This paper presented the experimental results of the strength capacity of studs embedded centrally in concrete with red mud synthetic coarse aggregates, with the variation of the handcrafted headed stud thickness (3.17, 4.76, 6.35, and 7.9 mm) and no shank bond influence with concrete. The results regarding the compressive strength of concrete showed considerable strength gain with synthetic coarse aggregate, ranging from 27.00 to 43.50 MPa, while in concrete with natural coarse aggregate, the variation was 27.00 to 36.50 MPa. Also, it was observed that the cracking in the concrete matrix of the synthetic coarse aggregate occurred in the aggregate instead of the transition zone, as occurred with the natural coarse aggregate concrete. However, the solid morphological formation of synthetic coarse aggregate provided excellent chemical adhesion to the headed stud, providing a hardening failure behavior after reaching the yield strength value of the steel bar with higher displacements. This can enable the optimized consumption of materials in the dosage of low‐strength structural concrete and the anchoring application of studs with smaller‐headed thicknesses, up to 8% of head diameter, generating economy and sustainability.
{"title":"Pull‐out tests of handcrafted studs embedded in concrete with red mud synthetic coarse aggregate","authors":"Aaron Nzambi, Dênio Oliveira","doi":"10.1002/suco.202300437","DOIUrl":"https://doi.org/10.1002/suco.202300437","url":null,"abstract":"This paper presented the experimental results of the strength capacity of studs embedded centrally in concrete with red mud synthetic coarse aggregates, with the variation of the handcrafted headed stud thickness (3.17, 4.76, 6.35, and 7.9 mm) and no shank bond influence with concrete. The results regarding the compressive strength of concrete showed considerable strength gain with synthetic coarse aggregate, ranging from 27.00 to 43.50 MPa, while in concrete with natural coarse aggregate, the variation was 27.00 to 36.50 MPa. Also, it was observed that the cracking in the concrete matrix of the synthetic coarse aggregate occurred in the aggregate instead of the transition zone, as occurred with the natural coarse aggregate concrete. However, the solid morphological formation of synthetic coarse aggregate provided excellent chemical adhesion to the headed stud, providing a hardening failure behavior after reaching the yield strength value of the steel bar with higher displacements. This can enable the optimized consumption of materials in the dosage of low‐strength structural concrete and the anchoring application of studs with smaller‐headed thicknesses, up to 8% of head diameter, generating economy and sustainability.","PeriodicalId":21988,"journal":{"name":"Structural Concrete","volume":"21 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141531832","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}
António Ramos, Carla Marchão, João Nuno Pacheco, Alejandro Enfedaque, Dario Coronelli, Duarte Faria, Jorge de Brito, Miguel Fernández Ruiz, Rui Marreiros
This paper presents a state‐of‐art regarding the punching of flat slabs made with coarse recycled concrete aggregate concrete (CRCAC). Punching shear is a phenomenon that occurs in reinforced concrete slabs when concentrated loads are applied near a column or other support. It refers to the failure mechanism where the concrete reaches shear failure at a critical section around the column. CRCAC is a structural material that conforms with circular economy concepts, but its design for punching using current formulae may be unsafe due to the lower strength of the concrete that can be caused by the shape or the surface cleanness of the recycled aggregates when compared with the natural ones. The results highlight the need for further research on this area, since the available experimental results are few and mainly from tests with thin slab specimens. Since the punching phenomenon is dependent on the scale effect, it is mandatory to have more results for slabs with representative thickness. The applicability of the models for punching resistance in EC2, ACI318‐19, and the upcoming second generation of EC2 was also investigated. These codes can produce safe estimates for CRCAC slabs. However, it was found that the second generation of EC2 is less conservative than the other models.
