Pub Date : 2026-02-04DOI: 10.1016/j.engstruct.2026.122256
Jing-Zhou Zhang , Xiao Hu , Guo-Qiang Li , Lei Xiao
This study develops a predictive framework for the dynamic response of point-restrained steel modular building (SMB) slabs under drop impact. The framework is established through three main steps. First, the static load-displacement behavior of the SMB slab is effectively approximated by a bilinear curve, with the yield-to-ultimate load ratio governed by the slab aspect ratio, thickness-to-width ratio, and reinforcement ratio. Based on the work-energy theorem, an explicit regression expression (R²=0.89) is then established for the energy transfer coefficient (ETC). The ETC ranges from 0.3 to 0.9, with a predominant concentration between 0.6 and 0.7, and is influenced by the mass ratio of impactor to slab, slab aspect ratio, impact height-to-slab width ratio, and normalized drop height. Subsequently, using the quantified bilinear static load-displacement relationships and the determined ETC, a closed-form solution is derived for the maximum dynamic displacement (MDD). Validation against finite element results shows excellent agreement, with R² value of 0.97. Parametric analysis reveals that slab thickness and rebar diameter are the dominant structural factors influencing MDD. A 40 % increase in rebar diameter (from 10 mm to 14 mm) decreases MDD by 26.61 %, while a 50 % increase in slab thickness (from 100 mm to 150 mm) reduces it by 38.40 %. Furthermore, empirical predictions are developed for both the maximum inter-module vertical shear force (R²=0.79) and the maximum column axial compression force (R²=0.83). Both forces exhibit proportionality to impact mass, with proportionality coefficients dependent on multiple dimensionless parameters including mass ratio, slab aspect ratio, impact height-to-slab width ratio, slab thickness-to-width ratio, normalized drop height, and reinforcement ratio.
{"title":"An energy-based closed-form solution for the dynamic response of point-restrained slab in SMBs under drop impact","authors":"Jing-Zhou Zhang , Xiao Hu , Guo-Qiang Li , Lei Xiao","doi":"10.1016/j.engstruct.2026.122256","DOIUrl":"10.1016/j.engstruct.2026.122256","url":null,"abstract":"<div><div>This study develops a predictive framework for the dynamic response of point-restrained steel modular building (SMB) slabs under drop impact. The framework is established through three main steps. First, the static load-displacement behavior of the SMB slab is effectively approximated by a bilinear curve, with the yield-to-ultimate load ratio governed by the slab aspect ratio, thickness-to-width ratio, and reinforcement ratio. Based on the work-energy theorem, an explicit regression expression (R²=0.89) is then established for the energy transfer coefficient (ETC). The ETC ranges from 0.3 to 0.9, with a predominant concentration between 0.6 and 0.7, and is influenced by the mass ratio of impactor to slab, slab aspect ratio, impact height-to-slab width ratio, and normalized drop height. Subsequently, using the quantified bilinear static load-displacement relationships and the determined ETC, a closed-form solution is derived for the maximum dynamic displacement (MDD). Validation against finite element results shows excellent agreement, with R² value of 0.97. Parametric analysis reveals that slab thickness and rebar diameter are the dominant structural factors influencing MDD. A 40 % increase in rebar diameter (from 10 mm to 14 mm) decreases MDD by 26.61 %, while a 50 % increase in slab thickness (from 100 mm to 150 mm) reduces it by 38.40 %. Furthermore, empirical predictions are developed for both the maximum inter-module vertical shear force (R²=0.79) and the maximum column axial compression force (R²=0.83). Both forces exhibit proportionality to impact mass, with proportionality coefficients dependent on multiple dimensionless parameters including mass ratio, slab aspect ratio, impact height-to-slab width ratio, slab thickness-to-width ratio, normalized drop height, and reinforcement ratio.</div></div>","PeriodicalId":11763,"journal":{"name":"Engineering Structures","volume":"353 ","pages":"Article 122256"},"PeriodicalIF":6.4,"publicationDate":"2026-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146185389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2026-02-04DOI: 10.1016/j.engstruct.2026.122268
Kee Dong Kim , Jeonghwa Lee , Kyoung Yong Park , Young-Goo Choi
Point lateral braces are essential for economical steel beam design by preventing out-of-plane deformations during construction. While previous studies have focused mainly on a single midspan brace, the behavior of beams with multiple braces under lateral–torsional buckling remains unclear. This study develops a unified framework for assessing the stiffness and strength requirements for beams with multiple braces. A modified stiffness coefficient, Ni, is proposed to more accurately define ideal brace stiffness varying brace numbers, load positions, and moment gradients, leading to a generalized stiffness requirement applicable to both single and multiple braces. The results indicate that, contrary to AISC provisions—which tend to overdesign as brace numbers increases—additional braces reduce both the required stiffness and bracing force, enabling more efficient designs. The buckling load equivalence model (BEM), originally formulated for columns, is adapted for beam bracing and, when combined with initial imperfections and threshold deflections, yields conservative and reliable predictions regardless of brace quantity. The proposed method offers a more rational approach to brace design compared with current AISC criteria.
