The speed of assembly and structural reliability of prefabricated prefinished volumetric constructions (PPVCs) are closely dependant on the interconnections linking modules. Among these interconnections, those with frictional mechanisms can offer greater efficiency in modular construction. This paper investigates the structural performance of a novel frictional interconnection through experimental and numerical studies. Initially, A joint composed of innovative interconnection and common intra-connection (beam-to-column connection) was prefabricated and tested under cyclic loading. The numerical models of the experimental sample are developed using ABAQUS software, subsequently validated against experimental results. Then, the impact of different support conditions (pin or roller) on joint behaviour is investigated. The outcomes indicates that the joint can effectively be used in moment-resisting frames in PPVCs as a result of its adequate stiffness, being classified as a rigid connection based on AISC 316–22. The interconnection reaches its maximum load capacity through rod yielding, while the other components remained intact. Numerical simulations reveal that no sliding occurs between the endplates during the test, indicating the adequacy of axial loads. Furthermore, changing the support conditions can affect the response of the joint, governed by the beam's and the interconnection's moment capacity.
{"title":"Rocking interconnection for moment resisting modular buildings: Experimental and numerical investigation","authors":"Babak Atashfaraz , Pejman Sharafi , Parisa Shadan , Alireza Goudarzi","doi":"10.1016/j.jcsr.2024.109139","DOIUrl":"10.1016/j.jcsr.2024.109139","url":null,"abstract":"<div><div>The speed of assembly and structural reliability of prefabricated prefinished volumetric constructions (PPVCs) are closely dependant on the interconnections linking modules. Among these interconnections, those with frictional mechanisms can offer greater efficiency in modular construction. This paper investigates the structural performance of a novel frictional interconnection through experimental and numerical studies. Initially, A joint composed of innovative interconnection and common intra-connection (beam-to-column connection) was prefabricated and tested under cyclic loading. The numerical models of the experimental sample are developed using ABAQUS software, subsequently validated against experimental results. Then, the impact of different support conditions (pin or roller) on joint behaviour is investigated. The outcomes indicates that the joint can effectively be used in moment-resisting frames in PPVCs as a result of its adequate stiffness, being classified as a rigid connection based on AISC 316–22. The interconnection reaches its maximum load capacity through rod yielding, while the other components remained intact. Numerical simulations reveal that no sliding occurs between the endplates during the test, indicating the adequacy of axial loads. Furthermore, changing the support conditions can affect the response of the joint, governed by the beam's and the interconnection's moment capacity.</div></div>","PeriodicalId":15557,"journal":{"name":"Journal of Constructional Steel Research","volume":"224 ","pages":"Article 109139"},"PeriodicalIF":4.0,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652336","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-13DOI: 10.1016/j.jcsr.2024.109156
Chengquan Wang , Huihui Li , Liang Xu , Kaixin Xu , Licai Zhao , Qian Chen
This study proposed a novel external replaceable energy-dissipating device (EREDD) to enhance the seismic performance of prefabricated segmental concrete filled steel tubular bridge piers (PS-CFST bridge piers), while maintaining the construction efficiency of conventional segmentally assembled prefabricated piers with dry joints. The effectiveness and applicability of EREDDs in improving the seismic performance of PS-CFST bridge piers were studied through the cyclic tests. The inelastic cyclic response of PS-CFST bridge pier specimens with different arrangements of EREDDs was experimentally examined. A detailed account of the test results was provided and discussed, including the stiffness and strength characteristics, strain distributions, residual displacements, failure patterns, as well as hysteretic response and energy dissipation capability. Particular attention was also given within the experimental assessment to investigating the effects of the inter-segmental joint opening positions for the different EREDD arrangements on the seismic response of PS-CFST bridge piers. Based on the experimental findings, an analytical approach was developed for determining the hysteretic response of the proposed PS-CFST bridge piers incorporating EREDDs, offering the basis for their design and assessment in practice. Finally, the results indicate that EREDDs could effectively improve the seismic performance of PS-CFST bridge piers and the hysteretic response could be accurately predicted by using the proposed analytical approach. In addition, EREDDs allow the damage of PS-CFST bridge piers to be concentrated within the easily replaceable component, and thereby facilitating the controlled damage. This study provides an effective method for the seismic design of PS-CFST bridge piers incorporating EREDDs.
