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Research

15 pages, 8283 KiB

Open AccessArticle

Experimental Investigations on the On-Site Crack Control of Pier Concrete in High-Altitude Environments

by Xiaochuan Hu, Lei Liu, Manping Liao, Ming Li, Cun Lu, Zaifeng Yao, Qiuming Huang and Mei-Ling Zhuang

Buildings 2024, 14(11), 3445; https://doi.org/10.3390/buildings14113445 - 29 Oct 2024

Viewed by 415

Abstract

Concrete structures in high-altitude environments face many challenges. Establishing concrete crack control methods in high-altitude environments is crucial for enhancing the service capacity of concrete structures. In this study, a multi-field (hydration-temperature–humidity-constraint) coupling model was used to quantitatively assess the cracking risk of [...] Read more.

Concrete structures in high-altitude environments face many challenges. Establishing concrete crack control methods in high-altitude environments is crucial for enhancing the service capacity of concrete structures. In this study, a multi-field (hydration-temperature–humidity-constraint) coupling model was used to quantitatively assess the cracking risk of pier bodies at high altitude. On-site crack control tests were conducted on pier bodies using a micro-expansion anti-cracking agent to demonstrate the effectiveness of deformation shrinkage compensation in crack control at high altitudes. The results indicated that there was a risk of cracking in the pier body at high-altitude conditions, especially within 0.3 m from the pile cap and ±2.5 m from the center of the pier side surface. Compared with conventional piers, the micro-expansion anti-cracking agent approximately doubled the unit expansion deflection of piers at high temperatures while reducing the unit shrinkage deflection of piers by 11% to 12% at low temperatures. The concrete in conventional pier bodies was in a tension state after long-term hardening, while the concrete treated with the micro-expansive anti-cracking agent was in compression. Therefore, the deformation compensation effect of the micro-expansive anti-cracking agent was significant and reduced the risk of concrete cracking. In addition, early freezing had a significant impact on concrete strength, underscoring the importance of effective temperature control during the early stages of concrete placement in high-altitude environments. Full article

(This article belongs to the Special Issue Intelligence Techniques Applied in Infrastructure, Engineering and Construction)

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18 pages, 5842 KiB

Open AccessArticle

Inversion Analysis for Thermal Parameters of Mass Concrete Based on the Sparrow Search Algorithm Improved by Mixed Strategies

by Yang Wang, Yang Gao, Kaixing Zhang, Mei-Ling Zhuang, Runze Xu, Xiumin Yan and Youzhi Wang

Buildings 2024, 14(10), 3273; https://doi.org/10.3390/buildings14103273 - 16 Oct 2024

Viewed by 461

Abstract

In the traditional mass concrete temperature field calculation, the accuracy of the thermal parameters is extremely important. However, the actual thermal parameters of mass concrete may have some errors with the laboratory-measured values or specification values due to the site ambient temperature, concrete [...] Read more.

In the traditional mass concrete temperature field calculation, the accuracy of the thermal parameters is extremely important. However, the actual thermal parameters of mass concrete may have some errors with the laboratory-measured values or specification values due to the site ambient temperature, concrete surface insulation measures, cooling water flow, etc. Therefore, it can be combined with the measured temperature of the field temperature sensors using the sparrow search algorithm (SSA) for the inverse analysis of thermal parameters. Firstly, to address the problem that SSA has low convergence accuracy and easily falls into local optimum, a mixed strategy was adopted to improve the algorithm, including Logistic Chaos mapping initialization of the population, the introduction of adaptive weighting factors, and the use of the Cauchy mutation strategy. Then, the performance test was carried out to compare the performance of the algorithm with three different intelligent algorithms and reflect the superiority of the SSA that was improved by mixed strategies (SSAIMSs). Finally, the proposed method was applied to the thermal parameter inversion of a mass concrete pile cap. The inversion results demonstrated that SSAIMSs can improve the accuracy and speed of thermal parameter inversion, and the calculated results of the thermal parameters and temperatures obtained using the SSAIMSs matched well with the measured results in the field, which can meet the accuracy requirements of the actual engineering. Full article

