Pub Date : 2026-05-01Epub Date: 2026-02-05DOI: 10.1016/j.jcsr.2026.110262
Ahmed T.M.A. El-Shweekh , Redhwan M. Algobahi , Aly G.A. AbdelShafy , Mohamed F.M. Fahmy
In accelerated bridge construction (ABC), the resilience of self-centering (SC) concrete-filled steel tube (CFST) bridge columns is closely linked to the performance of their energy dissipation (ED) system, which in this study is provided by a buckling-restrained steel (BRS) plate; however, ensuring stable BRS behavior under seismic loading remains a critical challenge. To address this issue, a three-dimensional finite element model (3D-FEM) was developed using commercial software to simulate SC CFST bridge columns equipped with BRS plates, and a total of 33 numerical models were analyzed by varying BRS geometry, axial load ratios, and material properties. The accuracy of the developed FEM was verified through strong agreement between the numerical predictions and available experimental data. The results demonstrated that the investigated design parameters exert a significant influence on overall system performance, and that the stability of the BRS plate is primarily governed by the out-of-plane slenderness ratio (L/i). Based on these findings, two design strategies are recommended to ensure the desired resilience: adopting a stability-based approach to optimize the geometry of the BRS plate, and employing a fully buckling-restrained steel system instead of a partial one.
{"title":"Controlled Inelastic Response of BRS Energy Dissipation System in Self-Centering CFST Bridge Columns","authors":"Ahmed T.M.A. El-Shweekh , Redhwan M. Algobahi , Aly G.A. AbdelShafy , Mohamed F.M. Fahmy","doi":"10.1016/j.jcsr.2026.110262","DOIUrl":"10.1016/j.jcsr.2026.110262","url":null,"abstract":"<div><div>In accelerated bridge construction (ABC), the resilience of self-centering (SC) concrete-filled steel tube (CFST) bridge columns is closely linked to the performance of their energy dissipation (ED) system, which in this study is provided by a buckling-restrained steel (BRS) plate; however, ensuring stable BRS behavior under seismic loading remains a critical challenge. To address this issue, a three-dimensional finite element model (3D-FEM) was developed using commercial software to simulate SC CFST bridge columns equipped with BRS plates, and a total of 33 numerical models were analyzed by varying BRS geometry, axial load ratios, and material properties. The accuracy of the developed FEM was verified through strong agreement between the numerical predictions and available experimental data. The results demonstrated that the investigated design parameters exert a significant influence on overall system performance, and that the stability of the BRS plate is primarily governed by the out-of-plane slenderness ratio (L/i). Based on these findings, two design strategies are recommended to ensure the desired resilience: adopting a stability-based approach to optimize the geometry of the BRS plate, and employing a fully buckling-restrained steel system instead of a partial one.</div></div>","PeriodicalId":15557,"journal":{"name":"Journal of Constructional Steel Research","volume":"240 ","pages":"Article 110262"},"PeriodicalIF":4.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190804","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 : 2026-05-01Epub Date: 2026-01-31DOI: 10.1016/j.jcsr.2026.110256
Peifeng Tian , Chen Wang , Tak-Ming Chan , Ahmed Y. Elghazouli
Despite the rapid development and application of modular buildings, the structural behaviour of high-rise configurations requires further detailed investigations. In order to enable extensive studies into the nonlinear seismic time history response of such large and complex buildings, there is a need to develop computationally efficient approaches. This investigation therefore, describes the development of a machine-learning approach for predicting the time history response of modular buildings using a transformer model architecture, which is found to be particularly suitable for such sequence-to-sequence tasks. The proposed machine learning model is trained using a large database comprising the seismic time history response of a prototype high-rise modular building configuration through nonlinear time history analysis under a suite of 3000 ground motions. A special designed encoding function was applied to reflect the unique structural characteristics of modular buildings, while convolutional neural networks are used to capture both global and local features of seismic vibrations, followed by feature concatenation for the machine learning prediction. The proposed model is shown to provide a highly efficient prediction procedure that captures the time history response of such buildings. Finally, to demonstrate the applicability and effectiveness of the developed machine learning model, an illustrative example is presented in which the influence of inter-module connection properties on the seismic response of modular buildings is examined and discussed. Compared to widely used nonlinear finite element procedures, the proposed machine modelling methodology offers a fundamental approach for modular buildings to enable efficient large scale structural evaluations.
