Pub Date : 2024-08-13DOI: 10.1108/ijsi-03-2024-0052
Hong Guo, Xiaokai Niu, Zhitian Xie
PurposeThe occurrence of segment cracks caused by load changes in shield tunnels would affect the safety of the tunnel structure. To this end, a three-dimensional fine shield tunnel segment model based on the extended finite element method (XFEM) is established.Design/methodology/approachThe cracking law of shield segment cracks is studied in two forms: overloading and unloading. The relationship between crack length, width and depth and transverse convergence and deformation is analyzed.FindingsThe results show that the cracks in shield tunnels mainly occur on the outer side of the arch waist and the inner side of the crown and bottom. Under overloading and unloading conditions, the length, width and depth of cracks increase non-linearly as the transverse convergence deformation increases. Under the same convergent deformation, the deeper the buried depth, the smaller the crack length, width and depth. Meanwhile, under overloading conditions, the influence of buried depth on the width and depth of cracks is more significant. In terms of crack width and depth, unloading conditions are more dangerous than overloading conditions.Originality/valueThe findings have a guiding effect for the management of cracks in shield tunnels during operation.
{"title":"Study on crack law of shield segment under load variation based on XFEM","authors":"Hong Guo, Xiaokai Niu, Zhitian Xie","doi":"10.1108/ijsi-03-2024-0052","DOIUrl":"https://doi.org/10.1108/ijsi-03-2024-0052","url":null,"abstract":"PurposeThe occurrence of segment cracks caused by load changes in shield tunnels would affect the safety of the tunnel structure. To this end, a three-dimensional fine shield tunnel segment model based on the extended finite element method (XFEM) is established.Design/methodology/approachThe cracking law of shield segment cracks is studied in two forms: overloading and unloading. The relationship between crack length, width and depth and transverse convergence and deformation is analyzed.FindingsThe results show that the cracks in shield tunnels mainly occur on the outer side of the arch waist and the inner side of the crown and bottom. Under overloading and unloading conditions, the length, width and depth of cracks increase non-linearly as the transverse convergence deformation increases. Under the same convergent deformation, the deeper the buried depth, the smaller the crack length, width and depth. Meanwhile, under overloading conditions, the influence of buried depth on the width and depth of cracks is more significant. In terms of crack width and depth, unloading conditions are more dangerous than overloading conditions.Originality/valueThe findings have a guiding effect for the management of cracks in shield tunnels during operation.","PeriodicalId":45359,"journal":{"name":"International Journal of Structural Integrity","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141919534","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-13DOI: 10.1108/ijsi-03-2024-0052
Hong Guo, Xiaokai Niu, Zhitian Xie
PurposeThe occurrence of segment cracks caused by load changes in shield tunnels would affect the safety of the tunnel structure. To this end, a three-dimensional fine shield tunnel segment model based on the extended finite element method (XFEM) is established.Design/methodology/approachThe cracking law of shield segment cracks is studied in two forms: overloading and unloading. The relationship between crack length, width and depth and transverse convergence and deformation is analyzed.FindingsThe results show that the cracks in shield tunnels mainly occur on the outer side of the arch waist and the inner side of the crown and bottom. Under overloading and unloading conditions, the length, width and depth of cracks increase non-linearly as the transverse convergence deformation increases. Under the same convergent deformation, the deeper the buried depth, the smaller the crack length, width and depth. Meanwhile, under overloading conditions, the influence of buried depth on the width and depth of cracks is more significant. In terms of crack width and depth, unloading conditions are more dangerous than overloading conditions.Originality/valueThe findings have a guiding effect for the management of cracks in shield tunnels during operation.
