Pub Date : 2018-12-01DOI: 10.7508/CEIJ.2018.02.007
V. Toufigh, Behnam Bagheri, R. Asadi, Amir Sadir, M. M. Toufigh
Various materials have been utilized for ground improvement techniques based on geoenvironmental compatibility. The application of lime mortar in soil has been catching the attention of researchers and engineers. However, there is a lack of research on the variation of moisture content in soil affecting the mechanical behavior of lime mortar. In this study, large-scale laboratory tests were conducted on approximately thirty specimens to evaluate the size effect on stiffness and load bearing capacity of compacted lime mortar (CLM) columns and clayey soil under different saturation conditions. In addition, approximately forty small-scale laboratory tests were carried out on dry clay, dry CLM column and lime mortar specimens to evaluate the unconfined compressive strength (UCS). According to results, UCS of CLM column under small-scale condition was higher than that of the large-scale. Moreover, high moisture content had a significant influence on the stiffness of improved ground and the bearing capacity of CLM columns. Finally, validation of results indicated that numerical model predictions are in agreement with experimental results.
{"title":"Relatively Large-Scale Experimental Study on Behavior of Compacted Lime Mortar (CLM) Columns: Influence of Moisture Content","authors":"V. Toufigh, Behnam Bagheri, R. Asadi, Amir Sadir, M. M. Toufigh","doi":"10.7508/CEIJ.2018.02.007","DOIUrl":"https://doi.org/10.7508/CEIJ.2018.02.007","url":null,"abstract":"Various materials have been utilized for ground improvement techniques based on geoenvironmental compatibility. The application of lime mortar in soil has been catching the attention of researchers and engineers. However, there is a lack of research on the variation of moisture content in soil affecting the mechanical behavior of lime mortar. In this study, large-scale laboratory tests were conducted on approximately thirty specimens to evaluate the size effect on stiffness and load bearing capacity of compacted lime mortar (CLM) columns and clayey soil under different saturation conditions. In addition, approximately forty small-scale laboratory tests were carried out on dry clay, dry CLM column and lime mortar specimens to evaluate the unconfined compressive strength (UCS). According to results, UCS of CLM column under small-scale condition was higher than that of the large-scale. Moreover, high moisture content had a significant influence on the stiffness of improved ground and the bearing capacity of CLM columns. Finally, validation of results indicated that numerical model predictions are in agreement with experimental results.","PeriodicalId":43959,"journal":{"name":"Civil Engineering Infrastructures Journal-CEIJ","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2018-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47838352","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 : 2018-12-01DOI: 10.7508/CEIJ.2018.02.005
A. Miyamoto, Hiroyoshi Asano
This paper describes a method of performance evaluation and remaining life prediction for an aged reinforced concrete (RC) T-girder bridge by J-BMS RC version via close visual inspection data, and also verifies the assessment results obtained as outputs from the Bridge Rating Expert System (RC-BREX) which is a subsystem of the J-BMS, to evaluate the effectiveness of the system. The Bridge Management System (J-BMS) that was previously developed by the authors, and which is capable of forecasting the deterioration process of existing bridge members, was applied to evaluate the safety indices (soundness score) and remaining life of the target bridge based on these test results. Using these methods, the remaining life of an aged RC-T girder bridge (SK-bridge) can be quantitatively estimated by applying the bridge rating expert (BREX) system, which is a subsystem of the J-BMS RC version that incorporates with the field inspection data. In this study, close visual inspection was carried out on the aged bridge by professional visual inspectors, during which all variations of the inspection results were evaluated using a five-step questionnaire. As a result, it was found that the soundness score (safety index) and remaining life predictions were influenced by the learning (supervised) data selection. Additionally, the predicted remaining lives were verified through concrete core tests extracted from main girders and deck slabs.