{"title":"Seismic time history response prediction of modular buildings using transformer-based machine learning models","authors":"Peifeng Tian , Chen Wang , Tak-Ming Chan , Ahmed Y. Elghazouli","doi":"10.1016/j.jcsr.2026.110256","DOIUrl":"10.1016/j.jcsr.2026.110256","url":null,"abstract":"<div><div>Despite the rapid development and application of modular buildings, the structural behaviour of high-rise configurations requires further detailed investigations. In order to enable extensive studies into the nonlinear seismic time history response of such large and complex buildings, there is a need to develop computationally efficient approaches. This investigation therefore, describes the development of a machine-learning approach for predicting the time history response of modular buildings using a transformer model architecture, which is found to be particularly suitable for such sequence-to-sequence tasks. The proposed machine learning model is trained using a large database comprising the seismic time history response of a prototype high-rise modular building configuration through nonlinear time history analysis under a suite of 3000 ground motions. A special designed encoding function was applied to reflect the unique structural characteristics of modular buildings, while convolutional neural networks are used to capture both global and local features of seismic vibrations, followed by feature concatenation for the machine learning prediction. The proposed model is shown to provide a highly efficient prediction procedure that captures the time history response of such buildings. Finally, to demonstrate the applicability and effectiveness of the developed machine learning model, an illustrative example is presented in which the influence of inter-module connection properties on the seismic response of modular buildings is examined and discussed. Compared to widely used nonlinear finite element procedures, the proposed machine modelling methodology offers a fundamental approach for modular buildings to enable efficient large scale structural evaluations.</div></div>","PeriodicalId":15557,"journal":{"name":"Journal of Constructional Steel Research","volume":"240 ","pages":"Article 110256"},"PeriodicalIF":4.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146076933","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 : 2026-05-01Epub Date: 2026-01-30DOI: 10.1016/j.jcsr.2026.110261
Xipeng Ma , Yonghui Wang , Ximei Zhai , Hong Zhang , Hongyuan Zhou
The lateral impact responses of partially-encased composite (PEC) members were investigated via both experimental and analytical approaches. The impact experiments were conducted on PEC members to obtain their deformation process, failure mode, impact force–time and displacement–time responses. The effects of the initial velocity, clear span, impact direction and types of transverse reinforcements (i.e., links and stirrup) on impact responses of PEC members were experimentally investigated. The results indicated that the higher impact velocity would result in higher impact force, larger specimen deformation and energy dissipation. The PEC member with larger span exhibited smaller impact resistance, inducing larger specimen deformation. The impact direction had significant influence on the impact response of PEC members due to the differences in bending resistance. While the types of the transverse reinforcements employed in this study had negligible effect on the impact behaviours. Moreover, a two degrees-of-freedom (2-DOFs) model was developed to calculate the responses of the PEC members under the lateral impact. The developed 2-DOFs model demonstrated its applicability by accurately predicting the test results.