{"title":"Seismic performance of PS-CFST bridge piers with novel external replaceable energy dissipating devices","authors":"Chengquan Wang , Huihui Li , Liang Xu , Kaixin Xu , Licai Zhao , Qian Chen","doi":"10.1016/j.jcsr.2024.109156","DOIUrl":"10.1016/j.jcsr.2024.109156","url":null,"abstract":"<div><div>This study proposed a novel external replaceable energy-dissipating device (EREDD) to enhance the seismic performance of prefabricated segmental concrete filled steel tubular bridge piers (PS-CFST bridge piers), while maintaining the construction efficiency of conventional segmentally assembled prefabricated piers with dry joints. The effectiveness and applicability of EREDDs in improving the seismic performance of PS-CFST bridge piers were studied through the cyclic tests. The inelastic cyclic response of PS-CFST bridge pier specimens with different arrangements of EREDDs was experimentally examined. A detailed account of the test results was provided and discussed, including the stiffness and strength characteristics, strain distributions, residual displacements, failure patterns, as well as hysteretic response and energy dissipation capability. Particular attention was also given within the experimental assessment to investigating the effects of the inter-segmental joint opening positions for the different EREDD arrangements on the seismic response of PS-CFST bridge piers. Based on the experimental findings, an analytical approach was developed for determining the hysteretic response of the proposed PS-CFST bridge piers incorporating EREDDs, offering the basis for their design and assessment in practice. Finally, the results indicate that EREDDs could effectively improve the seismic performance of PS-CFST bridge piers and the hysteretic response could be accurately predicted by using the proposed analytical approach. In addition, EREDDs allow the damage of PS-CFST bridge piers to be concentrated within the easily replaceable component, and thereby facilitating the controlled damage. This study provides an effective method for the seismic design of PS-CFST bridge piers incorporating EREDDs.</div></div>","PeriodicalId":15557,"journal":{"name":"Journal of Constructional Steel Research","volume":"224 ","pages":"Article 109156"},"PeriodicalIF":4.0,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652337","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-12DOI: 10.1016/j.jcsr.2024.109135
Sibo Qian , Xiuli Xu , Jian Guan , Rengui Wang , Chong Wu , Changqing Chu , Zhijun Li , Xuehong Li
To mitigate the risk of fatigue cracking in orthotropic steel decks (OSDs), this study proposed a new open-rib orthotropic steel deck (NOSD). The NOSD incorporates spherical flat steel open ribs and apple-shaped cut-outs in the floorbeam. The fatigue performance in the floorbeam region of the NOSD was evaluated through numerical analysis and fatigue tests and compared with that of a conventional double-sided welded U-rib orthotropic steel deck (UOSD). The results indicate that the NOSD effectively eliminates the fatigue cracking mode at the rib-to-deck welded joint, ensuring that this area is no longer fatigue critical. Under the most unfavorable loading conditions, the primary factor contributing to fatigue damage on the floorbeam side of the rib-to-floorbeam welded joint of the NOSD is out-of-plane stress, whereas in-plane stress is the main fatigue damage factor in the arc cutouts. Compared with the UOSD, the NOSD exhibited a significantly longer fatigue life, highlighting its enhanced fatigue resistance. The fatigue cracking modes in the floorbeam region of the NOSD include cracks initiating near the weld toe on the floorbeam side and propagating upward along the weld, as well as cracks starting at the arcs of the two cutouts, expanding toward the center, and ultimately intersecting.
