Pub Date : 2022-01-02DOI: 10.1080/24705314.2021.1971891
Wassel Al-Bodour, Y. Murad, Rana Imam, Yahia Smadi
ABSTRACT Existing analytical and numerical models available in the literature can predict the shear strength of CFRP in RC beams based on the FRP strains and this requires measuring the FRP strain values. This research aims to predict the shear strength of CFRP in RC beams without the need to calculate the strains in FRP. Therefore, Gene Expression Programming (GEP) is used in this research to forecast the contribution of the CFRP to shear strength in the RC beams without the need for calculating the strain of the CFRP. A comparison was later performed amongst the empirical findings of the developed GEP model and other models available in published research. The adequate accuracy and highest predictive ability were noticed for the developed GEP model relative to the models published previously. Strengthened reinforced concrete (RC) beams with epoxy-bonded carbon fiber reinforced polymer (CFRP) sheets at various angles of orientation were examined to investigate their shear behavior. The experimental outcomes of the tested specimens were then applied to build a finite element (FE) model using ABAQUS. The proposed FE model was able to forecast the experimental behavior of the samples examined with sufficient precision.
{"title":"Shear strength investigation of the carbon fiber reinforced polymer-wrapped concrete beams using gene expression programming and finite element analysis","authors":"Wassel Al-Bodour, Y. Murad, Rana Imam, Yahia Smadi","doi":"10.1080/24705314.2021.1971891","DOIUrl":"https://doi.org/10.1080/24705314.2021.1971891","url":null,"abstract":"ABSTRACT Existing analytical and numerical models available in the literature can predict the shear strength of CFRP in RC beams based on the FRP strains and this requires measuring the FRP strain values. This research aims to predict the shear strength of CFRP in RC beams without the need to calculate the strains in FRP. Therefore, Gene Expression Programming (GEP) is used in this research to forecast the contribution of the CFRP to shear strength in the RC beams without the need for calculating the strain of the CFRP. A comparison was later performed amongst the empirical findings of the developed GEP model and other models available in published research. The adequate accuracy and highest predictive ability were noticed for the developed GEP model relative to the models published previously. Strengthened reinforced concrete (RC) beams with epoxy-bonded carbon fiber reinforced polymer (CFRP) sheets at various angles of orientation were examined to investigate their shear behavior. The experimental outcomes of the tested specimens were then applied to build a finite element (FE) model using ABAQUS. The proposed FE model was able to forecast the experimental behavior of the samples examined with sufficient precision.","PeriodicalId":43844,"journal":{"name":"Journal of Structural Integrity and Maintenance","volume":"7 1","pages":"15 - 24"},"PeriodicalIF":2.1,"publicationDate":"2022-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41582201","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 : 2022-01-02DOI: 10.1080/24705314.2021.1971894
L. Šedková, V. Vlk, J. Šedek
ABSTRACT This paper investigates debonding and delamination assessment by means of Lamb waves in adhesively bonded composite joints. Adhesively bonded wide CFRP panels with initial delamination were subjected to fatigue loading. A segment of a group velocity dispersion curve was constructed for the plain panel and the bonded section. The fundamental asymmetrical Lamb wave mode (A0) was utilized to evaluate damage propagation. The depth of debonding/delamination and the extent of the damage within the bonded section were analyzed in relation to the group velocity change of the A0 mode. The results indicate that a suitable sensor placement and a proper frequency selection enable the assessment of the interface failure in the three-layer system. Based on the time delays, it was possible to distinguish delamination in the specific adherent. Metallographic analysis confirmed the depth of delamination propagation. Guided wave-based measurements were compared to and verified with ultrasonic A-scans. Additionally, RAPID algorithm was utilized to visualize damage extent with the first damage detection in 29.4 % of the fatigue life.