{"title":"Study on crack law of shield segment under load variation based on XFEM","authors":"Hong Guo, Xiaokai Niu, Zhitian Xie","doi":"10.1108/ijsi-03-2024-0052","DOIUrl":"https://doi.org/10.1108/ijsi-03-2024-0052","url":null,"abstract":"PurposeThe occurrence of segment cracks caused by load changes in shield tunnels would affect the safety of the tunnel structure. To this end, a three-dimensional fine shield tunnel segment model based on the extended finite element method (XFEM) is established.Design/methodology/approachThe cracking law of shield segment cracks is studied in two forms: overloading and unloading. The relationship between crack length, width and depth and transverse convergence and deformation is analyzed.FindingsThe results show that the cracks in shield tunnels mainly occur on the outer side of the arch waist and the inner side of the crown and bottom. Under overloading and unloading conditions, the length, width and depth of cracks increase non-linearly as the transverse convergence deformation increases. Under the same convergent deformation, the deeper the buried depth, the smaller the crack length, width and depth. Meanwhile, under overloading conditions, the influence of buried depth on the width and depth of cracks is more significant. In terms of crack width and depth, unloading conditions are more dangerous than overloading conditions.Originality/valueThe findings have a guiding effect for the management of cracks in shield tunnels during operation.","PeriodicalId":45359,"journal":{"name":"International Journal of Structural Integrity","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141919087","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-15DOI: 10.1108/ijsi-02-2024-0021
G. Gusev, Roman Tsvetkov, I. Shardakov
Purpose This study aims to ensure safe operation of buildings in the mining area.Design/methodology/approachThe strain energy value was taken as one of the parameters characterizing the deformation process at critical stages in these problems and providing a link between them. Based on the data obtained for the structural element of loading diagrams and assessment of the stress–strain state of the structure as a whole, the maximum permissible horizontal deformations of the soil around the foundation are determined, at which the building elements reach the stress–strain state preceding the loss of bearing capacity. For this purpose, a parameter is used that characterizes the deformation process at the stages of critical deformation in these problems and provides a link between them. This parameter is the value of strain energy.FindingsBased on the obtained force behavior diagrams of structural elements and assessment of the stress–strain state of the structure as a whole, the maximum permissible horizontal ground deformations in the vicinity of the foundation are determined, at which the building elements reach the stress–strain state preceding the loss of bearing capacity.Originality/valueThe research provides new data in the form of regularities of deformation behavior of building structures in the zones of mine workings. These data formed the basis for the normative documentation being developed. The research results were used for the development of internal instructions of a large mining enterprise.
{"title":"Research of criteria for analyzing the load-bearing capacity of buildings in areas of technogenic impact caused by mining operations","authors":"G. Gusev, Roman Tsvetkov, I. Shardakov","doi":"10.1108/ijsi-02-2024-0021","DOIUrl":"https://doi.org/10.1108/ijsi-02-2024-0021","url":null,"abstract":"Purpose This study aims to ensure safe operation of buildings in the mining area.Design/methodology/approachThe strain energy value was taken as one of the parameters characterizing the deformation process at critical stages in these problems and providing a link between them. Based on the data obtained for the structural element of loading diagrams and assessment of the stress–strain state of the structure as a whole, the maximum permissible horizontal deformations of the soil around the foundation are determined, at which the building elements reach the stress–strain state preceding the loss of bearing capacity. For this purpose, a parameter is used that characterizes the deformation process at the stages of critical deformation in these problems and provides a link between them. This parameter is the value of strain energy.FindingsBased on the obtained force behavior diagrams of structural elements and assessment of the stress–strain state of the structure as a whole, the maximum permissible horizontal ground deformations in the vicinity of the foundation are determined, at which the building elements reach the stress–strain state preceding the loss of bearing capacity.Originality/valueThe research provides new data in the form of regularities of deformation behavior of building structures in the zones of mine workings. These data formed the basis for the normative documentation being developed. The research results were used for the development of internal instructions of a large mining enterprise.","PeriodicalId":45359,"journal":{"name":"International Journal of Structural Integrity","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141646367","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-12DOI: 10.1108/ijsi-04-2024-0059
M. Saifeldeen, Ahmed Monier, N. Fouad
PurposeThis paper presents a novel method for identifying damage in reinforced concrete (RC) bridges, utilizing macro-strain data from distributed long-gauge sensors installed on the concrete surface.Design/methodology/approachThe method relies on the principle that heavy vehicles induce larger dynamic vibrations, leading to increased strain and crack formation compared to lighter vehicles. By comparing the absolute macro-strain ratio (AMSR) of a reference sensor with a network of distributed sensors, damage locations can be effectively pinpointed from a single data collection session. Finite-element modeling was employed to validate the method's efficacy, demonstrating that the AMSR ratio increases significantly in the presence of cracks. Experimental validation was conducted on a real-world bridge in Japan, confirming the method's reliability under normal traffic conditions.FindingsThis approach offers a practical and efficient means of detecting bridge damage, potentially enhancing the safety and longevity of infrastructure systems.Originality/valueOriginal research paper.
