annealing and dynamic mutation control， thereby solving the scheduling challenges arising from uneven operation durations and discrete resource allocation. Validation through field data and simulations demonstrated that the optimized solution significantly enhanced line takt balance and resource utilization， indicating good engineering adaptability and promotion value.
2026, 56(2): 136-142.
doi: 10.3724/j.gyjzG25091101
Abstract:
To address the high-quality manufacturing demand for multi-functional integrated exterior enclosure components in ultra-low energy consumption buildings， this study focuses on the key technical challenges in the lean manufacturing of large-scale lightweight ultra-high performance concrete （UHPC） ribbed wall panels. Starting from the structural and performance requirements of such wall panels， a high-performance steel fiber-reinforced UHPC mixture was developed， and a complete lean manufacturing system integrating three core processes was established， including right-side-up ribbed formwork， high-precision casting molding， and high-temperature low-humidity steam curing. The research results indicate that this technical system can effectively control the shrinkage， warpage deformation， and surface discoloration of large-scale lightweight UHPC ribbed wall panels， successfully improving the product quality and production efficiency of these novel exterior wall panels and achieving the goal of lean manufacturing. This study provides technical support and practical examples for advancing the high-level manufacturing of exterior enclosure components in ultra-low energy prefabricated buildings.
To address the high-quality manufacturing demand for multi-functional integrated exterior enclosure components in ultra-low energy consumption buildings， this study focuses on the key technical challenges in the lean manufacturing of large-scale lightweight ultra-high performance concrete （UHPC） ribbed wall panels. Starting from the structural and performance requirements of such wall panels， a high-performance steel fiber-reinforced UHPC mixture was developed， and a complete lean manufacturing system integrating three core processes was established， including right-side-up ribbed formwork， high-precision casting molding， and high-temperature low-humidity steam curing. The research results indicate that this technical system can effectively control the shrinkage， warpage deformation， and surface discoloration of large-scale lightweight UHPC ribbed wall panels， successfully improving the product quality and production efficiency of these novel exterior wall panels and achieving the goal of lean manufacturing. This study provides technical support and practical examples for advancing the high-level manufacturing of exterior enclosure components in ultra-low energy prefabricated buildings.
2026, 56(2): 143-149.
doi: 10.3724/j.gyjzG25072101
Abstract:
Aiming at the complex problems of tolerance allocation in the manufacture， embedded parts of the main structure of multifunctional integrated composite exterior wall panel， combined with the improved genetic algorithm， a tolerance allocation optimization method driven by comprehensive cost coefficient was proposed. A two-dimensional chain analysis model including longitudinal joints， transverse joints， and diagonal lines between wallboards was established based on the synergistic effect of various tolerances in the horizontal and vertical directions. An optimization function was constructed to minimize the sum of comprehensive cost coefficients， and the constraints of tolerance and dimensional chain models were determined. Different tolerance levels were encoded as chromosomes， and the initial population was randomly generated. The selection， crossover and mutation operations were carried out by calculating the fitness of each individual （the reciprocal of the optimization function）， and the elitism principle was introduced. Finally， the optimal tolerance allocation scheme satisfying the constraint conditions was obtained iteratively. Through the comparison and analysis of specific examples， the allocation scheme determined by this method can reduce the comprehensive cost coefficient by 11.25% ，compared with the traditional genetic algorithm method， and provide theoretical support for the tolerance allocation of multifunctional integrated composite exterior wall panels.
Aiming at the complex problems of tolerance allocation in the manufacture， embedded parts of the main structure of multifunctional integrated composite exterior wall panel， combined with the improved genetic algorithm， a tolerance allocation optimization method driven by comprehensive cost coefficient was proposed. A two-dimensional chain analysis model including longitudinal joints， transverse joints， and diagonal lines between wallboards was established based on the synergistic effect of various tolerances in the horizontal and vertical directions. An optimization function was constructed to minimize the sum of comprehensive cost coefficients， and the constraints of tolerance and dimensional chain models were determined. Different tolerance levels were encoded as chromosomes， and the initial population was randomly generated. The selection， crossover and mutation operations were carried out by calculating the fitness of each individual （the reciprocal of the optimization function）， and the elitism principle was introduced. Finally， the optimal tolerance allocation scheme satisfying the constraint conditions was obtained iteratively. Through the comparison and analysis of specific examples， the allocation scheme determined by this method can reduce the comprehensive cost coefficient by 11.25% ，compared with the traditional genetic algorithm method， and provide theoretical support for the tolerance allocation of multifunctional integrated composite exterior wall panels.
