Structural Concrete最新文献

{"title":"Machine learning assisted prediction of the mechanical properties of carbon nanotube‐incorporated concrete","authors":"Muhammad Imran, Hassan Amjad, Shayan Khan, Shehroze Ali","doi":"10.1002/suco.202400727","DOIUrl":"https://doi.org/10.1002/suco.202400727","url":null,"abstract":"The incorporation of carbon nanotubes (CNTs) in concrete can improve the physical, mechanical, and durability properties. However, the interaction of CNTs with concrete and their effect on the mechanical properties remains a challenging issue. Also, the determination of mechanical properties through experimental testing is time‐consuming, laborious, and uneconomical. This study focuses on the development of machine learning (ML) models for the prediction of the mechanical properties of concrete. A comprehensive data set of 758 CNT‐modified concrete specimens was established for the compressive strength (CS), split tensile strength (STS), flexural strength (FS), and modulus of elasticity (MOE) values from the experimental studies in the literature. Afterward, the predictive models were developed using multilinear regression (MLR), support vector machine (SVM), ensemble methods (EN), regression tree (RT), and Gaussian process regression (GPR). It was found that among ML models, the GPR model predicted the CS, STS, and FS at the highest efficiency with the coefficient of determination (<jats:italic>R</jats:italic><jats:sup>2</jats:sup>) of 0.83, 0.78, and 0.93, respectively while the performance of the SVM model was superior for predicting MOE with an <jats:italic>R</jats:italic><jats:sup>2</jats:sup> value of 0.91. The mean absolute error (MAE) of the GPR model for CS, STS, FS, and MOE were 2.92, 0.26, 0.35, and 1.31, respectively which were also lesser than other models. The training time of different models demonstrated that the GPR model has also a lower training time (~3 s) as compared to other models which indicates it has a high accuracy‐to‐time cost ratio. Further, the most influential parameters on CS were age, cement, water–cement ratio, and carbon nanotubes. The one‐way partial dependence analysis showed a direct correlation for age and cement but an inverse correlation for the water–cement ratio and fine aggregate. The graphical user interface provides the implication of the developed models for practical applications.","PeriodicalId":21988,"journal":{"name":"Structural Concrete","volume":"4 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142204013","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An analytical solution for shear bearing capacity of circumferential joints of precast concrete segmental tunnel linings considering dowel action","authors":"Rizwan Amjad, Yumeng Zhang, Xian Liu","doi":"10.1002/suco.202400250","DOIUrl":"https://doi.org/10.1002/suco.202400250","url":null,"abstract":"The capacity of the circumferential joint of the precast concrete segmental tunnel lining (PCTL) structure in terms of shear performance principally includes the dowel action by connector/bolt as well as friction force, and it is a vital parameter to assess the mechanical response of the circumferential joint. Further, as there was no analytical model available for precise estimation of a circumferential joint in terms of the shear‐bearing capacity considering the dowel action of the bolt in the presence of axial/normal force, therefore in this investigation, an analytical model has been proposed to estimate the shear‐bearing capacity of the circumferential joint. Furthermore, the analytical model's precision and accuracy were validated via large‐scale experimental investigation on a circumferential joint of PCTL. Upon comparing analytical model outcomes with experimental results, absolute error varied between +5% and −9%, with an average value of the coefficient of friction at the yield point of the bolt. Moreover, the formation of hinges on the side of the bolt within the segment was considered a failure of the circumferential joint. Additionally, the parametric investigation revealed that with just a 1% change in axial force, the diameter, pre‐tightening, and yield strength of the bolt and concrete strength improved by 2.85%, 1%, 0.27%, 0.26% and 0.17% shear‐bearing capacity of the circumferential joint respectively. Axial force variation greatly influences the shear‐bearing capacity of circumferential joint followed by diameter, pre‐tightening, yield strength of the bolt, and concrete strength. Conclusively, with analysis of axial force distribution around the ring for the tunnel, the proposed model has been applied to a full ring to estimate shear bearing capacity.","PeriodicalId":21988,"journal":{"name":"Structural Concrete","volume":"40 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142204017","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Shear performance of basalt fiber composite RC beams with different laminated heights of basalt fiber","authors":"Ting Xia, Wei Zhang, Min Huang, Hua Huang","doi":"10.1002/suco.202400032","DOIUrl":"https://doi.org/10.1002/suco.202400032","url":null,"abstract":"Basalt