{"title":"Improved stiffness and strength requirements for point lateral bracing in beams","authors":"Kee Dong Kim , Jeonghwa Lee , Kyoung Yong Park , Young-Goo Choi","doi":"10.1016/j.engstruct.2026.122268","DOIUrl":"10.1016/j.engstruct.2026.122268","url":null,"abstract":"<div><div>Point lateral braces are essential for economical steel beam design by preventing out-of-plane deformations during construction. While previous studies have focused mainly on a single midspan brace, the behavior of beams with multiple braces under lateral–torsional buckling remains unclear. This study develops a unified framework for assessing the stiffness and strength requirements for beams with multiple braces. A modified stiffness coefficient, <em>N</em><sub><em>i</em></sub>, is proposed to more accurately define ideal brace stiffness varying brace numbers, load positions, and moment gradients, leading to a generalized stiffness requirement applicable to both single and multiple braces. The results indicate that, contrary to AISC provisions—which tend to overdesign as brace numbers increases—additional braces reduce both the required stiffness and bracing force, enabling more efficient designs. The buckling load equivalence model (BEM), originally formulated for columns, is adapted for beam bracing and, when combined with initial imperfections and threshold deflections, yields conservative and reliable predictions regardless of brace quantity. The proposed method offers a more rational approach to brace design compared with current AISC criteria.</div></div>","PeriodicalId":11763,"journal":{"name":"Engineering Structures","volume":"353 ","pages":"Article 122268"},"PeriodicalIF":6.4,"publicationDate":"2026-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146185002","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2026-02-04DOI: 10.1016/j.engstruct.2026.122182
Benkun Tan , Fanghuai Chen , Da Wang , Jialin Shi , Chengong Zhao
Within this work, a physics-informed (PI) Stacking ensemble machine learning framework is proposed for the fatigue life prediction and key parameter identification of stud connectors in steel–concrete composite structures. The proposed PI-based framework achieves high accuracy and strong generalization capability in predicting the fatigue life of stud connectors under various material properties, loading conditions, and geometric configurations, outperforming traditional physics-based formulations and conventional machine learning models. In addition, global sensitivity analysis using the Morris and Sobol methods is conducted to accurately identify the dominant variables influencing stud fatigue behavior. The shear stress range, tensile and compressive strengths, and the PI feature derived from linear elastic fracture mechanics are recognized as the most critical parameters controlling fatigue performance. Furthermore, SHapley Additive exPlanations are employed to enhance interpretability and clarify the nonlinear relationships between model inputs and predicted fatigue life. Finally, a graphical user interface is developed based on the trained PI- based model, enabling rapid, visual, and user-friendly fatigue life prediction. In practical applications, the proposed framework can be efficiently applied to fatigue life evaluation of stud connectors, providing a powerful tool for design optimization, maintenance planning, and safety assessment.