{"title":"Fatigue behavior in the Floorbeam region of new open-rib orthotropic steel deck","authors":"Sibo Qian , Xiuli Xu , Jian Guan , Rengui Wang , Chong Wu , Changqing Chu , Zhijun Li , Xuehong Li","doi":"10.1016/j.jcsr.2024.109135","DOIUrl":"10.1016/j.jcsr.2024.109135","url":null,"abstract":"<div><div>To mitigate the risk of fatigue cracking in orthotropic steel decks (OSDs), this study proposed a new open-rib orthotropic steel deck (NOSD). The NOSD incorporates spherical flat steel open ribs and apple-shaped cut-outs in the floorbeam. The fatigue performance in the floorbeam region of the NOSD was evaluated through numerical analysis and fatigue tests and compared with that of a conventional double-sided welded U-rib orthotropic steel deck (UOSD). The results indicate that the NOSD effectively eliminates the fatigue cracking mode at the rib-to-deck welded joint, ensuring that this area is no longer fatigue critical. Under the most unfavorable loading conditions, the primary factor contributing to fatigue damage on the floorbeam side of the rib-to-floorbeam welded joint of the NOSD is out-of-plane stress, whereas in-plane stress is the main fatigue damage factor in the arc cutouts. Compared with the UOSD, the NOSD exhibited a significantly longer fatigue life, highlighting its enhanced fatigue resistance. The fatigue cracking modes in the floorbeam region of the NOSD include cracks initiating near the weld toe on the floorbeam side and propagating upward along the weld, as well as cracks starting at the arcs of the two cutouts, expanding toward the center, and ultimately intersecting.</div></div>","PeriodicalId":15557,"journal":{"name":"Journal of Constructional Steel Research","volume":"224 ","pages":"Article 109135"},"PeriodicalIF":4.0,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652365","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-11DOI: 10.1016/j.jcsr.2024.109136
Lan Kang , Jufei Jin , Xinpei Liu , Haizhou Chen
Laser-cladding (LC) additive manufacturing technology can be applied to repair local damage in steel structures. However, the process creates a distinctive surface morphology due to the overlap of weld beads on the repair surface, resulting in noticeable pit defects between adjacent weld beads. Under specific load conditions, these defects, or saying surface roughness, may cause significant stress concentration in localised areas of LC additively manufactured sheets. This stress concentration could adversely impact the mechanical properties of the LC additively manufactured sheets, including their stiffness, strength and ductility. This paper addresses this issue by testing smooth and rough surface tensile coupon specimens with different thicknesses produced by laser-cladding additive manufacturing technology. The rough surface specimens were geometrically characterised in detail by using 3D scanning technique, and the thickness distribution characteristics of the rough surface specimens were analysed based on the 3D scanning results. Tensile tests were then conducted on both smooth and rough surface specimens of different thicknesses, revealing that surface roughness indeed adversely affects the mechanical parameters of the LC sheets. The degree of degradation was also found to be related to the thickness of the specimens. Accordingly, a correlation analysis was performed among the degree of degradation, surface roughness and specimen thickness. Empirical formulae were proposed to predict the degree of degradation in the mechanical properties of the LC sheets due to surface roughness based on the results of the correlation analysis.
{"title":"Effects of surface roughness on mechanical properties of laser-cladding additively manufactured 316L stainless steel sheets","authors":"Lan Kang , Jufei Jin , Xinpei Liu , Haizhou Chen","doi":"10.1016/j.jcsr.2024.109136","DOIUrl":"10.1016/j.jcsr.2024.109136","url":null,"abstract":"<div><div>Laser-cladding (LC) additive manufacturing technology can be applied to repair local damage in steel structures. However, the process creates a distinctive surface morphology due to the overlap of weld beads on the repair surface, resulting in noticeable pit defects between adjacent weld beads. Under specific load conditions, these defects, or saying surface roughness, may cause significant stress concentration in localised areas of LC additively manufactured sheets. This stress concentration could adversely impact the mechanical properties of the LC additively manufactured sheets, including their stiffness, strength and ductility. This paper addresses this issue by testing smooth and rough surface tensile coupon specimens with different thicknesses produced by laser-cladding additive manufacturing technology. The rough surface specimens were geometrically characterised in detail by using 3D scanning technique, and the thickness distribution characteristics of the rough surface specimens were analysed based on the 3D scanning results. Tensile tests were then conducted on both smooth and rough surface specimens of different thicknesses, revealing that surface roughness indeed adversely affects the mechanical parameters of the LC sheets. The degree of degradation was also found to be related to the thickness of the specimens. Accordingly, a correlation analysis was performed among the degree of degradation, surface roughness and specimen thickness. Empirical formulae were proposed to predict the degree of degradation in the mechanical properties of the LC sheets due to surface roughness based on the results of the correlation analysis.</div></div>","PeriodicalId":15557,"journal":{"name":"Journal of Constructional Steel Research","volume":"224 ","pages":"Article 109136"},"PeriodicalIF":4.0,"publicationDate":"2024-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652451","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-10DOI: 10.1016/j.jcsr.2024.109147