(This article belongs to the Special Issue Intelligence Techniques Applied in Infrastructure, Engineering and Construction)

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18 pages, 7887 KiB

Open AccessArticle

Experimental and Numerical Simulation Investigations on the Bearing Capacity of Stepped Variable-Section DX Piles under Vertical Loading

by Jinsheng Cheng, Lei Tong, Chuanzhi Sun, Hanbo Zhu and Jibing Deng

Buildings 2024, 14(10), 3078; https://doi.org/10.3390/buildings14103078 - 26 Sep 2024

Viewed by 469

Abstract

As a new type of pile, the bearing characteristics of stepped variable-section DX piles (multi-joint extruded and expanded piles) are quite complicated; thus, their design concepts and pile-forming processes are still in the exploration stage, and their application in actual engineering is not [...] Read more.

As a new type of pile, the bearing characteristics of stepped variable-section DX piles (multi-joint extruded and expanded piles) are quite complicated; thus, their design concepts and pile-forming processes are still in the exploration stage, and their application in actual engineering is not particularly mature. The settlement law and load transfer law of the variable section DX pile have not been studied deeply, and the values of the parameters of engineering design are not clear, which are the problems to be solved for the variable section DX pile. To solve the above problems, the present study on the bearing characteristics of stepped variable-section DX piles under vertical loading is of great scientific significance and engineering practical value. In this study, the bearing capacity of a DX pile with two variable steps was first analyzed experimentally. Then, the bearing capacity of variable cross-section DX piles and equal cross-section piles were simulated under the same soil conditions. Later, the numerical simulation results were compared with the experimental results to verify the validity and accuracy of the numerical models established in ABAQUS software. Finally, the bearing capacity of stepped variable-section DX piles in different soil layers was analyzed numerically to compare the effect of different soils on the compressive bearing capacity of piles. The results indicated that the load-bearing plates had a greater influence on the bearing capacity of the stepped variable-section DX piles. At the optimum variable section ratio, which was close to 0.9, DX piles had a good bearing capacity. The relative errors of the numerical simulation ultimate loads were below 10%, which verified the accuracy of the developed numerical model. The simulated ultimate load of the equal-section pile was the smallest. The vertical compressive bearing capacity and the effect of controlling settlement under the same level of load of the variable section DX pile in sandy soil were both better than those in silt soil. There was little difference between the bearing capacities of the piles with a load-bearing plate. The bearing capacity of the pile with two load-bearing plates was the best, which can be used in practical engineering. Full article

(This article belongs to the Special Issue Intelligence Techniques Applied in Infrastructure, Engineering and Construction)

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18 pages, 9754 KiB

Open AccessArticle

Bridge Surface Defect Localization Based on Panoramic Image Generation and Deep Learning-Assisted Detection Method

by Tao Yin, Guodong Shen, Liang Yin and Guigang Shi

Buildings 2024, 14(9), 2964; https://doi.org/10.3390/buildings14092964 - 19 Sep 2024

Viewed by 655

Abstract

Applying unmanned aerial vehicles (UAVs) and vision-based analysis methods to detect bridge surface damage significantly improves inspection efficiency, but the existing techniques have difficulty in accurately locating damage, making it difficult to use the results to assess a bridge’s degree of deterioration. Therefore, [...] Read more.