{"title":"A review of punching behavior of slab–column connections with recycled coarse aggregate concrete","authors":"António Ramos, Carla Marchão, João Nuno Pacheco, Alejandro Enfedaque, Dario Coronelli, Duarte Faria, Jorge de Brito, Miguel Fernández Ruiz, Rui Marreiros","doi":"10.1002/suco.202400435","DOIUrl":"https://doi.org/10.1002/suco.202400435","url":null,"abstract":"This paper presents a state‐of‐art regarding the punching of flat slabs made with coarse recycled concrete aggregate concrete (CRCAC). Punching shear is a phenomenon that occurs in reinforced concrete slabs when concentrated loads are applied near a column or other support. It refers to the failure mechanism where the concrete reaches shear failure at a critical section around the column. CRCAC is a structural material that conforms with circular economy concepts, but its design for punching using current formulae may be unsafe due to the lower strength of the concrete that can be caused by the shape or the surface cleanness of the recycled aggregates when compared with the natural ones. The results highlight the need for further research on this area, since the available experimental results are few and mainly from tests with thin slab specimens. Since the punching phenomenon is dependent on the scale effect, it is mandatory to have more results for slabs with representative thickness. The applicability of the models for punching resistance in EC2, ACI318‐19, and the upcoming second generation of EC2 was also investigated. These codes can produce safe estimates for CRCAC slabs. However, it was found that the second generation of EC2 is less conservative than the other models.","PeriodicalId":21988,"journal":{"name":"Structural Concrete","volume":"46 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141531833","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}
The scarcity of comprehensive data on the shear properties of reinforced GP‐concrete beams without shear reinforcement has hindered their widespread use, mainly due to challenges in predicting their shear performance. This study examines the influence of incorporating up to 15% waste glass powder (GP) with two separate particle size categories: GP‐A (55 to 135 μm) and GP‐B (finer than 55 μm) as a cement replacement on the 180‐day shear performance of reinforced concrete beams with varying cement content and without stirrups. To accomplish this, a total of 14 beams were used, all sharing identical dimensions measuring 200 mm × 250 mm × 2000 mm. The aforementioned parameters were investigated for their effects on the shear performance of beams, including crack patterns, modes of failure, load–deflection behavior, and strength capacities at different loading stages. Furthermore, this investigation explores the applicability of the most commonly used design codes of practice for predicting the shear strength of reinforced GP‐modified concrete beams. These codes are typically employed to design the shear strength of reinforced conventional concrete shallow beams without shear reinforcement. The study's findings indicate that the impact of GP particle size on the shear performance of beams with the same GP content is almost negligible. Additionally, the study found that incorporating GP into concrete beams does not have any negative effects on their cracking load capacity, shear strength, or flexural cracking load capacity. In fact, it can even improve the latter. A comparison of experimental results with predictions from the design codes revealed that both the CEB‐FIP (1990) equation and the ACI equations provided safe estimates of shear strength for the tested beams. However, the CEB‐FIP (1990) equation yielded predictions with a lower mean, standard deviation, and coefficient of variation compared with the ACI equations, suggesting a higher level of accuracy in its estimates. The findings affirm the suitability of GP‐concrete as a viable alternative in concrete structures specifically engineered to withstand shear forces.