{"title":"Responses of partially-encased composite structural members subjected to lateral impact load: Experimental and analytical study","authors":"Xipeng Ma , Yonghui Wang , Ximei Zhai , Hong Zhang , Hongyuan Zhou","doi":"10.1016/j.jcsr.2026.110261","DOIUrl":"10.1016/j.jcsr.2026.110261","url":null,"abstract":"<div><div>The lateral impact responses of partially-encased composite (PEC) members were investigated via both experimental and analytical approaches. The impact experiments were conducted on PEC members to obtain their deformation process, failure mode, impact force–time and displacement–time responses. The effects of the initial velocity, clear span, impact direction and types of transverse reinforcements (i.e., links and stirrup) on impact responses of PEC members were experimentally investigated. The results indicated that the higher impact velocity would result in higher impact force, larger specimen deformation and energy dissipation. The PEC member with larger span exhibited smaller impact resistance, inducing larger specimen deformation. The impact direction had significant influence on the impact response of PEC members due to the differences in bending resistance. While the types of the transverse reinforcements employed in this study had negligible effect on the impact behaviours. Moreover, a two degrees-of-freedom (2-DOFs) model was developed to calculate the responses of the PEC members under the lateral impact. The developed 2-DOFs model demonstrated its applicability by accurately predicting the test results.</div></div>","PeriodicalId":15557,"journal":{"name":"Journal of Constructional Steel Research","volume":"240 ","pages":"Article 110261"},"PeriodicalIF":4.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146076932","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 : 2026-05-01Epub Date: 2026-01-29DOI: 10.1016/j.jcsr.2026.110265
Zhou-Peng Cai , Ji-Ping Hao , Xiao-Ling Sun , Qiang Xue , Jing-Hua Wang
A novel prestressed high-performance exposed column base (NECB) for concrete-filled steel tubular (CFST) columns is proposed, incorporating an innovative steel shoe beam configuration and high-strength prestressed anchor bolts (HPABs). The seismic performance of the NECB was evaluated through quasi-static cyclic tests and finite element (FE) simulations. Three half-scale specimens were examined to characterize failure mechanisms, hysteretic response, stiffness and strength degradation, and energy dissipation capacity. Experimental results show that the NECB consistently achieves superior load-bearing capacity, stiffness, deformation capacity, and energy dissipation compared with a conventional concrete-encased column base (CECB). Validated FE models were subsequently established to perform parametric studies investigating the effects of axial load ratio, steel shoe beam parameters, and HPAB prestressing levels on seismic behavior. The FE analyses reveal that increased axial load, greater stiffener thickness, and the application of anchor-bolt prestress all enhance the initial stiffness and energy dissipation capacity of the column base, with anchor-bolt prestressing providing the most significant improvement.
{"title":"Seismic performance of a novel prestressed high-performance exposed CFST column base","authors":"Zhou-Peng Cai , Ji-Ping Hao , Xiao-Ling Sun , Qiang Xue , Jing-Hua Wang","doi":"10.1016/j.jcsr.2026.110265","DOIUrl":"10.1016/j.jcsr.2026.110265","url":null,"abstract":"<div><div>A novel prestressed high-performance exposed column base (NECB) for concrete-filled steel tubular (CFST) columns is proposed, incorporating an innovative steel shoe beam configuration and high-strength prestressed anchor bolts (HPABs). The seismic performance of the NECB was evaluated through quasi-static cyclic tests and finite element (FE) simulations. Three half-scale specimens were examined to characterize failure mechanisms, hysteretic response, stiffness and strength degradation, and energy dissipation capacity. Experimental results show that the NECB consistently achieves superior load-bearing capacity, stiffness, deformation capacity, and energy dissipation compared with a conventional concrete-encased column base (CECB). Validated FE models were subsequently established to perform parametric studies investigating the effects of axial load ratio, steel shoe beam parameters, and HPAB prestressing levels on seismic behavior. The FE analyses reveal that increased axial load, greater stiffener thickness, and the application of anchor-bolt prestress all enhance the initial stiffness and energy dissipation capacity of the column base, with anchor-bolt prestressing providing the most significant improvement.</div></div>","PeriodicalId":15557,"journal":{"name":"Journal of Constructional Steel Research","volume":"240 ","pages":"Article 110265"},"PeriodicalIF":4.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146076931","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 : 2026-05-01Epub Date: 2026-01-31DOI: 10.1016/j.jcsr.2026.110264
Shaohui Shi , Huijun Wang , Xing Wei , Jian Ren , Heng Liu
In this paper, a novel U-shaped steel-concrete composite bent cap (USCBC) is introduced, and numerical models of the USCBC are established to investigate their failure mechanism. Parametric analyses use parameters such as steel plate thickness, material strength, cross-sectional dimensions, and shear connector capacity. Formulas are derived to calculate the cracking and peak load applicable to the USCBC. The research findings indicate that under a four-point loading condition at mid-span, the USCBC exhibits flexural behavior prior to yielding and then shear behavior post-yielding, ultimately failing when the concrete in the shear span region reaches its tensile ultimate strength. During the loading process, a positive shear lag effect is observed along the transverse direction of the cross-section. The most significant factors affecting the flexural performance of the USCBC are the cross-sectional height and concrete strength, while the cross-sectional width and steel strength have less notable impacts. The shear connector capacity considerably influences the structure's post-cracking behavior. The calculated results from the proposed formulas for cracking load and peak load of the USCBC align well with the finite element simulation results, thereby providing theoretical support for the flexural calculations of the USCBC. The proposed design formulas are applicable to USCBCs with conventional materials (e.g., steel grades Q235-Q460 and concrete grades C30-C80) and within the studied geometric parameter ranges.