Guixiang Xue , Jingli Miao , Dan Zhang , Shixu Zuo , Chen Zhang , Ning Li
Precast segment self-centering concrete filled steel tube (PSCFST) bridge has become a research hotspot in the field of infrastructure because of its excellent seismic performance and self-centering resilience. However, the highly nonlinear response of bridge structures due to their size and complexity poses a serious challenge to the accurate prediction of their seismic response, especially under extreme conditions such as earthquakes. This study presents a prediction method utilizing a temporal convolutional neural network prediction method to accurately forecasting the acceleration response of PSCFST bridge under seismic actions. The dataset was constructed by integrating data obtained from PSCFST single-span bridge shaking table tests and finite element model simulations. The Temporal Convolutional Network (TCN) model is employed as the training architecture, using acceleration time histories from diverse ground motions as inputs and the acceleration response of the bridge's superstructure as the training output. The TCN model employs causal expansion convolution to effectively capture long-term dependence in the time series data of the bridge structure's acceleration response. Furthermore, superposition of residual blocks enables the extraction of more profound nonlinear features at each data layer, thereby facilitating precise forecasting of acceleration responses in the bridge superstructure. The TCN model ensures capturing longer-span temporal correlations while reducing the model parameters, thereby achieving accurate and efficient prediction of bridge seismic response. Detailed comparative experiments were conducted among various algorithmic models, including Recurrent Neural Network (RNN), Long Short-Term Memory (LSTM), Support Vector Regression (SVR), Extreme Gradient Boosting (XGBoost), and Random Forest Regression (RFR). The results validate that the TCN model demonstrates higher prediction accuracy, better generalization capability, faster training speed, and fewer model parameters. These findings comprehensively demonstrate the superiority of the TCN model in predicting bridge vibration responses, offering an effective prediction methodology for enhancing the safety and reliability of bridge structures under seismic actions.
{"title":"Seismic acceleration response prediction method of the PSCFST bridge based on TCN","authors":"Guixiang Xue , Jingli Miao , Dan Zhang , Shixu Zuo , Chen Zhang , Ning Li","doi":"10.1016/j.jcsr.2024.109147","DOIUrl":"10.1016/j.jcsr.2024.109147","url":null,"abstract":"<div><div>Precast segment self-centering concrete filled steel tube (PSCFST) bridge has become a research hotspot in the field of infrastructure because of its excellent seismic performance and self-centering resilience. However, the highly nonlinear response of bridge structures due to their size and complexity poses a serious challenge to the accurate prediction of their seismic response, especially under extreme conditions such as earthquakes. This study presents a prediction method utilizing a temporal convolutional neural network prediction method to accurately forecasting the acceleration response of PSCFST bridge under seismic actions. The dataset was constructed by integrating data obtained from PSCFST single-span bridge shaking table tests and finite element model simulations. The Temporal Convolutional Network (TCN) model is employed as the training architecture, using acceleration time histories from diverse ground motions as inputs and the acceleration response of the bridge's superstructure as the training output. The TCN model employs causal expansion convolution to effectively capture long-term dependence in the time series data of the bridge structure's acceleration response. Furthermore, superposition of residual blocks enables the extraction of more profound nonlinear features at each data layer, thereby facilitating precise forecasting of acceleration responses in the bridge superstructure. The TCN model ensures capturing longer-span temporal correlations while reducing the model parameters, thereby achieving accurate and efficient prediction of bridge seismic response. Detailed comparative experiments were conducted among various algorithmic models, including Recurrent Neural Network (RNN), Long Short-Term Memory (LSTM), Support Vector Regression (SVR), Extreme Gradient Boosting (XGBoost), and Random Forest Regression (RFR). The results validate that the TCN model demonstrates higher prediction accuracy, better generalization capability, faster training speed, and fewer model parameters. These findings comprehensively demonstrate the superiority of the TCN model in predicting bridge vibration responses, offering an effective prediction methodology for enhancing the safety and reliability of bridge structures under seismic actions.</div></div>","PeriodicalId":15557,"journal":{"name":"Journal of Constructional Steel Research","volume":"224 ","pages":"Article 109147"},"PeriodicalIF":4.0,"publicationDate":"2024-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652401","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-08DOI: 10.1016/j.jcsr.2024.109127