Applying unmanned aerial vehicles (UAVs) and vision-based analysis methods to detect bridge surface damage significantly improves inspection efficiency, but the existing techniques have difficulty in accurately locating damage, making it difficult to use the results to assess a bridge’s degree of deterioration. Therefore, this study proposes a method to generate panoramic bridge surface images using multi-view images captured by UAVs, in order to automatically identify and locate damage. The main contributions are as follows: (1) We propose a UAV-based image-capturing method for various bridge sections to collect close-range, multi-angle, and overlapping images of the surface; (2) we propose a 3D reconstruction method based on multi-view images to reconstruct a textured bridge model, through which an ultra-high resolution panoramic unfolded image of the bridge surface can be obtained by projecting from multiple angles; (3) we applied the Swin Transformer to optimize the YOLOv8 network and improve the detection accuracy of small-scale damages based on the established bridge damage dataset and employed sliding window segmentation to detect damage in the ultra-high resolution panoramic image. The proposed method was applied to detect surface damage on a three-span concrete bridge. The results indicate that this method automatically generates panoramic images of the bridge bottom, deck, and sides with hundreds of millions of pixels and recognizes damage in the panoramas. In addition, the damage detection accuracy reached 98.7%, which is improved by 13.6% when compared with the original network. Full article

(This article belongs to the Special Issue Intelligence Techniques Applied in Infrastructure, Engineering and Construction)

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15 pages, 3030 KiB

Open AccessArticle

Research on Construction Risk Assessment of Long-Span Cantilever Casting Concrete Arch Bridges Based on Triangular Fuzzy Theory and Bayesian Networks

by Zhengyi He, Yi Xiang, Linshu Li, Mei Wei, Bonan Liu and Shuyao Wu

Buildings 2024, 14(9), 2627; https://doi.org/10.3390/buildings14092627 - 24 Aug 2024

Viewed by 717

Abstract

Considering the complex construction processes involved, there are significant risks during the construction of long-span cantilever casting arch bridges. In this study, a risk assessment method for the construction process of cantilever casting concrete arch bridges was developed. The compositional elements and characteristics [...] Read more.

Considering the complex construction processes involved, there are significant risks during the construction of long-span cantilever casting arch bridges. In this study, a risk assessment method for the construction process of cantilever casting concrete arch bridges was developed. The compositional elements and characteristics of safety risks in the construction of cantilever casting concrete arch bridges were clarified, and a safety risk source list that includes seven major risk sources and thirty-three minor risk sources was formed. Then, a Bayesian model for the risk analysis of cantilever casting concrete arch bridge construction was established, and a method was proposed to determine the prior and posterior probabilities of the Bayesian network using triangular fuzzy numbers. This method fully utilizes the experience of experts while avoiding the subjectivity of expert opinions. A cantilever casting concrete open spandrel arch bridge (Bridge A) with a total span length of 287 m was taken as an example, and a safety risk assessment was conducted during its construction process. The calculation results show that the construction safety risk level of Bridge A was level III. This engineering application verified the feasibility of determining key node parameters of the Bayesian network using triangular fuzzy numbers. Full article

(This article belongs to the Special Issue Intelligence Techniques Applied in Infrastructure, Engineering and Construction)

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20 pages, 4316 KiB

Open AccessArticle

Hybrid Intelligent Model for Estimating the Cost of Huizhou Replica Traditional Vernacular Dwellings

by Jian Huang, Wei Huang, Wei Quan and Yandong Xing

Buildings 2024, 14(9), 2623; https://doi.org/10.3390/buildings14092623 - 24 Aug 2024

Viewed by 773

Abstract

Amidst the backdrop of rural revitalization and cultural renaissance, there is a surge in the construction demand for replica traditional vernacular dwellings. Traditional cost estimation methods struggle to meet the need for rapid and precise estimation due to the complexity inherent in their [...] Read more.