{"title":"Flexural behavior of novel U-shaped steel-concrete composite bent cap","authors":"Shaohui Shi , Huijun Wang , Xing Wei , Jian Ren , Heng Liu","doi":"10.1016/j.jcsr.2026.110264","DOIUrl":"10.1016/j.jcsr.2026.110264","url":null,"abstract":"<div><div>In this paper, a novel U-shaped steel-concrete composite bent cap (USCBC) is introduced, and numerical models of the USCBC are established to investigate their failure mechanism. Parametric analyses use parameters such as steel plate thickness, material strength, cross-sectional dimensions, and shear connector capacity. Formulas are derived to calculate the cracking and peak load applicable to the USCBC. The research findings indicate that under a four-point loading condition at mid-span, the USCBC exhibits flexural behavior prior to yielding and then shear behavior post-yielding, ultimately failing when the concrete in the shear span region reaches its tensile ultimate strength. During the loading process, a positive shear lag effect is observed along the transverse direction of the cross-section. The most significant factors affecting the flexural performance of the USCBC are the cross-sectional height and concrete strength, while the cross-sectional width and steel strength have less notable impacts. The shear connector capacity considerably influences the structure's post-cracking behavior. The calculated results from the proposed formulas for cracking load and peak load of the USCBC align well with the finite element simulation results, thereby providing theoretical support for the flexural calculations of the USCBC. The proposed design formulas are applicable to USCBCs with conventional materials (e.g., steel grades Q235-Q460 and concrete grades C30-C80) and within the studied geometric parameter ranges.</div></div>","PeriodicalId":15557,"journal":{"name":"Journal of Constructional Steel Research","volume":"240 ","pages":"Article 110264"},"PeriodicalIF":4.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190790","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 : 2026-05-01Epub Date: 2026-02-06DOI: 10.1016/j.jcsr.2026.110267
Wei Li, Hao Guan
This study conducts experimental and numerical investigations on the seismic behaviour of high-strength circular CFST column-to-composite beam joint using external diaphragm. Both high-strength steel and high-strength concrete were used, where the yield strength of steel tube was 620.6 MPa and 771.7 MPa, and the cube compressive strength of core concrete was 78.5 MPa. The same profile of circular steel tubes (Φ 203 mm × 4 mm) and the size of external diaphragms (60 mm × 8 mm) were applied for all specimens. Columns were subjected to constant axial load ratios of 0.23 and 0.38, while beams were subjected to reverse cyclic loading. The experimental parameters were the steel tube strength, the axial load ratio of the CFST column and the beam cross-sectional configuration. A finite element model was established and validated, accounting for material nonlinearity and damage, confinement effect and inter-component interactions. Parametric studies were conducted to explore the effects of various critical parameters. The hysteretic model for the shear strength-shear deformation relation of panel zone was analysed. By increasing the steel tube yield strength from 620.6 MPa to 771.7 MPa, the average maximum shear of the panel zone was enhanced by 13.0%, and the dissipated energy increased by 26.7%. The panel zone shear model for joints using normal-strength materials remained applicable for those using high-strength materials.