{"title":"Physics-informed stacking ensemble machine learning for fatigue life prediction of stud connectors in steel-concrete composite structures","authors":"Benkun Tan , Fanghuai Chen , Da Wang , Jialin Shi , Chengong Zhao","doi":"10.1016/j.engstruct.2026.122182","DOIUrl":"10.1016/j.engstruct.2026.122182","url":null,"abstract":"<div><div>Within this work, a physics-informed (PI) Stacking ensemble machine learning framework is proposed for the fatigue life prediction and key parameter identification of stud connectors in steel–concrete composite structures. The proposed PI-based framework achieves high accuracy and strong generalization capability in predicting the fatigue life of stud connectors under various material properties, loading conditions, and geometric configurations, outperforming traditional physics-based formulations and conventional machine learning models. In addition, global sensitivity analysis using the Morris and Sobol methods is conducted to accurately identify the dominant variables influencing stud fatigue behavior. The shear stress range, tensile and compressive strengths, and the PI feature derived from linear elastic fracture mechanics are recognized as the most critical parameters controlling fatigue performance. Furthermore, SHapley Additive exPlanations are employed to enhance interpretability and clarify the nonlinear relationships between model inputs and predicted fatigue life. Finally, a graphical user interface is developed based on the trained PI- based model, enabling rapid, visual, and user-friendly fatigue life prediction. In practical applications, the proposed framework can be efficiently applied to fatigue life evaluation of stud connectors, providing a powerful tool for design optimization, maintenance planning, and safety assessment.</div></div>","PeriodicalId":11763,"journal":{"name":"Engineering Structures","volume":"353 ","pages":"Article 122182"},"PeriodicalIF":6.4,"publicationDate":"2026-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146185395","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2026-02-04DOI: 10.1016/j.engstruct.2026.122272
Guoxu Zhao , Gao Ma , Min-Jeong Cho , Hyeon-Jong Hwang
With the advancement of artificial intelligence technologies, automated structural design has emerged as a new research focus in recent years. This study proposes a deep reinforcement learning (DRL) method for design of reinforced concrete shear walls. Based on the Soft Actor-Critic (SAC) algorithm, DRL agent was trained with deep learning network. Design code-based constraints were incorporated into the DRL framework to automate structural design while ensuring compliance with design codes. Additionally, for structures where the shear strength cannot be accurately determined, a machine learning technique for shear strength estimation was integrated with DRL on automated design. For DRL training, reward functions were established to meet the design code requirements and minimize cost. After 100,000 training iterations, DRL agent was successfully trained to design shear walls with an acceptable cost. This method is capable of designing compliant and cost-efficient shear wall structures within only 0.1 s. Further, a practical case study was conducted to compare DRL with traditional optimization algorithms, demonstrating the superior computational efficiency of DRL in automatic design of shear walls. The speed and accuracy of the DRL design agent validated the feasibility of the proposed method, and highlighted its potential in effectively solving complex civil engineering design problems.