由于缺乏有关无剪切配筋的加筋 GP 混凝土梁剪切性能的全面数据，阻碍了它们的广泛应用，这主要是由于在预测其剪切性能方面存在挑战。本研究探讨了掺入 15% 的废玻璃粉（GP）对两种不同粒径类别的影响：GP-A（55 至 135 μm）和 GP-B（细于 55 μm）作为水泥替代品，对水泥含量不同且无箍筋的钢筋混凝土梁 180 天抗剪性能的影响。为此，共使用了 14 根梁，所有梁的尺寸相同，均为 200 mm × 250 mm × 2000 mm。研究了上述参数对梁剪切性能的影响，包括裂缝模式、破坏模式、荷载-挠度行为以及不同加载阶段的强度能力。此外，这项研究还探讨了最常用的设计规范对预测钢筋 GP 改性混凝土梁抗剪强度的适用性。这些规范通常用于设计无抗剪钢筋的传统钢筋混凝土浅梁的抗剪强度。研究结果表明，在 GP 含量相同的情况下，GP 粒径对梁剪切性能的影响几乎可以忽略不计。此外，研究还发现，在混凝土梁中加入 GP 不会对其开裂承载能力、抗剪强度或抗弯开裂承载能力产生任何负面影响。事实上，它甚至可以提高后者。将实验结果与设计规范的预测结果进行比较后发现，CEB-FIP（1990 年）方程和 ACI 方程都为测试梁提供了安全的剪切强度估计值。不过，与 ACI 方程相比，CEB-FIP（1990）方程得出的预测结果的平均值、标准偏差和变异系数都更低，这表明其估计结果的准确性更高。这些研究结果肯定了 GP 混凝土作为专门设计用于承受剪力的混凝土结构的可行替代品的适用性。
{"title":"Evaluating the shear performance of reinforced concrete beams using waste glass powder as a sustainable cement substitute","authors":"Brwa Omer, Jalal Saeed","doi":"10.1002/suco.202301002","DOIUrl":"https://doi.org/10.1002/suco.202301002","url":null,"abstract":"The scarcity of comprehensive data on the shear properties of reinforced GP‐concrete beams without shear reinforcement has hindered their widespread use, mainly due to challenges in predicting their shear performance. This study examines the influence of incorporating up to 15% waste glass powder (GP) with two separate particle size categories: GP‐A (55 to 135 μm) and GP‐B (finer than 55 μm) as a cement replacement on the 180‐day shear performance of reinforced concrete beams with varying cement content and without stirrups. To accomplish this, a total of 14 beams were used, all sharing identical dimensions measuring 200 mm × 250 mm × 2000 mm. The aforementioned parameters were investigated for their effects on the shear performance of beams, including crack patterns, modes of failure, load–deflection behavior, and strength capacities at different loading stages. Furthermore, this investigation explores the applicability of the most commonly used design codes of practice for predicting the shear strength of reinforced GP‐modified concrete beams. These codes are typically employed to design the shear strength of reinforced conventional concrete shallow beams without shear reinforcement. The study's findings indicate that the impact of GP particle size on the shear performance of beams with the same GP content is almost negligible. Additionally, the study found that incorporating GP into concrete beams does not have any negative effects on their cracking load capacity, shear strength, or flexural cracking load capacity. In fact, it can even improve the latter. A comparison of experimental results with predictions from the design codes revealed that both the CEB‐FIP (1990) equation and the ACI equations provided safe estimates of shear strength for the tested beams. However, the CEB‐FIP (1990) equation yielded predictions with a lower mean, standard deviation, and coefficient of variation compared with the ACI equations, suggesting a higher level of accuracy in its estimates. The findings affirm the suitability of GP‐concrete as a viable alternative in concrete structures specifically engineered to withstand shear forces.","PeriodicalId":21988,"journal":{"name":"Structural Concrete","volume":"20 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141523053","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}
Zineb Moujoud, Said Sair, Hanane Ait Ousaleh, Othmane Amadine, Ikrame Ayouch, Mohamed Zahouily, Abdeslam El Bouari, Omar Tanane
This study presents a cost‐effective and eco‐friendly method to produce aluminosilicate materials using red brick waste (RBW) and metakaolin (MK) as silica and alumina precursors. RBW was subjected to alkaline fusion to increase its dissolution for geopolymerization reaction. Response surface methodology was used to investigate the effect of NaOH concentration and fusion temperature on the leaching of silica and alumina from RBW. The microstructure of the alkali‐fused RBW was analyzed using x‐ray diffraction and Fourier‐transform infrared spectroscopy. Response surface methodology confirmed and revealed that higher NaOH concentration (14 M) and a temperature of 660°C favored solubilized phase development, resulting in 85% and 50% leached silica and alumina, respectively. These optimized parameters were then employed to prepare geopolymer materials with different proportions of alkali‐fused RBW and MK, using NaOH and Na2SiO3 as the alkaline solution. The elaborated geopolymer binders were characterized using various techniques such as x‐ray diffraction (DRX), Fourier‐transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermal conductivity (λ), and fire resistance. The results showed that geopolymers containing 30 wt.% of alkali‐fused RBW exerted good mechanical and thermal insulation properties compared to conventional cement materials. However, excessive RBW addition causes negative effects. In addition, it was found that the blended geopolymers exhibited an increase in heat release rate (HRR), resulting in reduced fire resistance due to the presence of unreacted NaOH. Overall, these findings confirmed the potential sustainable use of RBW to partially replace MK in geopolymer as a material for building construction.