{"title":"Delamination/disbond propagation analysis in adhesively bonded composite joints using guided waves","authors":"L. Šedková, V. Vlk, J. Šedek","doi":"10.1080/24705314.2021.1971894","DOIUrl":"https://doi.org/10.1080/24705314.2021.1971894","url":null,"abstract":"ABSTRACT This paper investigates debonding and delamination assessment by means of Lamb waves in adhesively bonded composite joints. Adhesively bonded wide CFRP panels with initial delamination were subjected to fatigue loading. A segment of a group velocity dispersion curve was constructed for the plain panel and the bonded section. The fundamental asymmetrical Lamb wave mode (A0) was utilized to evaluate damage propagation. The depth of debonding/delamination and the extent of the damage within the bonded section were analyzed in relation to the group velocity change of the A0 mode. The results indicate that a suitable sensor placement and a proper frequency selection enable the assessment of the interface failure in the three-layer system. Based on the time delays, it was possible to distinguish delamination in the specific adherent. Metallographic analysis confirmed the depth of delamination propagation. Guided wave-based measurements were compared to and verified with ultrasonic A-scans. Additionally, RAPID algorithm was utilized to visualize damage extent with the first damage detection in 29.4 % of the fatigue life.","PeriodicalId":43844,"journal":{"name":"Journal of Structural Integrity and Maintenance","volume":"7 1","pages":"25 - 33"},"PeriodicalIF":2.1,"publicationDate":"2022-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43755766","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 : 2021-11-11DOI: 10.1080/24705314.2021.2018840
V. Gharehbaghi, H. Kalbkhani, E. N. Farsangi, Tony T. Y. Yang, A. Nguyen, S. Mirjalili, C. Málaga‐Chuquitaype
ABSTRACT In this paper, a novel deterioration and damage identification procedure (DIP) is presented and applied to building models. The challenge associated with applications on these types of structures is related to the strong correlation of responses, an issue that gets further complicated when coping with real ambient vibrations with high levels of noise. Thus, a DIP is designed utilizing low-cost ambient vibrations to analyze the acceleration responses using the Stockwell transform (ST) to generate spectrograms. Subsequently, the ST outputs become the input of two series of Convolutional Neural Networks (CNNs) established for identifying deterioration and damage on the building models. To the best of our knowledge, this is the first time that both damage and deterioration are evaluated on building models through a combination of ST and CNN with high accuracy.
{"title":"A novel approach for deterioration and damage identification in building structures based on Stockwell-Transform and deep convolutional neural network","authors":"V. Gharehbaghi, H. Kalbkhani, E. N. Farsangi, Tony T. Y. Yang, A. Nguyen, S. Mirjalili, C. Málaga‐Chuquitaype","doi":"10.1080/24705314.2021.2018840","DOIUrl":"https://doi.org/10.1080/24705314.2021.2018840","url":null,"abstract":"ABSTRACT In this paper, a novel deterioration and damage identification procedure (DIP) is presented and applied to building models. The challenge associated with applications on these types of structures is related to the strong correlation of responses, an issue that gets further complicated when coping with real ambient vibrations with high levels of noise. Thus, a DIP is designed utilizing low-cost ambient vibrations to analyze the acceleration responses using the Stockwell transform (ST) to generate spectrograms. Subsequently, the ST outputs become the input of two series of Convolutional Neural Networks (CNNs) established for identifying deterioration and damage on the building models. To the best of our knowledge, this is the first time that both damage and deterioration are evaluated on building models through a combination of ST and CNN with high accuracy.","PeriodicalId":43844,"journal":{"name":"Journal of Structural Integrity and Maintenance","volume":"7 1","pages":"136 - 150"},"PeriodicalIF":2.1,"publicationDate":"2021-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44445355","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 : 2021-10-02DOI: 10.1080/24705314.2021.1934798
Andrew P. Schanck, W. Davids
ABSTRACT The proxy finite-element analysis (PFEA) technique is significantly extended to improve its utility and its predictions of bridge ultimate capacity are verified. Refinements and extensions to the method include a substantial reduction in up-front computational effort, explicit consideration of the effects of skewness on bridge behavior, and expansion of the technique’s mechanics formulation to include the effects of prestressing. PFEA’s prediction of ultimate flexural capacity is verified by simulating the capacity of a previously conducted, full-scale destructive test of a prestressed concrete girder bridge with good prediction of recorded load-deflection data. Live-load testing (LLT) of five, skewed, reinforced concrete bridges is described. The tested bridges are then load-rated by PFEA, leading to average increase in rating factor exceeding 120%, as compared with an average increase of 34.9% with LLT. This demonstrates that PFEA’s consideration of material nonlinearity leads to larger increases in predicted capacity while retaining the conservative assumptions required by design and analysis codes. Practical usage and implementation of PFEA are addressed, including application to ratings and permitting.