{"title":"Automated design of shear wall structures using reinforcement learning with code compliance","authors":"Guoxu Zhao , Gao Ma , Min-Jeong Cho , Hyeon-Jong Hwang","doi":"10.1016/j.engstruct.2026.122272","DOIUrl":"10.1016/j.engstruct.2026.122272","url":null,"abstract":"<div><div>With the advancement of artificial intelligence technologies, automated structural design has emerged as a new research focus in recent years. This study proposes a deep reinforcement learning (DRL) method for design of reinforced concrete shear walls. Based on the Soft Actor-Critic (SAC) algorithm, DRL agent was trained with deep learning network. Design code-based constraints were incorporated into the DRL framework to automate structural design while ensuring compliance with design codes. Additionally, for structures where the shear strength cannot be accurately determined, a machine learning technique for shear strength estimation was integrated with DRL on automated design. For DRL training, reward functions were established to meet the design code requirements and minimize cost. After 100,000 training iterations, DRL agent was successfully trained to design shear walls with an acceptable cost. This method is capable of designing compliant and cost-efficient shear wall structures within only 0.1 s. Further, a practical case study was conducted to compare DRL with traditional optimization algorithms, demonstrating the superior computational efficiency of DRL in automatic design of shear walls. The speed and accuracy of the DRL design agent validated the feasibility of the proposed method, and highlighted its potential in effectively solving complex civil engineering design problems.</div></div>","PeriodicalId":11763,"journal":{"name":"Engineering Structures","volume":"353 ","pages":"Article 122272"},"PeriodicalIF":6.4,"publicationDate":"2026-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146185386","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2026-02-03DOI: 10.1016/j.engstruct.2026.122267
Ngoc San Ha , Vuong Nguyen-Van , Yi Min Xie , Dilan Robert , Kate Nguyen
This study explores a sustainable reinforcement strategy for cementitious beams by embedding architected triply periodic minimal surface (TPMS-Primitive) scaffolds manufactured from recycled acrylonitrile butadiene styrene (ABS). The scaffold at a 20 % reinforcement ratio is 3D printed to fabricate composite-cement beams for three-point bending tests. Other companion beams with 0 %, 5 %, 10 %, 15 %, and 30 % reinforcement are examined numerically to evaluate the effect of reinforcement volume fraction on flexural response. A validated finite element framework incorporating a simplified cement damage plasticity model is developed to capture load-deflection behaviour and crack propagation under a perfect-bond assumption due to geometric interlocking. The results demonstrate that TPMS-Primitive scaffolds effectively transform brittle matrix fracture into distributed, ductile failure modes, enhancing both flexural strength and toughness within a reinforcement range (20 %). The findings establish TPMS-Primitive reinforced-cement composites as a promising pathway toward lightweight, material-efficient, and sustainable reinforcement systems in digitally fabricated concrete structures.
{"title":"Sustainable development of reinforced-concrete composite beams with bio-inspired geometry and recycled plastic","authors":"Ngoc San Ha , Vuong Nguyen-Van , Yi Min Xie , Dilan Robert , Kate Nguyen","doi":"10.1016/j.engstruct.2026.122267","DOIUrl":"10.1016/j.engstruct.2026.122267","url":null,"abstract":"<div><div>This study explores a sustainable reinforcement strategy for cementitious beams by embedding architected triply periodic minimal surface (TPMS-Primitive) scaffolds manufactured from recycled acrylonitrile butadiene styrene (ABS). The scaffold at a 20 % reinforcement ratio is 3D printed to fabricate composite-cement beams for three-point bending tests. Other companion beams with 0 %, 5 %, 10 %, 15 %, and 30 % reinforcement are examined numerically to evaluate the effect of reinforcement volume fraction on flexural response. A validated finite element framework incorporating a simplified cement damage plasticity model is developed to capture load-deflection behaviour and crack propagation under a perfect-bond assumption due to geometric interlocking. The results demonstrate that TPMS-Primitive scaffolds effectively transform brittle matrix fracture into distributed, ductile failure modes, enhancing both flexural strength and toughness within a reinforcement range (20 %). The findings establish TPMS-Primitive reinforced-cement composites as a promising pathway toward lightweight, material-efficient, and sustainable reinforcement systems in digitally fabricated concrete structures.</div></div>","PeriodicalId":11763,"journal":{"name":"Engineering Structures","volume":"353 ","pages":"Article 122267"},"PeriodicalIF":6.4,"publicationDate":"2026-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146184860","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2026-02-03DOI: 10.1016/j.engstruct.2026.122250