本文对采用外隔板的高强度圆形钢管混凝土柱-组合梁节点的抗震性能进行了试验和数值研究。采用高强钢和高强混凝土，其中钢管屈服强度为620.6 MPa和771.7 MPa，核心混凝土立方体抗压强度为78.5 MPa。所有试件均采用相同的圆钢管外形（Φ 203 mm × 4 mm）和外隔板尺寸（60 mm × 8 mm）。柱承受恒定轴向荷载比为0.23和0.38，而梁承受反向循环荷载。试验参数为钢管强度、钢管混凝土柱轴向载荷比和梁截面构型。建立并验证了考虑材料非线性与损伤、约束效应和构件间相互作用的有限元模型。进行了参数研究，以探讨各种关键参数的影响。分析了板区抗剪强度-剪切变形关系的滞回模型。将钢管屈服强度由620.6 MPa提高到771.7 MPa，板区平均最大剪切强度提高13.0%，耗散能提高26.7%。采用普通强度材料的节点面板区域剪切模型仍然适用于采用高强度材料的节点。
{"title":"Seismic performance of high-strength circular CFST column-to-composite beam joint using external diaphragm","authors":"Wei Li, Hao Guan","doi":"10.1016/j.jcsr.2026.110267","DOIUrl":"10.1016/j.jcsr.2026.110267","url":null,"abstract":"<div><div>This study conducts experimental and numerical investigations on the seismic behaviour of high-strength circular CFST column-to-composite beam joint using external diaphragm. Both high-strength steel and high-strength concrete were used, where the yield strength of steel tube was 620.6 MPa and 771.7 MPa, and the cube compressive strength of core concrete was 78.5 MPa. The same profile of circular steel tubes (Φ 203 mm × 4 mm) and the size of external diaphragms (60 mm × 8 mm) were applied for all specimens. Columns were subjected to constant axial load ratios of 0.23 and 0.38, while beams were subjected to reverse cyclic loading. The experimental parameters were the steel tube strength, the axial load ratio of the CFST column and the beam cross-sectional configuration. A finite element model was established and validated, accounting for material nonlinearity and damage, confinement effect and inter-component interactions. Parametric studies were conducted to explore the effects of various critical parameters. The hysteretic model for the shear strength-shear deformation relation of panel zone was analysed. By increasing the steel tube yield strength from 620.6 MPa to 771.7 MPa, the average maximum shear of the panel zone was enhanced by 13.0%, and the dissipated energy increased by 26.7%. The panel zone shear model for joints using normal-strength materials remained applicable for those using high-strength materials.</div></div>","PeriodicalId":15557,"journal":{"name":"Journal of Constructional Steel Research","volume":"240 ","pages":"Article 110267"},"PeriodicalIF":4.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190910","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 : 2026-05-01Epub Date: 2026-02-10DOI: 10.1016/j.jcsr.2026.110289
Haowen Hou , Wei Wang , M. Shahria Alam , Shiye Wang
This study focuses on the seismic performance of the Coupled-Double Skin Composite Wall (C-DSCW) system including Double Skin Composite Wall (DSCW) and shear-type steel coupling beams. A series of well-calibrated finite element models are developed, and comprehensive parametric analyses are conducted to examine the effects of coupling ratio, axial load ratio, ultimate deformation capacity of DSCW piers, and structural aspect ratio on the seismic performance of the C-DSCW system. The results reveal that: (1) The coupling ratio exhibits a non-monotonic relationship with the ductility and energy dissipation capacity of the system; (2) Low plastic deformation capacity of the DSCW piers (Ru < 0.025 rad) and high axial load ratio (n > 0.4) adversely affect the seismic performance of the system; (3) A higher coupling ratio is required to improve integrity while mitigating the unfavourable P-Delta impacts when the system is slender (H/Lw > 10.8). (4) Based on the interactive influences of parameters on the seismic performance of the system, a quantitative relationship between CRpn range corresponding to different combinations of parameters is proposed to facilitate engineering applications and the design of the C-DSCW system.