2026, 56(2): 150-157.
doi: 10.3724/j.gyjzG25082204
Abstract:
The cloud-based construction factory is an industrialized and intelligent formwork platform system designed for super high-rise building construction， also referred to as a building construction machine platform. However， research on the wall-attached support systems of such platforms， specifically for prefabricated shear wall structures， remains relatively limited in China. To address this gap， this study conducted a full-scale （1∶1） test to simulate the loading conditions of the wall-attached support system in a cloud-based prefabricated shear wall construction factory. The test results were compared with refined finite element analysis to investigate the development of shear cracks， reinforcement strain， and stress levels in the wall-attached supports under a vertical load of 1400 kN. The results demonstrated that the system exhibited adequate bearing capacity under this vertical load， with a maximum crack width of 0.27 mm. Under normal service conditions with crack control measures implemented， the crack width remained below 0.2 mm at a vertical load of 1100 kN. Therefore， it was concluded that the design vertical load for the wall-attached support system should be set at 1000 kN. These findings have been successfully applied to the prefabricated shear wall project of China State Construction’s Yinghua Yuefu Development.
The cloud-based construction factory is an industrialized and intelligent formwork platform system designed for super high-rise building construction， also referred to as a building construction machine platform. However， research on the wall-attached support systems of such platforms， specifically for prefabricated shear wall structures， remains relatively limited in China. To address this gap， this study conducted a full-scale （1∶1） test to simulate the loading conditions of the wall-attached support system in a cloud-based prefabricated shear wall construction factory. The test results were compared with refined finite element analysis to investigate the development of shear cracks， reinforcement strain， and stress levels in the wall-attached supports under a vertical load of 1400 kN. The results demonstrated that the system exhibited adequate bearing capacity under this vertical load， with a maximum crack width of 0.27 mm. Under normal service conditions with crack control measures implemented， the crack width remained below 0.2 mm at a vertical load of 1100 kN. Therefore， it was concluded that the design vertical load for the wall-attached support system should be set at 1000 kN. These findings have been successfully applied to the prefabricated shear wall project of China State Construction’s Yinghua Yuefu Development.
2026, 56(2): 158-169.
doi: 10.3724/j.gyjzG25070402
Abstract:
Sleeve grouting connections are one of the primary connection methods for reinforcing steel in prefabricated concrete structures. To investigate the effect of concrete cover on the mechanical properties of sleeve grout connections after exposure to high temperatures from fire， 12 sleeve grout connection components with a 30 mm concrete cover and 12 specimens without a concrete cover were subjected to uniaxial tensile and high-stress repeated tensile tests after high temperatures exposure. The study explored the influence of the concrete cover on the failure mode， load-bearing capacity， and ductility of sleeve grout connection components under different loading conditions. The test results indicated that the concrete cover had a significant impact on the failure mode of sleeve grouting connections after exposure to high temperature. After 60 minutes of exposure， the specimens with concrete covers exhibited reinforcement breakage failure under both uniaxial tensile and high-stress repeated tensile test， whereas the specimens without concrete covers exhibited bond failure. After high-temperature exposure， the concrete protective layer enhanced the ultimate load and ductility of the sleeve grout connection under both loading conditions， but the ultimate load and ductility of specimens with a protective layer under high-stress repeated tensile loading were slightly lower than those under uniaxial tensile loading. Based on the experiments， a numerical model was established using the finite element software ABAQUS， with concrete protective layer thickness and fire exposure time as the parameters. Finite element results indicated that the thickness of the concrete protective layer and exposure time significantly affected the ultimate load and bond strength of the specimens. Both the ultimate load and bond strength increased with increasing protective layer thickness and decreased with prolonged exposure time. Based on the experimental and finite element analysis results， a calculation method for the ultimate bond stress of sleeve grouting connections， considering the combined effects of protective layer thickness and exposure time， was proposed.