Peijun Zhang , Ning Li , Huaigu Tian , Jianquan Li , Hadi Arvin
<div><div>The nonlinear dynamics of fluid-conveying pipes present both challenges and opportunities for engineers. While large-amplitude oscillations can be harnessed for energy harvesting, damage detection, and system identification, they can also lead to structural faults. This study explores how graphene nanofillers can be used to control these nonlinear vibrations, providing key insights into the primary and secondary resonance responses of flow-filled graphene-reinforced composite pipes and characterizing their bistable frequency behavior.</div><div>The effective mechanical properties of the graphene sheet/Poly(methyl methacrylate) (GS/PMMA) reinforced composite (GSRC) are defined using the refined Halpin–Tsai micromechanical model calibrated with molecular dynamics (MD) simulations. The method of multiple scales (MMS) is applied to the gyroscopically coupled governing equations to derive closed-form analytical solutions that address the nonlinear dynamics of GSRC pipes, focusing on the bistability bandwidth of the response, which is governed by the interplay of the pipe’s wall thickness, damping constant, flow velocity, GS distribution pattern (GSDP), and stacking sequence.</div><div>The analytical solutions determine the activation zone and bifurcation map under subharmonic excitation, as well as the full frequency response under primary, subharmonic, and superharmonic excitations. The results are validated quantitatively against existing literature and via the Runge–Kutta fourth-order method (RK4M), and qualitatively with fast Fourier transform (FFT) spectrum and Poincaré section analysis. Numerical simulations reveal that, independent of the damping constant, a simply-supported (SS) thin-walled pipe (with a radius ratio <span><math><mrow><mo>></mo><mo>∼</mo><mn>0</mn><mo>.</mo><mn>9</mn></mrow></math></span>) does not exhibit subharmonic resonance for dimensionless flow velocities above 0.1. Furthermore, its superharmonic response is not bistable. Additionally, for damping constants above 0.075, a bistable subharmonic response will not occur, irrespective of the pipe’s wall thickness, for dimensionless flow velocities above 0.1. Moreover, a thick-walled pipe featuring a functionally graded-V (FGV) GSDP exhibits the widest bistable response range in subharmonic resonance, whereas a functionally graded-A (FGA) GSDP pipe demonstrates the broadest bistable response range in primary resonance. For superharmonic resonance, the bistable range is influenced by both the GSDP and the force amplitude.</div><div>Furthermore, the frequency response under superharmonic resonance depends considerably on the stacking sequence, showing a maximum 8% difference in steady state amplitude, whereas the subharmonic response is largely independent of the stacking sequence, with a maximum 0.3% amplitude difference. Collectively, these findings provide a practical design framework for optimizing GSRC pipes, whether the goal is to enhance energy harvesting or s
{"title":"Characterization of bistable frequency responses in nonlinear oscillations of flow-filled graphene-reinforced pipes under various resonances","authors":"Peijun Zhang , Ning Li , Huaigu Tian , Jianquan Li , Hadi Arvin","doi":"10.1016/j.engstruct.2026.122250","DOIUrl":"10.1016/j.engstruct.2026.122250","url":null,"abstract":"<div><div>The nonlinear dynamics of fluid-conveying pipes present both challenges and opportunities for engineers. While large-amplitude oscillations can be harnessed for energy harvesting, damage detection, and system identification, they can also lead to structural faults. This study explores how graphene nanofillers can be used to control these nonlinear vibrations, providing key insights into the primary and secondary resonance responses of flow-filled graphene-reinforced composite pipes and characterizing their bistable frequency behavior.</div><div>The effective mechanical properties of the graphene sheet/Poly(methyl methacrylate) (GS/PMMA) reinforced composite (GSRC) are defined using the refined Halpin–Tsai micromechanical model calibrated with molecular dynamics (MD) simulations. The method of multiple scales (MMS) is applied to the gyroscopically coupled governing equations to derive closed-form analytical solutions that address the nonlinear dynamics of GSRC pipes, focusing on the bistability bandwidth of the response, which is governed by the interplay of the pipe’s wall thickness, damping constant, flow velocity, GS distribution pattern (GSDP), and stacking sequence.