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2025 Vol. 25, No. 5

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Cover and Contents of Vol.25, No.5, 2025
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Special Column on Innovations and Challenges in Road Infrastructure for Climate Resilience and Sustainable Development
Population-based structural health monitoring of bridges: Review and challenges
YU Zhong-ru, SHAN De-shan, SUN Rong-hui
Abstract: To solve the practical challenges faced in bridge structural health monitoring (BSHM), such as data scarcity, label deficiency, large operational environment variations, and high monitoring computational costs, the framework of population-based structural health monitoring (PBSHM) was systematically reviewed and summarized. A brief overview of the fundamental concepts of PBSHM was provided by thoroughly analyzing relevant studies reported in recent years. The definitions of different structural population types, including homogeneous populations and heterogeneous populations, were elaborated on from three perspectives: geometry, material, and topology. Key issues that PBSHM aims to solve were also summarized. Research status in the field of PBSHM was reviewed and analyzed in detail from two aspects: structural similarity measurement, and knowledge transfer methods and applications under different population types. Specific application scenarios and solution approaches under this framework were summarized, and the functions and connections of different technical methods were analyzed. In light of the practical engineering problems faced in the field of BSHM, the challenges and potential solutions for PBSHM of bridges were discussed. Review results indicate that structural populations form the basis of the PBSHM framework. Utilizing indicators of structural mechanical behavior similarity and data distribution similarity can effectively determine the knowledge transferability among bridge population members. Explicit transfer methods show good performance in anomaly monitoring and feature alignment for bridge structural populations, while implicit transfer methods based on deep neural network models exhibit stronger adaptability, which can automatically extract more representative features, meeting the end-to-end requirements in practical BSHM applications. Based on leveraging knowledge transfer technology, the PBSHM framework shows great potential in addressing issues such as differences in complex operational conditions, data imbalance impacts, damage identification, data prediction and generation, feature alignment, and normalization in bridge structural health monitoring tasks.More>
2025, 25(5): 1-22. doi: 10.19818/j.cnki.1671-1637.2025.05.001
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Review on road infrastructure carbon emission accounting and low-carbon reduction technologies based on LCA
RAN Mao-ping, DENG Xu-hong, GUAN Jia-xi, XIAO Shen-qing, JIANG Rui-qie, ZHOU Xing-lin
Abstract: To clarify the application of life cycle assessment (LCA) in carbon emission accounting methods for road infrastructure and the development status of existing emission reduction technologies, the current research hotspots on carbon emissions from road transportation systems were identified through quantitative analysis of existing literature. The carbon emission accounting analysis framework for road infrastructure LCA was summarized, and the characteristics of carbon emission accounting methods and evaluation tools for different types of LCA were comparatively analyzed. According to the five life stages, i.e., raw material acquisition, construction, operation and use, maintenance and repair, and scrapping and recycling, the carbon emission contribution levels, influencing factors, and main emission reduction measures of road infrastructure at each stage were summarized respectively. The research results show that during the entire life cycle of road infrastructure, the material production and use stages contribute the most to carbon emissions. The main factors affecting carbon emissions during the stages of material production, construction, use, and maintenance are derived from materials and their production and processing plans, road surface types and structures, construction machinery, vehicle emissions, maintenance techniques, and the resulting traffic delays. Correspondingly, the primary emission reduction measures throughout the entire life cycle of road infrastructure include optimizing material production processes, using clean production technologies and recycling materials, shortening material transportation distances, and selecting environmentally friendly restoration technologies. Some future studies, such as establishing on-site accounting databases, building standardized carbon accounting system frameworks, and developing standardized evaluation methods, could be carried out for road infrastructure LCA, to provide technical support for the low-carbon and sustainable development of road infrastructure.More>
2025, 25(5): 23-37. doi: 10.19818/j.cnki.1671-1637.2025.05.002
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Analysis of subgrade deformation driving factors and climate resilience for highway in the Qinghai-Xizang Plateau permafrost region
QUAN Lei, TIAN Bo, LI Si-li, LI Li-hui, ZHANG Pan-pan, YOU Shuo-sen, PENG Zhi-xin, FU Min-yi
Abstract: To identify the main driving factors of deformation for inservice highway subgrades in the permafrost region of the Qinghai-Xizang Plateau and their adaptability to climate change, three inservice highways crossing the two major engineering corridors — Golmud to Nagqu and Gonghe to Yushu in the permafrost region of the Qinghai-Xizang Plateau were selected. The spatial correlations between indicators of subgrade deformation and a range of factors, including climate environment parameters, traffic loading differences, inherent parameters of subgrade engineering, and parameters of the site where the subgrade engineering was located were examined. The concept of climate resilience for highway subgrades in the permafrost region of the Qinghai-Xizang Plateau was proposed. Analysis results show that elevation and maximum frozen depth, as well as vegetation coverage and annual cumulative precipitation, are the predominant driving factors influencing the variation of the international roughness index and bumpiness index, with absolute correlation coefficients exceeding 0.4, significantly distinguishing them from other factors. In the seasonal frozen zone, regardless of the annual cumulative precipitation, the road quality index (RQI) remains above good level. In the permafrost zone, when the annual cumulative precipitation is in the range of 220-370 mm, the RQI is mostly poor. However, when the annual cumulative precipitation exceeds 370 mm, the main driving factors of subgrade deformation are the ice content of permafrost, groundwater, soil type, and the jump-like distribution of roadside accumulated water erosion along the route. Furthermore, the heat accumulation effect caused by annual precipitation exceeding 370 mm and roadside water accumulation leads to the alternating development of thaw zones and permafrost islands, which is the main reason for the lack of clear strong correlation with the driving factors in this region. The subgrade overall follows the long-cycle subsidence and seasonal frost heave-thaw collapse of the natural terrain, and the use of subgrades with special structures can slow down the subsidence rate, while pile-raft foundation can effectively terminate the subsidence trend. It is recommended to enhance the structural resilience of the pavement-subgrade-foundation system and reduce the adverse impact of climate environment on site parameters to improve the climate resilience of highway subgrades in permafrost regions. This study provides theoretical guidance and practical reference for the maintenance and renovation of highway engineering in this region.More>
2025, 25(5): 38-52. doi: 10.19818/j.cnki.1671-1637.2025.05.003
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Preparation of self-leveling epoxy asphalt concrete and its rheological properties during mixing and paving periods
LIU Gang, QIAN Zhen-dong, CHEN Lei-lei, LU Guo-yang, NG Shiu Tong Thomas
Abstract:

To meet the precast assembly and service performance demands of bridge deck asphalt pavements (BDAP), the balance design method and development procedures of self-leveling epoxy asphalt concrete (SLEA) were proposed based on guss asphalt concrete and epoxy asphalt concrete. The effects of different gradations and asphalt-aggregate ratios on the flowability and mechanical strength of SLEA were investigated. The rheological properties of SLEA during the mixing and paving periods were analyzed. Based on Bingham's plastic fluid mechanics properties, the generalized mixing viscosity of SLEA was defined. Considering aggregate morphological features including needle flake index, fractal dimension, as well as gradation composition characteristics including shape parameters and scale parameters, a prediction model for the rheological properties of SLEA during mixing and paving periods was built. Research results show that the flowability (at 200 ℃) of fine, medium, and coarse-graded SLEA10 is 15, 25, and 32 s, respectively, while the penetration (at 60 ℃) reaches 245, 233, and 228 (0.01 mm). All values exceed the specification requirements, demonstrating excellent flowability and mechanical strength to meet precast assembly and service performance demands. Gradation significantly influences SLEA10 flowability but has relatively small influences on its strength. The flowability mainly depends on the gradation fineness and aggregate characteristics, while the strength after molding mainly depends on the consolidation of epoxy asphalt, with gradation fineness playing a minor role. The established prediction model of generalized mixing viscosity achieves an determination coefficient of 0.94 between measured values and fitted values, demonstrating its effectiveness in predicting rheological properties. Based on the analysis results, it is recommended to choose the aggregates with regular size, low surface roughness, and finer gradation to realize the self-leveling and compaction-free function.