B. Kövesdi, D. Kollár, B. Szabó, L. Dunai
Corrosion measurements were performed on the 175-years-old historical Széchenyi Chain Bridge within the last four decades; most lately under its reconstruction process in 2022. Measurement results are evaluated, and the findings encompass the structural corrosion loss of the chain elements (eyebars). A multi-phase nonlinear corrosion model, with time-dependent Weibull distribution parameters, is developed for bridges over rivers in urban environment. The model is capable of considering the time prior to corrosion initiation corresponding to the start of corrosion protection coating failure. Prediction of structural integrity and performance of chain elements is crucial to ensure reliable operation of such a historical structure. Therefore, multiple scenarios of possible corrosion progression are analysed with and without maintenance to estimate the evolution of corrosion damage over time. Probabilistic finite element calculations are carried out to predict the probability of failure of the chain elements subjected to pure tension. Partial safety factor of Eurocode, determined through Monte Carlo simulations with a response surface, ranges from 1.16 to 1.41 for corroded elements, assuming no renewal of the corrosion protection. Renewal of the coating significantly reduces probability, resulting in a partial safety factor of 1.17. Stochastic analysis indicates adequate load-bearing capacity of the chain elements for at least 20 years without significant renewal of the corrosion protection system.
{"title":"Probabilistic failure assessment of steel eyebars by considering multi-phase nonlinear corrosion model","authors":"B. Kövesdi, D. Kollár, B. Szabó, L. Dunai","doi":"10.1016/j.jcsr.2024.109127","DOIUrl":"10.1016/j.jcsr.2024.109127","url":null,"abstract":"<div><div>Corrosion measurements were performed on the 175-years-old historical Széchenyi Chain Bridge within the last four decades; most lately under its reconstruction process in 2022. Measurement results are evaluated, and the findings encompass the structural corrosion loss of the chain elements (eyebars). A multi-phase nonlinear corrosion model, with time-dependent Weibull distribution parameters, is developed for bridges over rivers in urban environment. The model is capable of considering the time prior to corrosion initiation corresponding to the start of corrosion protection coating failure. Prediction of structural integrity and performance of chain elements is crucial to ensure reliable operation of such a historical structure. Therefore, multiple scenarios of possible corrosion progression are analysed with and without maintenance to estimate the evolution of corrosion damage over time. Probabilistic finite element calculations are carried out to predict the probability of failure of the chain elements subjected to pure tension. Partial safety factor of Eurocode, determined through Monte Carlo simulations with a response surface, ranges from 1.16 to 1.41 for corroded elements, assuming no renewal of the corrosion protection. Renewal of the coating significantly reduces probability, resulting in a partial safety factor of 1.17. Stochastic analysis indicates adequate load-bearing capacity of the chain elements for at least 20 years without significant renewal of the corrosion protection system.</div></div>","PeriodicalId":15557,"journal":{"name":"Journal of Constructional Steel Research","volume":"224 ","pages":"Article 109127"},"PeriodicalIF":4.0,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652400","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-07DOI: 10.1016/j.jcsr.2024.109145
Son Tung Vy , Anh Tuan Vu
In this research study, based on suitable and rational thermal and sequentially coupled structural FE (finite element) analyses, the fire resistance behaviour and FRLs (fire resistance levels) of non-load bearing LSF (light gauge steel framed) walls with restrained thermal elongation were deeply analysed. The FE analysis results confirmed that CFS (cold-formed steel) channel studs of the mentioned walls collapsed prematurely due to additional compression loads caused by the effects of fire and the thermal elongation restraints at stud ends, which led to the reduced FRLs of these walls. Besides, the wall height and the clearance between the stud ends and rigid floors were shown as having significant effects on the FRLs of non-load bearing LSF walls with restrained thermal elongation. In contrast, the effects of the thickness and depth of CFS channel studs and cavity insulation were inconsiderable. Finally, a simplified and reliable design equation and some recommendations were proposed for some types of non-load bearing fire-rated LSF walls commonly used in Australia. This paper presents details of this study, including its analyses, outcomes, and proposals.