{"title":"Flexural load-rating of slab-on-girder bridges by nonlinear proxy finite-element analysis","authors":"Andrew P. Schanck, W. Davids","doi":"10.1080/24705314.2021.1934798","DOIUrl":"https://doi.org/10.1080/24705314.2021.1934798","url":null,"abstract":"ABSTRACT The proxy finite-element analysis (PFEA) technique is significantly extended to improve its utility and its predictions of bridge ultimate capacity are verified. Refinements and extensions to the method include a substantial reduction in up-front computational effort, explicit consideration of the effects of skewness on bridge behavior, and expansion of the technique’s mechanics formulation to include the effects of prestressing. PFEA’s prediction of ultimate flexural capacity is verified by simulating the capacity of a previously conducted, full-scale destructive test of a prestressed concrete girder bridge with good prediction of recorded load-deflection data. Live-load testing (LLT) of five, skewed, reinforced concrete bridges is described. The tested bridges are then load-rated by PFEA, leading to average increase in rating factor exceeding 120%, as compared with an average increase of 34.9% with LLT. This demonstrates that PFEA’s consideration of material nonlinearity leads to larger increases in predicted capacity while retaining the conservative assumptions required by design and analysis codes. Practical usage and implementation of PFEA are addressed, including application to ratings and permitting.","PeriodicalId":43844,"journal":{"name":"Journal of Structural Integrity and Maintenance","volume":"6 1","pages":"209 - 222"},"PeriodicalIF":2.1,"publicationDate":"2021-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45812993","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 : 2021-10-02DOI: 10.1080/24705314.2021.1902662
Chaoran Xu, C. Fu, Y. Ye, Kuang-yuan Hou, Yifan Zhu
ABSTRACT To improve the fatigue performance of these traffic signs, luminaries and signals structures, the wing plate, a type of aerodynamic damper, is adopted to control the dynamic responses due to wind-induced fatigue load. In this study, one-way 2D fluid-structure interaction (FSI) analysis is conducted to investigate the mitigation ability of the wing plate. Parametric study is involved to investigate the influence on the damping effect caused by the different configuration of the wing plate, as well as the wind speed. The different configurations of signals and signs applied in Maryland, USA, have been studied to find the potential aerodynamic instability due to galloping. The required length of wing plate for the 23-m mast-arm signal structure in Maryland have been analyzed. The study shows that small space between the wing plate and the arm will reduce the mitigation ability. Wing plate may lose mitigation ability due to stalling. Large vortex shedding is observed in the FSI analysis. The wing plate with dimension 610 mm × 610 mm applied by PennDOT can effectively prevent galloping for signal pole structures in Maryland. This research can be used as a reference for the selection of mitigation devices to satisfy the “effective mitigation devices” stated by AASHTO.