Amidst the backdrop of rural revitalization and cultural renaissance, there is a surge in the construction demand for replica traditional vernacular dwellings. Traditional cost estimation methods struggle to meet the need for rapid and precise estimation due to the complexity inherent in their construction. To address this challenge, this study aims to enhance the accuracy and efficiency of cost estimation by innovatively developing an Adaptive Self-Explanatory Convolutional Neural Network (ASCNN) model, tailored to meet the specific cost estimation needs of replica traditional vernacular dwellings in the Huizhou region. The ASCNN model employs a Random Forest model to filter key features, inputs these into the CNN for cost estimation, and utilizes Particle Swarm Optimization (PSO) to optimize parameters, thereby improving predictive accuracy. The decision-making process of the model is thoroughly interpreted through SHAP value analysis, ensuring credibility and transparency. During the construction of the ASCNN model, this study collected and analyzed bidding control price data from 98 replica traditional vernacular dwellings. The empirical results demonstrate that the ASCNN model exhibits outstanding predictive performance on the test set, with a Root Mean Square Error (RMSE) of 9828.06 yuan, a Mean Absolute Percentage Error (MAPE) of 0.6%, and a Coefficient of Determination (R²) as high as 0.989, confirming the model’s high predictive accuracy and strong generalization capability. Through SHAP value analysis, this study further identifies key factors such as floor plan layout, roof area, and column material coefficient that are central to cost prediction. The ASCNN model proposed in this study not only significantly improves the accuracy of cost estimation for Huizhou replica traditional vernacular dwellings, but also enhances its transparency and credibility through model interpretation methods, providing a reliable basis for related investment decisions. The findings of this study also offer valuable references and insights for rapid and precise cost estimation of replica buildings in other regions worldwide. Full article

(This article belongs to the Special Issue Intelligence Techniques Applied in Infrastructure, Engineering and Construction)

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10 pages, 5171 KiB

Open AccessArticle

Study on Deformation of New Tunnels Overcrossing Existing Tunnels Underneath Operating Railways

by Can Xie, Yuhang Qu, Haiyan Lu and Shuguang Song

Buildings 2024, 14(8), 2420; https://doi.org/10.3390/buildings14082420 - 6 Aug 2024

Viewed by 894

Abstract

With the increasing utilization of urban underground space, new tunnels frequently intersect with existing tunnels and operational railways. However, sometimes the excavation and unloading of new tunnels can cause deformation of adjacent existing tunnels and railways, significantly affecting their normal operation. We used [...] Read more.

With the increasing utilization of urban underground space, new tunnels frequently intersect with existing tunnels and operational railways. However, sometimes the excavation and unloading of new tunnels can cause deformation of adjacent existing tunnels and railways, significantly affecting their normal operation. We used finite element software to predict the influence of new tunnel construction on overcrossing existing tunnels and down-traversing operational railways by a dynamic tunneling model based on a connection channel project of the east and west squares of a railway station. This article is not only control the distance between the two tunnels, but the new tunnel and the existing tunnel, as well as the new tunnel and the operation of the railway, the positional relationship between the three, the deformation laws of existing tunnels and operational railways during the construction of new tunnels with different buried depths are analyzed. The results show that the deformation curves of existing tunnels and operational railways present a normal distribution. The maximum deformation position is at the intersection with the new tunnel upon completion of the new tunnel excavation construction. Moreover, an increase in the buried depth of the new tunnel increases the deformation of the operational railway and the existing tunnel. The influence of the depth change of the new tunnel on the settlement of the operational railway is greater than that of the existing tunnel. Full article

(This article belongs to the Special Issue Intelligence Techniques Applied in Infrastructure, Engineering and Construction)

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20 pages, 6504 KiB

Open AccessArticle

Intelligent Identification of Surrounding Rock Grades Based on a Self-Developed Rock Drilling Test System

by Quanwei Liu, Junlong Yan, Hongzhao Li, Peiyuan Zhang, Yankai Liu, Linsheng Liu, Shoujie Ye and Haitao Liu

Buildings 2024, 14(7), 2176; https://doi.org/10.3390/buildings14072176 - 15 Jul 2024

Viewed by 779

Abstract

The classification of surrounding rock is crucial for formulating safe tunnel construction plans and support measures. However, the complex geological environment of tunnels presents a challenge in obtaining accurate drilling parameters for rock mass classification. This paper presents the development of a rock [...] Read more.