{"title":"Detection of bridge damage through analysis of dynamic response to vehicular loads utilizing long-gauge sensors","authors":"M. Saifeldeen, Ahmed Monier, N. Fouad","doi":"10.1108/ijsi-04-2024-0059","DOIUrl":"https://doi.org/10.1108/ijsi-04-2024-0059","url":null,"abstract":"PurposeThis paper presents a novel method for identifying damage in reinforced concrete (RC) bridges, utilizing macro-strain data from distributed long-gauge sensors installed on the concrete surface.Design/methodology/approachThe method relies on the principle that heavy vehicles induce larger dynamic vibrations, leading to increased strain and crack formation compared to lighter vehicles. By comparing the absolute macro-strain ratio (AMSR) of a reference sensor with a network of distributed sensors, damage locations can be effectively pinpointed from a single data collection session. Finite-element modeling was employed to validate the method's efficacy, demonstrating that the AMSR ratio increases significantly in the presence of cracks. Experimental validation was conducted on a real-world bridge in Japan, confirming the method's reliability under normal traffic conditions.FindingsThis approach offers a practical and efficient means of detecting bridge damage, potentially enhancing the safety and longevity of infrastructure systems.Originality/valueOriginal research paper.","PeriodicalId":45359,"journal":{"name":"International Journal of Structural Integrity","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141652503","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
PurposeIn order to achieve the desired macroscopic mechanical properties of woven fiber reinforced polymer (FRP) materials, it is necessary to conduct a detailed analysis of their microscopic load-bearing capacity.Design/methodology/approachUtilizing the representative volume element (RVE) model, this study delves into how the material composition influences mechanical parameters and failure processes.FindingsTo study the ultimate strength of the materials, this study considers the damage situation in various parts and analyzes the stress-strain curves under uniaxial and multiaxial loading conditions. Furthermore, the study investigates the degradation of macroscopic mechanical properties of fiber and resin layers due to fatigue induced performance degradation. Additionally, the research explores the impact of fatigue damage on key material properties such as the elastic modulus, shear modulus and Poisson's ratio.Originality/valueBy studying the load-bearing mechanisms at different scales, a direct correlation is established between the macroscopic mechanical behavior of the material and the microstructure of woven FRP materials. This comprehensive analysis ultimately elucidates the material's mechanical response under conditions of fatigue damage.