摘要:为了改善交通标志、照明灯和信号结构的疲劳性能，采用翼板气动阻尼器控制其在风致疲劳荷载作用下的动力响应。本研究采用单向二维流固耦合分析(FSI)研究翼板的减振能力。通过参数化研究，考察了不同翼板构型和风速对阻尼效果的影响。研究了在美国马里兰州应用的不同配置的信号和标志，以发现由于飞奔而潜在的空气动力学不稳定性。分析了马里兰州23m桅杆臂信号结构所需翼板长度。研究表明，翼板与臂之间的空间过小会降低减振能力。翼板可能因失速而失去减缓能力。在FSI分析中观察到较大的涡脱落。PennDOT应用的尺寸为610 mm × 610 mm的翼板可以有效地防止马里兰州信号杆结构的飞奔。本研究可为缓解装置的选择提供参考，以满足AASHTO提出的“有效缓解装置”。
{"title":"Study of the aerodynamic damping of wing plates on traffic signal structures based on the 2D one-way FSI analysis","authors":"Chaoran Xu, C. Fu, Y. Ye, Kuang-yuan Hou, Yifan Zhu","doi":"10.1080/24705314.2021.1902662","DOIUrl":"https://doi.org/10.1080/24705314.2021.1902662","url":null,"abstract":"ABSTRACT To improve the fatigue performance of these traffic signs, luminaries and signals structures, the wing plate, a type of aerodynamic damper, is adopted to control the dynamic responses due to wind-induced fatigue load. In this study, one-way 2D fluid-structure interaction (FSI) analysis is conducted to investigate the mitigation ability of the wing plate. Parametric study is involved to investigate the influence on the damping effect caused by the different configuration of the wing plate, as well as the wind speed. The different configurations of signals and signs applied in Maryland, USA, have been studied to find the potential aerodynamic instability due to galloping. The required length of wing plate for the 23-m mast-arm signal structure in Maryland have been analyzed. The study shows that small space between the wing plate and the arm will reduce the mitigation ability. Wing plate may lose mitigation ability due to stalling. Large vortex shedding is observed in the FSI analysis. The wing plate with dimension 610 mm × 610 mm applied by PennDOT can effectively prevent galloping for signal pole structures in Maryland. This research can be used as a reference for the selection of mitigation devices to satisfy the “effective mitigation devices” stated by AASHTO.","PeriodicalId":43844,"journal":{"name":"Journal of Structural Integrity and Maintenance","volume":"6 1","pages":"197 - 208"},"PeriodicalIF":2.1,"publicationDate":"2021-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46224487","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 : 2021-10-02DOI: 10.1080/24705314.2021.1892573
Aditya Chilukuri, N. Raja, K. Balasubramaniam
ABSTRACT The use of guided ultrasonic waves has been identified as a promising technology for continuous monitoring of pipes and tubes for the detection of corrosion damage defects of cross-sectional area ratio less than 5%, particularly in the process industry applications. Here, we present an approach to use torsional guided wave mode T(0,1) generated using leave-in-place magnetostriction patch sensors for the health monitoring of thin and small diameter stainless steel tubes operating at elevated temperatures in the range of 150°C. These tubes are used in the transportation of gas in the Silicon wafer manufacturing semiconductor industries. The detection of small pitting defects is demonstrated using both numerical and experimental approach. The phenomenon of scattering of the high frequency fundamental torsional guided wave mode T(0,1) from small pitting type defects in thin and small diameter tubes is closely examined, and its excitation parameters are selected using finite element (FE) simulations. The sensitivity of the reflected signal from defects as low as 2% of the cross-sectional area ratio was feasible even at high temperature. This work is of great interest to many processes in semiconductor manufacturing.