{"title":"Fire resistance behaviour of non-load bearing LSF walls with restrained thermal elongation","authors":"Son Tung Vy , Anh Tuan Vu","doi":"10.1016/j.jcsr.2024.109145","DOIUrl":"10.1016/j.jcsr.2024.109145","url":null,"abstract":"<div><div>In this research study, based on suitable and rational thermal and sequentially coupled structural FE (finite element) analyses, the fire resistance behaviour and FRLs (fire resistance levels) of non-load bearing LSF (light gauge steel framed) walls with restrained thermal elongation were deeply analysed. The FE analysis results confirmed that CFS (cold-formed steel) channel studs of the mentioned walls collapsed prematurely due to additional compression loads caused by the effects of fire and the thermal elongation restraints at stud ends, which led to the reduced FRLs of these walls. Besides, the wall height and the clearance between the stud ends and rigid floors were shown as having significant effects on the FRLs of non-load bearing LSF walls with restrained thermal elongation. In contrast, the effects of the thickness and depth of CFS channel studs and cavity insulation were inconsiderable. Finally, a simplified and reliable design equation and some recommendations were proposed for some types of non-load bearing fire-rated LSF walls commonly used in Australia. This paper presents details of this study, including its analyses, outcomes, and proposals.</div></div>","PeriodicalId":15557,"journal":{"name":"Journal of Constructional Steel Research","volume":"224 ","pages":"Article 109145"},"PeriodicalIF":4.0,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652351","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Steel frame structures repaired after fire exposure exhibit markedly different collapse behavior, compared to their performance under ambient conditions, when subjected to extreme loads. This study investigates the progressive collapse resistance of steel frame structures with reduced beam section (RBS) connections in post-fire conditions, using ten beam-column substructures: one tested at room temperature and nine exposed to various fire conditions. Results show that fire exposure shifts the failure from the RBS to the beam-column connection, significantly impairing the RBS's ability to relocate the plastic hinge, especially at higher fire temperatures. Fire temperature significantly affects collapse resistance, especially above 600 °C, whereas fire duration has a comparatively smaller influence on deformation capacity, particularly at 800 °C. Elevated temperatures weaken tensile catenary action (TCA), with substructures exposed to 800 °C for 90 min failing to transition to the TCA-dominated stage. Numerical simulations show that for substructures exposed to 400 °C and 600 °C, collapse resistance increases with greater flange reduction length, while the relationship between collapse resistance and starting reduction distance follows a rise-and-fall pattern. At 800 °C, collapse resistance remains relatively consistent across different starting reduction distances, but increasing the reduction length initially enhances and then reduces resistance. Increasing the reduction depth to 30 mm significantly reduces both the flexural and tensile capacities of the RBS region, shifting the failure mode from the beam-column connection to the RBS region.