{"title":"Application of J-BMS to Performance Evaluation and Remaining Life Prediction of an Existing RC Bridge","authors":"A. Miyamoto, Hiroyoshi Asano","doi":"10.7508/CEIJ.2018.02.005","DOIUrl":"https://doi.org/10.7508/CEIJ.2018.02.005","url":null,"abstract":"This paper describes a method of performance evaluation and remaining life prediction for an aged reinforced concrete (RC) T-girder bridge by J-BMS RC version via close visual inspection data, and also verifies the assessment results obtained as outputs from the Bridge Rating Expert System (RC-BREX) which is a subsystem of the J-BMS, to evaluate the effectiveness of the system. The Bridge Management System (J-BMS) that was previously developed by the authors, and which is capable of forecasting the deterioration process of existing bridge members, was applied to evaluate the safety indices (soundness score) and remaining life of the target bridge based on these test results. Using these methods, the remaining life of an aged RC-T girder bridge (SK-bridge) can be quantitatively estimated by applying the bridge rating expert (BREX) system, which is a subsystem of the J-BMS RC version that incorporates with the field inspection data. In this study, close visual inspection was carried out on the aged bridge by professional visual inspectors, during which all variations of the inspection results were evaluated using a five-step questionnaire. As a result, it was found that the soundness score (safety index) and remaining life predictions were influenced by the learning (supervised) data selection. Additionally, the predicted remaining lives were verified through concrete core tests extracted from main girders and deck slabs.","PeriodicalId":43959,"journal":{"name":"Civil Engineering Infrastructures Journal-CEIJ","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2018-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47840200","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 : 2018-06-01DOI: 10.7508/CEIJ.2018.01.003
R. Chenari, A. Ghorbani, A. Eslami, Fazeleh Mirabbasi
In the case of problematic soils and tall buildings where the design requirements cannot be satisfied merely by a raft foundation, it is of common practice to improve the raft performance by adding a number of piles so that the ultimate load capacity and settlement behavior can be enhanced. In this study, the effect of spatial variability of soil parameters on the bearing capacity of piled raft foundation is investigated based on the random field theory using the finite difference software of FLAC3D. The coefficient of variation (COV) of the soil’s undrained shear strength, the ratio of standard deviation to the mean, was considered as a random variable. Moreover, the effect of variation of this parameter on the bearing capacity of piled raft foundation in undrained clayey soils was studied taking the Monte Carlo simulation approach and the normal statistical distribution. According to the results, taking into account the soil heterogeneity generally results in more contribution of the raft in bearing capacity than that of the homogenous soils obtained by experimental relationships, which implies the significance of carrying out stochastic analyses where the soil properties are intensively variant.
{"title":"Behavior of Piled Raft Foundation on Heterogeneous Clay Deposits Using Random Field Theory","authors":"R. Chenari, A. Ghorbani, A. Eslami, Fazeleh Mirabbasi","doi":"10.7508/CEIJ.2018.01.003","DOIUrl":"https://doi.org/10.7508/CEIJ.2018.01.003","url":null,"abstract":"In the case of problematic soils and tall buildings where the design requirements cannot be satisfied merely by a raft foundation, it is of common practice to improve the raft performance by adding a number of piles so that the ultimate load capacity and settlement behavior can be enhanced. In this study, the effect of spatial variability of soil parameters on the bearing capacity of piled raft foundation is investigated based on the random field theory using the finite difference software of FLAC3D. The coefficient of variation (COV) of the soil’s undrained shear strength, the ratio of standard deviation to the mean, was considered as a random variable. Moreover, the effect of variation of this parameter on the bearing capacity of piled raft foundation in undrained clayey soils was studied taking the Monte Carlo simulation approach and the normal statistical distribution. According to the results, taking into account the soil heterogeneity generally results in more contribution of the raft in bearing capacity than that of the homogenous soils obtained by experimental relationships, which implies the significance of carrying out stochastic analyses where the soil properties are intensively variant.","PeriodicalId":43959,"journal":{"name":"Civil Engineering Infrastructures Journal-CEIJ","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41518566","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 : 2018-06-01DOI: 10.7508/CEIJ.2018.01.010
M. Emami, M. Eskandari‐Ghadi