{"title":"Ultimate resistance and fatigue performance predictions of woven-based fiber reinforced polymers using a computational homogenization method","authors":"Junqiang Li, Haohui Xin, Youyou Zhang, Qinglin Gao, Hengyu Zhang","doi":"10.1108/ijsi-03-2024-0049","DOIUrl":"https://doi.org/10.1108/ijsi-03-2024-0049","url":null,"abstract":"PurposeIn order to achieve the desired macroscopic mechanical properties of woven fiber reinforced polymer (FRP) materials, it is necessary to conduct a detailed analysis of their microscopic load-bearing capacity.Design/methodology/approachUtilizing the representative volume element (RVE) model, this study delves into how the material composition influences mechanical parameters and failure processes.FindingsTo study the ultimate strength of the materials, this study considers the damage situation in various parts and analyzes the stress-strain curves under uniaxial and multiaxial loading conditions. Furthermore, the study investigates the degradation of macroscopic mechanical properties of fiber and resin layers due to fatigue induced performance degradation. Additionally, the research explores the impact of fatigue damage on key material properties such as the elastic modulus, shear modulus and Poisson's ratio.Originality/valueBy studying the load-bearing mechanisms at different scales, a direct correlation is established between the macroscopic mechanical behavior of the material and the microstructure of woven FRP materials. This comprehensive analysis ultimately elucidates the material's mechanical response under conditions of fatigue damage.","PeriodicalId":45359,"journal":{"name":"International Journal of Structural Integrity","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141657041","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-14DOI: 10.1108/ijsi-03-2024-0043
Adnan Rasul, S. Karuppanan, V. Perumal, M. Ovinis, Mohsin Iqbal, Khurshid Alam
PurposeStress concentration factors (SCFs) are commonly used to assess the fatigue life of tubular T-joints in offshore structures. SCFs are usually estimated from parametric equations derived from experimental data and finite element analysis (FEA). However, these equations provide the SCF at the crown and saddle points of tubular T-joints only, while peak SCF might occur anywhere along the brace. Using the SCF at the crown and saddle can lead to inaccurate hotspot stress and fatigue life estimates. There are no equations available for calculating the SCF along the T-joint's brace axis under in-plane and out-of-plane bending moments.Design/methodology/approachIn this work, parametric equations for estimating SCFs are developed based on the training weights and biases of an artificial neural network (ANN), as ANNs are capable of representing complex correlations. 1,250 finite element simulations for tubular T-joints with varying dimensions subjected to in-plane bending moments and out-of-plane bending moments were conducted to obtain the corresponding SCFs for training the ANN.FindingsThe ANN was subsequently used to obtain equations to calculate the SCFs based on dimensionless parameters (α, β, γ and τ). The equations can predict the SCF around the T-joint's brace axis with an error of less than 8% and a root mean square error (RMSE) of less than 0.05.Originality/valueAccurate SCF estimation for determining the fatigue life of offshore structures reduces the risks associated with fatigue failure while ensuring their durability and dependability. The current study provides a systematic approach for calculating the stress distribution at the weld toe and SCF in T-joints using FEA and ANN, as ANNs are better at approximating complex phenomena than typical data fitting techniques. Having a database of parametric equations enables fast estimation of SCFs, as opposed to costly testing and time-consuming FEA.
目的应力集中系数（SCF）通常用于评估海上结构中管状 T 形接头的疲劳寿命。SCF 通常根据实验数据和有限元分析 (FEA) 得出的参数方程估算。然而，这些方程只提供了管状 T 形接头的冠点和鞍点处的 SCF，而 SCF 峰值可能出现在支撑的任何位置。使用冠部和鞍部的 SCF 会导致对热点应力和疲劳寿命的估计不准确。设计/方法/途径在这项工作中，基于人工神经网络（ANN）的训练权重和偏差，开发了用于估算 SCF 的参数方程，因为人工神经网络能够表示复杂的相关性。对承受平面内弯矩和平面外弯矩的不同尺寸的管状 T 形接头进行了 1,250 次有限元模拟，以获得相应的 SCFs，用于训练人工神经网络。研究结果随后使用人工神经网络获得了基于无量纲参数（α、β、γ 和 τ）的 SCFs 计算公式。这些方程可以预测 T 形接头支撑轴周围的 SCF，误差小于 8%，均方根误差（RMSE）小于 0.05。原创性/价值准确估算 SCF 以确定海上结构的疲劳寿命，可降低疲劳失效的相关风险，同时确保其耐用性和可靠性。与典型的数据拟合技术相比，ANN 能更好地逼近复杂现象，因此本研究提供了一种利用有限元分析和 ANN 计算 T 形接头焊趾处应力分布和 SCF 的系统方法。与昂贵的测试和耗时的有限元分析相比，拥有参数方程数据库可快速估算 SCF。