{"title":"High‐performance geopolymer from brick wastes and metakaolin: Alkali treatment optimization, phase transformation, and property analysis","authors":"Zineb Moujoud, Said Sair, Hanane Ait Ousaleh, Othmane Amadine, Ikrame Ayouch, Mohamed Zahouily, Abdeslam El Bouari, Omar Tanane","doi":"10.1002/suco.202400142","DOIUrl":"https://doi.org/10.1002/suco.202400142","url":null,"abstract":"This study presents a cost‐effective and eco‐friendly method to produce aluminosilicate materials using red brick waste (RBW) and metakaolin (MK) as silica and alumina precursors. RBW was subjected to alkaline fusion to increase its dissolution for geopolymerization reaction. Response surface methodology was used to investigate the effect of NaOH concentration and fusion temperature on the leaching of silica and alumina from RBW. The microstructure of the alkali‐fused RBW was analyzed using x‐ray diffraction and Fourier‐transform infrared spectroscopy. Response surface methodology confirmed and revealed that higher NaOH concentration (14 M) and a temperature of 660°C favored solubilized phase development, resulting in 85% and 50% leached silica and alumina, respectively. These optimized parameters were then employed to prepare geopolymer materials with different proportions of alkali‐fused RBW and MK, using NaOH and Na<jats:sub>2</jats:sub>SiO<jats:sub>3</jats:sub> as the alkaline solution. The elaborated geopolymer binders were characterized using various techniques such as x‐ray diffraction (DRX), Fourier‐transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermal conductivity (<jats:italic>λ</jats:italic>), and fire resistance. The results showed that geopolymers containing 30 wt.% of alkali‐fused RBW exerted good mechanical and thermal insulation properties compared to conventional cement materials. However, excessive RBW addition causes negative effects. In addition, it was found that the blended geopolymers exhibited an increase in heat release rate (HRR), resulting in reduced fire resistance due to the presence of unreacted NaOH. Overall, these findings confirmed the potential sustainable use of RBW to partially replace MK in geopolymer as a material for building construction.","PeriodicalId":21988,"journal":{"name":"Structural Concrete","volume":"23 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141523056","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}
Fetih Kefyalew, Thanongsak Imjai, Reyes Garcia, Nguyen Khanh Son
Recycled aggregate concrete (RAC) is increasingly being used in the construction of structural elements. However, the performance of RAC elements under fire is usually considered to be inferior to that of normal concrete (NC) elements. This study investigates the fire behavior of RAC composite steel slabs with and without openings. Ten slabs of size of 1.0 m × 2.2 m were cast either with no opening, one or two circular openings, and one or two square openings. Five of the slabs were manufactured with 100% RAC, while the other five slabs were made with NC. The concrete slabs were loaded and subjected to fire tests at a temperature of about 900°C for 120 min. Test results show that RAC composite slabs have lower stiffness (thus larger mid‐span deflections) under fire exposure compared to their counterpart NC slabs. In terms of the recorded temperature–time curves, RAC slabs showed similar performance to that of NC slabs. The ratio of soffit temperature to the temperature at the top of slab was considerably smaller for RAC slabs compared to NC slabs. RAC slabs also showed more spalling than NC slabs. Experimental test results were numerically verified using PyroSim® software with the two showing good agreement. A series of new design charts for composite RAC slabs with desired fire endurance are proposed. This study is expected to promote the wider use of RAC in construction of structural elements, particularly of composite slabs exposed to extreme temperatures.