A general initial-boundary value problem of one-dimensional transient wave propagation in a multi-layered elastic medium due to arbitrary boundary or interface excitations (either prescribed tractions or displacements) is considered. Laplace transformation technique is utilised and the Laplace transform inversion is facilitated via an unconventional method, where the expansion of complex-valued functions in the Laplace domain in the form of general Dirichlet series is used. The final solutions are presented in the form of finite series involving forward and backward travelling wave functions of the d’Alembert type for a finite time interval. This elegant method of Laplace transform inversion used for the special class of problems at hand eliminates the need for finding singularities of the complex-valued functions in the Laplace domain and it does not need utilising the tedious calculations of the more conventional methods which use complex integration on the Bromwich contour and the techniques of residue calculus. Justification for the solutions is then considered. Some illustrations of the exact solutions as time-histories of stress or displacement of different points in the medium due to excitations of arbitrary form or of impulsive nature are presented to further investigate and interpret the mathematical solutions. It is shown via illustrations that the one-dimensional wave motions in multi-layered elastic media are generally of complicated forms and are affected significantly by the changes in the geometrical and mechanical properties of the layers as well as the nature of the excitation functions. The method presented here can readily be extended for three-dimensional problems. It is also particularly useful in seismology and earthquake engineering since the exact time-histories of response in a multi-layered medium due to arbitrary excitations can be obtained as finite sums.
{"title":"Analytical D’Alembert Series Solution for Multi-Layered One-Dimensional Elastic Wave Propagation with the Use of General Dirichlet Series","authors":"M. Emami, M. Eskandari‐Ghadi","doi":"10.7508/CEIJ.2018.01.010","DOIUrl":"https://doi.org/10.7508/CEIJ.2018.01.010","url":null,"abstract":"A general initial-boundary value problem of one-dimensional transient wave propagation in a multi-layered elastic medium due to arbitrary boundary or interface excitations (either prescribed tractions or displacements) is considered. Laplace transformation technique is utilised and the Laplace transform inversion is facilitated via an unconventional method, where the expansion of complex-valued functions in the Laplace domain in the form of general Dirichlet series is used. The final solutions are presented in the form of finite series involving forward and backward travelling wave functions of the d’Alembert type for a finite time interval. This elegant method of Laplace transform inversion used for the special class of problems at hand eliminates the need for finding singularities of the complex-valued functions in the Laplace domain and it does not need utilising the tedious calculations of the more conventional methods which use complex integration on the Bromwich contour and the techniques of residue calculus. Justification for the solutions is then considered. Some illustrations of the exact solutions as time-histories of stress or displacement of different points in the medium due to excitations of arbitrary form or of impulsive nature are presented to further investigate and interpret the mathematical solutions. It is shown via illustrations that the one-dimensional wave motions in multi-layered elastic media are generally of complicated forms and are affected significantly by the changes in the geometrical and mechanical properties of the layers as well as the nature of the excitation functions. The method presented here can readily be extended for three-dimensional problems. It is also particularly useful in seismology and earthquake engineering since the exact time-histories of response in a multi-layered medium due to arbitrary excitations can be obtained as finite sums.","PeriodicalId":43959,"journal":{"name":"Civil Engineering Infrastructures Journal-CEIJ","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47661596","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 : 2018-06-01DOI: 10.7508/CEIJ.2018.01.004
M. Mohammadizadeh, Babak Yasi
One of the numerous methods recently employed to study the health of structures is the identification of anomaly in data obtained for the condition of the structure, e.g. the frequencies for the structural modes, stress, strain, displacement, speed, and acceleration) which are obtained and stored by various sensors. The methods of identification applied for anomalies attempt to discover and recognize patterns governing data which run in sharp contrast to the statistical population. In the case of data obtained from sensors, data appearing in contrast to others, i.e. outliers, may signal the occurrence of damage in the structure. The present research aims to employ computer algorithms to identify structural defects based on data gathered by sensors indicating structural conditions. The present research investigates the performance of various methods including Artificial Neural Networks (ANN), Density-Based Spatial Clustering of Applications with Noise (DBSCAN), Manhattan Distance, Curve Fitting, and Box Plot in the identification of samples from damages in a case study using frequency values related to a cable-support bridge. Subsequent to the implementation of the methods in the datasets, it was shown that the ANN provided the optimal performance.