{"title":"Post-fire progressive collapse resistance of beam-column substructures with RBS connections","authors":"Weiwei Zhang , Zhijun Xu , Haolong Xu , Wanpeng Zhang , Zongcheng Wang , Yu Chen","doi":"10.1016/j.jcsr.2024.109137","DOIUrl":"10.1016/j.jcsr.2024.109137","url":null,"abstract":"<div><div>Steel frame structures repaired after fire exposure exhibit markedly different collapse behavior, compared to their performance under ambient conditions, when subjected to extreme loads. This study investigates the progressive collapse resistance of steel frame structures with reduced beam section (RBS) connections in post-fire conditions, using ten beam-column substructures: one tested at room temperature and nine exposed to various fire conditions. Results show that fire exposure shifts the failure from the RBS to the beam-column connection, significantly impairing the RBS's ability to relocate the plastic hinge, especially at higher fire temperatures. Fire temperature significantly affects collapse resistance, especially above 600 °C, whereas fire duration has a comparatively smaller influence on deformation capacity, particularly at 800 °C. Elevated temperatures weaken tensile catenary action (TCA), with substructures exposed to 800 °C for 90 min failing to transition to the TCA-dominated stage. Numerical simulations show that for substructures exposed to 400 °C and 600 °C, collapse resistance increases with greater flange reduction length, while the relationship between collapse resistance and starting reduction distance follows a rise-and-fall pattern. At 800 °C, collapse resistance remains relatively consistent across different starting reduction distances, but increasing the reduction length initially enhances and then reduces resistance. Increasing the reduction depth to 30 mm significantly reduces both the flexural and tensile capacities of the RBS region, shifting the failure mode from the beam-column connection to the RBS region.</div></div>","PeriodicalId":15557,"journal":{"name":"Journal of Constructional Steel Research","volume":"224 ","pages":"Article 109137"},"PeriodicalIF":4.0,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652399","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-07DOI: 10.1016/j.jcsr.2024.109128
Qi Cai , Jiaming Ma , Yi Min Xie , Bingbing San , Yiyi Zhou
Ensuring the bar stability is crucial in truss design. However, unstable nodes lacking lateral support complicate the calculation of bar buckling lengths. bar buckling constraints make the feasible region of optimization problems concave, further complicating the solution process. Moreover, traditional truss optimization methods typically yield a single optimal result, limiting the design options available to engineers. In this study, nominal disturbing load conditions are applied to the structure to eliminate unstable nodes, thereby ensuring accurate buckling length calculations. Additionally, the advanced allowable stress iteration (AASI) approach is proposed to address truss optimization problems with bar buckling constraints. To generate geometrically diverse and structurally competitive trusses, we develop a bar-length penalty (BLP) method. To validate the effectiveness of these methods, three numerical studies are presented. The results demonstrate that the proposed AASI approach produces optimized structures free from unstable nodes and bar buckling. Compared to structures optimized using the allowable stress iteration (ASI) method, which can only optimize for a single load case, those designed with the new approach maintain bar stability under all load conditions. Compared to the traditional method of increasing the cross-sectional area of unstable bars to ensure stability, much lighter trusses can be generated while maintaining the same load-bearing capacity. By applying the proposed BLP method to penalize specific bars, it is possible to achieve optimized structures with distinct topologies, similar masses, and equivalent load-carrying capacities. The proposed methods provide valuable insights for truss optimization design.
{"title":"Topology optimization and diverse truss designs considering nodal stability and bar buckling","authors":"Qi Cai , Jiaming Ma , Yi Min Xie , Bingbing San , Yiyi Zhou","doi":"10.1016/j.jcsr.2024.109128","DOIUrl":"10.1016/j.jcsr.2024.109128","url":null,"abstract":"<div><div>Ensuring the bar stability is crucial in truss design. However, unstable nodes lacking lateral support complicate the calculation of bar buckling lengths. bar buckling constraints make the feasible region of optimization problems concave, further complicating the solution process. Moreover, traditional truss optimization methods typically yield a single optimal result, limiting the design options available to engineers. In this study, nominal disturbing load conditions are applied to the structure to eliminate unstable nodes, thereby ensuring accurate buckling length calculations. Additionally, the advanced allowable stress iteration (AASI) approach is proposed to address truss optimization problems with bar buckling constraints. To generate geometrically diverse and structurally competitive trusses, we develop a bar-length penalty (BLP) method. To validate the effectiveness of these methods, three numerical studies are presented. The results demonstrate that the proposed AASI approach produces optimized structures free from unstable nodes and bar buckling. Compared to structures optimized using the allowable stress iteration (ASI) method, which can only optimize for a single load case, those designed with the new approach maintain bar stability under all load conditions. Compared to the traditional method of increasing the cross-sectional area of unstable bars to ensure stability, much lighter trusses can be generated while maintaining the same load-bearing capacity. By applying the proposed BLP method to penalize specific bars, it is possible to achieve optimized structures with distinct topologies, similar masses, and equivalent load-carrying capacities. The proposed methods provide valuable insights for truss optimization design.