The classification of surrounding rock is crucial for formulating safe tunnel construction plans and support measures. However, the complex geological environment of tunnels presents a challenge in obtaining accurate drilling parameters for rock mass classification. This paper presents the development of a rock drilling testing system, which includes a propulsion speed acquisition system, oil pressure acquisition system, air pressure acquisition system, and an automatic data acquisition system. This system enables real-time, high-precision automatic collection and storage of parameters such as propulsion speed, with data collected twice per second for each parameter. Leveraging the Qingdao Metro Line 6 as a case study, we conducted rock mass drilling and constructed a rock mass classification database. By employing kernel density estimation and Pearson correlation analysis, we quantified the correlation between rock mass classification and the drilling parameters. The results indicated that relying on a single drilling parameter is insufficient for accurately determining rock mass classification. Both impact pressure and rotational pressure showed the strongest correlation with rock mass classification, each with a correlation coefficient below −0.8 (indicating a strong negative correlation). Outlier values of drilling parameters were excluded using the interval method. Based on the remaining data, we established an intelligent rock mass classification model using the random forest algorithm. This model demonstrated good accuracy and generalization performance, with an average accuracy exceeding 0.9. The proposed rock drilling testing system, combined with the intelligent rock mass classification model, forms an integrated system for the intelligent identification of rock mass grades. This system has significant implications for the intelligent and safe construction of drill-and-blast tunnels. Full article

(This article belongs to the Special Issue Intelligence Techniques Applied in Infrastructure, Engineering and Construction)

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33 pages, 3699 KiB

Open AccessArticle

Adoption of Fourth Industrial Revolution Technologies in the Construction Sector: Evidence from a Questionnaire Survey

by Julia Menegon Lopes and Luiz Carlos Pinto da Silva Filho

Buildings 2024, 14(7), 2132; https://doi.org/10.3390/buildings14072132 - 11 Jul 2024

Viewed by 1130

Abstract

The fourth industrial revolution (4IR) can significantly benefit the construction sector, improving productivity, efficiency, collaborative efforts, and product quality while promoting safety and sustainability. However, research on applying 4IR technologies in construction is scarce in developing countries. It is crucial to understand the [...] Read more.

The fourth industrial revolution (4IR) can significantly benefit the construction sector, improving productivity, efficiency, collaborative efforts, and product quality while promoting safety and sustainability. However, research on applying 4IR technologies in construction is scarce in developing countries. It is crucial to understand the ability of construction companies to adopt new technologies and identify factors influencing the success of technology implementation. In this study, a questionnaire-based survey was conducted with construction professionals to evaluate the level of technological development of the construction market in an emerging economy, assess the potential for innovation implementation, and identify factors that might influence technological development. The results showed that most innovations are in the early stages of implementation in the construction sector, and their adoption tends to occur differently, depending on the size of the company and the stage of the construction lifecycle in which they operate. Furthermore, technologies tend to be progressively adopted and driven by virtualization technologies. This article presents a framework to assist in decision-making regarding the adoption of 4IR technologies at different phases of the lifecycle of construction projects and identifies the potential barriers and promoters of this adoption in the analyzed context. Full article

(This article belongs to the Special Issue Intelligence Techniques Applied in Infrastructure, Engineering and Construction)

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18 pages, 10065 KiB

Open AccessArticle

Investigations on the Environmental Characteristics and Cracking Control of Plateau Concrete

by Xiaochuan Hu, Manping Liao, Ming Li, Fuqiang Wang, Xiang Lyu and Mei-Ling Zhuang

Buildings 2024, 14(7), 2104; https://doi.org/10.3390/buildings14072104 - 9 Jul 2024

Viewed by 570

Abstract

In the present study, first, the environmental challenges and cracking characteristics during the construction of plateau concrete on the Sichuan–Tibet route were revealed. Then, using a multi-field coupled shrinkage model with hydration temperature humidity constraints, the early and long-term cracking risks in the [...] Read more.