Sleeve grouting connections are one of the primary connection methods for reinforcing steel in prefabricated concrete structures. To investigate the effect of concrete cover on the mechanical properties of sleeve grout connections after exposure to high temperatures from fire， 12 sleeve grout connection components with a 30 mm concrete cover and 12 specimens without a concrete cover were subjected to uniaxial tensile and high-stress repeated tensile tests after high temperatures exposure. The study explored the influence of the concrete cover on the failure mode， load-bearing capacity， and ductility of sleeve grout connection components under different loading conditions. The test results indicated that the concrete cover had a significant impact on the failure mode of sleeve grouting connections after exposure to high temperature. After 60 minutes of exposure， the specimens with concrete covers exhibited reinforcement breakage failure under both uniaxial tensile and high-stress repeated tensile test， whereas the specimens without concrete covers exhibited bond failure. After high-temperature exposure， the concrete protective layer enhanced the ultimate load and ductility of the sleeve grout connection under both loading conditions， but the ultimate load and ductility of specimens with a protective layer under high-stress repeated tensile loading were slightly lower than those under uniaxial tensile loading. Based on the experiments， a numerical model was established using the finite element software ABAQUS， with concrete protective layer thickness and fire exposure time as the parameters. Finite element results indicated that the thickness of the concrete protective layer and exposure time significantly affected the ultimate load and bond strength of the specimens. Both the ultimate load and bond strength increased with increasing protective layer thickness and decreased with prolonged exposure time. Based on the experimental and finite element analysis results， a calculation method for the ultimate bond stress of sleeve grouting connections， considering the combined effects of protective layer thickness and exposure time， was proposed.
2026, 56(2): 170-174.
doi: 10.3724/j.gyjzG25072403
Abstract:
To address the issues of excessive manual intervention， difficulty in posture adjustment， and low precision during the hoisting process of prefabricated building wall panels， a collaborative control method integrating intelligent hooks， self-balancing lifting beams， and machine vision is proposed. An intelligent hook coupling a magnetic adsorption positioning mechanism with a two-stage gear reduction mechanism is designed to achieve automatic hooking and unhooking of lifting rings. A self-balancing adjustable three-point lifting beam based on ball screws is developed， employing a posture sensor-PID closed-loop control strategy to enable continuous tilt angle adjustment within the range of 0.5° to 15°. A binocular vision-embedded fusion recognition system is constructed， utilizing a geometric contour matching algorithm to achieve 3D feature reconstruction of wall panels. Through 200 sample tests， the type recognition accuracy reached 98.2%. The system integrates LoRa wireless communication and a modular architecture. Engineering tests demonstrate that the entire hoisting process for typical wall panels is reduced to 62.4% of the time required by traditional methods， providing an efficient and highly reliable solution for automation in prefabricated building construction.
To address the issues of excessive manual intervention， difficulty in posture adjustment， and low precision during the hoisting process of prefabricated building wall panels， a collaborative control method integrating intelligent hooks， self-balancing lifting beams， and machine vision is proposed. An intelligent hook coupling a magnetic adsorption positioning mechanism with a two-stage gear reduction mechanism is designed to achieve automatic hooking and unhooking of lifting rings. A self-balancing adjustable three-point lifting beam based on ball screws is developed， employing a posture sensor-PID closed-loop control strategy to enable continuous tilt angle adjustment within the range of 0.5° to 15°. A binocular vision-embedded fusion recognition system is constructed， utilizing a geometric contour matching algorithm to achieve 3D feature reconstruction of wall panels. Through 200 sample tests， the type recognition accuracy reached 98.2%. The system integrates LoRa wireless communication and a modular architecture. Engineering tests demonstrate that the entire hoisting process for typical wall panels is reduced to 62.4% of the time required by traditional methods， providing an efficient and highly reliable solution for automation in prefabricated building construction.
2026, 56(2): 175-182.