{"title":"Identification of Structural Defects Using Computer Algorithms","authors":"M. Mohammadizadeh, Babak Yasi","doi":"10.7508/CEIJ.2018.01.004","DOIUrl":"https://doi.org/10.7508/CEIJ.2018.01.004","url":null,"abstract":"One of the numerous methods recently employed to study the health of structures is the identification of anomaly in data obtained for the condition of the structure, e.g. the frequencies for the structural modes, stress, strain, displacement, speed, and acceleration) which are obtained and stored by various sensors. The methods of identification applied for anomalies attempt to discover and recognize patterns governing data which run in sharp contrast to the statistical population. In the case of data obtained from sensors, data appearing in contrast to others, i.e. outliers, may signal the occurrence of damage in the structure. The present research aims to employ computer algorithms to identify structural defects based on data gathered by sensors indicating structural conditions. The present research investigates the performance of various methods including Artificial Neural Networks (ANN), Density-Based Spatial Clustering of Applications with Noise (DBSCAN), Manhattan Distance, Curve Fitting, and Box Plot in the identification of samples from damages in a case study using frequency values related to a cable-support bridge. Subsequent to the implementation of the methods in the datasets, it was shown that the ANN provided the optimal performance.","PeriodicalId":43959,"journal":{"name":"Civil Engineering Infrastructures Journal-CEIJ","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41872992","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 : 2018-06-01DOI: 10.7508/ceij.2018.01.012
J. Akbari, Faezeh Jafari
Current approach for designing of reinforced concrete members is based on the load and resistance factor. However the load and resistance parameters are random variables, the constant values have been designated for them in the designing procedure. Assuming these factors as the constants, will be led to the unsafe and uneconomical designs. Safe designing of structures requires appropriate recognition of the effective parameters and their uncertainties. Therefore, this achievement is possible through clarifying the effective design parameters and applying risk-based design methods. The main purpose of this paper is reliability based design of the reinforcement concrete structures under bending action. Rectangular sections with tension rebars (singly reinforced), rectangular sections with tension and also compression rebars (doubly reinforced) and T-shape sections are designed based on probabilistic methods. The appropriate tool for reliability calculations is selected based on pros and cons of each method. Evaluation of the load and the resistance factors for all mentioned beams is the next goal of this investigation. In this research, the steel usages for desired safety level are determined through the produced graphs. Using the proposed methodologies, the economic and fully probabilistic design of the concrete beams for bending is now available.
