Pub Date : 2020-06-01DOI: 10.22059/CEIJ.2019.255014.1475
B. Zehtab, A. Tarighat
In this paper, the effects of different aluminum to silicon ratios in silicate chains of calcium silicate hydrates (C-S-H) are evaluated on the diffusion coefficient of chloride ions by molecular dynamics method. Tobermorite is a crystalline phase that is used for studying C-S-H properties in nano scale, because of its analogous chemical composition to C-S-H. Aluminum incorporation in C-S-H and the formation of calcium aluminosilicate hydrates (C-A-S-H) is due to both of hydration of tricalcium aluminate (C3A) in portland cement and aluminum oxides in pozzolans. There exist different Al/Si ratios in the tetrahedral chains of C-A-S-H depending on available aluminum oxides in cementitious raw materials. In order to compare the simulation results with previously-published experimental researches on cement pastes, a novel method is introduced here to calculate Al/Si ratio in tetrahedral chains of C-A-S-H using pozzolan replacement ratio in cementitious paste. MK (metakaolin) and FC3R (Fluid Catalytic Cracking Catalyst Residue) are the pozzolans that are used to validate the obtained results in this paper. Results showed that diffusion coefficients of chloride ions in C-A-S-H decrease by Al/Si ratio increasing in the tetrahedral chains as it was observed experimentally in previous researches.
{"title":"Effects of Aluminum Incorporation in Tobermorite Structure on Chloride Diffusion: A Molecular Dynamics Simulation Study","authors":"B. Zehtab, A. Tarighat","doi":"10.22059/CEIJ.2019.255014.1475","DOIUrl":"https://doi.org/10.22059/CEIJ.2019.255014.1475","url":null,"abstract":"In this paper, the effects of different aluminum to silicon ratios in silicate chains of calcium silicate hydrates (C-S-H) are evaluated on the diffusion coefficient of chloride ions by molecular dynamics method. Tobermorite is a crystalline phase that is used for studying C-S-H properties in nano scale, because of its analogous chemical composition to C-S-H. Aluminum incorporation in C-S-H and the formation of calcium aluminosilicate hydrates (C-A-S-H) is due to both of hydration of tricalcium aluminate (C3A) in portland cement and aluminum oxides in pozzolans. There exist different Al/Si ratios in the tetrahedral chains of C-A-S-H depending on available aluminum oxides in cementitious raw materials. In order to compare the simulation results with previously-published experimental researches on cement pastes, a novel method is introduced here to calculate Al/Si ratio in tetrahedral chains of C-A-S-H using pozzolan replacement ratio in cementitious paste. MK (metakaolin) and FC3R (Fluid Catalytic Cracking Catalyst Residue) are the pozzolans that are used to validate the obtained results in this paper. Results showed that diffusion coefficients of chloride ions in C-A-S-H decrease by Al/Si ratio increasing in the tetrahedral chains as it was observed experimentally in previous researches.","PeriodicalId":43959,"journal":{"name":"Civil Engineering Infrastructures Journal-CEIJ","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2020-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49395322","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 : 2020-06-01DOI: 10.22059/CEIJ.2019.263233.1503
Mojtaba Aslmand, I. M. Kani
Wave propagation in unbounded layered media with a new formulation of Axisymmetric Scaled Boundary Finite Element Method (AXI-SBFEM) is derived. Dividing the general three-dimensional unbounded domain into a number of independent two-dimensional ones, the problem could be solved by a significant reduction in required storage and computational time. The equations of the corresponding Axisymmetric Scaled Boundary Finite Element (AXI-SBFE) are derived in detail. For an arbitrary excitation frequency, the dynamic stiffness could be solved by a numerical integration method. The dynamic response of layered unbounded media has been verified with the literature. Numerical examples indicate the applicability and high accuracy of the new method.