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2025, 25(5): 53-64. doi: 10.19818/j.cnki.1671-1637.2025.05.005
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Optimization of carbon emission reduction technology for asphalt mixture production enterprises under carbon cap-and-trade policy
LI Song, NIU Zi-heng, BAO Bin-shuo, HAO Ting-ting, SI Chun-di
Abstract: The purpose of this study is to effectively enhance the carbon emission reduction enthusiasm of highway construction enterprises in asphalt pavement construction projects. Carbon emissions during the construction phase of the asphalt surface were focused on. A quantitative analysis was conducted across various stages. The raw material production stage and the aggregate heating process within the asphalt mixture production stage were determined as the critical links influencing carbon emissions during the construction phase of the asphalt surface. From the research perspective of asphalt mixture production enterprises responsible for these key links, two carbon emission reduction technologies, namely solid waste utilization and warm-mix technology, were specifically selected. A profit model for asphalt mixture production enterprises was constructed under the carbon cap-and-trade policy framework. The key control indicators of different carbon emission reduction technologies were optimized based on this model. Research results show that whether solid waste utilization or warm-mix technology is adopted, asphalt mixture production enterprises can achieve profit potential only when the carbon quota set by the government exceeds the minimum carbon emission reduction achievable through the implementation of carbon emission reduction technologies. Moreover, when the carbon quota is between the minimum and maximum carbon emissions corresponding to the implementation of carbon emission reduction technologies, asphalt mixture production enterprises need to control the solid waste content or aggregate heating temperature within a reasonable threshold based on the different characteristics of the solid waste utilization and warm-mix technology. It ensures that the enterprises achieve profitability, and achieves the optimization of key control indicators for both solid waste utilization and warm-mix technology. The research conclusions provide strong theoretical support for the scientific selection and application of carbon emission reduction technologies by asphalt mixture production enterprises.More>
2025, 25(5): 65-81. doi: 10.19818/j.cnki.1671-1637.2025.05.006
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Influence of LCA allocation methods on the life cycle carbon emission from roads and uncertainty analysis
QIAO Ya-ning, WEN Xia, GAO Yang-ming, HE Liang
Abstract:

To analyze the effect of allocation method selection on the life cycle carbon emissions of roads, two common allocation methods (50/50 and Cut-off) were selected to quantify and compare the life cycle carbon emissions of roads. According to a single-factor sensitivity analysis, the influence of different parameters on the carbon emission comparison was evaluated to identify critical parameters affecting the comparison between the two allocation methods. Additionally, the probability density distribution functions of the parameters were introduced to quantify the parameter uncertainty of the model in comparison, and the Monte Carlo simulation method was used to propagate the parameter uncertainty to the results. Analysis results show that the carbon emission ratio of the 50/50 to the Cut-off allocation method is approximately 1.022 (no milling and resurfacing), 1.024 (one milling and resurfacing), 1.025 (two millings and resurfacings), and 1.026 (three millings and resurfacings), respectively. After the uncertainty analysis, the ratio decreases to 1.020, 1.021, 1.023, and 1.023, respectively. Since the difference between the 50/50 and Cut-off allocation methods is narrowed, the allocation method selection does not significantly influence the calculation of life cycle carbon emissions of roads. Moreover, despite different milling and resurfacing times, when the few calculation parameters change by 1%, the ratio of the rate of change in the carbon emission ratio to that in the calculation parameter exceeds 0.012. The density of the base and subbase, N2O emissions from diesel production, and the recycling rate of reclaimed pavement materials are critical parameters having an influence on the comparison of life cycle carbon emissions of roads between the 50/50 and the Cut-off allocation methods. The argumentation of allocation method selection in road life cycle assessment and the uncertainty analysis framework in this study can improve the method for calculating life cycle carbon emissions of roads and reduce the uncertainty in the calculations.

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2025, 25(5): 82-95. doi: 10.19818/j.cnki.1671-1637.2025.05.007
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Surface structural characteristics of heat-reflective cooling pavement and their influence on optical and thermal performance
LI Hui, ZHANG Xue, LYU Xing-guo, JIA Ming
Abstract: To study the influence of pavement surface structural characteristics on the optical reflection and cooling effect of heat-reflective cooling coatings in practical applications and provide a reference for the design of heat-reflective cooling asphalt pavement materials to alleviate the urban heat island effect. The orthogonal design method was used to set nine representative gradations, and white, gray, and black heat-reflective coatings with a wide reflectance coverage range were prepared and optimized. Experimental methods including laser texture scanning, digital image processing of surface voids, reflection spectrum testing, and cooling effect tests based on laboratory solar radiation simulation were used to obtain the macro and micro morphology and optical and thermal performance indicators of the pavement, respectively, and then the correlation and significance analysis were conducted. Research results indicate that by taking into account the full-spectrum reflectance of the coatings and anti-glare visual safety, the optimal gradation type is the dense-graded fine-grained asphalt concrete with a maximum nominal particle size of 5 mm. The vertical texture of the heat-reflective pavement surface (especially the arithmetical mean deviation of the profile) has a more significant impact on the reflectance compared with the horizontal distribution and spatial morphology, with a correlation coefficient of 0.9. In order to reduce the influence of road surface texture on reflective cooling performance, it is recommended to control the vertical texture evaluation parameter, namely arithmetical mean deviation of the pavement surface after coating, within 0.2 mm and the root mean square deviation to be less than 0.4 mm. Under the optimal gradation conditions, the cooling effects of white, gray, and black heat-reflective cooling pavements can reach 14.0 ℃, 10.6 ℃, and 7.3 ℃, respectively. As the surface void ratio increases, the total reflectance of the heat-reflective pavement decreases linearly, and the reduction rate of the cooling effect is 13% - 21%. This factor can be considered when designing heat-reflective coatings based on specific application scenarios such as urban roads, parking lots, and sidewalks. The proposed influence law of surface structural characteristics of heat-reflective cooling pavements on their optical and thermal performance can serve as a theoretical basis for the precise design and performance improvement of heat-reflective cooling pavement materials.More>
2025, 25(5): 96-116. doi: 10.19818/j.cnki.1671-1637.2025.05.008
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Causes of arch expansion and anti-arching design method for cement-stablized base layer in arid desert regions of northwest China
JI Xiao-ping, ZHU Shi-yu, LIU Jie, YUAN Teng, MA Jian-yong, WU Tong-da, PU Chao