In the present study, first, the environmental challenges and cracking characteristics during the construction of plateau concrete on the Sichuan–Tibet route were revealed. Then, using a multi-field coupled shrinkage model with hydration temperature humidity constraints, the early and long-term cracking risks in the core of plateau pier bodies were investigated. Later, the effects of tensile strength, pouring interval age and adiabatic temperature rise on the cracking risk were analyzed. Finally, various control measures for high-altitude concrete cracking were proposed. The results indicated that the complex environment of the plateau led to different forms of cracks in the pier body, especially vertical cracks in the straight sections. The long-term risk of core cracking in the plateau pier body is significantly greater than the risk of early cracking. This risk was strongly influenced by factors such as the concrete tensile strength, pouring interval age and adiabatic temperature rise, which should be given more attention. Deformation compensation can significantly enhance the peak and residual deformation capacities of plateau concrete, with peak values greater than 900 με and residual deformation greater than 200 με at day 60, as well as its resistance to cracking. Strategies such as adopting radiant cooling techniques, improving construction techniques and implementing effective management measures can all play a vital role in improving the cracking resistance of highland concrete. Full article

(This article belongs to the Special Issue Intelligence Techniques Applied in Infrastructure, Engineering and Construction)

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21 pages, 2886 KiB

Open AccessArticle

Displacement and Internal Force Response of Mechanically Connected Precast Piles Subjected to Horizontal Load Based on the m-Method

by Li Gao, Mei-Ling Zhuang, Qunqun Zhang, Guangdong Bao, Xiaoyang Yu, Jiahao Du, Shengbo Zhou and Mingsen Wang

Buildings 2024, 14(7), 1943; https://doi.org/10.3390/buildings14071943 - 26 Jun 2024

Viewed by 980

Abstract

Mechanically connected precast piles are a type of precast piles that utilise snap-type mechanical connectors to restrain the pile ends of two identical or different precast piles at the top and bottom so as to quickly realise the purpose of the connection. However, [...] Read more.

Mechanically connected precast piles are a type of precast piles that utilise snap-type mechanical connectors to restrain the pile ends of two identical or different precast piles at the top and bottom so as to quickly realise the purpose of the connection. However, the gap problem in the connectors of mechanically connected piles can lead to uneven and uniform deformation of the piles under horizontal loading, resulting in additional displacements and rotation angles of the piles at the connection. Solving the problem of calculating the internal force response of discontinuous deformed piles is a prerequisite for promoting and applying mechanically connected precast piles. Firstly, the theoretical derivation of mechanically connected piles with fixed constraints at the pile bottom is carried out. Secondly, the pile response equations of mechanically connected piles are established, and the theoretical solutions of pile displacement and internal force response of mechanically connected piles under horizontal loading are derived. Thirdly, the pile-soil model of the test pile is established using ABAQUS software (ABAQUS 2016) in combination with the design data of the test pile. The numerical simulation displacements and angles of rotation are compared with the test results. Finally, the theoretical and numerical simulation displacements and internal forces of the ordinary pile and the mechanically connected pile are compared. The relative errors of the displacements and angles of rotation of the established pile-soil model are less than 10%, indicating that the established model has good accuracy. The relative errors of the theoretical and numerical simulation displacements and internal forces of the mechanically connected pile are less than 10%, proving the correctness of the theoretical calculation by the m-method. This study can provide effective theoretical support and methodological guidance for the displacement and internal force response of discontinuous piles. Full article

(This article belongs to the Special Issue Intelligence Techniques Applied in Infrastructure, Engineering and Construction)

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12 pages, 1948 KiB

Open AccessArticle

Classification and Prediction of Rock Mass Boreability Based on Daily Advancement during TBM Tunneling

by Zhiqiang Li, Yufan Tao, Yuchao Du and Xinjie Wang

Buildings 2024, 14(7), 1893; https://doi.org/10.3390/buildings14071893 - 21 Jun 2024

Viewed by 634

Abstract

The rock classification system was initially applied to drill-and-blast tunnels and subsequently adapted for TBM tunnels; however, the majority of these systems primarily focused on rock stability while neglecting considerations of boreability. Compared with conventional tunnels, TBM tunnels are characterized by their rapid [...] Read more.