fiber (BF) is known for its high tensile strength, low elastic modulus, and environmental friendliness. To investigate the influence of basalt fiber reinforced concrete (BFRC) lamination heights on the beams' shear performance, four basalt fiber reinforced concrete and reinforced concrete (BFRC‐RC) beams featuring diverse laminated heights were fabricated and underwent bending tests. To further investigate the impact of stirrup and shear span ratios on the shear performance of BFRC‐RC beams, finite element models (FEMs) were established based on the experiments. The results indicated that four test beams experienced diagonal shear failure. Compared to RC beams, BFRC‐RC beams exhibited heightened ductility and stiffness. Additionally, as the BFRC laminated height rose, both cracking and peak loads increased. Compared to BFRC‐RC beams without stirrups, stirrups in those beams transitioned the diagonal shear failure to flexural failure. Stirrups in BFRC‐RC beams increased both the yield and peak loads, thereby enhancing their ductility. With a reduction in the shear span ratio, BFRC‐RC beams increased in both yield and peak loads, accompanied by a simultaneous decrease in yield and peak displacement. Finally, a model incorporating the influence of laminated height on BFRC‐RC beams' behavior was introduced to predict their bearing capacity. The theoretical values aligned well with the experimental results.","PeriodicalId":21988,"journal":{"name":"Structural Concrete","volume":"66 1 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142204015","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Probabilistic evaluation of failure time of reinforced concrete frame in post‐earthquake fire scenario","authors":"Majid Moradi, HamidReza Tavakoli, GholamReza Abdollahzade","doi":"10.1002/suco.202300353","DOIUrl":"https://doi.org/10.1002/suco.202300353","url":null,"abstract":"This paper aims at assessing the failure time of a 7‐story reinforced concrete (RC) frame in a post‐earthquake fire (PEF) event probabilistically. Cumulative distribution functions (CDF) of the studied frame's failure time in various seismic load intensities have been calculated and presented with the aid of Monte Carlo analysis. Seismic load intensity, failure time, and failure probability are three parameters that are correlated through probabilistic analysis. The effects of cracking, spalling, and residual deformations resulted from the seismic load are considered in the strength of structure against the fire load. Seismic load intensity, materials properties, gravity load, and geometry are considered as random variables and one probabilistic analysis has been carried out for each seismic load intensity. The results have illustrated that in low seismic load intensities, probabilistic values of failure time in a structure subjected to pure fire load are equal to the one exposed to PEF. With the increase of seismic load intensity, the effects of cracking, spalling, and residual deformations would lead to a decline in the strength of structural elements against PEF scenario. The failure time in 50% failure probability for Sa = 0.2 g, Sa = 1 g, and Sa = 2 g intensities has been calculated as 14,300, 12,200, and 5100 s, respectively. The analysis results have shown that in an unspecified seismic load intensity, the failure time of the 7‐story RC frame for the 50% occurrence probability is equal to 9750 s.","PeriodicalId":21988,"journal":{"name":"Structural Concrete","volume":"1 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142204016","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Simplified method for predicting the internal forces in strut‐and‐tie model of cable pylon anchorage zone in a cable‐stayed bridge","authors":"Shengyu Li, Erwin Lim, Zhengqing Chen, Yu Hong, Qianhui Pu","doi":"10.1002/suco.202300926","DOIUrl":"https://doi.org/10.1002/suco.202300926","url":null,"abstract":"The mechanical behavior of cable pylon anchorage zone in a cable‐stayed bridge is complex due to high localized stresses. A strut‐and‐tie model (STM) has been introduced in this paper, which is recommended as an efficient way to analyze the disturbed region. However, predicting the internal forces in the tie members in the STM by integrating stresses was time‐consuming and inefficient. To address this issue, the principle of minimum strain energy was used to analyze the STM of the cable pylon anchorage zone. A simplified method was presented to assess the internal forces in the cable pylon anchorage zone. Moreover, an actual bridge (Cao'e River Bridge) was employed to be analyzed, and the prestressed steel strands in the bridge were obtained by the simplified method. A full‐scale test model of the bridge was fabricated to validate the accuracy of the simplified method. Furthermore, based on the simplified method, the effect of the thickness of front wall, the length of inner opening straight section, the thickness of side wall, the thickness of inner wall and the width of inner opening straight section on