Abstract: To address the severe arch expansion that has emerged in recent years in cement-stablized base layers in the arid desert regions of northwest China, passive prevention measures were conventionally applied. With the cement-stablized base layers exhibiting arch expansion in multiple sections of Xinjiang as research objects, by combining field investigations, laboratory tests, and theoretical analysis, core samples from both arched and non-arched sections of the base and subgrade were drilled to test their physicochemical properties, mechanical strength, microscopic morphology, and phase composition. Controlled laboratory expansion tests under multiple factors were conducted, and the anti-arching effect was verified through water-heat-salt multi-field coupling tests on optimized materials and structures to systematically elucidate the multi-field coupling disaster mechanism of arching in cement-stablized base layers. Accordingly, a set of integrated optimization design methods for materials and structures was proposed for active prevention. Research results indicates that the arch expansion in cement-stablized base layers in the northwestern saline soil regions is triggered by the coupled effects of "water-heat-salt" factors. The fundamental mechanism lies in the chemical reaction between sulfate ions (with contents 1.5-3.6 times the limit specified in the Technical Guidelines for Construction of Highway Roadbases (JTG/T F20—2015)) and cement hydration products, generating expansive substances such as ettringite and gypsum. This leads to an average reduction of 59.74% in the compressive strength of the base layers, while high temperatures significantly accelerate salt migration and reaction processes. The active prevention and control method centered on "salt control, temperature reduction, cement reduction, and structural adjustment" indicates that material optimization is the key. Using large-grade (37.5 mm) and extra-large-grade (53 mm) base layers with low cement content reduces expansion deformation by 12.12% and 27.27%, respectively. The installation of a graded crushed stone insulation layer reduces the expansion strain at the top of the base layer by approximately 83%. A graded gravel interception layer effectively blocks capillary water-salt migration and reduces salt enrichment concentration from 5.1% to 3.9%. For generally low-salt, extremely high temperature, medium-to-high saline soil, and high-salt-high-temperature composite regions, the combinations of anti-arching base layer, anti-arching base layer + insulation layer, interception layer + anti-arching base layer, and insulation layer + anti-arching base layer + interception layer are recommended, respectively. This achieves targeted, zonal, and categorized prevention and control from mechanism to practice.More>
2025, 25(5): 117-130. doi: 10.19818/j.cnki.1671-1637.2025.05.009
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Water and salt migration and erosion characteristics of gravel sulfate salty soil subgrade under effect of pavement covering
ZHANG Sha-sha, CAO Ju-yuan, ZHANG Yi, YANG Xiao-hua, HAN Jin-bao, ZHAO Yan-hu, HU Chao
Abstract: To clarify the water and salt migration characteristics of sulfate-containing gravel mix under the effect of airport pavement covering in the seasonal frozen area of Western China and to identify the erosion hazards at the bottom of the subgrade due to water and salt migration, based on the reconstruction and expansion project of an airport in Northwest China, independently-designed experimental equipment was used to conduct experiments on the water and salt migration and deformation of models with different combinations of salt content in upper and lower parts of the subgrade under the effect of pavement covering and the working condition of freeze-thaw cycles in the temperature range of —30 ℃ - 25 ℃ for the first time. The pavement bottom erosion characteristics under the joint action of freeze-thaw cycles and water and salt migration were analyzed by a scanning electron microscope and an X-ray diffractometer. Experimental results show that the change in water content is 0.37% between working conditions when the salt content in the upper part of the subgrade increases from 0 to 0.3%, which is an increase of 83.8% compared with the situation when the salt content in the lower part of the subgrade increases from 0.3% to 0.7%. During the nine freeze-thaw cycles, the salt content of the gravel mix in each working condition changes significantly within the range of 35 cm below the subgrade, and the migration of the salts upward in the range is greater than the replenishment of the salts migrating from the lower part. When the salt content of the upper part of the salt-containing gravel mix subgrade increases from 0 to 0.3%, the final cumulative deformation of the sample increases by 47.8%, whereas when the salt content of the lower part of the subgrade increases from 0.3% to 0.7%, the final cumulative deformation of the sample increases by only 7.4%. In the prediction model of cumulative deformation of a salt-containing gravel mix subgrade under conditions of varying salt content and cycle time, salt content in the upper part of the subgrade is the dominant factor driving deformation of the sulfate-containing gravel mix subgrade. Under the coupling effect of the water-salt phase change and sulfate erosion, when the salt content of the lower part of the subgrade increases from 0.3% to 0.7%, the salts fail to be replenished to the bottom of the subgrade to maintain the high alkaline environment required for the stability of ettringite. Instead, the amount of ettringite on the bottom surface of the subgrade decreases. The research results provide basic data for revealing the water and salt migration of sulfate-containing gravel mix subgrade under the effect of pavement covering and its erosion law on cement base in the seasonal frozen area.More>
2025, 25(5): 131-144. doi: 10.19818/j.cnki.1671-1637.2025.05.010
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Resilient and accumulative plastic deformation characteristics of subgrade lateritic soil under different loading modes and moisture content
HUANG Xuan-jia, LIU Wei-zheng, CHEN Zhao-feng
Abstract: To investigate the resilient and accumulative plastic deformation laws of in-service lateritic soil subgrades in humid and rainy areas under different dynamic load conditions and wetting effects, dynamic triaxial tests were conducted under different moisture content, loading modes, dynamic stress amplitudes, and confining pressures. The influences of the single-stage, intermittent, and multi-stage loading, wetting amplitude, and stress level on the resilient strain, dynamic resilient modulus, and accumulative plastic strain of lateritic soil samples were analyzed. The analysis results indicate that under single-stage loading conditions, the resilient strain exhibits a characteristic of nonlinear decay which is fast first and then slow with the increase of loading times, while the accumulative plastic strain shows a rapid increase first and then tends to stabilize. The effect of dynamic stress amplitude on the resilient strain and accumulative plastic strain of lateritic soil increases with the increase of moisture content and decreases with the increase of confining pressure. When the moisture content increases from the optimum moisture content (OMC) to OMC+4.5%, the resilient strain and accumulative plastic strain increase by 2.99 times and 59%, respectively. When the confining pressure increases from 30 to 90 kPa, the resilient strain and accumulative plastic strain decrease by 52% and 38%, respectively. A fuzzy multiple regression model considering the uncertainty of critical dynamic stress was established based on the structural element theory, which can well reflect the relationships of critical dynamic stress with moisture content and confining pressure. The accumulative plastic strain under multi-stage loading is lower than that under single-stage loading at the same stress level. The low-stress-level loading in the first stage significantly reduces the accumulative plastic strain after the second, third, and fourth stages of loading. When the dynamic deviatoric stress is below 30 kPa, the differences in resilient and accumulative plastic strain between single-stage loading and intermittent loading are small. When the dynamic deviatoric stress is higher than 90 kPa, the plastic strain under single-stage loading is significantly higher than that under intermittent loading. The research results can provide a reference for the toughness design and long-term service performance evaluation of subgrades in lateritic soil areas.More>
2025, 25(5): 145-158. doi: 10.19818/j.cnki.1671-1637.2025.05.011
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Special Column on Steel-concrete Composite Bridges
Review on thermal behavior of concrete-filled steel tube bridges under environmental effects
LIU Yong-jian, YAN Xin-kai, LIU Jiang, CHEN Bao-chun, JIANG Lei, LYU Yi