{"title":"Axisymmetric Scaled Boundary Finite Element Formulation for Wave Propagation in Unbounded Layered Media","authors":"Mojtaba Aslmand, I. M. Kani","doi":"10.22059/CEIJ.2019.263233.1503","DOIUrl":"https://doi.org/10.22059/CEIJ.2019.263233.1503","url":null,"abstract":"Wave propagation in unbounded layered media with a new formulation of Axisymmetric Scaled Boundary Finite Element Method (AXI-SBFEM) is derived. Dividing the general three-dimensional unbounded domain into a number of independent two-dimensional ones, the problem could be solved by a significant reduction in required storage and computational time. The equations of the corresponding Axisymmetric Scaled Boundary Finite Element (AXI-SBFE) are derived in detail. For an arbitrary excitation frequency, the dynamic stiffness could be solved by a numerical integration method. The dynamic response of layered unbounded media has been verified with the literature. Numerical examples indicate the applicability and high accuracy of the new method.","PeriodicalId":43959,"journal":{"name":"Civil Engineering Infrastructures Journal-CEIJ","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2020-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45099736","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 : 2020-06-01DOI: 10.22059/CEIJ.2019.276064.1553
E. Z. Beydokhti, Hashem Khatibi
In this paper, the effect of elliptical shape openings was numerically compared to the case when circular openings were used in the steel panel shear walls. At first, the finite element model in ABAQUS was calibrated by experimental results, obtained from previous studies. Then, three steel shear panels with different sizes of elliptical openings were analyzed under cyclic loads, and the results were compared to those circular perforations. Moreover, comparisons of cyclic response parameters such as elastic stiffness, ductility ratio, and energy absorption were made. According to the results, the shape of the openings has a significant effect on the seismic behavior of the perforated shear wall. The elliptical opening with the smaller to larger diameter ratio, equal to 0.5, increased the ultimate capacity by 15%. Furthermore, the elastic stiffness, ductility ratio of the frame, and the absorbed energy were promoted by 28%, 3%, and 8%, respectively. Finally, the distance between the openings was improved. Using a ratio of about 0.17 for the center to center distance of elliptical openings to the total width of steel panel led to the best performance.
{"title":"Improving Cyclic Behavior of Steel Plate Shear Walls with Elliptical Perforations","authors":"E. Z. Beydokhti, Hashem Khatibi","doi":"10.22059/CEIJ.2019.276064.1553","DOIUrl":"https://doi.org/10.22059/CEIJ.2019.276064.1553","url":null,"abstract":"In this paper, the effect of elliptical shape openings was numerically compared to the case when circular openings were used in the steel panel shear walls. At first, the finite element model in ABAQUS was calibrated by experimental results, obtained from previous studies. Then, three steel shear panels with different sizes of elliptical openings were analyzed under cyclic loads, and the results were compared to those circular perforations. Moreover, comparisons of cyclic response parameters such as elastic stiffness, ductility ratio, and energy absorption were made. According to the results, the shape of the openings has a significant effect on the seismic behavior of the perforated shear wall. The elliptical opening with the smaller to larger diameter ratio, equal to 0.5, increased the ultimate capacity by 15%. Furthermore, the elastic stiffness, ductility ratio of the frame, and the absorbed energy were promoted by 28%, 3%, and 8%, respectively. Finally, the distance between the openings was improved. Using a ratio of about 0.17 for the center to center distance of elliptical openings to the total width of steel panel led to the best performance.","PeriodicalId":43959,"journal":{"name":"Civil Engineering Infrastructures Journal-CEIJ","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2020-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42670018","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 : 2020-06-01DOI: 10.22059/CEIJ.2020.269910.1529
Mohamadreza Shokri, H. Tavakoli, A. Rahmani
In this paper, the formulation of a modified applied element method for linear analysis of structures in the range of small and large deformations is expressed. To calculate deformations in the structure, the minimum total potential energy principle is used. This method estimates the linear behavior of the structure in the range of small and large deformations, with a very good accuracy and low analytical time. The results show that analysis of a console beam by proposed method, even with minimum numbers of elements, in range of small deformations, has a computation error of less than 2%. Meanwhile, solving the same problem by Applied Element Method (AEM), has more than 31% error. Also, the buckling and post-buckling behavior of the structure, within the range of large deformations, is well-suited. So, with minimum number of elements, and very high accuracy, the buckling behavior of the fixed-base column was simulated. Also, the computational time of the proposed method is less than 40 percent of the computational time in the application of the applied elements method with 10 series of connection springs.