doi: 10.3724/j.gyjzG25121707
Abstract:
A precast slab-assembled concrete utility tunnel connected by Ultra-High Performance Concrete （UHPC） consists of a base slab， sidewalls， and a roof slab， and the rebars protruding from the base slab are lap-spliced with the longitudinal reinforcement of the sidewall by UHPC. To study the mechanical properties of the precast slab-assembled concrete utility tunnel with UHPC connections， an overall model of the utility tunnel was established based on the commercial finite element software ABAQUS. A joint test of the utility tunnel was conducted to validate the model’s rationality. The failure modes， bearing capacity， and ductility of the specimens were in good agreement with the finite element calculation results. On this basis， a parametric finite element analysis was conducted， focusing on key parameters such as the axial compression ratio （0.05， 0.1， and 0.15） and the vertical location of the UHPC cast-in-place segment （at the base slab top surface， and 350 mm above it， and 500 mm above it）. The finite element analysis results showed that both precast and cast-in-place models failed due to sidewall flexure， with the bearing capacity of the precast model being 3% lower than that of the cast-in-place model. Compared to the utility tunnel with an axial compression ratio of 0， the bearing capacities of the models with axial compression ratios of 0.05， 0.1， and 0.15 increased by 11.6%， 15.4%， and 18.3%， respectively， while their ductility coefficients decreased by 2.4%， 5.4%， and 8.6%， respectively. The location of the UHPC cast-in-place segment had little effect on the overall bearing capacity and ductility of the utility tunnel structure. In general， the precast slab-assembled concrete utility tunnel with UHPC connections has good mechanical properties and shows broad prospects for engineering applications.
A precast slab-assembled concrete utility tunnel connected by Ultra-High Performance Concrete （UHPC） consists of a base slab， sidewalls， and a roof slab， and the rebars protruding from the base slab are lap-spliced with the longitudinal reinforcement of the sidewall by UHPC. To study the mechanical properties of the precast slab-assembled concrete utility tunnel with UHPC connections， an overall model of the utility tunnel was established based on the commercial finite element software ABAQUS. A joint test of the utility tunnel was conducted to validate the model’s rationality. The failure modes， bearing capacity， and ductility of the specimens were in good agreement with the finite element calculation results. On this basis， a parametric finite element analysis was conducted， focusing on key parameters such as the axial compression ratio （0.05， 0.1， and 0.15） and the vertical location of the UHPC cast-in-place segment （at the base slab top surface， and 350 mm above it， and 500 mm above it）. The finite element analysis results showed that both precast and cast-in-place models failed due to sidewall flexure， with the bearing capacity of the precast model being 3% lower than that of the cast-in-place model. Compared to the utility tunnel with an axial compression ratio of 0， the bearing capacities of the models with axial compression ratios of 0.05， 0.1， and 0.15 increased by 11.6%， 15.4%， and 18.3%， respectively， while their ductility coefficients decreased by 2.4%， 5.4%， and 8.6%， respectively. The location of the UHPC cast-in-place segment had little effect on the overall bearing capacity and ductility of the utility tunnel structure. In general， the precast slab-assembled concrete utility tunnel with UHPC connections has good mechanical properties and shows broad prospects for engineering applications.
2026, 56(2): 183-189.
doi: 10.3724/j.gyjzG26012504
Abstract:
The composite slab-assembled utility tunnel with bottom-slab protruding rebars consists of double-sided composite sidewalls， a single-sided composite roof slab， and a cast-in-place bottom slab. The sidewalls are connected to the bottom slab by reserved L-shaped protruding rebars. This type of utility tunnel has advantages such as good waterproof performance， fast construction speed， and good structural integrity. Based on the finite element analysis software ABAQUS， a finite element model of the composite slab-assembled utility tunnel with bottom-slab protruding rebars was established. To verify the accuracy of the model， a full-process loading test of a single-cell utility tunnel was carried out. The failure modes， peak bearing capacity， and lateral deformation obtained from the test were in good agreement with the finite element analysis results. On this basis， nonlinear mechanical analysis of the composite slab-assembled concrete double-cell utility tunnel with bottom-slab protruding rebars was conducted， focusing on the effects of haunch height （0 mm， 150 mm， 200 mm， and 250 mm） and axial compression ratio （0 to 0.1） on the structural performance. The results showed that the tunnel mainly exhibited flexural failure. Plastic hinges first formed at both ends of the inner sidewalls， then at both ends of the roof and bottom slabs， and finally at the joints between the outer sidewalls and the bottom slab. Increasing the haunch height significantly improved the peak bearing capacity， but reduced the ductility to some extent. The axial compression ratio had no significant effect on the peak bearing capacity， but led to a reduction in ductility. Overall， the composite slab-assembled concrete double-cell utility tunnel with bottom-slab protruding rebars showed good mechanical properties.