Abstract: Key temperature issues faced by concrete-filled steel tube (CFST) bridges under the influence of hydration heat and environmental factors were compiled to enhance their capacity in addressing temperature response. Research advances in temperature actions and effects during construction and operation, interfacial thermal debonding, and computational methods for temperature effects were reviewed, and future research directions were discussed. Research findings indicate that the assembly of empty steel tubes is significantly influenced by the solar temperature field during the construction stage, and thus assembly demands precise alignment control. The hydration heat of concrete in the tubes results in that the temperature rise at large-diameter (> 1.2 m) sections and the core-surface temperature differences are over 30 ℃, raising concrete cracking risks. There is controversy regarding the selection of the closure temperature for CFST arches. It requires back-calculation with cumulative internal force. In operation, air temperature variations induce uniform temperature changes, while solar radiation creates nonlinear temperature gradients (temperature difference > 10 ℃) at sections. Temperature effects significantly impact stress, internal force, deformation, and stability and alter the long-term response of the structure by accelerating concrete creep. The temperature difference between the steel tube and core concrete can easily induce excessive tensile stress at the steel-concrete interface and thermal debonding, with the debonding height ranging from approximately 0.03 to 0.72 mm. Interface debonding can be effectively detected via infrared thermography, distributed fiber optic sensing, and other temperature sensing technologies. Current codes lack precise definitions for temperature action patterns and linear expansion coefficients. Analytical methods (such as thermoelastic analysis and energy method) and refined thermo-mechanical coupling simulation provides support for calculations of temperature effects. Future priorities include developing materials with low hydration heat and radiation absorptivity, promoting the application of interface connectors, implementing long-term thermal damage evolution and assessment, optimizing temperature control strategies for super-long-span CFST bridges, and refining relevant design codes. The research results offer a theoretical reference for the high-quality construction and long-life operation and maintenance of CFST bridges.More>
2025, 25(5): 159-179. doi: 10.19818/j.cnki.1671-1637.2025.05.012
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Research review on demountable shear connectors for prefabricated steel-concrete composite beams
HE Jun, WANG Zi-tong, HE Yao-bei, PEI Hui-teng, XU Jin-long, ZHOU Chen-tai
Abstract: In response to the national "dual carbon" strategy for green and sustainable development of transportation infrastructure, a systematic study was conducted on the key technologies for demountable shear connections in prefabricated steel-concrete composite beams. Modular design and prefabricated construction were adopted to effectively address the challenges of resource recycling in traditional composite girders with welded shear connections. Based on a review of relevant research achievements over the past decade, the structural characteristics and mechanical performance of four categories of demountable shear connectors were particularly analyzed, including high-strength bolted, blind-bolted, detachable profiled sheeting, and innovative demountable types. Static and fatigue tests on demountable connectors via push-out and beam tests were conducted to reveal the slip evolution, failure modes, and load-bearing mechanisms under different connection configurations. Test results indicate that the ultimate shear strength of single-nut bolted connectors reaches 95% of that of conventional welded studs, while through-bolted connectors exhibit significantly enhanced fatigue performance. Innovative demountable connectors demonstrate excellent long-term performance, but generally face technical challenges such as high manufacturing precision requirements and complex disassembly processes. Based on current design specifications, proposed calculation formulas for shear capacity and shear stiffness considering concrete crushing, bolt shear, and composite failure modes. The accuracy of the predictions is notably improved by modifying relevant coefficients. Future efforts should be made to optimize connector details to overcome cost and process limitations, clarify long-term performance under complex service conditions, establish life-cycle performance prediction models, and refine relevant design and construction specifications. The research findings provide theoretical and technical support for promoting the engineering application of demountable connectors and advancing the prefabrication and sustainable development of bridge engineering.More>
2025, 25(5): 180-207. doi: 10.19818/j.cnki.1671-1637.2025.05.013
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Reliability analysis of RC arch bridge during cantilever casting construction based on improved SO
PENG Tao, LU Xiao-long, LANG Qi-lin, TIAN Zhong-chu, WANG Xiao-hui
Abstract: To improve the reliability calculation accuracy and efficiency of long-span reinforced concrete (RC) arch bridges during cantilever casting construction, a reliability analysis method based on an improved snake optimizer (SO) was proposed. In order to improve the optimization performance of the standard SO, Tent chaotic mapping was introduced to generate the initial population. Gaussian difference variation was performed on the optimal snake individuals in the iterative process, and the effectiveness of the improved algorithm was verified by common test functions. A C80 concrete strength development model with time was established based on the experimental data and existing studies. The design sample points of each random variable were generated by the Latin hypervertical method, and the target response values at the corresponding sample points were solved based on the finite element model. On this basis, the optimal response surface between the design sample points and the target response values was constructed by using the improved SO to optimize the parameters of the support vector machine (SVM), and the reliability analysis model of the RC arch bridge during cantilever casting construction was established by combining the response surface with the Monte Carlo (MC) method. The reliability of two typical failure modes during the whole construction of a real bridge was calculated by using the method proposed in this paper, and the sensitivity of the parameters was analyzed. Analysis results show that the improved SO has obvious advantages over the comparison algorithm. In a case study of a certain actual bridge during cantilever casting construction, it has enhanced the prediction accuracy of the main arch ring stress to 0.994 5 and that of the stay cable stress to 0.986 2, thereby enhancing the precision of reliability analysis for cantilever-cast RC arch bridges during construction. In the cantilever casting construction of long-span RC arch bridges, the initial tension of temporary cables, elastic modulus, and unit weight of the main arch ring are identified as the most significant stochastic variables affecting stress reliability. In contrast, the elastic modulus and unit weight of the cable tower and temporary cables are insensitive factors.More>
2025, 25(5): 208-219. doi: 10.19818/j.cnki.1671-1637.2025.05.014
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Fatigue performance analysis and life prediction of steel-UHPC stud weld based on fracture mechanics
WANG Da, LIU Jing-an, SHI Jia-lin, TAN Ben-kun