{"title":"Calibration of Load and Resistance Factors for Reinforced Concrete","authors":"J. Akbari, Faezeh Jafari","doi":"10.7508/ceij.2018.01.012","DOIUrl":"https://doi.org/10.7508/ceij.2018.01.012","url":null,"abstract":"Current approach for designing of reinforced concrete members is based on the load and resistance factor. However the load and resistance parameters are random variables, the constant values have been designated for them in the designing procedure. Assuming these factors as the constants, will be led to the unsafe and uneconomical designs. Safe designing of structures requires appropriate recognition of the effective parameters and their uncertainties. Therefore, this achievement is possible through clarifying the effective design parameters and applying risk-based design methods. The main purpose of this paper is reliability based design of the reinforcement concrete structures under bending action. Rectangular sections with tension rebars (singly reinforced), rectangular sections with tension and also compression rebars (doubly reinforced) and T-shape sections are designed based on probabilistic methods. The appropriate tool for reliability calculations is selected based on pros and cons of each method. Evaluation of the load and the resistance factors for all mentioned beams is the next goal of this investigation. In this research, the steel usages for desired safety level are determined through the produced graphs. Using the proposed methodologies, the economic and fully probabilistic design of the concrete beams for bending is now available.","PeriodicalId":43959,"journal":{"name":"Civil Engineering Infrastructures Journal-CEIJ","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42210055","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 : 2018-06-01DOI: 10.7508/CEIJ.2018.01.005
A. Tarighat, yaghout modarres, M. Mohammadi
Sulfate attack is a series of physico-chemical reactions between hardened cement paste and sulfate ions. Sulfate ion penetration into the hydrated cement results in the formation of voluminous and deleterious phases such as gypsum and ettringite which are believed to cause deterioration and expansion of concrete. Concrete deterioration due to sulfate attack depends on many parameters, however, in experimental studies, the implementation of the parameters and obtaining the results in a short time are too difficult. In this paper the effect of wollastonite, with and without silica fume, on the performance of cement based materials during hydration and magnesium sulfate attack was studied by thermodynamic modeling. Thermodynamic modelling was carried out using the Gibbs free energy minimization program GEMS. By this method, in addition to investigating the type and volume of the produced material, the optimal substitution percentage of wollastonite and silica fume were studied as well. In sulfate attack, especially at higher percentages of substitution, wollasonite is not very effective in itself. Wollasonite replacement has a reverse effect on monosulfate and ettringite phases. Volume of these phases increases with addition of the substitution percentage. Substituting a portion of the cement with wollastonite and silica fume would improve sulfate resistance. Substitution of 5% of wollasonite and 10% of silica fume has shown the best performance, highest increase in C-S-H gel volume and reduction in harmful phases such as gypsum, ettringite and brucite.
{"title":"Thermodynamic Modeling of the Effects of Wollastonite-Silica Fume Combination in the Cement Hydration and Sulfate Attack","authors":"A. Tarighat, yaghout modarres, M. Mohammadi","doi":"10.7508/CEIJ.2018.01.005","DOIUrl":"https://doi.org/10.7508/CEIJ.2018.01.005","url":null,"abstract":"Sulfate attack is a series of physico-chemical reactions between hardened cement paste and sulfate ions. Sulfate ion penetration into the hydrated cement results in the formation of voluminous and deleterious phases such as gypsum and ettringite which are believed to cause deterioration and expansion of concrete. Concrete deterioration due to sulfate attack depends on many parameters, however, in experimental studies, the implementation of the parameters and obtaining the results in a short time are too difficult. In this paper the effect of wollastonite, with and without silica fume, on the performance of cement based materials during hydration and magnesium sulfate attack was studied by thermodynamic modeling. Thermodynamic modelling was carried out using the Gibbs free energy minimization program GEMS. By this method, in addition to investigating the type and volume of the produced material, the optimal substitution percentage of wollastonite and silica fume were studied as well. In sulfate attack, especially at higher percentages of substitution, wollasonite is not very effective in itself. Wollasonite replacement has a reverse effect on monosulfate and ettringite phases. Volume of these phases increases with addition of the substitution percentage. Substituting a portion of the cement with wollastonite and silica fume would improve sulfate resistance. Substitution of 5% of wollasonite and 10% of silica fume has shown the best performance, highest increase in C-S-H gel volume and reduction in harmful phases such as gypsum, ettringite and brucite.","PeriodicalId":43959,"journal":{"name":"Civil Engineering Infrastructures Journal-CEIJ","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46169576","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 : 2018-06-01DOI: 10.7508/CEIJ.2018.01.009
M. Ghassemieh, Seyed Mohyeddin Ghodratian, Mohammad Khanmohmmadi, M. Baei
Irregularities in bridge pier stiffness concentrate the ductility demand on short piers; while not operating on the longer and more flexible ones. The existence of non-uniform, ductility demand distribution in bridges significantly influences seismic response. As such, this paper proposes a new approach for balancing the ductility demand in irregular bridges by utilizing shape memory alloys (SMAs). An irregular, single column bent viaduct with unequal pier heights is modeled and used as a reference bridge. To enhance seismic behavior of the bridge, a fixed bearing at the top of the short pier is replaced by a sliding bearing and two groups of SMA bars. SMAs are designed to keep their maximum strain within the super-elastic range. The seismic response of the controlled bridge is compared with a reference bridge through parametric studies using a set of suitable ground motion records. Study parameters include SMA lengths, short pier reinforcement ratios, design strain of SMA elements, and the heights of the medium and long piers. The proposed method successfully reduced the response of the short pier and, hence, improved the overall seismic behavior.