{"title":"A Modification on Applied Element Method for Linear Analysis of Structures in the Range of Small and Large Deformations Based on Energy Concept","authors":"Mohamadreza Shokri, H. Tavakoli, A. Rahmani","doi":"10.22059/CEIJ.2020.269910.1529","DOIUrl":"https://doi.org/10.22059/CEIJ.2020.269910.1529","url":null,"abstract":"In this paper, the formulation of a modified applied element method for linear analysis of structures in the range of small and large deformations is expressed. To calculate deformations in the structure, the minimum total potential energy principle is used. This method estimates the linear behavior of the structure in the range of small and large deformations, with a very good accuracy and low analytical time. The results show that analysis of a console beam by proposed method, even with minimum numbers of elements, in range of small deformations, has a computation error of less than 2%. Meanwhile, solving the same problem by Applied Element Method (AEM), has more than 31% error. Also, the buckling and post-buckling behavior of the structure, within the range of large deformations, is well-suited. So, with minimum number of elements, and very high accuracy, the buckling behavior of the fixed-base column was simulated. Also, the computational time of the proposed method is less than 40 percent of the computational time in the application of the applied elements method with 10 series of connection springs.","PeriodicalId":43959,"journal":{"name":"Civil Engineering Infrastructures Journal-CEIJ","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2020-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44576408","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 : 2020-06-01DOI: 10.22059/CEIJ.2020.267723.1521
M. Tajdini, A. Taherkhani
Occurrence of top down and bottom up fatigue cracking in asphaltic pavements is common. Conventional pavement analysis methods ignore the existence of cracks in asphaltic layers. However, it seems that the responses of cracked pavement would not be the same as a pavement without crack. This paper describes effects of crack type, position and length, and vehicles tire inflation pressure and axle load on the performance of cracked asphalt pavement. Tensile strain at the bottom of asphaltic layer, the vertical strain on subgrade, maximum deflection on the surface, rut depth and the stress intensity factors of cracked pavement, with top down and bottom up crack have been computed using 3D Finite Elements method in ABAQUS. Moving load of standard single axle with different loads and tire pressures have been used in the analysis. Standard 8.2 ton single axle load at different tire pressures of 552(80), 690(100), 828(120) and 1035(150) kPa(psi) and single axle at different loads of 5, 8.2 and 15 ton, all at the same tire pressure of 690 kPa, have been used. Results show that the pavement responses increase with increasing tire pressure and axle load with higher values and rate of increase with increasing tire pressure and axle load for the cracked pavement compared with the pavement without crack. For the pavement structure investigated in this study, it was found that, in general, top down crack results in higher responses than bottom up crack.
{"title":"Investigating the Performance of Cracked Asphalt Pavement Using Finite Elements Analysis","authors":"M. Tajdini, A. Taherkhani","doi":"10.22059/CEIJ.2020.267723.1521","DOIUrl":"https://doi.org/10.22059/CEIJ.2020.267723.1521","url":null,"abstract":"Occurrence of top down and bottom up fatigue cracking in asphaltic pavements is common. Conventional pavement analysis methods ignore the existence of cracks in asphaltic layers. However, it seems that the responses of cracked pavement would not be the same as a pavement without crack. This paper describes effects of crack type, position and length, and vehicles tire inflation pressure and axle load on the performance of cracked asphalt pavement. Tensile strain at the bottom of asphaltic layer, the vertical strain on subgrade, maximum deflection on the surface, rut depth and the stress intensity factors of cracked pavement, with top down and bottom up crack have been computed using 3D Finite Elements method in ABAQUS. Moving load of standard single axle with different loads and tire pressures have been used in the analysis. Standard 8.2 ton single axle load at different tire pressures of 552(80), 690(100), 828(120) and 1035(150) kPa(psi) and single axle at different loads of 5, 8.2 and 15 ton, all at the same tire pressure of 690 kPa, have been used. Results show that the pavement responses increase with increasing tire pressure and axle load with higher values and rate of increase with increasing tire pressure and axle load for the cracked pavement compared with the pavement without crack. For the pavement structure investigated in this study, it was found that, in general, top down crack results in higher responses than bottom up crack.","PeriodicalId":43959,"journal":{"name":"Civil Engineering Infrastructures Journal-CEIJ","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2020-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47125135","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 : 2020-06-01DOI: 10.22059/CEIJ.2019.283780.1593
Nasser Parishad, Kayvan Aghabayk, R. Rezaie, Alireza Samerei, Amin Mohammadi
The Driver Behaviour Questionnaire (DBQ) is widely used around the world to investigate driving behaviours. However, it has several different versions extracted from the 50-items Manchester driver behaviour questionnaire for variety of societies. This study aims to calibrate the DBQ for the Iranian driver population and explore their aberrant driver behaviour. In total, 524 participants (325 men and 199 women) between the ages of 18 and 79 years from different cities of Iran with more than one million populations were engaged in this study (Tehran, Mashhad, Esfahan, Qom, Tabriz, Karaj, Ahvaz, Shiraz). Principal Component Analysis (PCA) with varimax rotation extracts four-factor that describes the aberrant driver behaviours: violations, dangerous errors, lapses, and aggressive behaviours. A short version of DBQ with 20 items is also developed on the same four factors using high factor loading of each of the axis categories. This DBQ can serve as an instrument of driver self-assessment and can use with other self-reporting measures. For reliability assessment, the Cronbach’s alpha test (α) is conducted for both long and short version of the questionnaire. Finally, regression analysis predicts the factor scores using demographic and some general questions.