{"title":"In-situ pitting corrosion detection using high-frequency T(0,1) guided wave mode in gas distribution tubes at operating temperatures","authors":"Aditya Chilukuri, N. Raja, K. Balasubramaniam","doi":"10.1080/24705314.2021.1892573","DOIUrl":"https://doi.org/10.1080/24705314.2021.1892573","url":null,"abstract":"ABSTRACT The use of guided ultrasonic waves has been identified as a promising technology for continuous monitoring of pipes and tubes for the detection of corrosion damage defects of cross-sectional area ratio less than 5%, particularly in the process industry applications. Here, we present an approach to use torsional guided wave mode T(0,1) generated using leave-in-place magnetostriction patch sensors for the health monitoring of thin and small diameter stainless steel tubes operating at elevated temperatures in the range of 150°C. These tubes are used in the transportation of gas in the Silicon wafer manufacturing semiconductor industries. The detection of small pitting defects is demonstrated using both numerical and experimental approach. The phenomenon of scattering of the high frequency fundamental torsional guided wave mode T(0,1) from small pitting type defects in thin and small diameter tubes is closely examined, and its excitation parameters are selected using finite element (FE) simulations. The sensitivity of the reflected signal from defects as low as 2% of the cross-sectional area ratio was feasible even at high temperature. This work is of great interest to many processes in semiconductor manufacturing.","PeriodicalId":43844,"journal":{"name":"Journal of Structural Integrity and Maintenance","volume":"6 1","pages":"247 - 256"},"PeriodicalIF":2.1,"publicationDate":"2021-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42649325","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 : 2021-10-02DOI: 10.1080/24705314.2021.1892574
P. Sathujoda, Aneesh Batchu, Bharath Obalareddy
ABSTRACT Corrosion is an unintentional degradation of a material, which transpires due to harsh environmental conditions. It is a surface phenomenon that results in loss of material, which affects the dynamic characteristics and structural integrity of any structure. Fundamental frequency analysis of a corroded functionally graded (FG) rotor-bearing system using finite element method (FEM) for flexural vibrations is presented in work. A functionally graded (FG) shaft, Stainless Steel as the inner-metal core and Zirconia as the outer-ceramic layer is considered. Exponential gradation law is followed to assign the material properties along the radial direction of the shaft. The exponential temperature distribution (ETD) method based on Fourier law of heat conduction has been used for the temperature distribution across the cross-section of the FG shaft. Finite element formulations of a corroded FG shaft element have been developed using Timoshenko beam theory. An FE code is developed to compute the natural and whirl frequencies of an FG rotor-bearing system for various parameters such as corrosion length, position, depth and thermal gradients to investigate the influence of corrosion on fundamental frequencies. It has been investigated that there is a significant influence of corrosion parameters on the natural and whirl frequencies of an FG rotor-bearing system.
{"title":"Fundamental frequency analysis of a thermally loaded corroded exponentially graded rotor bearing system","authors":"P. Sathujoda, Aneesh Batchu, Bharath Obalareddy","doi":"10.1080/24705314.2021.1892574","DOIUrl":"https://doi.org/10.1080/24705314.2021.1892574","url":null,"abstract":"ABSTRACT Corrosion is an unintentional degradation of a material, which transpires due to harsh environmental conditions. It is a surface phenomenon that results in loss of material, which affects the dynamic characteristics and structural integrity of any structure. Fundamental frequency analysis of a corroded functionally graded (FG) rotor-bearing system using finite element method (FEM) for flexural vibrations is presented in work. A functionally graded (FG) shaft, Stainless Steel as the inner-metal core and Zirconia as the outer-ceramic layer is considered. Exponential gradation law is followed to assign the material properties along the radial direction of the shaft. The exponential temperature distribution (ETD) method based on Fourier law of heat conduction has been used for the temperature distribution across the cross-section of the FG shaft. Finite element formulations of a corroded FG shaft element have been developed using Timoshenko beam theory. An FE code is developed to compute the natural and whirl frequencies of an FG rotor-bearing system for various parameters such as corrosion length, position, depth and thermal gradients to investigate the influence of corrosion on fundamental frequencies. It has been investigated that there is a significant influence of corrosion parameters on the natural and whirl frequencies of an FG rotor-bearing system.","PeriodicalId":43844,"journal":{"name":"Journal of Structural Integrity and Maintenance","volume":"6 1","pages":"257 - 269"},"PeriodicalIF":2.1,"publicationDate":"2021-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42349370","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 : 2021-10-02DOI: 10.1080/24705314.2021.1950379