Abstract: To investigate the influence of weld dimensions on the fatigue life and failure modes of stud connectors in steel-UHPC composite structures, a 1/4 symmetric finite element model of pushing specimens was established based on ABAQUS software. For pushing specimens with three stud diameters of 13, 16, and 19 mm, the influence mechanisms of weld parameters (weld diameter and weld height) and initial fatigue crack depth on fatigue performance were systematically investigated. Analysis reliability of the finite element model was verified using experimental data, and a fatigue life prediction method incorporating weld dimensions was proposed. Analysis results indicate that the SWT parameter on path 1 is negatively correlated with weld diameter, and the critical plane is concentrated in the middle of the stud weld. The crack initiation life on path 1 and path 3 increases with the increase of weld diameter, while it shows the opposite trend on path 2. Additionally, the crack initiation life on path 1 is significantly lower than that on path2 and path3, which indicates that cracks preferentially initiate on path 1. The total fatigue life of the stud initially increases and then decreases as weld diameter decreases. When the ratios of the weld diameters to the diameters of the 13, 16 and 19 mm studs drops to 1.15, 1.19 and 1.16 respectively, the failure mode transitions from path 2 to path 1. At this point, the total fatigue life of the stud reaches its peak, corresponding to the optimal weld diameter to stud diameter combination for the stud. The SWT parameter on path 1 is positively correlated with weld height, while the crack initiation life on path 1 decreases with increasing weld height but increases on path 2 and path 3. When weld height decreases, the crack initiation location shifts from path 1 to path 2, and the failure mode of the stud under low load amplitudes undergoes a corresponding transition. The total fatigue life of the stud exhibits a monotonically increasing trend with the increase of weld height. The increase of initial fatigue crack depth leads to a marked decrease in the total fatigue life of the stud. A fatigue life prediction model that quantifies the coupled effect of weld dimensions on fatigue performance is proposed in this study, which provides a theoretical foundation for the optimization design and life evaluation of stud connectors in steel-UHPC composite structures.More>
2025, 25(5): 220-233. doi: 10.19818/j.cnki.1671-1637.2025.05.015
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Seismic performance of RC columns strengthened by steel tube-confined ultra-high performance concrete
LUO Xia, YU Xin-ye, WEI Jian-gang, YANG Yan, YANG Yi-lin
Abstract: To address the seismic retrofitting demand for existing reinforced concrete (RC) bridge piers in high-intensity seismic regions, a novel strengthening technique using steel tube-confined ultra-high performance concrete (UHPC) was proposed. To investigate the seismic performance of the newly strengthened piers, quasi-static tests were conducted on five specimens, with strengthening type and initial axial load ratio as parameters. Failure modes, hysteretic curves, skeleton curves, and seismic performance indices were measured. Then, based on the experimental results, a finite element model was built to accurately simulate the quasi-static behavior of the strengthened columns. Subsequently, parametric analyses were carried out using finite element simulations, considering the UHPC layer thickness, UHPC strength, and steel tube thickness. Research results show that after strengthening with steel tube-confined UHPC, the plastic hinge region of the RC columns was reduced and concentrated near the cut in the steel tube at the column base. Compared with the UHPC section enlargement method, the steel tube-confined UHPC strengthening technique provides greater improvement in displacement ductility coefficient, cumulative hysteretic energy dissipation, and initial stiffness, along with a more significant reduction in residual deformation under the same conditions. As the initial axial load ratio increases within the range of 0 - 0.3, the failure mode, bearing capacity, and energy dissipation capacity remain largely unchanged. However, displacement ductility and initial stiffness decrease, and residual displacement tends to increase. Increasing the UHPC strength in the strengthening layer significantly improves the energy dissipation capacity. Increasing the thickness of the steel tube in the strengthening layer significantly reduces the residual displacement. Increasing the UHPC thickness in the strengthening layer enhances bearing capacity, displacement ductility, cumulative hysteretic energy dissipation, and initial stiffness, while also markedly reducing residual displacement. These findings are expected to provide a theoretical basis for the application of steel tube-confined UHPC in the preventive seismic strengthening of existing RC bridge piers.More>
2025, 25(5): 234-249. doi: 10.19818/j.cnki.1671-1637.2025.05.016
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Pushing test and bonding performance of LUHPC outsourcing steel tube with all-solid waste coal gangue aggregate
FU Jun, YANG Miao, QIU Hong-an, SUN Zhao, DING Qing-jun, ZHANG Gao-zhan
Abstract: Lightweight ultra-high performance concrete (LUHPC) with a density lower than 2 100 kg·m-3 was prepared by using all-solid waste coal gangue aggregates. The mechanical properties of LUHPC were tested. Its damage constitutive model was analyzed, and the quasi-static and dynamic compressive strengths were measured. The interface bonding and pushing resistance performance between the steel tubes and the encased LUHPC were investigated. A scaled-down model of the engineering prototype structure in a 1∶6 ratio was prepared. A pushing test on the all-solid waste coal gangue aggregate LUHPC concrete was conducted using the scaled-down model in the reduced scale. The loading process and failure modes of the scaled-down model were observed. The interface shear adhesion strength was analyzed by compiling and drawing the load-slip curve diagram. The ABAQUS was employed to establish a finite element model of LUHPC-steel pipe concrete. A multi-parameter analysis of the test was carried out using finite element method. Test results show that the quasi-static loading strength of LUHPC containing waste coal gangue aggregate is 92.20 MPa. The dynamic compressive strength increases by 13%~40% compared with the quasi-static strength. Based on the damage constitutive model analysis, the peak stress is 109 MPa, the strain is 3.4×10-3, and the elastic modulus is 37.5 GPa. For the LUHPC-steel tube concrete, the low water-binder ratio in the LUHPC binder material provides a strong bonding effect, and the inclusion of steel fibers effectively enhances the bond performance at the steel tube interface. The bonding strength reaches 1.96 MPa, significantly higher than that of ordinary concrete, which contributes to improved structural safety and integrity. The finite element simulation analysis, considering concrete plastic damage and steel ductile damage, yields a load-slip curve for the entire loading process of the pushing specimen model, which aligns with the experimental curve. The pushing resistance and bonding performance of the specimen can be improved by adjusting the design parameters of the LUHPC-encased steel tube.More>
2025, 25(5): 250-262. doi: 10.19818/j.cnki.1671-1637.2025.05.017
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Study on fatigue performance of steel-AAUHPC composite bridge deck
LIU Bin, JIANG Lei, YUAN Min, LIU Yong-jian, PU Bei-chen
Abstract: To improve the fatigue performance of orthotropic steel bridge decks and enhance the overall performance of steel-concrete composite bridge decks, alkali-activated ultra-high performance concrete (AAUHPC)—a material with green and low-carbon advantages, was applied over an orthotropic steel bridge deck to form a steel-AAUHPC composite bridge deck. Two types of stiffening ribs for the steel-AAUHPC composite bridge deck were designed: open T-ribs and closed U-ribs. Segment models of the two composite bridge decks were established using the finite element software ABAQUS to analyze their fatigue performance. The influence of different elastic moduli, different stiffening rib forms, different paving layer thicknesses, and different steel top plate thicknesses on the fatigue performance of five common types of structural details was studied. The fatigue performance of the composite bridge decks was evaluated using the S-N curve method. Analysis results show that both types of steel-AAUHPC composite bridge decks exhibit significantly improved fatigue performance compared to the conventional orthotropic steel bridge deck. In the deck with open T-ribs, the maximum stress reduction occurs at fatigue structural detail ①, with a magnitude of 75.66%, while the minimum reduction occurs at fatigue structural detail ③, with a magnitude of 42.88%. In the deck with closed U-ribs, the maximum reduction occurs at fatigue structural detail ④, with an amplitude of 68.49%, and the minimum reduction occurs at fatigue structural detail ⑤, with an amplitude of 26.92%. Increasing the AAUHPC layer thickness by 10 mm from the base 30 mm reduces the most unfavorable stress at each fatigue structural detail, following an approximately linear trend. When the steel top plate thickness is reduced from 18 to 16 and 14 mm, the most unfavorable stress of each fatigue increases at the structural detail in both types of composite bridge decks. In the closed U-rib composite bridge deck, the stress increase at fatigue structural detail ② is the largest, with values of 4.30 MPa and 9.20 MPa, respectively, while increases in the most unfavorable stresses at fatigue structural details ③, ④, and ⑤ are negligible. In the open T-rib composite bridge deck, the increase in the most unfavorable stress at fatigue structural detail ① is the largest, with values of 3.13 MPa and 4.08 MPa, respectively. Fatigue performance evaluation using the hot spot stress method shows that the stress amplitudes at each fatigue structural detail are below the corresponding fatigue cutoff limits.More>