{"title":"Validation of the Driver Behavior Questionnaire in a Representative Sample of Iranian Drivers","authors":"Nasser Parishad, Kayvan Aghabayk, R. Rezaie, Alireza Samerei, Amin Mohammadi","doi":"10.22059/CEIJ.2019.283780.1593","DOIUrl":"https://doi.org/10.22059/CEIJ.2019.283780.1593","url":null,"abstract":"The Driver Behaviour Questionnaire (DBQ) is widely used around the world to investigate driving behaviours. However, it has several different versions extracted from the 50-items Manchester driver behaviour questionnaire for variety of societies. This study aims to calibrate the DBQ for the Iranian driver population and explore their aberrant driver behaviour. In total, 524 participants (325 men and 199 women) between the ages of 18 and 79 years from different cities of Iran with more than one million populations were engaged in this study (Tehran, Mashhad, Esfahan, Qom, Tabriz, Karaj, Ahvaz, Shiraz). Principal Component Analysis (PCA) with varimax rotation extracts four-factor that describes the aberrant driver behaviours: violations, dangerous errors, lapses, and aggressive behaviours. A short version of DBQ with 20 items is also developed on the same four factors using high factor loading of each of the axis categories. This DBQ can serve as an instrument of driver self-assessment and can use with other self-reporting measures. For reliability assessment, the Cronbach’s alpha test (α) is conducted for both long and short version of the questionnaire. Finally, regression analysis predicts the factor scores using demographic and some general questions.","PeriodicalId":43959,"journal":{"name":"Civil Engineering Infrastructures Journal-CEIJ","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2020-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41920958","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 : 2020-06-01DOI: 10.22059/CEIJ.2019.280596.1580
A. Ezoddin, A. Kheyroddin, M. Gholhaki
This study investigates the effect of different link beam lengths in the Reinforced Concrete (RC) frame retrofitted with the Linked Column Frame (LCF) system. It also investigates the ratio of the link beam length (e) to the span length of the RC frame (L) from 0 to 1.5 for the 9 models of the RC frame retrofitted by the LCF system has been investigated. In addition, it studies the formation of plastic hinges in the RC and Linked Column (LC) frame, distribution of stiffness between the RC and LC frame and the ratio of the structural displacement with the formation of the first plastic hinge in the member of the RC frame at the collapse prevention level (Dp LCF) to the structural displacement with the formation of the first plastic hinge in the link beam (Dy LCF) has been studied. Based on the nonlinear static analysis results, the model with the ratio of e/L= 0.45 has a better performance than other different lengths of the link beam. In this model, the stiffness of the LC frame has increased about 78% in comparison with the model with the ratio of e/L that is more than 0.6. Also, the ratio of Dp LCF to Dy LCF for the model of e/L = 0.45 in comparison with two models of e/L = 0.3 and 0.6 is more about 14% and 22%, respectively. It means that, the model of e/L = 0.45 has more potential to reach the performance level of Rapid Repair (RR) to occupancy.