{"title":"Fire behavior of high‐contents recycled aggregate concrete composite slabs with small openings","authors":"Fetih Kefyalew, Thanongsak Imjai, Reyes Garcia, Nguyen Khanh Son","doi":"10.1002/suco.202400242","DOIUrl":"https://doi.org/10.1002/suco.202400242","url":null,"abstract":"Recycled aggregate concrete (RAC) is increasingly being used in the construction of structural elements. However, the performance of RAC elements under fire is usually considered to be inferior to that of normal concrete (NC) elements. This study investigates the fire behavior of RAC composite steel slabs with and without openings. Ten slabs of size of 1.0 m × 2.2 m were cast either with no opening, one or two circular openings, and one or two square openings. Five of the slabs were manufactured with 100% RAC, while the other five slabs were made with NC. The concrete slabs were loaded and subjected to fire tests at a temperature of about 900°C for 120 min. Test results show that RAC composite slabs have lower stiffness (thus larger mid‐span deflections) under fire exposure compared to their counterpart NC slabs. In terms of the recorded temperature–time curves, RAC slabs showed similar performance to that of NC slabs. The ratio of soffit temperature to the temperature at the top of slab was considerably smaller for RAC slabs compared to NC slabs. RAC slabs also showed more spalling than NC slabs. Experimental test results were numerically verified using PyroSim® software with the two showing good agreement. A series of new design charts for composite RAC slabs with desired fire endurance are proposed. This study is expected to promote the wider use of RAC in construction of structural elements, particularly of composite slabs exposed to extreme temperatures.","PeriodicalId":21988,"journal":{"name":"Structural Concrete","volume":"344 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141505599","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}
Ahmed Monier, Mohamed A. Saifeldeen, Nariman Fouad
This paper presents a finite element (FE) modeling approach to assess the performance of reinforced concrete (RC) beams strengthened in shear using external polymer cement mortar (PCM)‐bonded basalt fiber‐reinforced polymer (BFRP) grids. The study begins with an experimental program and FE modeling of a double shear bond test, simulating the bond behavior between the BFRP grid and RC beams with PCM. Subsequently, a FE model for BFRP shear‐strengthened beams explores key parameters, including shear span to depth ratio, bonding agent type (PCM and epoxy resin), and angles between BFRP grid bars and the beam axis. Comparative analysis with experimental results verifies the accuracy of the FE models. Additionally, a critical parameter, the BFRP reinforcement ratio, is numerically investigated, revealing that achieving a ratio between 1.33% and 1.55% enhances both maximum load and deflection in beams strengthened with externally bonded composite reinforced mortar.
{"title":"Numerical analysis of reinforced concrete beams enhanced in shear with external polymer cement mortar‐bonded FRP grid","authors":"Ahmed Monier, Mohamed A. Saifeldeen, Nariman Fouad","doi":"10.1002/suco.202400054","DOIUrl":"https://doi.org/10.1002/suco.202400054","url":null,"abstract":"This paper presents a finite element (FE) modeling approach to assess the performance of reinforced concrete (RC) beams strengthened in shear using external polymer cement mortar (PCM)‐bonded basalt fiber‐reinforced polymer (BFRP) grids. The study begins with an experimental program and FE modeling of a double shear bond test, simulating the bond behavior between the BFRP grid and RC beams with PCM. Subsequently, a FE model for BFRP shear‐strengthened beams explores key parameters, including shear span to depth ratio, bonding agent type (PCM and epoxy resin), and angles between BFRP grid bars and the beam axis. Comparative analysis with experimental results verifies the accuracy of the FE models. Additionally, a critical parameter, the BFRP reinforcement ratio, is numerically investigated, revealing that achieving a ratio between 1.33% and 1.55% enhances both maximum load and deflection in beams strengthened with externally bonded composite reinforced mortar.","PeriodicalId":21988,"journal":{"name":"Structural Concrete","volume":"57 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141531834","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}
Karel Van Den Hende, Robby Caspeele, Miroslav Sykora, Andrew Way
In the last decade, structural reliability and safety efforts have been oriented toward the assessment of existing structures and the development of related target reliability levels. However, up‐to‐date there is no consensus on the reliability philosophy that should be followed when considering the assessment of heritage structures, and the level of reliability which is appropriate to them. In this study, a framework is proposed which derives new values for the economically optimal target reliability for the upgrade of a structure, , and the reliability threshold for upgrade, , considering the cultural heritage value of the structure. The total expected life cycle cost is minimized, assuming that the structure is given up after collapse, as heritage value is typically lost after failure. The target reliability values are based on three main parameters: the relative annual benefit of using the structure (affected by its heritage value), the relative cost of failure and the relative cost of increasing the reliability. Target reliability values are proposed specifically for heritage structures, considering a range of the main input parameters.