{"title":"Investigation of seismic performance and coupling effects for coupled-double skin composite walls","authors":"Haowen Hou , Wei Wang , M. Shahria Alam , Shiye Wang","doi":"10.1016/j.jcsr.2026.110289","DOIUrl":"10.1016/j.jcsr.2026.110289","url":null,"abstract":"<div><div>This study focuses on the seismic performance of the Coupled-Double Skin Composite Wall (C-DSCW) system including Double Skin Composite Wall (DSCW) and shear-type steel coupling beams. A series of well-calibrated finite element models are developed, and comprehensive parametric analyses are conducted to examine the effects of coupling ratio, axial load ratio, ultimate deformation capacity of DSCW piers, and structural aspect ratio on the seismic performance of the C-DSCW system. The results reveal that: (1) The coupling ratio exhibits a non-monotonic relationship with the ductility and energy dissipation capacity of the system; (2) Low plastic deformation capacity of the DSCW piers (<em>R</em><sub>u</sub> < 0.025 rad) and high axial load ratio (<em>n</em> > 0.4) adversely affect the seismic performance of the system; (3) A higher coupling ratio is required to improve integrity while mitigating the unfavourable P-Delta impacts when the system is slender (<em>H</em>/<em>L</em><sub>w</sub> > 10.8). (4) Based on the interactive influences of parameters on the seismic performance of the system, a quantitative relationship between <em>CR</em><sub>pn</sub> range corresponding to different combinations of parameters is proposed to facilitate engineering applications and the design of the C-DSCW system.</div></div>","PeriodicalId":15557,"journal":{"name":"Journal of Constructional Steel Research","volume":"240 ","pages":"Article 110289"},"PeriodicalIF":4.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190913","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 : 2026-05-01Epub Date: 2026-02-05DOI: 10.1016/j.jcsr.2026.110281
Hao Zhang , Jiajian Yi , Mingzhou Su , Gengyao Tian
In this study, the residual mechanical performance of post-fire low-yield-point (LYP) steel was investigated. Forty-two LY160 specimens were heated to different exposure temperatures for different durations and then subjected to cooling in air (CIA) or cooling in water (CIW); subsequently, monotonic tensile tests were conducted to evaluate their failure modes, fracture surfaces, stress–strain curves, and mechanical properties. All post-fire specimens exhibited significant necking, and microstructural analyses revealed numerous spherical dimples, indicating ductile fracture. All stress–strain curves were highly nonlinear, and the yield plateaus of the CIA and CIW specimens disappeared once the exposure temperature exceeded 600 and 400 °C, respectively. The yield strength (fy,T) and tensile-to-yield-strength ratio (fu,T/fy,T) of LY160 steel were markedly influenced by the exposure temperature and cooling method. Notably, fy,T significantly decreased and fu,T/fy,T substantially increased once the LY160 specimens were heated above 600 °C. This trend was different from that of other steels. The average fy,T and fu,T/fy,T of the CIA specimens heated to 900 °C were 0.44 and 1.98 times, respectively, those of the control specimens, and the corresponding values of the CIW specimens heated to 900 °C were 0.58 and 1.57 times, respectively, those of the control specimens. As the exposure temperature increased, the tensile strength of LY160 steel initially remained constant and then decreased; the elongation after fracture and ultimate strain initially decreased and then increased; and the elastic modulus exhibited no change. Exposure time affected only the fy,T value of the CIA LY160 and had minimal impact on the properties of the CIW LY160. Finally, equations were derived to predict the post-fire mechanical properties of LY160 steel according to exposure temperature and cooling method. The prediction equations were applied to formulate two constitutive models utilizing the Mander and Ramberg–Osgood models. The findings of this study offer a valuable benchmark for assessing the post-fire residual performance of energy-dissipating members made of LYP steel.