{"title":"Investigation of the Effects of Link Beam Length on the RC Frame Retrofitted with the Linked Column Frame System","authors":"A. Ezoddin, A. Kheyroddin, M. Gholhaki","doi":"10.22059/CEIJ.2019.280596.1580","DOIUrl":"https://doi.org/10.22059/CEIJ.2019.280596.1580","url":null,"abstract":"This study investigates the effect of different link beam lengths in the Reinforced Concrete (RC) frame retrofitted with the Linked Column Frame (LCF) system. It also investigates the ratio of the link beam length (e) to the span length of the RC frame (L) from 0 to 1.5 for the 9 models of the RC frame retrofitted by the LCF system has been investigated. In addition, it studies the formation of plastic hinges in the RC and Linked Column (LC) frame, distribution of stiffness between the RC and LC frame and the ratio of the structural displacement with the formation of the first plastic hinge in the member of the RC frame at the collapse prevention level (Dp LCF) to the structural displacement with the formation of the first plastic hinge in the link beam (Dy LCF) has been studied. Based on the nonlinear static analysis results, the model with the ratio of e/L= 0.45 has a better performance than other different lengths of the link beam. In this model, the stiffness of the LC frame has increased about 78% in comparison with the model with the ratio of e/L that is more than 0.6. Also, the ratio of Dp LCF to Dy LCF for the model of e/L = 0.45 in comparison with two models of e/L = 0.3 and 0.6 is more about 14% and 22%, respectively. It means that, the model of e/L = 0.45 has more potential to reach the performance level of Rapid Repair (RR) to occupancy.","PeriodicalId":43959,"journal":{"name":"Civil Engineering Infrastructures Journal-CEIJ","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2020-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49396751","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 : 2019-12-01DOI: 10.22059/CEIJ.2019.277400.1559
E. Ebrahimi, G. Abdollahzadeh, E. Jahani
In order to increase the accuracy of evaluating seismic response of structures, it is critical to conduct dynamic analyses based upon precise nonlinear models being as consistent as possible with the real conditions of corresponding structures. The concentrated plasticity model including one elastic element and two nonlinear spring elements at both ends has been considered within the research community for simulating beams and columns, counting the effect of strength and stiffness degradation. In this type of simulation, the axial force ratio generated in each structural component, which is a major factor in introducing nonlinear springs, has always been considered constant in the literature. The main objective of the present research is, therefore, to modify the fundamental weakness in this type of modeling approach; indeed, any variation of element’s axial effort, owing to redistribution of axial forces during an earthquake, is applied in the calculation of parameters of the concentrated plasticity model as a decisive step toward the development of nonlinear dynamic analysis. Moreover, an algorithm is presented for implementing this approach in the OpenSees software. Verification is established and the efficiency of the proposed method is illustrated through a reinforced concrete moment frame subjected to a specific record, as a case study building. Regarding the results, it is confirmed that the proposed algorithm is an appropriate tool for achieving quite a realistic nonlinear model and estimating reasonably accurate responses of structural systems with cyclic degrading behavior under earthquake loading.
{"title":"The Effect of Axial Force Variations on Nonlinear Modeling and Seismic Response of Reinforced Concrete Structures","authors":"E. Ebrahimi, G. Abdollahzadeh, E. Jahani","doi":"10.22059/CEIJ.2019.277400.1559","DOIUrl":"https://doi.org/10.22059/CEIJ.2019.277400.1559","url":null,"abstract":"In order to increase the accuracy of evaluating seismic response of structures, it is critical to conduct dynamic analyses based upon precise nonlinear models being as consistent as possible with the real conditions of corresponding structures. The concentrated plasticity model including one elastic element and two nonlinear spring elements at both ends has been considered within the research community for simulating beams and columns, counting the effect of strength and stiffness degradation. In this type of simulation, the axial force ratio generated in each structural component, which is a major factor in introducing nonlinear springs, has always been considered constant in the literature. The main objective of the present research is, therefore, to modify the fundamental weakness in this type of modeling approach; indeed, any variation of element’s axial effort, owing to redistribution of axial forces during an earthquake, is applied in the calculation of parameters of the concentrated plasticity model as a decisive step toward the development of nonlinear dynamic analysis. Moreover, an algorithm is presented for implementing this approach in the OpenSees software. Verification is established and the efficiency of the proposed method is illustrated through a reinforced concrete moment frame subjected to a specific record, as a case study building. Regarding the results, it is confirmed that the proposed algorithm is an appropriate tool for achieving quite a realistic nonlinear model and estimating reasonably accurate responses of structural systems with cyclic degrading behavior under earthquake loading.","PeriodicalId":43959,"journal":{"name":"Civil Engineering Infrastructures Journal-CEIJ","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2019-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45364825","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 : 2019-12-01DOI: 10.22059/CEIJ.2019.273386.1540
Mohammad Mahdi Dibaee, A. Kavussi
Fatigue characteristics of asphalt binder have an important role in asphalt mix resistance against cracking. Viscoelastic Continuum Damage (VECD) analysis of asphalt binders has been successfully used in highway research works in order to predict fatigue behavior of hot mix asphalt (HMA). In this method an intrinsic property of the material, called damage function is obtained which is independent of damage path. However, achieving damage function needs application of various loading paths and a trial and error procedure. In this study, a quick characterization procedure has been proposed to implement VECD analysis that results in fatigue prediction of HMA. The procedure is comprised of a testing setup, along with the analysis required to derive VECD parameters from experimental data. The test consists of a stepwise loading scheme including a few strain levels with relatively large increments in between. Subsequently, an optimization method has been introduced to be performed on the test results, to yield damage function, i.e. modulus as a state function of Internal State Variable (ISV). The analytical framework leading to the optimization problem, along with its solution methods are presented. Consequently, the fatigue life prediction model has been obtained, relating the change in shear modulus to loading conditions such as strain level and frequency. Eventually, the introduced characterization method was validated, comparing the results with those achieved in conventional procedure. The validation showed that the results of optimization and conventional methods agree, with an acceptable precision.