{"title":"Empirical modeling of stress concentration factors using artificial neural networks for fatigue design of tubular T-joint under in-plane and out-of-Plane bending moments","authors":"Adnan Rasul, S. Karuppanan, V. Perumal, M. Ovinis, Mohsin Iqbal, Khurshid Alam","doi":"10.1108/ijsi-03-2024-0043","DOIUrl":"https://doi.org/10.1108/ijsi-03-2024-0043","url":null,"abstract":"PurposeStress concentration factors (SCFs) are commonly used to assess the fatigue life of tubular T-joints in offshore structures. SCFs are usually estimated from parametric equations derived from experimental data and finite element analysis (FEA). However, these equations provide the SCF at the crown and saddle points of tubular T-joints only, while peak SCF might occur anywhere along the brace. Using the SCF at the crown and saddle can lead to inaccurate hotspot stress and fatigue life estimates. There are no equations available for calculating the SCF along the T-joint's brace axis under in-plane and out-of-plane bending moments.Design/methodology/approachIn this work, parametric equations for estimating SCFs are developed based on the training weights and biases of an artificial neural network (ANN), as ANNs are capable of representing complex correlations. 1,250 finite element simulations for tubular T-joints with varying dimensions subjected to in-plane bending moments and out-of-plane bending moments were conducted to obtain the corresponding SCFs for training the ANN.FindingsThe ANN was subsequently used to obtain equations to calculate the SCFs based on dimensionless parameters (α, β, γ and τ). The equations can predict the SCF around the T-joint's brace axis with an error of less than 8% and a root mean square error (RMSE) of less than 0.05.Originality/valueAccurate SCF estimation for determining the fatigue life of offshore structures reduces the risks associated with fatigue failure while ensuring their durability and dependability. The current study provides a systematic approach for calculating the stress distribution at the weld toe and SCF in T-joints using FEA and ANN, as ANNs are better at approximating complex phenomena than typical data fitting techniques. Having a database of parametric equations enables fast estimation of SCFs, as opposed to costly testing and time-consuming FEA.","PeriodicalId":45359,"journal":{"name":"International Journal of Structural Integrity","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2024-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141342789","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
PurposeA risk-based method is proposed to identify the dominant influencing factors of secondary lining cracking in an operating mountain tunnel with weak surrounding rock.Design/methodology/approachBased on the inspection data from a mountain tunnel in Southwest China, a lognormal proportional hazard model is established to describe the statistical distribution of secondary lining cracks. Then, the model parameters are obtained by using the Bayesian regression method, and the importance of influencing factors can be sorted based on the absolute values of the parameters.FindingsThe results show that the order of importance of the influencing factors of secondary lining cracks is as follows: location of the crack on the tunnel profile, rock mass grade of the surrounding rock, time to completion of the secondary lining, and void behind the secondary lining. Accordingly, the location of the crack on the tunnel profile and rock mass grade of the surrounding rock are the two most important influencing factors of secondary lining cracks in the investigated mountain tunnel, and appropriate maintenance measures should be focused on these two aspects.Originality/valueThis study provides a general and effective reference for identifying the dominant influencing factors of secondary lining cracks to guide the targeted maintenance in mountain tunnels.