The composite slab-assembled utility tunnel with bottom-slab protruding rebars consists of double-sided composite sidewalls， a single-sided composite roof slab， and a cast-in-place bottom slab. The sidewalls are connected to the bottom slab by reserved L-shaped protruding rebars. This type of utility tunnel has advantages such as good waterproof performance， fast construction speed， and good structural integrity. Based on the finite element analysis software ABAQUS， a finite element model of the composite slab-assembled utility tunnel with bottom-slab protruding rebars was established. To verify the accuracy of the model， a full-process loading test of a single-cell utility tunnel was carried out. The failure modes， peak bearing capacity， and lateral deformation obtained from the test were in good agreement with the finite element analysis results. On this basis， nonlinear mechanical analysis of the composite slab-assembled concrete double-cell utility tunnel with bottom-slab protruding rebars was conducted， focusing on the effects of haunch height （0 mm， 150 mm， 200 mm， and 250 mm） and axial compression ratio （0 to 0.1） on the structural performance. The results showed that the tunnel mainly exhibited flexural failure. Plastic hinges first formed at both ends of the inner sidewalls， then at both ends of the roof and bottom slabs， and finally at the joints between the outer sidewalls and the bottom slab. Increasing the haunch height significantly improved the peak bearing capacity， but reduced the ductility to some extent. The axial compression ratio had no significant effect on the peak bearing capacity， but led to a reduction in ductility. Overall， the composite slab-assembled concrete double-cell utility tunnel with bottom-slab protruding rebars showed good mechanical properties.
2026, 56(2): 190-197.
doi: 10.3724/j.gyjzG26012704
Abstract:
The upper and lower prefabricated U-shaped components are connected by prestressed tendons at the construction site to form a prefabricated U-shaped assembled utility tunnel. This type of tunnel offers convenient transportation and installation， a short construction period， and minimal environmental impact. A finite element model of the U-shaped assembled utility tunnel was established using the commercial software ABAQUS， and its validity was verified through a circumferential loading test on a single-chamber U-shaped assembled utility tunnel conducted in an earlier study. Based on this model， a nonlinear analysis of the entire loading process of a double-chamber utility tunnel under circumferential loading （simulating earth pressure and top overload） was carried out. The parameters investigated included： utility tunnel type （cast-in-place vs. prefabricated）， lateral earth pressure coefficient （0.55， 0.65， and 0.75）， and effective prestress of the prestressed tendons （400， 500， and 600 MPa）. The finite element analysis showed that， unlike cast-in-place utility tunnels， plastic hinges in prefabricated tunnels first appeared at the mid-span of the top and bottom slabs， then at the junctions between the slabs and the middle wall， and finally at the joints of the side walls， leading to structural failure. The bearing capacity and ductility of prefabricated tunnels were higher than those of cast-in-place tunnels （by 2% and 33%， respectively）. Compared to the tunnel with a lateral earth pressure coefficient of 0.55， the bearing capacity of tunnels with coefficients of 0.65 and 0.75 increased by 6.4% and 11.75%， respectively， while ductility decreased by 2.3% and 18.6%. The effective prestress level of the prestressed tendons had little effect on the bearing capacity and ductility of the tunnel. Overall， the double-chamber prefabricated U-shaped assembled utility tunnel has high bearing capacity and good ductility， offering broad prospects for engineering applications.
The upper and lower prefabricated U-shaped components are connected by prestressed tendons at the construction site to form a prefabricated U-shaped assembled utility tunnel. This type of tunnel offers convenient transportation and installation， a short construction period， and minimal environmental impact. A finite element model of the U-shaped assembled utility tunnel was established using the commercial software ABAQUS， and its validity was verified through a circumferential loading test on a single-chamber U-shaped assembled utility tunnel conducted in an earlier study. Based on this model， a nonlinear analysis of the entire loading process of a double-chamber utility tunnel under circumferential loading （simulating earth pressure and top overload） was carried out. The parameters investigated included： utility tunnel type （cast-in-place vs. prefabricated）， lateral earth pressure coefficient （0.55， 0.65， and 0.75）， and effective prestress of the prestressed tendons （400， 500， and 600 MPa）. The finite element analysis showed that， unlike cast-in-place utility tunnels， plastic hinges in prefabricated tunnels first appeared at the mid-span of the top and bottom slabs， then at the junctions between the slabs and the middle wall， and finally at the joints of the side walls， leading to structural failure. The bearing capacity and ductility of prefabricated tunnels were higher than those of cast-in-place tunnels （by 2% and 33%， respectively）. Compared to the tunnel with a lateral earth pressure coefficient of 0.55， the bearing capacity of tunnels with coefficients of 0.65 and 0.75 increased by 6.4% and 11.75%， respectively， while ductility decreased by 2.3% and 18.6%. The effective prestress level of the prestressed tendons had little effect on the bearing capacity and ductility of the tunnel. Overall， the double-chamber prefabricated U-shaped assembled utility tunnel has high bearing capacity and good ductility， offering broad prospects for engineering applications.