{"title":"A Superelastic Retrofitting Method for Mitigating the Effects of Seismic Excitations on Irregular Bridges","authors":"M. Ghassemieh, Seyed Mohyeddin Ghodratian, Mohammad Khanmohmmadi, M. Baei","doi":"10.7508/CEIJ.2018.01.009","DOIUrl":"https://doi.org/10.7508/CEIJ.2018.01.009","url":null,"abstract":"Irregularities in bridge pier stiffness concentrate the ductility demand on short piers; while not operating on the longer and more flexible ones. The existence of non-uniform, ductility demand distribution in bridges significantly influences seismic response. As such, this paper proposes a new approach for balancing the ductility demand in irregular bridges by utilizing shape memory alloys (SMAs). An irregular, single column bent viaduct with unequal pier heights is modeled and used as a reference bridge. To enhance seismic behavior of the bridge, a fixed bearing at the top of the short pier is replaced by a sliding bearing and two groups of SMA bars. SMAs are designed to keep their maximum strain within the super-elastic range. The seismic response of the controlled bridge is compared with a reference bridge through parametric studies using a set of suitable ground motion records. Study parameters include SMA lengths, short pier reinforcement ratios, design strain of SMA elements, and the heights of the medium and long piers. The proposed method successfully reduced the response of the short pier and, hence, improved the overall seismic behavior.","PeriodicalId":43959,"journal":{"name":"Civil Engineering Infrastructures Journal-CEIJ","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41405414","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 : 2018-06-01DOI: 10.7508/CEIJ.2018.01.007
A. Ramezani, M. Esfahani
Hybrid fiber reinforced concrete (HFRC) consisting of two or more different types of fibers has been widely investigated because of its superior mechanical properties. In the present study, the effect of the addition of steel (0.25%, 0.5%, 0.75%, and 1% of concrete volume) and Polypropylene (0.2%, 0.4%, and 0.6% of concrete volume) fibers on the surface scaling resistance of concrete, depth of penetration of water, and compressive strength of concrete is investigated. The permeability test is conducted for all the specimens to measure the depth of penetration of water under pressure. Moreover, scaling resistance of concrete subjected to freezing and thawing cycles in the presence of salt solution is assessed to simulate the durability of concrete under field exposure conditions. The results showed that the addition of fibers increases the permeability of concrete. However, it enhances the scaling resistance and compressive strength of concrete. The mixture containing 0.4% of Polypropylene (PP) fibers and 0.75% of steel fibers demonstrated the highest scaling resistance since the scaled materials in this mixture were almost half weight of the materials scaled from the control mixture after 84 cycles of freezing and thawing. Increasing the scaling resistance of concrete leads to a better long-term serviceability performance of HFRC compared to plain concrete, making these composites a great choice for application in environments exposed to cold weather.