</div><div>The analytical solutions determine the activation zone and bifurcation map under subharmonic excitation, as well as the full frequency response under primary, subharmonic, and superharmonic excitations. The results are validated quantitatively against existing literature and via the Runge–Kutta fourth-order method (RK4M), and qualitatively with fast Fourier transform (FFT) spectrum and Poincaré section analysis. Numerical simulations reveal that, independent of the damping constant, a simply-supported (SS) thin-walled pipe (with a radius ratio <span><math><mrow><mo>></mo><mo>∼</mo><mn>0</mn><mo>.</mo><mn>9</mn></mrow></math></span>) does not exhibit subharmonic resonance for dimensionless flow velocities above 0.1. Furthermore, its superharmonic response is not bistable. Additionally, for damping constants above 0.075, a bistable subharmonic response will not occur, irrespective of the pipe’s wall thickness, for dimensionless flow velocities above 0.1. Moreover, a thick-walled pipe featuring a functionally graded-V (FGV) GSDP exhibits the widest bistable response range in subharmonic resonance, whereas a functionally graded-A (FGA) GSDP pipe demonstrates the broadest bistable response range in primary resonance. For superharmonic resonance, the bistable range is influenced by both the GSDP and the force amplitude.</div><div>Furthermore, the frequency response under superharmonic resonance depends considerably on the stacking sequence, showing a maximum 8% difference in steady state amplitude, whereas the subharmonic response is largely independent of the stacking sequence, with a maximum 0.3% amplitude difference. Collectively, these findings provide a practical design framework for optimizing GSRC pipes, whether the goal is to enhance energy harvesting or s","PeriodicalId":11763,"journal":{"name":"Engineering Structures","volume":"353 ","pages":"Article 122250"},"PeriodicalIF":6.4,"publicationDate":"2026-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146184858","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2026-02-03DOI: 10.1016/j.engstruct.2026.122243
Cheng Chen , Evan Wei Wen Cheok , Xudong Qian
This paper presents an innovative method to quantify the J-integral of circular hollow section (CHS) joint using displacement data obtained from digital image correlation (DIC). The through-thickness crack initiates and propagates along the weld connections. Through coordinate transformation, this study determines the 3D strain and stress of the CHS joint and computes the J-integral from local 2D contours enclosing the crack tip, thereby demonstrating path-independent J results on tubular structures. The DIC-based J integrals agree closely with the through-thickness averaged J in both partial joint penetration (PJP) and complete joint penetration (CJP) welds. The experimental studies further validate the proposed DIC approach in tracking the J-integrals during high-cycle and low-cycle fatigue tests of CHS joints. This study proposes a generalized DIC approach that enables fracture-mechanics-based fatigue assessment of engineering structures with complex geometries. The fatigue crack growth of the CHS joint deviates from both small-scale specimen data and the BS7910 reference curves.
{"title":"DIC-based J-integral quantification for through-thickness crack in CHS joints","authors":"Cheng Chen , Evan Wei Wen Cheok , Xudong Qian","doi":"10.1016/j.engstruct.2026.122243","DOIUrl":"10.1016/j.engstruct.2026.122243","url":null,"abstract":"<div><div>This paper presents an innovative method to quantify the <em>J</em>-integral of circular hollow section (CHS) joint using displacement data obtained from digital image correlation (DIC). The through-thickness crack initiates and propagates along the weld connections. Through coordinate transformation, this study determines the 3D strain and stress of the CHS joint and computes the <em>J</em>-integral from local 2D contours enclosing the crack tip, thereby demonstrating path-independent <em>J</em> results on tubular structures. The DIC-based <em>J</em> integrals agree closely with the through-thickness averaged <em>J</em> in both partial joint penetration (PJP) and complete joint penetration (CJP) welds. The experimental studies further validate the proposed DIC approach in tracking the <em>J</em>-integrals during high-cycle and low-cycle fatigue tests of CHS joints. This study proposes a generalized DIC approach that enables fracture-mechanics-based fatigue assessment of engineering structures with complex geometries. The fatigue crack growth of the CHS joint deviates from both small-scale specimen data and the BS7910 reference curves.</div></div>","PeriodicalId":11763,"journal":{"name":"Engineering Structures","volume":"353 ","pages":"Article 122243"},"PeriodicalIF":6.4,"publicationDate":"2026-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146184859","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2026-02-03DOI: 10.1016/j.engstruct.2026.122265