{"title":"Target reliabilities for heritage structures derived from cost optimization","authors":"Karel Van Den Hende, Robby Caspeele, Miroslav Sykora, Andrew Way","doi":"10.1002/suco.202400268","DOIUrl":"https://doi.org/10.1002/suco.202400268","url":null,"abstract":"In the last decade, structural reliability and safety efforts have been oriented toward the assessment of existing structures and the development of related target reliability levels. However, up‐to‐date there is no consensus on the reliability philosophy that should be followed when considering the assessment of heritage structures, and the level of reliability which is appropriate to them. In this study, a framework is proposed which derives new values for the economically optimal target reliability for the upgrade of a structure, , and the reliability threshold for upgrade, , considering the cultural heritage value of the structure. The total expected life cycle cost is minimized, assuming that the structure is given up after collapse, as heritage value is typically lost after failure. The target reliability values are based on three main parameters: the relative annual benefit of using the structure (affected by its heritage value), the relative cost of failure and the relative cost of increasing the reliability. Target reliability values are proposed specifically for heritage structures, considering a range of the main input parameters.","PeriodicalId":21988,"journal":{"name":"Structural Concrete","volume":"39 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141523054","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}
Jundong Fu, Shui Wan, Jie Xiao, Xiao Wang, Peng Zhou, Kevin Dekemele
Accelerated bridge construction is crucial in bridge engineering. In order to improve the seismic performance of prefabricated columns, this study proposes using ultra‐high performance concrete (UHPC) in the plastic hinge areas of prefabricated columns with bellows grouting connections. In particular, cyclic loading tests are carried out on four 1/3‐scaled columns, including two cast‐in‐place columns and two bellows grouting connection columns. The results show that columns with UHPC in the plastic hinge areas exhibit larger lateral and ultimate bearing capacity, ductility, cumulative energy dissipation, and stiffness compared to those with conventional concrete. Additionally, bellows grouting connection column with UHPC shows superior seismic performance compared to cast‐in‐place column with conventional concrete. The proposed finite element analysis model is in a good agreement with the test results. Through using finite element analysis, three key parameters influencing the seismic performance of bellows grouting columns are examined, and the optimal combination of these parameters is identified.
{"title":"Cyclic loading test for prefabricated ultra‐high performance concrete columns with bellows grouting connection","authors":"Jundong Fu, Shui Wan, Jie Xiao, Xiao Wang, Peng Zhou, Kevin Dekemele","doi":"10.1002/suco.202301170","DOIUrl":"https://doi.org/10.1002/suco.202301170","url":null,"abstract":"Accelerated bridge construction is crucial in bridge engineering. In order to improve the seismic performance of prefabricated columns, this study proposes using ultra‐high performance concrete (UHPC) in the plastic hinge areas of prefabricated columns with bellows grouting connections. In particular, cyclic loading tests are carried out on four 1/3‐scaled columns, including two cast‐in‐place columns and two bellows grouting connection columns. The results show that columns with UHPC in the plastic hinge areas exhibit larger lateral and ultimate bearing capacity, ductility, cumulative energy dissipation, and stiffness compared to those with conventional concrete. Additionally, bellows grouting connection column with UHPC shows superior seismic performance compared to cast‐in‐place column with conventional concrete. The proposed finite element analysis model is in a good agreement with the test results. Through using finite element analysis, three key parameters influencing the seismic performance of bellows grouting columns are examined, and the optimal combination of these parameters is identified.","PeriodicalId":21988,"journal":{"name":"Structural Concrete","volume":"19 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141505600","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}