2026, 56(2): 198-207.
doi: 10.3724/j.gyjzG26012808
Abstract:
Nuclear Power Plants （NPPs） are typically characterized by concrete structures with thick walls and thick slabs. Their shear wall-slab joints are generally regarded as fixed supports， which are the key components affecting the mechanical properties and failure modes of the overall structure. Cast-in-situ concrete slabs are currently the predominant floor systems adopted in such structures； however， they suffer from drawbacks including great demand for formwork and propping， prolonged construction periods， and high energy consumption. Applying the formwork-free and minimal-propping concrete composite slab technology to wall-slab joints can effectively overcome these limitations. This study proposed a concrete shear wall-concrete composite slab joint with slab-end hooked projecting reinforcement anchorage for nuclear power plant structures. Based on an ABAQUS three-dimensional solid finite element model validated against seismic test results of the joint， the effects of concrete strength （C40， C50， and C60） and slab reinforcement ratio （0.45%， 0.58%， and 0.71%） on the seismic performance of the joint were systematically analyzed. The results indicated that all models failed in a flexural mode at the slab ends. Concrete strength had a negligible effect on joint bearing capacity， with differences of less than 2%. However， increasing concrete strength led to higher initial stiffness and reduced ductility. Compared with joints using C40 concrete， those with C50 and C60 concrete exhibited increases in forward （reverse） initial stiffness of 10.92% （6.89%） and 20.30% （11.87%）， respectively， while the forward （reverse） ductility coefficients decreased by 6.28% （2.45%） and 17.93% （14.08%）， respectively. Increasing the slab reinforcement ratio enhanced the bearing capacity and initial stiffness but reduced ductility. Compared with joints having a reinforcement ratio of 0.45%， those with ratios of 0.58% and 0.71% showed increases in forward （reverse） bearing capacity of 15.97% （23.58%） and 30.79% （34.69%）， respectively； increases in initial stiffness of 17.22% （7.48%） and 31.55% （19.34%）， respectively； and decreases in ductility coefficients of 16.45% （20.37%） and 19.59% （29.79%）， respectively. For all parameter cases， the bearing capacity of the precast joint differed from the theoretical value of the cast-in-situ joint by less than 10%， and all ductility coefficients exceeded 5. These results indicate that shear wall-concrete composite slab joints anchored by slab-end projecting reinforcement can achieve reliable fixed connections and exhibit satisfactory seismic performance.
Nuclear Power Plants （NPPs） are typically characterized by concrete structures with thick walls and thick slabs. Their shear wall-slab joints are generally regarded as fixed supports， which are the key components affecting the mechanical properties and failure modes of the overall structure. Cast-in-situ concrete slabs are currently the predominant floor systems adopted in such structures； however， they suffer from drawbacks including great demand for formwork and propping， prolonged construction periods， and high energy consumption. Applying the formwork-free and minimal-propping concrete composite slab technology to wall-slab joints can effectively overcome these limitations. This study proposed a concrete shear wall-concrete composite slab joint with slab-end hooked projecting reinforcement anchorage for nuclear power plant structures. Based on an ABAQUS three-dimensional solid finite element model validated against seismic test results of the joint， the effects of concrete strength （C40， C50， and C60） and slab reinforcement ratio （0.45%， 0.58%， and 0.71%） on the seismic performance of the joint were systematically analyzed. The results indicated that all models failed in a flexural mode at the slab ends. Concrete strength had a negligible effect on joint bearing capacity， with differences of less than 2%. However， increasing concrete strength led to higher initial stiffness and reduced ductility. Compared with joints using C40 concrete， those with C50 and C60 concrete exhibited increases in forward （reverse） initial stiffness of 10.92% （6.89%） and 20.30% （11.87%）， respectively， while the forward （reverse） ductility coefficients decreased by 6.28% （2.45%） and 17.93% （14.08%）， respectively. Increasing the slab reinforcement ratio enhanced the bearing capacity and initial stiffness but reduced ductility. Compared with joints having a reinforcement ratio of 0.45%， those with ratios of 0.58% and 0.71% showed increases in forward （reverse） bearing capacity of 15.97% （23.58%） and 30.79% （34.69%）， respectively； increases in initial stiffness of 17.22% （7.48%） and 31.55% （19.34%）， respectively； and decreases in ductility coefficients of 16.45% （20.37%） and 19.59% （29.79%）， respectively. For all parameter cases， the bearing capacity of the precast joint differed from the theoretical value of the cast-in-situ joint by less than 10%， and all ductility coefficients exceeded 5. These results indicate that shear wall-concrete composite slab joints anchored by slab-end projecting reinforcement can achieve reliable fixed connections and exhibit satisfactory seismic performance.