Xiang-Hua Yue , Yue-Ling Long , Jun Huang , Jun-Jie Zeng , Jinjing Liao , Shun-Yi Lin
Axial compressive behaviour of FRP-confined structural bamboo tubes (F-BTs) and FRP-confined concrete-filled structural bamboo tubes (F-CFBTs) was experimentally investigated. A total 32 specimens including 12 F-BT specimens, 12 F-CFBT specimens, 4 concrete-filled bamboo tube specimens (CFBTs) and 4 conventional bamboo tube specimens were tested, aiming at the influences of FRP jackets, bamboo node and specimen size on the axial compressive behaviour. It was found that the presence of FRP jackets led to significantly improved axial compressive behaviour of F-BTs and F-CFBTs, compared with those without FRP jackets, which ascertained the effectiveness of FRP jackets for structural bamboo. FRP jackets changed the local buckling mode of bamboo tubes. F-BTs buckled inwards due to that the FRP jackets restrain the outward buckling of the bamboo. However, F-CFBTs still buckled outwards due to the presence of infilled concrete. The ultimate capacity of FRP-confined bamboo tubes (F-BTs) increases with FRP thickness increasing only to a certain limited thickness. When the thickness of FRP jacket is beyond the threshold thickness, the bearing capacity of F-BTs can not increase with thicker FRP jacket. However, the ultimate capacity of F-CFBTs remained increasing with FRP thickness increasing. F-CFBTs possess better mechanical performance than F-BTs and CFBTs. The axial load-strain responses of F-BTs are distinct from F-CFBTs. In addition, the presence of bamboo nodes modestly influences the compressive behaviour of F-BTs and F-CFBTs specimens. Furthermore, preliminary comparisons of the specimens under similar confinement ratios suggest minimal size effect. Finally, the maximum of effective confining stress of FRP is originally proposed for hollow normal-sized bamboo.
{"title":"Axial compressive behaviour of FRP-confined structural bamboo with and without concrete infilled","authors":"Xiang-Hua Yue , Yue-Ling Long , Jun Huang , Jun-Jie Zeng , Jinjing Liao , Shun-Yi Lin","doi":"10.1016/j.engstruct.2026.122265","DOIUrl":"10.1016/j.engstruct.2026.122265","url":null,"abstract":"<div><div>Axial compressive behaviour of FRP-confined structural bamboo tubes (F-BTs) and FRP-confined concrete-filled structural bamboo tubes (F-CFBTs) was experimentally investigated. A total 32 specimens including 12 F-BT specimens, 12 F-CFBT specimens, 4 concrete-filled bamboo tube specimens (CFBTs) and 4 conventional bamboo tube specimens were tested, aiming at the influences of FRP jackets, bamboo node and specimen size on the axial compressive behaviour. It was found that the presence of FRP jackets led to significantly improved axial compressive behaviour of F-BTs and F-CFBTs, compared with those without FRP jackets, which ascertained the effectiveness of FRP jackets for structural bamboo. FRP jackets changed the local buckling mode of bamboo tubes. F-BTs buckled inwards due to that the FRP jackets restrain the outward buckling of the bamboo. However, F-CFBTs still buckled outwards due to the presence of infilled concrete. The ultimate capacity of FRP-confined bamboo tubes (F-BTs) increases with FRP thickness increasing only to a certain limited thickness. When the thickness of FRP jacket is beyond the threshold thickness, the bearing capacity of F-BTs can not increase with thicker FRP jacket. However, the ultimate capacity of F-CFBTs remained increasing with FRP thickness increasing. F-CFBTs possess better mechanical performance than F-BTs and CFBTs. The axial load-strain responses of F-BTs are distinct from F-CFBTs. In addition, the presence of bamboo nodes modestly influences the compressive behaviour of F-BTs and F-CFBTs specimens. Furthermore, preliminary comparisons of the specimens under similar confinement ratios suggest minimal size effect. Finally, the maximum of effective confining stress of FRP is originally proposed for hollow normal-sized bamboo.