Y. Obaidat, A. Ashteyat, Ala’ Taleb Obaidat, Muna N. Abu-Lebdeh
ABSTRACT Previous studies showed that near-surface mounting (NSM) strengthening technique with rigid CFRP materials has potential advantages over the externally bonded reinforcing (EBR), therefore, it becomes efficient methodology for concrete strengthening. However, rigid NSM-CFRP cannot be wrapped around a deteriorated structural element; the need for the existence of flexible material has appeared. Therefore, in this study the flexible NSM-CFRP (cord) is investigated as strengthening technique instead of rigid NSM-CFRP. The aim of this study is to recognize the parameters affecting the bond performance of carbon fiber-reinforced concrete (CFRP) cord and concrete. These parameters are cords’ bonded length, the ratio between cord’s width and depth, concrete compressive strength, number of CFRP cords used and the distance separating cords in multi-cord specimens. Fifty-four concrete prisms were cast from 25 MPa and 50 MPa concrete compressive strengths. Thirtyeight prisms reinforced by a single cord with various cord sizes were prepared. Twelve and four specimens were reinforced with two and three cords, respectively. In the case of multi-cord specimens, a unified bond length and cord’s aspect ratio were carried out. The main parameter to be studied in this case is the cords’ separating spacing. The test results indicated that increasing (NSMCFRP) cords bonded length, concrete compressive strength, number of applied CFRP cords, the spacing between cords and reducing cords’ aspect ratio (width/depth ratio) cause an increment in the pull-out force, and then a better strengthening is achieved. Rupture was the predominant failure mode for specimens with the same bond and equal cord dimension, while debonding of the CFRP cords is the most frequent failure mode for multi-cords specimens with greater spacing.
{"title":"Bond characteristics between concrete and near-surface mounted carbon fiber reinforced polymer cords","authors":"Y. Obaidat, A. Ashteyat, Ala’ Taleb Obaidat, Muna N. Abu-Lebdeh","doi":"10.1080/24705314.2021.1950379","DOIUrl":"https://doi.org/10.1080/24705314.2021.1950379","url":null,"abstract":"ABSTRACT Previous studies showed that near-surface mounting (NSM) strengthening technique with rigid CFRP materials has potential advantages over the externally bonded reinforcing (EBR), therefore, it becomes efficient methodology for concrete strengthening. However, rigid NSM-CFRP cannot be wrapped around a deteriorated structural element; the need for the existence of flexible material has appeared. Therefore, in this study the flexible NSM-CFRP (cord) is investigated as strengthening technique instead of rigid NSM-CFRP. The aim of this study is to recognize the parameters affecting the bond performance of carbon fiber-reinforced concrete (CFRP) cord and concrete. These parameters are cords’ bonded length, the ratio between cord’s width and depth, concrete compressive strength, number of CFRP cords used and the distance separating cords in multi-cord specimens. Fifty-four concrete prisms were cast from 25 MPa and 50 MPa concrete compressive strengths. Thirtyeight prisms reinforced by a single cord with various cord sizes were prepared. Twelve and four specimens were reinforced with two and three cords, respectively. In the case of multi-cord specimens, a unified bond length and cord’s aspect ratio were carried out. The main parameter to be studied in this case is the cords’ separating spacing. The test results indicated that increasing (NSMCFRP) cords bonded length, concrete compressive strength, number of applied CFRP cords, the spacing between cords and reducing cords’ aspect ratio (width/depth ratio) cause an increment in the pull-out force, and then a better strengthening is achieved. Rupture was the predominant failure mode for specimens with the same bond and equal cord dimension, while debonding of the CFRP cords is the most frequent failure mode for multi-cords specimens with greater spacing.","PeriodicalId":43844,"journal":{"name":"Journal of Structural Integrity and Maintenance","volume":"6 1","pages":"223 - 236"},"PeriodicalIF":2.1,"publicationDate":"2021-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47740599","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 : 2021-09-15DOI: 10.1080/24705314.2021.1892572