Haytham F. Isleem, Tang Qiong, Naga Dheeraj Kumar Reddy Chukka, Rakesh Kumar, T. Vamsi Nagaraju, Asmaa Y. Hamed
Fiber‐reinforced polymer (FRP)‐confined double‐skin tubular columns (DSTCs) are an innovative type of hybrid columns that consist of an outer tube made of FRP, an inner circular steel tube, and a concrete core sandwiched between them. Available literature focuses on hollow DSTCs with limited research on DSTCs made with inner steel tubes filled with concrete. Overall, DSTCs have many applications, highlighting the importance of studying the effects of concrete filling and strength on the composite system. To address this gap, finite element models (FEMs) and both traditional and innovative machine learning (ML) techniques were used to develop accurate models for predicting load‐bearing capacity and confined ultimate strain under axial loads. A comprehensive database of 60 experimental tests and 45 FEMs simulations of columns was analyzed, with five parameters selected as input variables for ML‐based models. New techniques like gradient boosting (GB), random forest (RF), convolutional neural networks, and long short‐term memory are compared with established algorithms like multiple linear regression, support vector regression (SVR), and empirical mode decomposition (EMD)‐SVR. Regression error characteristics curve, Shapley Additive Explanation analysis, and statistical metrics are used to assess the performance of these models using a database containing 105 FEMs test results that cover a range of input variables. While EMD‐SVR and GB perform well for confined ultimate strain, the suggested EMD‐SVR, GB, and RF models show superior predictive accuracy for confined ultimate load. To be more precise, for confined ultimate load prediction, EMD‐SVR, GB, and RF obtain values of 0.99, 0.989, and 0.960, respectively. The values for GB and EMD‐SVR at confined ultimate strain are 0.690 and 0.99, respectively. However, design engineers are limited by the “black‐box” nature of ML. In order to solve this, the study presents an open‐source GUI based on GB, which gives engineers the ability to precisely estimate confined ultimate load and strain under various test conditions, enabling them to make well‐informed decisions about mix proportion.
{"title":"Machine learning and nonlinear finite element analysis of fiber‐reinforced polymer‐confined concrete‐steel double‐skin tubular columns under axial compression","authors":"Haytham F. Isleem, Tang Qiong, Naga Dheeraj Kumar Reddy Chukka, Rakesh Kumar, T. Vamsi Nagaraju, Asmaa Y. Hamed","doi":"10.1002/suco.202300835","DOIUrl":"https://doi.org/10.1002/suco.202300835","url":null,"abstract":"Fiber‐reinforced polymer (FRP)‐confined double‐skin tubular columns (DSTCs) are an innovative type of hybrid columns that consist of an outer tube made of FRP, an inner circular steel tube, and a concrete core sandwiched between them. Available literature focuses on hollow DSTCs with limited research on DSTCs made with inner steel tubes filled with concrete. Overall, DSTCs have many applications, highlighting the importance of studying the effects of concrete filling and strength on the composite system. To address this gap, finite element models (FEMs) and both traditional and innovative machine learning (ML) techniques were used to develop accurate models for predicting load‐bearing capacity and confined ultimate strain under axial loads. A comprehensive database of 60 experimental tests and 45 FEMs simulations of columns was analyzed, with five parameters selected as input variables for ML‐based models. New techniques like gradient boosting (GB), random forest (RF), convolutional neural networks, and long short‐term memory are compared with established algorithms like multiple linear regression, support vector regression (SVR), and empirical mode decomposition (EMD)‐SVR. Regression error characteristics curve, Shapley Additive Explanation analysis, and statistical metrics are used to assess the performance of these models using a database containing 105 FEMs test results that cover a range of input variables. While EMD‐SVR and GB perform well for confined ultimate strain, the suggested EMD‐SVR, GB, and RF models show superior predictive accuracy for confined ultimate load. To be more precise, for confined ultimate load prediction, EMD‐SVR, GB, and RF obtain values of 0.99, 0.989, and 0.960, respectively. The values for GB and EMD‐SVR at confined ultimate strain are 0.690 and 0.99, respectively. However, design engineers are limited by the “black‐box” nature of ML. In order to solve this, the study presents an open‐source GUI based on GB, which gives engineers the ability to precisely estimate confined ultimate load and strain under various test conditions, enabling them to make well‐informed decisions about mix proportion.","PeriodicalId":21988,"journal":{"name":"Structural Concrete","volume":"30 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141523055","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}