</div></div>","PeriodicalId":11763,"journal":{"name":"Engineering Structures","volume":"353 ","pages":"Article 122265"},"PeriodicalIF":6.4,"publicationDate":"2026-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146185390","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper investigates the structural performance of hollow precast high-strength concrete-filled steel tube (H-HSCFST) piles under cyclic flexural and varying high axial loads, simulating severe seismic conditions. An experimental program on eight real-scale specimens was conducted to examine the influence of steel tube thickness, concrete shell thickness, and the presence of concrete infill on the capacity and the ductility of the H-HSCFSTs. The investigation showed that ductility is significantly enhanced by using compact steel tubes and concrete infill, while thick concrete shell enhanced the moment capacity, whereas noncompact tubes combined with thin concrete shells exhibit poor performance. Furthermore, the results found that existing design codes (AISC 360–22, AIJ 2022 guideline on foundation members, and Eurocode 4) are inadequate for predicting pile behavior under these demanding loads. Recommendations to update these existing codes were suggested. To address the identified modeling deficiencies, a computationally efficient multi-spring fiber-based numerical model was developed. This model incorporates novel constitutive laws where new coefficients are proposed for both the steel and concrete material models to directly reflect the observed experimental phenomena. The modified steel model uses these coefficients to account for strength loss after concrete crushing, while the concrete model uses them to correlate strength and residual stress to shell slenderness. Comparison against experimental data demonstrated that the proposed model accurately reproduces the global moment-drift responses and local strain distributions. Furthermore, the model was successfully validated against 11 specimens from an independent dataset. The developed model provides an efficient and reliable tool for the seismic design of H-HSCFST piles for engineering practice.
{"title":"Structural performance of circular hollow precast high-strength concrete-filled steel tube piles under cyclic flexural and varying high axial loads","authors":"Clarissa Jasinda , Keito Nagao , Trevor Zhiqing Yeow , Susumu Kono , David Mukai , Kiyoshi Miyahara","doi":"10.1016/j.engstruct.2026.122248","DOIUrl":"10.1016/j.engstruct.2026.122248","url":null,"abstract":"<div><div>This paper investigates the structural performance of hollow precast high-strength concrete-filled steel tube (H-HSCFST) piles under cyclic flexural and varying high axial loads, simulating severe seismic conditions. An experimental program on eight real-scale specimens was conducted to examine the influence of steel tube thickness, concrete shell thickness, and the presence of concrete infill on the capacity and the ductility of the H-HSCFSTs. The investigation showed that ductility is significantly enhanced by using compact steel tubes and concrete infill, while thick concrete shell enhanced the moment capacity, whereas noncompact tubes combined with thin concrete shells exhibit poor performance. Furthermore, the results found that existing design codes (AISC 360–22, AIJ 2022 guideline on foundation members, and Eurocode 4) are inadequate for predicting pile behavior under these demanding loads. Recommendations to update these existing codes were suggested. To address the identified modeling deficiencies, a computationally efficient multi-spring fiber-based numerical model was developed. This model incorporates novel constitutive laws where new coefficients are proposed for both the steel and concrete material models to directly reflect the observed experimental phenomena. The modified steel model uses these coefficients to account for strength loss after concrete crushing, while the concrete model uses them to correlate strength and residual stress to shell slenderness. Comparison against experimental data demonstrated that the proposed model accurately reproduces the global moment-drift responses and local strain distributions. Furthermore, the model was successfully validated against 11 specimens from an independent dataset. The developed model provides an efficient and reliable tool for the seismic design of H-HSCFST piles for engineering practice.</div></div>","PeriodicalId":11763,"journal":{"name":"Engineering Structures","volume":"353 ","pages":"Article 122248"},"PeriodicalIF":6.4,"publicationDate":"2026-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146184998","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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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