the internal force in the tie members in the STM was studied. The results show that the length of inner opening straight section has negligible effect on the internal forces in all tie members. Compared with the thickness of the side wall, the thickness of inner wall and the width of inner opening straight section have limited effect on the internal force of tie members. This study was expected to promote the design of cable pylon anchorage zone.","PeriodicalId":21988,"journal":{"name":"Structural Concrete","volume":"1 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142204014","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ductility‐oriented design of UHPC T‐beams: Mechanical model and design recommendations","authors":"Mujahed Alsomiri, Zhao Liu, Tao Wang, Jie Meng","doi":"10.1002/suco.202400214","DOIUrl":"https://doi.org/10.1002/suco.202400214","url":null,"abstract":"Ultrahigh performance concrete (UHPC) has recently become a major focus garnering substantial attention due to its remarkable mechanical properties. UHPC has been increasingly employed across diverse projects in the construction industry. However, the structural ductility of UHPC members has yet to be fully established and is often compromised by the manifestation of the crack localization phenomenon. This paper presents the flexural test results of five T‐beams and introduces a model for predicting the flexural capacity and failure modes of UHPC T‐beams. The model employs the curvature ductility index as a measurement for evaluating and ensuring the member's ductility. The results show that the flexural behavior of UHPC T‐beams can be characterized by four key points representing cracking, reinforcement yielding, crack localization, and post‐localization capacity. The validity of the model is substantiated by experimental data from this study and complemented by test data collected from the literature. The proposed model is then employed to derive ductility‐oriented design limits, including minimum and maximum reinforcement ratios and minimum localization strain capacity. Finally, the paper summarizes the design recommendations and provides a classification of section conditions, reinforcement limits, localization strain limits, adequate ductility range, and the feasible ductile design range.","PeriodicalId":21988,"journal":{"name":"Structural Concrete","volume":"33 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142204020","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of fire severity and concrete properties on the thermo‐hygral behavior of concrete during fire exposure","authors":"Umang Pulkit, Satadru Das Adhikary, Venkatesh Kodur","doi":"10.1002/suco.202400067","DOIUrl":"https://doi.org/10.1002/suco.202400067","url":null,"abstract":"Since the world is transitioning toward performance based design, the study of thermo‐hygral behavior of concrete when subjected to real fire becomes crucial. Fire accidents have revealed that nominal fire curves cannot be applied because of varying severity of real fire. In 2008, traveling fire concept was developed in which severity is dependent on heat release rate and fire size. This study explores the effect of fire severity and other concrete properties like strength, aggregate type, and relative humidity. The proposed model has been developed by combining the principles of mechanics and thermodynamics and upon validation with the experimental results, a reasonable agreement has been observed. It can be concluded that severity of fire is directly related to thermo‐hygral behavior of concrete. On the other hand, this study also highlights the influence of type of aggregate and moisture content in addition to the traditional variables like volume fraction of solid and permeability. On studying the influence of type of aggregate, it can be concluded that recycled aggregate concrete performed better than conventional concrete. The integration of proposed model in the performance based design is a leap toward development of resilient structure subjected to dynamic fire conditions.","PeriodicalId":21988,"journal":{"name":"Structural Concrete","volume":"6 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142204018","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Research on the mechanical performance of circular concrete‐filled steel tube columns under bending‐torsional coupling","authors":"Fa‐xing Ding, Xin‐yu Huang, Chen‐jie Gong, Zheng‐bo Pi","doi":"10.1002/suco.202400128","DOIUrl":"https://doi.org/10.1002/suco.202400128","url":null,"abstract":"Under the influence of wind and horizontal seismic forces, structures such as piers in curved beam bridges, main arches of steel tube concrete arch bridges, and frame columns may experience combined bending‐torsion stress states, affecting the safe usage of the structure. To investigate the mechanical performance of circular concrete‐filled steel tube(CFST) columns under bending‐torsional coupling, a three‐dimensional solid‐shell finite element model of circular concrete‐filled steel tube columns under various bending and