The rock classification system was initially applied to drill-and-blast tunnels and subsequently adapted for TBM tunnels; however, the majority of these systems primarily focused on rock stability while neglecting considerations of boreability. Compared with conventional tunnels, TBM tunnels are characterized by their rapid tunneling speed and excellent self-stabilization of the rock mass. Therefore, it is imperative to develop a novel rock mass classification system that considers both the tunneling efficiency of TBMs and the required support measures for tunnel construction. This paper introduces a novel rock classification system for TBM tunnels that accurately predicts the construction rate by evaluating the penetration rate and daily utilization, enabling a more precise assessment of daily advancement in tunneling. Firstly, the penetration rate and construction utilization in different rock strata are analyzed based on comprehensive statistics of existing construction data. Consequently, a discriminant matrix for classifying the boreability of rock is derived. Subsequently, employing the Ensemble Classifier method, a regression prediction model for rock boreability classification is established by incorporating input parameters such as thrust, torque, rotational speed, field penetration index, and the uniaxial compressive strength of rock. The validity of the proposed model is verified by comparing predicted machine performance with actual data sets. The proposed method presents a novel approach for predicting the performance of TBM construction. Full article

(This article belongs to the Special Issue Intelligence Techniques Applied in Infrastructure, Engineering and Construction)

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12 pages, 3006 KiB

Open AccessArticle

Effect of Moisture Content and Wet–Dry Cycles on the Strength Properties of Unsaturated Clayey Sand

by Chuan Wang, Weimin Yang, Ning Zhang, Senwei Wang, Chuanyi Ma, Meixia Wang and Zhiyuan Zhang

Buildings 2024, 14(5), 1375; https://doi.org/10.3390/buildings14051375 - 11 May 2024

Viewed by 883

Abstract

Based on the actual situation of the project on the Weihai–Yanhai Expressway section of Rongwu Expressway, the effects of water content change and the dry–wet cycle on the mechanical behavior of unsaturated clayey sandy soil were analyzed in this study. In this study, [...] Read more.

Based on the actual situation of the project on the Weihai–Yanhai Expressway section of Rongwu Expressway, the effects of water content change and the dry–wet cycle on the mechanical behavior of unsaturated clayey sandy soil were analyzed in this study. In this study, ventilated undrained triaxial shear tests were carried out on unsaturated clayey sandy soils with different water contents (6%, 8%, 10%, 12%, 14% and 16%). Concurrently, the soil samples were subjected to three distinct wet and dry cycle pathways (2~22%, 2~12%, and 12~22%) to gain an understanding of how the mechanical features of the soil changed under the different conditions. The test findings demonstrate that when the water content increases, the unsaturated clayey sandy soil’s cohesiveness and shear strength diminish. The strength of shear decline exhibits a pattern of first being quick, followed by sluggish. The strength of shear and cohesiveness of clayey sandy soil declined under the influence of the dry and wet cycles, with the first cycle primarily affecting variations in cohesiveness and strength of shear. Furthermore, the strength of shear and cohesiveness of clayey sandy soil diminish more with increasing wet and dry cycle amplitude and upper water content limits. Lastly, the drying shrinkage and hygroscopic expansion of clay particles in clayey sandy soils during wet and dry cycles are not significant, resulting in less structural damage and deterioration of the mechanical properties of the soils. The study’s findings have a significant impact on the durability of roadbeds made of unsaturated clayey sandy soil in both wet and dry situations. Full article

(This article belongs to the Special Issue Intelligence Techniques Applied in Infrastructure, Engineering and Construction)

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18 pages, 7074 KiB

Open AccessArticle

Numerical Investigation on the Seismic Behavior of Novel Precast Beam–Column Joints with Mechanical Connections

by Mei-Ling Zhuang, Chuanzhi Sun, Zhen Yang, Ran An, Liutao Bai, Yixiang Han and Guangdong Bao

Buildings 2024, 14(5), 1199; https://doi.org/10.3390/buildings14051199 - 23 Apr 2024

Cited by 1 | Viewed by 1098

Abstract

Traditional cast-in-place beam–column joints have the defects of high complexity and high construction difficulty, which seriously affect the efficiency and safety of the building construction line, and precast beam–column joints (PBCJs) can greatly improve the construction efficiency and quality. At present, the investigations [...] Read more.