2026, 56(2): 208-214.
doi: 10.3724/j.gyjzG25091002
Abstract:
A prefabricated steel-reinforced concrete structure for column-free underground metro stations was proposed. The seismic performance of the bottom joints of outer walls was studied by quasi-static loading tests on three 1/3-scale specimens， including one specimen with concrete solid sidewalls， one specimen with concrete composite sidewalls， and one cast-in-place specimen. The results showed that the bottom joints of the prefabricated steel-reinforced concrete outer walls with solid sidewall and composite sidewall configurations all exhibited excellent structural integrity， with their bearing capacities close to that of the cast-in-place specimen. The ductility coefficients of the specimens with solid concrete sidewalls and composite concrete sidewalls were 3.1 and 3.0， respectively， which were 7.0% and 3.4% higher than those of the corresponding cast-in-place specimen.The energy dissipation capacity and stiffness degradation characteristics of the two prefabricated steel-reinforced concrete specimens were similar to those of the cast-in-place specimen.
A prefabricated steel-reinforced concrete structure for column-free underground metro stations was proposed. The seismic performance of the bottom joints of outer walls was studied by quasi-static loading tests on three 1/3-scale specimens， including one specimen with concrete solid sidewalls， one specimen with concrete composite sidewalls， and one cast-in-place specimen. The results showed that the bottom joints of the prefabricated steel-reinforced concrete outer walls with solid sidewall and composite sidewall configurations all exhibited excellent structural integrity， with their bearing capacities close to that of the cast-in-place specimen. The ductility coefficients of the specimens with solid concrete sidewalls and composite concrete sidewalls were 3.1 and 3.0， respectively， which were 7.0% and 3.4% higher than those of the corresponding cast-in-place specimen.The energy dissipation capacity and stiffness degradation characteristics of the two prefabricated steel-reinforced concrete specimens were similar to those of the cast-in-place specimen.
2026, 56(2): 215-223.
doi: 10.3724/j.gyjzG26020904
Abstract:
Nuclear power plant buildings commonly adopt wall-slab structural systems composed of shear walls and floor slabs， which are typically constructed using the cast-in-place open-top method， resulting in long construction periods. Moreover， wall-slab joints are characterized by large-diameter and densely arranged reinforcement， making it difficult to control the quality of concrete casting. To address these issues， a joint connecting cast-in-place shear walls and precast slabs using ultra-high-performance concrete （UHPC） is proposed. Based on previous seismic tests， a nonlinear finite element model of the joint was established in ABAQUS and validated against experimental results， with bearing capacity discrepancies of less than 5%. A parametric finite element study was then conducted to examine the effects of axial compression ratio （0.1， 0.2， 0.3） and precast slab reinforcement ratio （0.75%， 0.95%， 1.15%） on the failure mode， ultimate bearing capacity， and initial stiffness. All joint models exhibited flexural failure at the slab ends. Increasing the axial compression ratio enhanced the ultimate bearing capacity， while its influence on initial stiffness was negligible （<1%）. When the precast slab reinforcement ratio was 0.95%， increasing the axial compression ratio from 0.1 to 0.2 and 0.3 increased the ultimate bearing capacity by 6.53% and 16.34%， respectively. At an axial compression ratio of 0.2， increasing the precast slab reinforcement ratio from 0.75% to 0.95% and 1.15% increased the ultimate bearing capacity by 5.81% and 15.15%， and the initial stiffness by 2.69% and 5.61%， respectively. Overall， the initial stiffness varied slightly， and the simulated bearing capacity differed from the theoretical values for cast-in-place joints by less than 15%， indicating favorable mechanical properties.