2025, 25(5): 263-277. doi: 10.19818/j.cnki.1671-1637.2025.05.018
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Shear test on interface of steel-UHPC composite slab with hybrid connection of headed stud and adhesive
LI Cong, MAO Qing-chao, HU Wen-xu, CHEN Bao-chun
Abstract: With the type of connectors and the diameter and number of headed studs as the parameters, 19 push-out tests were conducted. The interface failure mode, load-slip curve, and load-strain curve were investigated. The shear combination effect and slip mechanism of headed studs and adhesives were analyzed, and the method for calculating the shear bearing capacity and the shear-slip prediction model were established. Test results show that the load-slip curve of the specimen with hybrid connection of headed stud and adhesive can be divided into elastic section, descending section (adhesive failure), elastic-plastic section, and descending section (stud fracture failure). The adhesive primarily bears the load before the adhesive failure, and the headed stud has little effect, which is similar to the specimen with the fully adhesive connection. After adhesive failure, the load is resisted by the headed studs, exhibiting an elastic-plastic section and descending section similar to the specimen with fully headed stud connection. The failure mode is characterized by debonding of adhesive from the steel slab interface, with tearing occurring along the lower edge of the shear pocket. The headed studs are all characterized by shear failure at the base. For the calculation method of shear bearing capacity established in consideration of the synergistic effect of the headed stud and adhesive, the ratio of the calculated value and the experimental value is 0.93, with a variance of 0.13, indicating that the method can predict the shear bearing capacity of the hybrid connector with reasonable accuracy. The interface shear performance of the steel-ultra-high performance concrete (UHPC) slab with hybrid connection of headed stud and adhesive is mainly determined by the headed stud, when the shear bearing capacity ratio of headed studs to adhesives is 2.26-4.91. A certain bearing capacity reserve without reduction in the shear stiffness can be provided when the adhesive fails. According to the shear-slip mechanism of the hybrid headed stud-adhesive connector, the models for exponential function prediction before adhesive failure and for inverse proportional function prediction after adhesive failure were established. They can provide reference for practical projects.More>
2025, 25(5): 278-296. doi: 10.19818/j.cnki.1671-1637.2025.05.019
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Seismic performance of ultra-high performance concrete-filled FRP tube composite columns reinforced with steel-FRP composite bars
ZHANG Zhi-wen, GE Wen-jie, ASHRAF Ashour, LI Sheng-cai, CAO Da-fu
Abstract: A novel steel-fiber reinforced polymer composite bar (SFCB) to reinforce ultra-high performance concrete-filled FRP tubes (UHPC-FFT) was proposed to address structural corrosion and minimize residual deformation. The seismic performance of these columns was investigated through quasi-static tests and finite element modeling. Parameters including longitudinal reinforcement type, axial load ratio, FRP tube thickness, tube material type, concrete type, and reinforcement ratio were examined for their effects on seismic behavior. Furthermore, based on a validated fiber model, the influences of SFCB cross-sectional steel ratio, core steel bar yield strength, external FRP elastic modulus, and ultimate tensile strength on the seismic performance were analyzed. The results indicate that UHPC-FFT columns reinforced with SFCBs exhibit fuller hysteretic loops, higher load-carrying capacity, and superior energy dissipation compared to those with conventional steel or FRP bars. Increasing axial load ratio from 0.15 to 0.25 enhances the initial stiffness and load-bearing capacity of the composite columns but reduces ductility and energy dissipation while increasing residual deformation. Increasing the FRP tube thickness from 4 to 6 mm shows limited improvement in seismic performance due to the limited circumferential confinement capacity of FRP tubes for UHPC. UHPC with high compressive strength and good toughness, as well as an increased reinforcement ratio, effectively enhances the seismic performance of the composite columns. Increasing the strength of the inner steel bar improves both bearing capacity and deformation of the composite columns without compromising ductility, initial stiffness, or stiffness degradation rate. Although a higher elastic modulus of the external FRP in SFCBs can improve the seismic performance of the composite columns, it may also lead to premature failure caused by FRP fracture. An FRP with an elastic modulus of 55 GPa is therefore recommended.More>
2025, 25(5): 297-312. doi: 10.19818/j.cnki.1671-1637.2025.05.020
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Radial temperature difference action model of concrete-filled steel tube in natural environments
BAI Yong-xin, LIU Yong-jian, LIU Jiang, WANG Zhuang, GUO Hua-jun
Abstract: To propose a temperature action model for calculating the interface stress of concrete-filled steel tube (CFST) in natural environments, four CFST components with different orientations and inclinations were fabricated for temperature field tests. Based on the measured data, a refined finite element model (FEM) was established for the numerical calculation of the temperature field. The radial temperature difference distribution and variation in different directions were analyzed using the measured data, and the radial distribution and circumferential distribution of radial temperature difference were fitted by the finite element calculation results and measured data. Finally, a comparison was made on the temperature deformation and stress calculated by the three-dimensional temperature field, radial temperature difference action model, and vertical temperature gradient model in the specification. Research results show that the radial and circumferential distributions of the radial temperature difference exhibit significant nonlinear distribution characteristics. The radial positive temperature difference is mainly influenced by solar radiation intensity, while the radial negative temperature difference is related to abrupt changes in air temperature. The measured maximum radial positive temperature difference can reach 23.16 ℃, and the minimum radial negative temperature difference is -10.43 ℃. The radial positive temperature difference can be described by the product of the radial power function and an improved one-dimensional Gaussian distribution in the circumferential direction, while the distribution of radial negative temperature difference can be characterized by the product of the radial power function and the minimum radial temperature difference. The proposed radial temperature difference action model is more precise than the vertical temperature gradient in the specification in the calculation of temperature effects in CFST, especially in the interface temperature stress. The maximum normal stress at the interface can reach 0.79 MPa under temperature action, which may lead to debonding or void of the steel-concrete interface. The proposed radial temperature difference action model can accurately assess the adverse effects of temperature, which provides support for the design of CFST interfaces.More>
2025, 25(5): 313-328. doi: 10.19818/j.cnki.1671-1637.2025.05.021
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Mechanical performance and stiffness calculation of integral abutment joints in Ⅰ-shaped composite girders
HUANG Yu-fan, FANG Yuan-wei, WU Qing-xiong, WANG Qu, CHEN Zhou-yu, CHEN Ming-sen