{"title":"Identifying the dominant influencing factors of secondary lining cracking risk in an operating mountain tunnel","authors":"Zhangtao Peng, Qian Fang, Qing Ai, Xiao-Qiang Jiang, Hui Wang, Xingchun Huang, Yong Yuan","doi":"10.1108/ijsi-03-2024-0047","DOIUrl":"https://doi.org/10.1108/ijsi-03-2024-0047","url":null,"abstract":"PurposeA risk-based method is proposed to identify the dominant influencing factors of secondary lining cracking in an operating mountain tunnel with weak surrounding rock.Design/methodology/approachBased on the inspection data from a mountain tunnel in Southwest China, a lognormal proportional hazard model is established to describe the statistical distribution of secondary lining cracks. Then, the model parameters are obtained by using the Bayesian regression method, and the importance of influencing factors can be sorted based on the absolute values of the parameters.FindingsThe results show that the order of importance of the influencing factors of secondary lining cracks is as follows: location of the crack on the tunnel profile, rock mass grade of the surrounding rock, time to completion of the secondary lining, and void behind the secondary lining. Accordingly, the location of the crack on the tunnel profile and rock mass grade of the surrounding rock are the two most important influencing factors of secondary lining cracks in the investigated mountain tunnel, and appropriate maintenance measures should be focused on these two aspects.Originality/valueThis study provides a general and effective reference for identifying the dominant influencing factors of secondary lining cracks to guide the targeted maintenance in mountain tunnels.","PeriodicalId":45359,"journal":{"name":"International Journal of Structural Integrity","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141362710","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-10DOI: 10.1108/ijsi-12-2023-0146
Lu Li, Dong-hua Zhou
PurposeThis paper aims to obtain a calculation method by hand without iteration.Design/methodology/approachThis paper adopts strains as known quantities to solve the internal forces and deformations of the section, simplifies the deflection curve of the column and obtains nomograms that can calculate the bearing capacity and reinforcement of circular reinforced concrete (RC) columns by hand.FindingsNomograms include five variables: mechanical reinforcement ratio, relative normal force, dimensionless bending moment, slenderness ratio and ultimate dimensionless curvature. Nomograms corresponding to all classes of concrete have been drawn, and their dimensionless form makes them widely applicable. The calculation results of nomograms are compared and analysed with numerical calculation results, and the difference is within 5%, meeting the engineering requirements.Originality/valueCalculating the bearing capacity of compression bending components requires considering second-order effects. Therefore, the calculation of the bearing capacity of circular RC columns requires iterative calculation, as it includes dual nonlinearity of material and geometry, and the two are coupled with each other. To calculate the bearing capacity of the section adopting ordinary concrete, it is necessary to solve the transcendental equation iteratively. For high-strength concrete, it can only be solved by numerical integration. A fast calculation method by hand is proposed in this paper.
{"title":"Combined nomograms for calculating the bearing capacity and reinforcement of high-strength and normal concrete RC columns","authors":"Lu Li, Dong-hua Zhou","doi":"10.1108/ijsi-12-2023-0146","DOIUrl":"https://doi.org/10.1108/ijsi-12-2023-0146","url":null,"abstract":"PurposeThis paper aims to obtain a calculation method by hand without iteration.Design/methodology/approachThis paper adopts strains as known quantities to solve the internal forces and deformations of the section, simplifies the deflection curve of the column and obtains nomograms that can calculate the bearing capacity and reinforcement of circular reinforced concrete (RC) columns by hand.FindingsNomograms include five variables: mechanical reinforcement ratio, relative normal force, dimensionless bending moment, slenderness ratio and ultimate dimensionless curvature. Nomograms corresponding to all classes of concrete have been drawn, and their dimensionless form makes them widely applicable. The calculation results of nomograms are compared and analysed with numerical calculation results, and the difference is within 5%, meeting the engineering requirements.Originality/valueCalculating the bearing capacity of compression bending components requires considering second-order effects. Therefore, the calculation of the bearing capacity of circular RC columns requires iterative calculation, as it includes dual nonlinearity of material and geometry, and the two are coupled with each other. To calculate the bearing capacity of the section adopting ordinary concrete, it is necessary to solve the transcendental equation iteratively. For high-strength concrete, it can only be solved by numerical integration. A fast calculation method by hand is proposed in this paper.","PeriodicalId":45359,"journal":{"name":"International Journal of Structural Integrity","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2024-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140994033","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-10DOI: 10.1108/ijsi-02-2024-0034