Nuclear power plant buildings commonly adopt wall-slab structural systems composed of shear walls and floor slabs， which are typically constructed using the cast-in-place open-top method， resulting in long construction periods. Moreover， wall-slab joints are characterized by large-diameter and densely arranged reinforcement， making it difficult to control the quality of concrete casting. To address these issues， a joint connecting cast-in-place shear walls and precast slabs using ultra-high-performance concrete （UHPC） is proposed. Based on previous seismic tests， a nonlinear finite element model of the joint was established in ABAQUS and validated against experimental results， with bearing capacity discrepancies of less than 5%. A parametric finite element study was then conducted to examine the effects of axial compression ratio （0.1， 0.2， 0.3） and precast slab reinforcement ratio （0.75%， 0.95%， 1.15%） on the failure mode， ultimate bearing capacity， and initial stiffness. All joint models exhibited flexural failure at the slab ends. Increasing the axial compression ratio enhanced the ultimate bearing capacity， while its influence on initial stiffness was negligible （<1%）. When the precast slab reinforcement ratio was 0.95%， increasing the axial compression ratio from 0.1 to 0.2 and 0.3 increased the ultimate bearing capacity by 6.53% and 16.34%， respectively. At an axial compression ratio of 0.2， increasing the precast slab reinforcement ratio from 0.75% to 0.95% and 1.15% increased the ultimate bearing capacity by 5.81% and 15.15%， and the initial stiffness by 2.69% and 5.61%， respectively. Overall， the initial stiffness varied slightly， and the simulated bearing capacity differed from the theoretical values for cast-in-place joints by less than 15%， indicating favorable mechanical properties.
2026, 56(2): 224-233.
doi: 10.3724/j.gyjzG25112703
Abstract:
This paper proposes a staggered longitudinal reinforcement configuration suitable for UHPC post-cast precast joints， which significantly improves assembly tolerance during construction. The hysteretic performance， stiffness degradation， and energy dissipation capacity of the joints were evaluated through quasi-static loading tests and finite element simulations on four full-scale specimens. Parametric studies isolated key variables， overcoming the limitation of concurrent changes in tests and allowing targeted evaluation. The results indicated that the proposed joint configuration maintained a peak bearing capacity comparable to that of the specimen RC-A-2， with slight improvements in cumulative energy dissipation and ductility. All specimens exhibited a flexural failure mode at the beam ends， in accordance with the “strong joint-weak component” principle. Furthermore， tests demonstrated that the larger-diameter longitudinal rebar scheme substantially reduced the number of rebars and increased rebar spacing in the joint zone while maintaining essentially equivalent bearing capacity. This effectively reduced the risk of rebar collision during assembly， thereby showing potential for improving construction efficiency. The numerical analysis results showed good agreement with the experimental data， validating the model. This confirmed that the UHPC post-cast precast joint exhibits superior seismic performance and shear resistance compared to joints with conventional cast-in-place materials.
This paper proposes a staggered longitudinal reinforcement configuration suitable for UHPC post-cast precast joints， which significantly improves assembly tolerance during construction. The hysteretic performance， stiffness degradation， and energy dissipation capacity of the joints were evaluated through quasi-static loading tests and finite element simulations on four full-scale specimens. Parametric studies isolated key variables， overcoming the limitation of concurrent changes in tests and allowing targeted evaluation. The results indicated that the proposed joint configuration maintained a peak bearing capacity comparable to that of the specimen RC-A-2， with slight improvements in cumulative energy dissipation and ductility. All specimens exhibited a flexural failure mode at the beam ends， in accordance with the “strong joint-weak component” principle. Furthermore， tests demonstrated that the larger-diameter longitudinal rebar scheme substantially reduced the number of rebars and increased rebar spacing in the joint zone while maintaining essentially equivalent bearing capacity. This effectively reduced the risk of rebar collision during assembly， thereby showing potential for improving construction efficiency. The numerical analysis results showed good agreement with the experimental data， validating the model. This confirmed that the UHPC post-cast precast joint exhibits superior seismic performance and shear resistance compared to joints with conventional cast-in-place materials.