A. Imam, B. Salami, T. Oyehan
ABSTRACT Concrete produced with ordinary Portland cement (OPC) along with insertion of supplementary materials increases the level of nonlinearity. Due to this increased non-linearity and difficulty in modeling numerically, the focus has increased on the exploration of computational intelligent models like artificial neural network (ANN) to estimate different concrete properties. In this study, a quaternary blend concrete was developed with OPC, fly ash (FA), metakaolin (MK) and rice husk ash (RHA). The experimental data were further used in training the proposed ANN models to approximate its compressive strength. The proposed neural network models were trained and optimized using three different regularization algorithms; the scaled conjugate gradient “trainsc” (SCG), Levenberg–Marquardt “trainlm” (LM) and Bayesian regularized “trainbr” (BR) algorithms. The percent proportion of OPC, FA, MK and RHA making up the quaternary blends and curing days are the five features used as input variables, while the compressive strength of each of the individual concrete mixture is the output variable (target). It was found out that ANN optimized with Bayesian regularization function performed best with the highest correlation coefficient, and lowest MAE, MSE and RMSE. The results obtained from the ANN approach show significant improvement with the experimental observations.
{"title":"Predicting the compressive strength of a quaternary blend concrete using Bayesian regularized neural network","authors":"A. Imam, B. Salami, T. Oyehan","doi":"10.1080/24705314.2021.1892572","DOIUrl":"https://doi.org/10.1080/24705314.2021.1892572","url":null,"abstract":"ABSTRACT Concrete produced with ordinary Portland cement (OPC) along with insertion of supplementary materials increases the level of nonlinearity. Due to this increased non-linearity and difficulty in modeling numerically, the focus has increased on the exploration of computational intelligent models like artificial neural network (ANN) to estimate different concrete properties. In this study, a quaternary blend concrete was developed with OPC, fly ash (FA), metakaolin (MK) and rice husk ash (RHA). The experimental data were further used in training the proposed ANN models to approximate its compressive strength. The proposed neural network models were trained and optimized using three different regularization algorithms; the scaled conjugate gradient “trainsc” (SCG), Levenberg–Marquardt “trainlm” (LM) and Bayesian regularized “trainbr” (BR) algorithms. The percent proportion of OPC, FA, MK and RHA making up the quaternary blends and curing days are the five features used as input variables, while the compressive strength of each of the individual concrete mixture is the output variable (target). It was found out that ANN optimized with Bayesian regularization function performed best with the highest correlation coefficient, and lowest MAE, MSE and RMSE. The results obtained from the ANN approach show significant improvement with the experimental observations.","PeriodicalId":43844,"journal":{"name":"Journal of Structural Integrity and Maintenance","volume":"6 1","pages":"237 - 246"},"PeriodicalIF":2.1,"publicationDate":"2021-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46721247","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 : 2021-07-03DOI: 10.1080/24705314.2021.1914806
S. Salawdeh
ABSTRACT The objective of this paper is to investigate and develop seismic design guidelines for multi-storey vertical irregular concentrically braced frames (CBFs). The work develops a direct displacement-based design (DDBD) procedure for irregular CBFs associated with steps in building plan area. In this procedure, design displacements considered are decided upon the code and material drift limits, then the strength required to achieve this displacement is calculated and finally all structural elements are designed. A case study of a 12-storey CBF structure with vertical irregularity is designed using the developed DDBD procedure. The configuration of the vertical irregularity assessed is in the form of setbacks up the vertical axis of the building where the frames have more bays at the base of the building than at the top. Non-linear time history analysis (NLTHA) using seven different accelerograms with displacement response spectra matching the design displacement spectrum are used to record the behaviour of the irregular CBF structure when subjected to real earthquakes. It is found that the design displacements and storey drifts from the DDBD procedure for the case study matched relatively well with those recorded through the NLTHA analyses and a new DDBD procedure for CBFs with vertical irregularity is validated.
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