{"title":"Evaluation of Hybrid Fiber Reinforced Concrete Exposed to Severe Environmental Conditions","authors":"A. Ramezani, M. Esfahani","doi":"10.7508/CEIJ.2018.01.007","DOIUrl":"https://doi.org/10.7508/CEIJ.2018.01.007","url":null,"abstract":"Hybrid fiber reinforced concrete (HFRC) consisting of two or more different types of fibers has been widely investigated because of its superior mechanical properties. In the present study, the effect of the addition of steel (0.25%, 0.5%, 0.75%, and 1% of concrete volume) and Polypropylene (0.2%, 0.4%, and 0.6% of concrete volume) fibers on the surface scaling resistance of concrete, depth of penetration of water, and compressive strength of concrete is investigated. The permeability test is conducted for all the specimens to measure the depth of penetration of water under pressure. Moreover, scaling resistance of concrete subjected to freezing and thawing cycles in the presence of salt solution is assessed to simulate the durability of concrete under field exposure conditions. The results showed that the addition of fibers increases the permeability of concrete. However, it enhances the scaling resistance and compressive strength of concrete. The mixture containing 0.4% of Polypropylene (PP) fibers and 0.75% of steel fibers demonstrated the highest scaling resistance since the scaled materials in this mixture were almost half weight of the materials scaled from the control mixture after 84 cycles of freezing and thawing. Increasing the scaling resistance of concrete leads to a better long-term serviceability performance of HFRC compared to plain concrete, making these composites a great choice for application in environments exposed to cold weather.","PeriodicalId":43959,"journal":{"name":"Civil Engineering Infrastructures Journal-CEIJ","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42360643","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 : 2018-06-01DOI: 10.7508/CEIJ.2018.01.008
M. Karimpour-Fard, Roghayeh Alimohammadi-jelodar
Clayey soils are the most common material used for water sealing and undertake an important role in controlling landfill-related pollution. Organic liquids can adversely affect the effectiveness of clay liners by drastically increasing their hydraulic conductivity. The aim of this study is to investigate and compare the permeability in two types of clay with different plasticity, exposed to the flow of kerosene and diesel as non-polar immiscible liquids and ethanol as a miscible liquid with an intermediate dielectric constant. The effects of plasticity and water content for a given compactive effort are also investigated. Two different clayey soils with different plasticity were provided and their physical properties determined. Next, modified constant-head permeability tests were conducted on the samples. Results show that the lower dielectric constant of the organic fluids, leads to an increase in hydraulic conductivity. Research has shown that organic fluids shrink the diffuse double layer due to their lower dielectric constant and reduce its thickness. Shrinkage of the double layer leads to higher permeability and lower plasticity in the soil. As a result, the void space for the passage of the fluid increases. With the decrease the dielectric constant from 80.1 to 1.8, permeability is increased up to 1800 times. On the other hand, results show that for a clay with a higher liquid limit and plastic limit, permeability for all the liquids investigated in the research is lower.
{"title":"Permeability of Two Clayey Soils Exposed to Petroleum Products and Organic Solvents","authors":"M. Karimpour-Fard, Roghayeh Alimohammadi-jelodar","doi":"10.7508/CEIJ.2018.01.008","DOIUrl":"https://doi.org/10.7508/CEIJ.2018.01.008","url":null,"abstract":"Clayey soils are the most common material used for water sealing and undertake an important role in controlling landfill-related pollution. Organic liquids can adversely affect the effectiveness of clay liners by drastically increasing their hydraulic conductivity. The aim of this study is to investigate and compare the permeability in two types of clay with different plasticity, exposed to the flow of kerosene and diesel as non-polar immiscible liquids and ethanol as a miscible liquid with an intermediate dielectric constant. The effects of plasticity and water content for a given compactive effort are also investigated. Two different clayey soils with different plasticity were provided and their physical properties determined. Next, modified constant-head permeability tests were conducted on the samples. Results show that the lower dielectric constant of the organic fluids, leads to an increase in hydraulic conductivity. Research has shown that organic fluids shrink the diffuse double layer due to their lower dielectric constant and reduce its thickness. Shrinkage of the double layer leads to higher permeability and lower plasticity in the soil. As a result, the void space for the passage of the fluid increases. With the decrease the dielectric constant from 80.1 to 1.8, permeability is increased up to 1800 times. On the other hand, results show that for a clay with a higher liquid limit and plastic limit, permeability for all the liquids investigated in the research is lower.","PeriodicalId":43959,"journal":{"name":"Civil Engineering Infrastructures Journal-CEIJ","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48184879","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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