Abstract: To investigate the influence law of different pile types on the mechanical performance of integral abutment joints in Ⅰ-shaped composite girders, reinforced concrete (RC) piles, H-shaped steel piles, and ultra-high-performance-concrete (UHPC) piles were used as variables to conduct full-scale model tests, develop finite element models, and analyze the mechanical characteristics, load-transfer mechanisms, and failure modes of the joints. A joint stiffness calculation method was proposed based on the principle of the force method. Analyse results show that all joint specimens with different pile types exhibit excellent longitudinal deformation performance under overall temperature rise loads. Failure forms of joints are caused by pile failure. The studs are not bent or damaged, and the overall performance of the joints is great. Under equivalent vertical bearing capacity conditions, steel piles demonstrate the highest shear and bending stiffness, followed by RC piles, while UHPC piles show the minimum values. H-shaped steel piles exhibit optimal longitudinal deformation adaptability and bearing capacity, followed by UHPC piles, with RC piles performing least favorably. Two stiffness mutation positions, including pile tops and beam-abutment interfaces, are identified as key points of the joint design of Ⅰ-shaped composite girders. By comparing the theoretical formula with the finite element results, the longitudinal deformation error of the bridge under temperature effects is less than 2.7%. verifying their reliability. The theoretical formula can be used to calculate the integral longitudinal deformation of the bridge. The proposed stiffness calculation method of different pile types achieves less than 5% deviation compared to experimental results. The research results provide theoretical support for the refined design of integral abutment joints in steel-concrete composite girders.More>
2025, 25(5): 329-341. doi: 10.19818/j.cnki.1671-1637.2025.05.022
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Positive bending performance test of UHPC-NC-steel plate composite bridge deck
PEI Bi-da, ZOU Long-teng, LI Li-feng, RAO Zheng-dong, LU Jie, XIAO Yong-gang, ZOU Ze-peng
Abstract: An experimental study was conducted on the bending bearing capacity of a novel UHPC-NC-steel plate composite bridge deck under longitudinal positive bending moments to investigate its longitudinal positive bending performance. The failure modes, bearing capacity, interface slip characteristics, and strain development under positive bending moments were examined. The calculation formulas for the shear capacity of the UHPC-NC interface from different standards were compared, and a calculation and analysis method was proposed for the ultimate bending bearing capacity of UHPC-NC-steel plate composite bridge decks. Experimental results show that before reaching the ultimate load, the deformation of the composite bridge deck cross-section conforms to the plane section assumption, and the initial cracking load of the UHPC-NC-steel plate composite bridge deck under positive bending moment reaches 161 kN. This indicates it possesses excellent crack resistance. The overall relative slip between the UHPC-NC interface and the steel plate-NC interface is small. The relative slip between the two is almost zero. This indicates that the PBL shear keys ensure the collaborative load-bearing of the steel plate and NC layer, making the deformation of the steel plate and NC layer consistent. Upon final failure, shear stress concentration occurs at the UHPC-NC interface after debonding of the interface, leading to shear failure in the NC layer within the shear-bending section. Before shear failure, the composite deck exhibits a series of damage signs, such as 45° diagonal cracks on the side face through the NC layer, transverse cracks in the UHPC-NC interface, and debonding of the UHPC-NC interface. Even after failure, the composite deck retains good ductility. The debonding load value of the NC layer and UHPC layer and the ultimate load value are 753.2 kN and 810.0 kN, respectively. The calculated ultimate positive bending capacity of the UHPC-NC-steel plate composite bridge deck has a coincidence degree of 94% with the experimental results. The calculation results are slightly conservative, which can serve as a reference for similar engineering designs.More>
2025, 25(5): 342-355. doi: 10.19818/j.cnki.1671-1637.2025.05.004
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Research on bending capacity of new steel-concrete composite girders in negative moment region
ZHAO Qiu, YE Jun-yu, ZHANG Hao
Abstract: An innovative structure with perforated steel plates integrated into the main girder flanges of traditional simply-supported-to-continuous composite girder bridges was proposed to address the issue of their concrete decks in the negative moment regions being prone to cracking. Through static tests and finite element simulation, the mechanical behavior and crack development law in the negative moment regions of the novel structural form were studied systematically. Based on test results and parametric analysis data, the corresponding calculation method of bending capacity was established. A calculation formula of the bending capacity was proposed for the middle bearing section in this novel structure simply-supported-to-continuous composite girder. Test results show that the ultimate bearing capacity of perforated steel plate components is increased by 71% compared with that of ordinary components. The mid-span slip of perforated steel plate components is smaller than that of ordinary components under the same load. A certain amount of retraction of mid-span slip occurs during unloading, suggesting that perforated steel plates contribute to enhancing ductility of the structure. During the negative moment loading process, the perforated steel plate components show a slower crack development rate and fewer cracks than ordinary components. By comparing the theoretical and test results, the calculation formula can be used to predict the ultimate bearing capacity of simply-supported-to-continuous composite girders with perforated steel plate components. The perforated steel plate significantly enhances the ultimate bearing capacity and crack resistance in the negative moment region, while also improving ductility of the structure to a certain extent. Reference can be provided by this study for the design of similar structures in the future.More>
2025, 25(5): 356-367. doi: 10.19818/j.cnki.1671-1637.2025.05.023
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Prediction of full-life axial compression performance of steel-reinforced concrete bridge piers in marine environments
LIN Yu-han, CHEN Li-bo, XING Zhi-quan, CHEN Yu
Abstract: To improve the durability and performance prediction accuracy of bridge structures in marine environments, the initial corrosion time of embedded steel in steel-reinforced concrete (SRC) bridge piers in marine environments was determined based on a semi-empirical time-dependent corrosion model. By analyzing the time-dependent degradation laws of the cross-sectional area and yield strength of reinforcement in marine environments, a quantitative characterization method for the time-varying corrosion rate and mechanical performance degradation of section steel was proposed. Based on the calculation results of the time-dependent corrosion model, 11 SRC bridge pier specimens with different service years were fabricated. Through electrochemical accelerated corrosion tests and axial compression performance tests, the failure modes and time-dependent degradation behavior of SRC bridge piers under axial load after corrosion damage were systematically investigated. Through theoretical analysis and derivation, a time-dependent axial compression bearing capacity prediction formula for SRC bridge piers in marine environments was proposed, and the rationality of the formula was verified by experimental data. Research results show that the thickness of the protective layer significantly affects the initial corrosion time of the steel, and the degradation rate of the steel performance is influenced by both service time and corrosion current density. As the service time increases, the axial compression performance of the bridge piers deteriorates significantly. The ultimate bearing capacity, ductility, and initial stiffness of SRC bridge piers decrease by 54.1%, 54.3%, and 68.2%, respectively, during the full-life cycle. The degradation inflection points of ultimate bearing capacity and initial stiffness occur at 20 years of service, while the ductility degradation inflection point is delayed to 50 years. Based on the proposed formula, the relative error in predicting the full-life axial compression bearing capacity of the experimental bridge piers is within 6%, lower than the prediction error of existing national standards. This indicates that considering the coupling effect of concrete cracking and the confinement effect of corroded steel can significantly improve the prediction accuracy of the full-life axial compression performance of SRC bridge piers.More>