torsion ratios (<jats:italic>k</jats:italic>) was established using ABAQUS software, and validated with existing experiments on such columns under bending‐torsional loading. Parametric analysis was conducted to explore the trends of interface slip and the restraining effect in circular concrete‐filled steel tube columns under different bending and torsion ratios, analyzing the impact of parameters such as the yield strength of steel, concrete strength, steel content in the cross‐section, and shear–span ratio on the combined bearing capacity. The results of the parametric analysis show that: (1) with the increase of <jats:italic>k</jats:italic>, the relative slip at the interface between the core concrete and the outer steel tube first increases and then decreases, with interface slip leading to a reduction in the load‐bearing capacity; (2) the relative slip at the interface between the core concrete and the outer steel tube first increases and then decreases, with interface slip leading to a reduction in the load‐bearing capacity; (3) with the increase of <jats:italic>k</jats:italic>, the circumferential and axial stresses in the steel tube surface of the circular concrete‐filled steel tube columns increase, while the shear stress decreases, leading to a transition in the failure mode of the columns from combined bending‐torsional failure to bending‐shear failure. Based on these findings, a practical calculation formula for the bending‐torsional combined bearing capacity of circular concrete‐filled steel tube columns is proposed, offering high calculation accuracy and serving as a reference for the design of such components.","PeriodicalId":21988,"journal":{"name":"Structural Concrete","volume":"36 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142204019","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Predicting slump for high‐performance concrete using decision tree and support vector regression approaches coupled with phasor particle swarm optimization algorithm","authors":"Qingmei Sun, Yu Gongping","doi":"10.1002/suco.202300450","DOIUrl":"https://doi.org/10.1002/suco.202300450","url":null,"abstract":"The main focus of this study is to assess the slump characteristics of high‐performance concrete (HPC) using decision tree (DT) and support vector regression (SVR) models. In the first step, the models were solely fed via HPC samples to reproduce the slump rates. By coupling phasor particle swarm optimization (PPSO) to main models, hybrid DT‐PPSO and SVR‐PPSO frameworks, simulate the slump rates accurately. Using the correlation of determination and root mean square error (MAE) metrics for the DT, 96.04 and 5.097 were computed, respectively. SVR was obtained at 92.62 and 6.965, alternatively. In the hybrid approach, DT‐PPSO could improve by 3% and 55% in terms of correlation of determination and root MAE, respectively. DT‐PPSO appeared high‐accuracy model compared to others; however, a single DT had more desirable results than SVR. Overall, the advantages of this study encompass its methodological approach, comparative insights, and practical relevance, offering valuable contributions to the understanding and prediction of mechanical slump in HPC.","PeriodicalId":21988,"journal":{"name":"Structural Concrete","volume":"43 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142204021","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Shear and interface shear fatigue of semi‐precast slabs with lattice girders under cyclic loading","authors":"Matthias Hillebrand, Annkathrin Sinning, Josef Hegger","doi":"10.1002/suco.202400219","DOIUrl":"https://doi.org/10.1002/suco.202400219","url":null,"abstract":"More and more often, semi‐precast reinforced concrete slabs with lattice girders are employed for industrial buildings or bridges, where they are exposed to high cycle fatigue loading. Despite research in recent years that has led to the formulation of an <jats:italic>S</jats:italic>–<jats:italic>N</jats:italic> curve for lattice girders, the effects of cyclic loading on semi‐precast slabs have not yet been sufficiently clarified. Moreover, research has so far been limited to single‐span slabs. The effects of continuous slab systems, which are mainly realized in buildings and bridges, cannot be considered in the calculation of fatigue resistance yet. To improve the fatigue design concept for shear and interface shear, theoretical and experimental investigations were conducted at the Institute of Structural Concrete, RWTH Aachen University. In addition to the fatigue behavior of 16 tests under cyclic loading, particular attention is paid to the increase in shear and interface shear resistance at the inner support of continuous slabs. Furthermore, the influences of the support detailing were investigated. The findings illustrate further potential for optimization of the design under cyclic loading.","PeriodicalId":21988,"journal":{"name":"Structural Concrete","volume":"11 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141930959","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}