Adnan Rasul, S. Karuppanan, V. Perumal, M. Ovinis, Mohsin Iqbal
PurposeThe stress concentration factor (SCF) is commonly utilized to assess the fatigue life of a tubular T-joint in offshore structures. Parametric equations derived from experimental testing and finite element analysis (FEA) are utilized to estimate the SCF efficiently. The mathematical equations provide the SCF at the crown and saddle of tubular T-joints for various load scenarios. Offshore structures are subjected to a wide range of stresses from all directions, and the hotspot stress might occur anywhere along the brace. It is critical to incorporate stress distribution since using the single-point SCF equation can lead to inaccurate hotspot stress and fatigue life estimates. As far as we know, there are no equations available to determine the SCF around the axis of the brace.Design/methodology/approachA mathematical model based on the training weights and biases of artificial neural networks (ANNs) is presented to predict SCF. 625 FEA simulations were conducted to obtain SCF data to train the ANN.FindingsUsing real data, this ANN was used to create mathematical formulas for determining the SCF. The equations can calculate the SCF with a percentage error of less than 6%.Practical implicationsEngineers in practice can use the equations to compute the hotspot stress precisely and rapidly, thereby minimizing risks linked to fatigue failure of offshore structures and assuring their longevity and reliability. Our research contributes to enhancing the safety and reliability of offshore structures by facilitating more precise assessments of stress distribution.Originality/valuePrecisely determining the SCF for the fatigue life of offshore structures reduces the potential hazards associated with fatigue failure, thereby guaranteeing their longevity and reliability. The present study offers a systematic approach for using FEA and ANN to calculate the stress distribution along the weld toe and the SCF in T-joints since ANNs are better at approximating complex phenomena than standard data fitting techniques. Once a database of parametric equations is available, it can be used to rapidly approximate the SCF, unlike experimentation, which is costly and FEA, which is time consuming.
目的应力集中系数（SCF）通常用于评估海上结构中管状 T 型接头的疲劳寿命。通过实验测试和有限元分析（FEA）得出的参数方程可有效估算 SCF。数学公式提供了各种载荷情况下管状 T 型接头冠部和鞍部的 SCF。海上结构会受到来自各个方向的各种应力，热点应力可能出现在支撑的任何位置。由于使用单点 SCF 方程会导致热点应力和疲劳寿命估计不准确，因此将应力分布考虑在内至关重要。据我们所知，目前还没有可用来确定支撑杆轴线周围 SCF 的方程。设计/方法/途径基于人工神经网络（ANN）的训练权重和偏差，提出了一个数学模型来预测 SCF。研究结果利用真实数据，该人工神经网络创建了用于确定 SCF 的数学公式。实际意义工程师在实践中可以使用该方程精确、快速地计算热点应力，从而最大限度地降低与海上结构疲劳失效相关的风险，并确保其使用寿命和可靠性。我们的研究有助于更精确地评估应力分布，从而提高近海结构的安全性和可靠性。原创性/价值精确确定近海结构疲劳寿命的 SCF 可降低与疲劳失效相关的潜在危险，从而保证其使用寿命和可靠性。与标准数据拟合技术相比，ANN 能更好地逼近复杂现象，因此本研究提供了一种系统方法，利用有限元分析和 ANN 计算 T 形接头沿焊趾的应力分布和 SCF。与成本高昂的实验和耗时的有限元分析不同，一旦有了参数方程数据库，就可以利用它快速逼近 SCF。
{"title":"An artificial neural network model for determining stress concentration factors for fatigue design of tubular T-joint under compressive loads","authors":"Adnan Rasul, S. Karuppanan, V. Perumal, M. Ovinis, Mohsin Iqbal","doi":"10.1108/ijsi-02-2024-0034","DOIUrl":"https://doi.org/10.1108/ijsi-02-2024-0034","url":null,"abstract":"PurposeThe stress concentration factor (SCF) is commonly utilized to assess the fatigue life of a tubular T-joint in offshore structures. Parametric equations derived from experimental testing and finite element analysis (FEA) are utilized to estimate the SCF efficiently. The mathematical equations provide the SCF at the crown and saddle of tubular T-joints for various load scenarios. Offshore structures are subjected to a wide range of stresses from all directions, and the hotspot stress might occur anywhere along the brace. It is critical to incorporate stress distribution since using the single-point SCF equation can lead to inaccurate hotspot stress and fatigue life estimates. As far as we know, there are no equations available to determine the SCF around the axis of the brace.Design/methodology/approachA mathematical model based on the training weights and biases of artificial neural networks (ANNs) is presented to predict SCF. 625 FEA simulations were conducted to obtain SCF data to train the ANN.FindingsUsing real data, this ANN was used to create mathematical formulas for determining the SCF. The equations