2025, 25(5): 368-384. doi: 10.19818/j.cnki.1671-1637.2025.05.024
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A novel box girder beam element considering equivalent shear deformation freedom of corrugated steel webs
LI Xia-yuan, WAN Shui, FU Li-xiang, CHEN Jian-bing, KANG Ai-hong, WANG Lei
Abstract: To investigate the influence of diaphragms on the bending forces and deformations of composite box girders with corrugated steel webs (CBG-CSWs), a novel box girder beam element named TBT-CSW, which incorporates the equivalent shear deformation degree of freedom of the CSWs, was proposed. Based on the mechanical characteristics and deformation compatibility of CBG-CSWs, a geometric relationship expression between the equivalent bending rotation and the equivalent shear deformation was established. Addressing the difference in bending shear flow distribution between the side webs and central webs in multi-cell CBG-CSW sections, a formula for determining the equivalent shear deformation coefficient of CSWs was proposed based on the principle of equivalent shear strain energy. The governing differential equations, considering the effects of equivalent bending rotation and equivalent shear deformation, were derived using the principle of minimum potential energy. Their homogeneous solutions were employed to construct interpolation functions for the generalized displacements (vertical deflection, equivalent shear deformation of CSWs, and equivalent bending rotation). Based on the energy variational principle, a two-node, six-degree-of-freedom box girder element (TBT-CSW) was developed, capable of accounting for the influence of end and intermediate diaphragms on the equivalent shear deformation of corrugated steel webs. The element stiffness matrix and equivalent nodal load vector were also derived. Numerical examples validated the computational accuracy and broad applicability of the TBT-CSW beam element. Research results show that, compared to the traditional TBTS beam element, the TBT-CSW beam element achieves up to a 30.8% higher accuracy in stress calculation at critical locations. End diaphragms have a minor influence on the global internal forces and deformation of the girder, but significantly affect the stress distribution in the adjacent flanges. The arrangement of intermediate diaphragms, however, markedly alters the local internal force distribution within the girder cross-section, increases the degree of static indeterminacy, and leads to significant changes in the stress at the top and bottom surfaces of the flanges, while the mid-surface stress remains relatively stable. As the number of intermediate diaphragms increases, the vertical deflection of the girder gradually decreases, but the overall internal force distribution remains essentially unchanged.More>
2025, 25(5): 385-398. doi: 10.19818/j.cnki.1671-1637.2025.05.025
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Lateral impact behavior of high-performance concrete-filled steel tubular composite structural members
YANG Xiao-qiang, ZHANG Yuan, ZHU Li-guo, LAI Zhi-chao
Abstract: Four square high-performance concrete-filled steel tubular (HPCFST) composite structural members were designed and fabricated, considering the influence of different concrete types, including C80 high-strength concrete and ultra-high-performance concrete (UHPC). Lateral impact tests were conducted using a drop-weight testing machine to evaluate critical performance indicators such as impact force, deformation, and energy absorption. A finite element (FE) model was developed, calibrated, and utilized for parametric analyses focusing on reinforcement configuration, thickness of steel tube, strength of steel tube, and axial compression ratio. Analysis results show that the composite structural members with both internal and external concrete being UHPC can withstand lateral impacts of greater energy. The impact resistance of UHPC reinforced composite structural members is significantly superior to those reinforced with C80 high-strength concrete, whose plateau value of impact force shows an approximately 10% improvement, while peak mid-span displacement and residual deformation are reduced by 11.2% and 21.6%, respectively. The established FE model achieves good agreement with experimental results in terms of impact force and deformation, which validates its reliability. Parametric analysis reveals that increasing thickness and strength of steel tube significantly increases the plateau value of impact force and reduces peak mid-span displacement, thereby improving impact resistance of the member. The inclusion of steel rebars in encased concrete can effectively enhance the impact resistance of members compared to plain concrete. However, once the minimum reinforcement ratio is satisfied, further increases in the quantity and diameter of rebars have limited effects on improving impact resistance of members. The influence of the axial compression ratio within 0.1 on the member is limited, but the further increase of the axial compression ratio will significantly weaken the impact resistance of the member, until the instability failure occurs. These findings illustrate the excellent impact resistance of HPCFST composite structural members and further enhance the application potential of such members in long-span tall-pier bridges.More>
2025, 25(5): 399-413. doi: 10.19818/j.cnki.1671-1637.2025.05.026
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Progressive collapse prevention design of fly-bird-type arch bridges considering tie bar failure
FAN Bing-hui, ZOU Jin-qi, CHEN Keng, CHEN Bao-chun, CHEN Kang-ming
Abstract: To enhance the progressive collapse prevention ability of the fly-bird-type arch bridges in the event of tie bar failure, four locally strengthened structural systems were proposed based on the alternative path method of robust design along with relevant engineering cases and studies: triangular stiffener zone system, concrete-filled steel tube column system, columns with diagonal compression bars system, and partially simply-supported column connection system. An explicit dynamic cable-breaking simulation method was established using LS-DYNA. Based on laboratory test data and simulation results, the method was compared and validated. The dynamic response of four structural systems under tie bar failure was simulated using this cable-breaking simulation method. The ultimate internal force indices of main-span and side-span members were compared, and the structural bearing capacity of each system under tie bar failure conditions was evaluated. According to the results, with smaller error, the LS-DYNA dynamic analysis is suitable for simulating the dynamic response of horizontal tie bar failure of the tied-arch bridge. All four structural systems effectively reduce the dynamic response of the rest structures under tie bar failure. Specifically, the concrete-filled steel tube column system is most advantageous for reducing the dynamic response of the bending moment of the side arch rib and longitudinal beam, while the partially simply-supported column connection system is most effective in minimizing the dynamic response of bending moment of the main arch rib and column. The application of concrete-filled steel tube column systems in the construction of new fly-bird-type arch bridges provides the best overall benefits in terms of structural dynamic performance and aesthetic coordination. Meanwhile, the application of partially simply-supported column joints in the reinforcement of existing fly-bird-type arch bridges not only enhances structural dynamic performance but also effectively prevents joint cracking. Additionally, this approach maintains a low construction cost with simplicity and practicality, achieving the optimal economic efficiency. Therefore, practical and viable approaches are provided for the robust design and reinforcement of this type of bridge.More>
2025, 25(5): 414-420. doi: 10.19818/j.cnki.1671-1637.2025.05.027
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