Cristiana Chiorino, Mario Alberto Chiorino, Elisabetta Margiotta Nervi
The legacy of Pier Luigi Nervi spans globally, showcasing excellence in construction and artistry. Conservation of his architectural marvels poses challenges due to material fragility and societal shifts. Preservation efforts require interdisciplinary collaboration among engineers, historians, and architects. Exhibitions on Nervi and UNESCO nominations highlight the importance of Nervi's work. Strategies for safeguarding his masterpieces are evolving, focusing on documentation and renovation. Although some structures faced damage during World War II, most remain structurally sound. However, common degradation of structural concrete, such as carbonation‐induced rebar corrosion, may affect structures in service since multiple decades, particularly in cases of inadequate concrete cover. Nervi's meticulous design and construction methods often mitigate such decay, especially in thin ferrocement elements. In addition, it must be considered that, as most of 20th century's structures, Nervi's structures were usually conceived without accounting for seismic actions, but only for static configurations, in accordance with the technical standards at the time. All this requires ongoing conservation and where needed rehabilitation efforts to ensure the cultural and social significance of Nervi's legacy is appreciated and preserved for future generations.
皮埃尔-路易吉-内尔维（Pier Luigi Nervi）的遗产遍布全球，展示了卓越的建筑艺术。由于材料的脆弱性和社会的变迁，保护他的建筑奇迹面临着挑战。保护工作需要工程师、历史学家和建筑师之间的跨学科合作。有关内尔维的展览和联合国教科文组织的提名凸显了内尔维作品的重要性。保护其杰作的战略正在不断发展，重点是文献和翻新。虽然一些建筑在二战期间遭到破坏，但大多数结构仍然完好。然而，混凝土结构的常见退化，如碳化引起的钢筋腐蚀，可能会影响几十年后仍在使用的结构，特别是在混凝土覆盖不足的情况下。Nervi 的精心设计和施工方法通常可以减轻这种退化，特别是在薄铁水泥构件中。此外，还必须考虑到，与 20 世纪的大多数结构一样，内尔维的结构在设计时通常没有考虑地震作用，而只是按照当时的技术标准进行静态配置。所有这些都需要持续的保护和必要的修复工作，以确保内尔维遗产的文化和社会意义得到重视，并为子孙后代保留下来。
{"title":"The art and science of building by pier Luigi Nervi: A modern vision and a heritage to be preserved","authors":"Cristiana Chiorino, Mario Alberto Chiorino, Elisabetta Margiotta Nervi","doi":"10.1002/suco.202400389","DOIUrl":"https://doi.org/10.1002/suco.202400389","url":null,"abstract":"The legacy of Pier Luigi Nervi spans globally, showcasing excellence in construction and artistry. Conservation of his architectural marvels poses challenges due to material fragility and societal shifts. Preservation efforts require interdisciplinary collaboration among engineers, historians, and architects. Exhibitions on Nervi and UNESCO nominations highlight the importance of Nervi's work. Strategies for safeguarding his masterpieces are evolving, focusing on documentation and renovation. Although some structures faced damage during World War II, most remain structurally sound. However, common degradation of structural concrete, such as carbonation‐induced rebar corrosion, may affect structures in service since multiple decades, particularly in cases of inadequate concrete cover. Nervi's meticulous design and construction methods often mitigate such decay, especially in thin ferrocement elements. In addition, it must be considered that, as most of 20th century's structures, Nervi's structures were usually conceived without accounting for seismic actions, but only for static configurations, in accordance with the technical standards at the time. All this requires ongoing conservation and where needed rehabilitation efforts to ensure the cultural and social significance of Nervi's legacy is appreciated and preserved for future generations.","PeriodicalId":21988,"journal":{"name":"Structural Concrete","volume":"29 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141195249","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}
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