{"title":"Post-fire mechanical properties and constitutive modeling of low-yield-point LY160 steel subjected to different cooling methods","authors":"Hao Zhang , Jiajian Yi , Mingzhou Su , Gengyao Tian","doi":"10.1016/j.jcsr.2026.110281","DOIUrl":"10.1016/j.jcsr.2026.110281","url":null,"abstract":"<div><div>In this study, the residual mechanical performance of post-fire low-yield-point (LYP) steel was investigated. Forty-two LY160 specimens were heated to different exposure temperatures for different durations and then subjected to cooling in air (CIA) or cooling in water (CIW); subsequently, monotonic tensile tests were conducted to evaluate their failure modes, fracture surfaces, stress–strain curves, and mechanical properties. All post-fire specimens exhibited significant necking, and microstructural analyses revealed numerous spherical dimples, indicating ductile fracture. All stress–strain curves were highly nonlinear, and the yield plateaus of the CIA and CIW specimens disappeared once the exposure temperature exceeded 600 and 400 °C, respectively. The yield strength (<em>f</em><sub>y,T</sub>) and tensile-to-yield-strength ratio (<em>f</em><sub>u,T</sub>/<em>f</em><sub>y,T</sub>) of LY160 steel were markedly influenced by the exposure temperature and cooling method. Notably, <em>f</em><sub>y,T</sub> significantly decreased and <em>f</em><sub>u,T</sub>/<em>f</em><sub>y,T</sub> substantially increased once the LY160 specimens were heated above 600 °C. This trend was different from that of other steels. The average <em>f</em><sub>y,T</sub> and <em>f</em><sub>u,T</sub>/<em>f</em><sub>y,T</sub> of the CIA specimens heated to 900 °C were 0.44 and 1.98 times, respectively, those of the control specimens, and the corresponding values of the CIW specimens heated to 900 °C were 0.58 and 1.57 times, respectively, those of the control specimens. As the exposure temperature increased, the tensile strength of LY160 steel initially remained constant and then decreased; the elongation after fracture and ultimate strain initially decreased and then increased; and the elastic modulus exhibited no change. Exposure time affected only the <em>f</em><sub>y,T</sub> value of the CIA LY160 and had minimal impact on the properties of the CIW LY160. Finally, equations were derived to predict the post-fire mechanical properties of LY160 steel according to exposure temperature and cooling method. The prediction equations were applied to formulate two constitutive models utilizing the Mander and Ramberg–Osgood models. The findings of this study offer a valuable benchmark for assessing the post-fire residual performance of energy-dissipating members made of LYP steel.</div></div>","PeriodicalId":15557,"journal":{"name":"Journal of Constructional Steel Research","volume":"240 ","pages":"Article 110281"},"PeriodicalIF":4.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190915","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 : 2026-05-01Epub Date: 2026-02-10DOI: 10.1016/j.jcsr.2026.110258
Andronikos Skiadopoulos , Dimitrios G. Lignos
Shear yielding enables beam-to-column connections in capacity-designed steel moment frames to dissipate energy and remain stable at lateral drifts up to 4% rad, as long as ductile fracture does not compromise their hysteretic behavior at lower drift levels. This paper characterizes the fracture potential of welded unreinforced flange-welded web (WUF-W) connections designed with such an alternative design concept that defies the current status quo of pre-qualified welded connections. The analysis relies on state-of-the-art micromechanics based fracture models along with detailed mechanical testing and scanning electron microscopy of samples extracted from WUF-W connections exhibiting ductile fracture originating at the kink points of their panel zone at deformation demands characteristic of earthquakes with a low probability of occurrence. The analysis results demonstrate that while the origin of ductile fracture is near the complete joint penetration (CJP) weld toe of the beam flange-to-column face joint, the overall hysteretic behavior of the connections meet the pre-qualification limits established in current seismic standards. Leaving a customized beveled backing bar in place after completing the CJP welds does not elevate the risk of ductile fracture at this location, thus enabling a more straightforward fabrication process than the current practice. The simulation of hypothetical extreme earthquake loading scenarios demonstrates that, the examined WUF-W connections are not prone to ductile fracture till at least 6% rad while achieving instability-free hysteretic response.