</div></div>","PeriodicalId":15557,"journal":{"name":"Journal of Constructional Steel Research","volume":"224 ","pages":"Article 109128"},"PeriodicalIF":4.0,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652398","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-07DOI: 10.1016/j.jcsr.2024.109114
Zijian Bi, Guotao Yang
The accordion effect of corrugated steel webs is widely recognized for significantly improving the prestressing efficiency of steel-concrete composite girders. Nevertheless, the negative influence of the accordion effect weakens the flexural capacity of composite girders. The conventional flexural design always ignores corrugated steel webs due to the accordion effect. Therefore, accounting for the accordion effect is an effective way to achieve economical structural design and obtain an accurate evaluation of the flexural capacity of composite girders. This paper experimentally investigates the accordion effect in steel-concrete composite girders with corrugated steel webs. Three evaluation indexes, involving the reduction factor η, web participation tw,eff/tw, and additional flexural capacity ratio δ, are introduced to quantify the accordion effect from different aspects. Subsequently, parametric studies are conducted to investigate the effects of steel strength, concrete strength, web height-to-thickness ratio, and steel flange-to-web thickness ratio. The research results indicate that about 20 % of the girder's flexural capacity is reduced by the accordion effect. Corrugated steel webs can contribute up to 30 % of the additional girder's flexural capacity, and the effective web thickness can reach up to 0.4 times the actual web thickness. Thus, completely ignoring the web's flexural contribution will lead to the conservative estimation of the girder's flexural capacity and uneconomical structural design. Furthermore, a flexural analytical model with satisfactory prediction efficiency is proposed for quantifying the accordion effect and estimating the ultimate flexural capacity of steel-concrete composite girders with corrugated steel webs considering the accordion effect.
{"title":"Steel-concrete composite girders with corrugated steel webs: Accordion effects","authors":"Zijian Bi, Guotao Yang","doi":"10.1016/j.jcsr.2024.109114","DOIUrl":"10.1016/j.jcsr.2024.109114","url":null,"abstract":"<div><div>The accordion effect of corrugated steel webs is widely recognized for significantly improving the prestressing efficiency of steel-concrete composite girders. Nevertheless, the negative influence of the accordion effect weakens the flexural capacity of composite girders. The conventional flexural design always ignores corrugated steel webs due to the accordion effect. Therefore, accounting for the accordion effect is an effective way to achieve economical structural design and obtain an accurate evaluation of the flexural capacity of composite girders. This paper experimentally investigates the accordion effect in steel-concrete composite girders with corrugated steel webs. Three evaluation indexes, involving the reduction factor <em>η</em>, web participation <em>t</em><sub>w,eff</sub>/<em>t</em><sub>w</sub>, and additional flexural capacity ratio <em>δ</em>, are introduced to quantify the accordion effect from different aspects. Subsequently, parametric studies are conducted to investigate the effects of steel strength, concrete strength, web height-to-thickness ratio, and steel flange-to-web thickness ratio. The research results indicate that about 20 % of the girder's flexural capacity is reduced by the accordion effect. Corrugated steel webs can contribute up to 30 % of the additional girder's flexural capacity, and the effective web thickness can reach up to 0.4 times the actual web thickness. Thus, completely ignoring the web's flexural contribution will lead to the conservative estimation of the girder's flexural capacity and uneconomical structural design. Furthermore, a flexural analytical model with satisfactory prediction efficiency is proposed for quantifying the accordion effect and estimating the ultimate flexural capacity of steel-concrete composite girders with corrugated steel webs considering the accordion effect.</div></div>","PeriodicalId":15557,"journal":{"name":"Journal of Constructional Steel Research","volume":"224 ","pages":"Article 109114"},"PeriodicalIF":4.0,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652350","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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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