can calculate the SCF with a percentage error of less than 6%.Practical implicationsEngineers in practice can use the equations to compute the hotspot stress precisely and rapidly, thereby minimizing risks linked to fatigue failure of offshore structures and assuring their longevity and reliability. Our research contributes to enhancing the safety and reliability of offshore structures by facilitating more precise assessments of stress distribution.Originality/valuePrecisely determining the SCF for the fatigue life of offshore structures reduces the potential hazards associated with fatigue failure, thereby guaranteeing their longevity and reliability. The present study offers a systematic approach for using FEA and ANN to calculate the stress distribution along the weld toe and the SCF in T-joints since ANNs are better at approximating complex phenomena than standard data fitting techniques. Once a database of parametric equations is available, it can be used to rapidly approximate the SCF, unlike experimentation, which is costly and FEA, which is time consuming.","PeriodicalId":45359,"journal":{"name":"International Journal of Structural Integrity","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2024-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140991639","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-07DOI: 10.1108/ijsi-01-2024-0005
Mohammad A. Gharaibeh, Jürgen Wilde
PurposeThe purpose of this paper is to investigate the thermomechanical response of four well-known lead-free die attach materials: sintered silver, sintered nano-copper particles, gold-tin solders and silver-tin transient liquid phase (TLP) bonds.Design/methodology/approachThis examination is conducted through finite element analysis. The mechanical properties of all die attach systems, including elastic and Anand creep parameters, are obtained from relevant literature and incorporated into the numerical analysis. Consequently, the bond stress-strain relationships, stored inelastic strain energies and equivalent plastic strains are thoroughly examined.FindingsThe results indicate that silver-tin TLP bonds are prone to exhibiting higher inelastic strain energy densities, while sintered silver and copper interconnects tend to possess higher levels of plastic strains and deformations. This suggests a higher susceptibility to damage in these metallic die attachments. On the other hand, the more expensive gold-based solders exhibit lower inelastic strain energy densities and plastic strains, implying an improved fatigue performance compared to other bonding configurations.Originality/valueThe utilization of different metallic material systems as die attachments in power electronics necessitates a comprehensive understanding of their thermomechanical behavior. Therefore, the results of the present paper can be useful in the die attach material selection in power electronics.
{"title":"Research on the creep response of lead-free die attachments in power electronics","authors":"Mohammad A. Gharaibeh, Jürgen Wilde","doi":"10.1108/ijsi-01-2024-0005","DOIUrl":"https://doi.org/10.1108/ijsi-01-2024-0005","url":null,"abstract":"PurposeThe purpose of this paper is to investigate the thermomechanical response of four well-known lead-free die attach materials: sintered silver, sintered nano-copper particles, gold-tin solders and silver-tin transient liquid phase (TLP) bonds.Design/methodology/approachThis examination is conducted through finite element analysis. The mechanical properties of all die attach systems, including elastic and Anand creep parameters, are obtained from relevant literature and incorporated into the numerical analysis. Consequently, the bond stress-strain relationships, stored inelastic strain energies and equivalent plastic strains are thoroughly examined.FindingsThe results indicate that silver-tin TLP bonds are prone to exhibiting higher inelastic strain energy densities, while sintered silver and copper interconnects tend to possess higher levels of plastic strains and deformations. This suggests a higher susceptibility to damage in these metallic die attachments. On the other hand, the more expensive gold-based solders exhibit lower inelastic strain energy densities and plastic strains, implying an improved fatigue performance compared to other bonding configurations.Originality/valueThe utilization of different metallic material systems as die attachments in power electronics necessitates a comprehensive understanding of their thermomechanical behavior. Therefore, the results of the present paper can be useful in the die attach material selection in power electronics.","PeriodicalId":45359,"journal":{"name":"International Journal of Structural Integrity","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141005490","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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