{"title":"Ductile crack initiation in welded connections with highly dissipative panel zones","authors":"Andronikos Skiadopoulos , Dimitrios G. Lignos","doi":"10.1016/j.jcsr.2026.110258","DOIUrl":"10.1016/j.jcsr.2026.110258","url":null,"abstract":"<div><div>Shear yielding enables beam-to-column connections in capacity-designed steel moment frames to dissipate energy and remain stable at lateral drifts up to 4% rad, as long as ductile fracture does not compromise their hysteretic behavior at lower drift levels. This paper characterizes the fracture potential of welded unreinforced flange-welded web (WUF-W) connections designed with such an alternative design concept that defies the current status quo of pre-qualified welded connections. The analysis relies on state-of-the-art micromechanics based fracture models along with detailed mechanical testing and scanning electron microscopy of samples extracted from WUF-W connections exhibiting ductile fracture originating at the kink points of their panel zone at deformation demands characteristic of earthquakes with a low probability of occurrence. The analysis results demonstrate that while the origin of ductile fracture is near the complete joint penetration (CJP) weld toe of the beam flange-to-column face joint, the overall hysteretic behavior of the connections meet the pre-qualification limits established in current seismic standards. Leaving a customized beveled backing bar in place after completing the CJP welds does not elevate the risk of ductile fracture at this location, thus enabling a more straightforward fabrication process than the current practice. The simulation of hypothetical extreme earthquake loading scenarios demonstrates that, the examined WUF-W connections are not prone to ductile fracture till at least 6% rad while achieving instability-free hysteretic response.</div></div>","PeriodicalId":15557,"journal":{"name":"Journal of Constructional Steel Research","volume":"240 ","pages":"Article 110258"},"PeriodicalIF":4.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190912","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 : 2026-05-01Epub Date: 2026-02-01DOI: 10.1016/j.jcsr.2026.110260
Siang Zhou , Syed Muhammad Oan Naqvi , Bikesh Sedhain
Cross-frames are important structural components for horizontally curved steel I-girder bridges, which provide stability but induce complex lateral bending for the superstructure under construction and in-service loading conditions. A state-of-the-art design practice review indicated that cross-frames are required to be designed as primary load-carrying members, while their design mostly applies standardized dimensions and layouts. Intermediate cross-frames are generally arranged radially to resist overall torsion of the bridge system, while cross-frames are often selectively omitted in the vicinity of skewed bearing lines to avoid large cross-frame forces and assist uplift alleviation. To advance cross-frame design for horizontally curved steel I-girder bridges for a more optimized load distribution, numerical parametric studies (on a total of sixty bridges) were conducted to evaluate the effects of different cross-frame type and arrangement (orientation and spacing) on structural responses of these bridges. Girder stress and movement as well as cross-frame stress were analyzed. Using X-Frames with inclination (to a maximum of 20°) in a staggered layout would potentially improve bridge performance given that constructability and fatigue concerns are properly evaluated. Decreasing girder and cross-frame responses were observed with decreased cross-frame spacing, which was more obvious for bridges with larger length-to-radius ratio.
{"title":"Effects of cross-frame design on single-span horizontally curved steel I-girder bridges","authors":"Siang Zhou , Syed Muhammad Oan Naqvi , Bikesh Sedhain","doi":"10.1016/j.jcsr.2026.110260","DOIUrl":"10.1016/j.jcsr.2026.110260","url":null,"abstract":"<div><div>Cross-frames are important structural components for horizontally curved steel I-girder bridges, which provide stability but induce complex lateral bending for the superstructure under construction and in-service loading conditions. A state-of-the-art design practice review indicated that cross-frames are required to be designed as primary load-carrying members, while their design mostly applies standardized dimensions and layouts. Intermediate cross-frames are generally arranged radially to resist overall torsion of the bridge system, while cross-frames are often selectively omitted in the vicinity of skewed bearing lines to avoid large cross-frame forces and assist uplift alleviation. To advance cross-frame design for horizontally curved steel I-girder bridges for a more optimized load distribution, numerical parametric studies (on a total of sixty bridges) were conducted to evaluate the effects of different cross-frame type and arrangement (orientation and spacing) on structural responses of these bridges. Girder stress and movement as well as cross-frame stress were analyzed. Using X-Frames with inclination (to a maximum of 20°) in a staggered layout would potentially improve bridge performance given that constructability and fatigue concerns are properly evaluated. Decreasing girder and cross-frame responses were observed with decreased cross-frame spacing, which was more obvious for bridges with larger length-to-radius ratio.</div></div>","PeriodicalId":15557,"journal":{"name":"Journal of Constructional Steel Research","volume":"240 ","pages":"Article 110260"},"PeriodicalIF":4.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190917","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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