Traditional cast-in-place beam–column joints have the defects of high complexity and high construction difficulty, which seriously affect the efficiency and safety of the building construction line, and precast beam–column joints (PBCJs) can greatly improve the construction efficiency and quality. At present, the investigations on the seismic behavior of precast reinforced concrete structures are still mainly focused on experiments, while the numerical simulations for their own characteristics are still relatively lacking. In the present study, the seismic behavior of novel precast beam–column joints with mechanical connections (PBCJs-MCs) is investigated numerically. Based on the available experimental data, fiber models for four PBCJs-MCs are developed. Then, the simulated and experimental seismic behaviors of the prefabricated BCJs are compared and discussed. Finally, the factors influencing the seismic behavior of the PBCJs-MCs are further investigated numerically. The numerical results indicate that the fiber models can consider the effect of the bond–slip relationship of concrete and reinforcement under reciprocating loads. The relative errors of the simulated seismic behavior indexes are about 15%. The bearing capacity and displacement ductility coefficients of the PBCJs-MCs decrease rapidly as the shear-to-span ratio (λ) increases. It is recommended that the optimum λ for PBCJs-MCs is 2.0–2.5. The effect of the axial load ratio on the seismic behavior of PBCJs-MCs can be negligible in the case of the PBCJs-MCs with a moderate value of λ. Full article

(This article belongs to the Special Issue Intelligence Techniques Applied in Infrastructure, Engineering and Construction)

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14 pages, 6648 KiB

Open AccessArticle

Study of Fatigue Performance of Ultra-Short Stud Connectors in Ultra-High Performance Concrete

by Ran An, You-Zhi Wang, Mei-Ling Zhuang, Zhen Yang, Chang-Jin Tian, Kai Qiu, Meng-Ying Cheng and Zhao-Yuan Lv

Buildings 2024, 14(4), 1179; https://doi.org/10.3390/buildings14041179 - 21 Apr 2024

Viewed by 1206

Abstract

Steel–UHPC composite bridge decking made of ultra-high performance concrete (UHPC) has been progressively employed to reinforce historic steel bridges. The coordinated force and deformation between the steel deck and UHPC are therefore greatly influenced by the shear stud connectors at the shear interface. [...] Read more.

Steel–UHPC composite bridge decking made of ultra-high performance concrete (UHPC) has been progressively employed to reinforce historic steel bridges. The coordinated force and deformation between the steel deck and UHPC are therefore greatly influenced by the shear stud connectors at the shear interface. Four fatigue push-out specimens of ultra-short studs with an aspect ratio of 1.84 in UHPC were examined to investigate the fatigue properties of ultra-short studs with an aspect ratio below 2.0 utilized in UHPC reinforcing aged steel bridges. The test results indicated that three failure modes—fracture surface at stud shank, fracture surface at steel flange, and fracture surface at stud cap—were noted for ultra-short studs in UHPC under various load ranges. The fatigue life decreased from 1287.3 × 10⁴ to 24.4 × 10⁴ as the shear stress range of the stud increased from 88.2 MPa to 158.8 MPa. The UHPC can ensure that the failure mode of the specimens was stud shank failure. Based on the test and literature results, a fatigue strength design S–N curve for short studs in UHPC was proposed, and calculation models for stiffness degradation and plastic slip accumulation of short studs in UHPC were established. The employment of ultra-short studs in the field of UHPC reinforcing aging steel bridges can be supported by the research findings. Full article

(This article belongs to the Special Issue Intelligence Techniques Applied in Infrastructure, Engineering and Construction)

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