{"title":"Determination of Asphalt Binder VECD Parameters Using an Accelerated Testing Procedure","authors":"Mohammad Mahdi Dibaee, A. Kavussi","doi":"10.22059/CEIJ.2019.273386.1540","DOIUrl":"https://doi.org/10.22059/CEIJ.2019.273386.1540","url":null,"abstract":"Fatigue characteristics of asphalt binder have an important role in asphalt mix resistance against cracking. Viscoelastic Continuum Damage (VECD) analysis of asphalt binders has been successfully used in highway research works in order to predict fatigue behavior of hot mix asphalt (HMA). In this method an intrinsic property of the material, called damage function is obtained which is independent of damage path. However, achieving damage function needs application of various loading paths and a trial and error procedure. In this study, a quick characterization procedure has been proposed to implement VECD analysis that results in fatigue prediction of HMA. The procedure is comprised of a testing setup, along with the analysis required to derive VECD parameters from experimental data. The test consists of a stepwise loading scheme including a few strain levels with relatively large increments in between. Subsequently, an optimization method has been introduced to be performed on the test results, to yield damage function, i.e. modulus as a state function of Internal State Variable (ISV). The analytical framework leading to the optimization problem, along with its solution methods are presented. Consequently, the fatigue life prediction model has been obtained, relating the change in shear modulus to loading conditions such as strain level and frequency. Eventually, the introduced characterization method was validated, comparing the results with those achieved in conventional procedure. The validation showed that the results of optimization and conventional methods agree, with an acceptable precision.","PeriodicalId":43959,"journal":{"name":"Civil Engineering Infrastructures Journal-CEIJ","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2019-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49660747","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 : 2019-12-01DOI: 10.22059/CEIJ.2019.267227.1517
Hadi Sabermahany, M. Bastami
Analytical methods presented to analyze the buried steel pipelines at strike-slip fault crossing use the Euler-Bernoulli beam theory. The cross-section of a buried pipe that is completely surrounded by soil cannot rotate freely and would not be remained perpendicular to the bending line after deformation. So it would be better to take into consideration a rotation between the cross-section and the bending line. The developed model improves the existing methodologies by using the Timoshenko beam theory and considering the shear deformations as a refinement to the existing methodologies. The proposed model results are compared with the results of an existing analytical model and it is found that the maximum bending and axial strains decrease with taking into consideration the shear deformations. Furthermore, it is shown that the difference between the results of models increases with an increase in the burial depth.
{"title":"Refinement to the Existing Analytical Methods of Analysis of Buried Pipelines due to Strike-Slip Faulting","authors":"Hadi Sabermahany, M. Bastami","doi":"10.22059/CEIJ.2019.267227.1517","DOIUrl":"https://doi.org/10.22059/CEIJ.2019.267227.1517","url":null,"abstract":"Analytical methods presented to analyze the buried steel pipelines at strike-slip fault crossing use the Euler-Bernoulli beam theory. The cross-section of a buried pipe that is completely surrounded by soil cannot rotate freely and would not be remained perpendicular to the bending line after deformation. So it would be better to take into consideration a rotation between the cross-section and the bending line. The developed model improves the existing methodologies by using the Timoshenko beam theory and considering the shear deformations as a refinement to the existing methodologies. The proposed model results are compared with the results of an existing analytical model and it is found that the maximum bending and axial strains decrease with taking into consideration the shear deformations. Furthermore, it is shown that the difference between the results of models increases with an increase in the burial depth.","PeriodicalId":43959,"journal":{"name":"Civil Engineering Infrastructures Journal-CEIJ","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2019-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44000931","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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