Pub Date : 2021-01-17DOI: 10.22075/JRCE.2021.20421.1416
H. Saffari, M. Pouladvand
The topic of pounding of adjacent structures has greatly attracted the attention of researchers in recent years. Among the observed damages due to the earthquake, one could refer to those damages induced by pounding of the adjacent structures which is a prevalent phenomenon. The reason for this issue is the lack of separation joint or its inadequacy between two adjacent buildings. When an earthquake occurs, difference in the structures' frequencies would result in difference in their reaction relative to the ground acceleration and pounding would take place. In this article the effects of site soil type, structure type, its height and distance from the fault on the separation joint for the steel and reinforced concrete moment resisting buildings with 3, 5, 8 and 12 stories are investigated. The structural models are first designed by structural design software and then are analyzed under various time histories using Seismostruct software. The obtained results show that the highest hazard risks corresponding to collision between the adjacent buildings belong to areas near the faults located on soft soil types and collision of two buildings with different types is the most severe collision. Different conditions have been discussed in this paper and based on the results, some editions to criteria of seismic design code of Iran has been proposed considering to distance to active faults, soil conditions and type of structure.
{"title":"Investigation of adequacy of adjacent building seismic joints in Tehran City corresponding to seismic hazard analysis, site effects and nonlinear dynamic analysis","authors":"H. Saffari, M. Pouladvand","doi":"10.22075/JRCE.2021.20421.1416","DOIUrl":"https://doi.org/10.22075/JRCE.2021.20421.1416","url":null,"abstract":"The topic of pounding of adjacent structures has greatly attracted the attention of researchers in recent years. Among the observed damages due to the earthquake, one could refer to those damages induced by pounding of the adjacent structures which is a prevalent phenomenon. The reason for this issue is the lack of separation joint or its inadequacy between two adjacent buildings. When an earthquake occurs, difference in the structures' frequencies would result in difference in their reaction relative to the ground acceleration and pounding would take place. In this article the effects of site soil type, structure type, its height and distance from the fault on the separation joint for the steel and reinforced concrete moment resisting buildings with 3, 5, 8 and 12 stories are investigated. The structural models are first designed by structural design software and then are analyzed under various time histories using Seismostruct software. The obtained results show that the highest hazard risks corresponding to collision between the adjacent buildings belong to areas near the faults located on soft soil types and collision of two buildings with different types is the most severe collision. Different conditions have been discussed in this paper and based on the results, some editions to criteria of seismic design code of Iran has been proposed considering to distance to active faults, soil conditions and type of structure.","PeriodicalId":52415,"journal":{"name":"Journal of Rehabilitation in Civil Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85437632","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 : 2021-01-16DOI: 10.22075/JRCE.2021.21251.1441
H. Hoseynzadeh, A. Mortezaei
Historical sites and remnant monuments from different eras in Iran are the main reasons of tourist attraction. One of the factors that endanger existence of these monuments is earthquakes and it is well known that Iran is located on the Alpide seismicbelt and earthquakes are inevitable. Understanding the structural behavior as well as possible weaknesses and then seismic strengthening under the earthquake are the ways of mitigating hazard in architectural heritage. Minaret of Tarikhanehmosque which is one of the oldest minarets and most precious historical monuments in Islamic world was built between 130 and 170 AH (750-760 AD). In the present study, this minaret is first modeled via ABAQUS finite element software considering geometric details and different seismic analysis such as pushover, modal and nonlinear time history analysis is conducted under the different earthquake frequency contents. After realizing the current state and weaknesses of the minaret, seismic strengthening is done via three different methods including FRP sheets, Ferro-cement (welded wire mesh with micro-concrete/mortar), and fiber reinforced cementitious matrix (FRCM) material. Finally, results of these three strengthening methods were evaluated and the most appropriate method was selected. According to the results, it was observed that Ferro-cement strengthening method is the most effective one among the proposed methods; so that, in comparison to the FRCM strengthening method, this method is effective by up to 100 %.
{"title":"Seismic Vulnerability and Rehabilitation of One of The World’s Oldest Masonry Minaret under The Different Earthquake Frequency Contents","authors":"H. Hoseynzadeh, A. Mortezaei","doi":"10.22075/JRCE.2021.21251.1441","DOIUrl":"https://doi.org/10.22075/JRCE.2021.21251.1441","url":null,"abstract":"Historical sites and remnant monuments from different eras in Iran are the main reasons of tourist attraction. One of the factors that endanger existence of these monuments is earthquakes and it is well known that Iran is located on the Alpide seismicbelt and earthquakes are inevitable. Understanding the structural behavior as well as possible weaknesses and then seismic strengthening under the earthquake are the ways of mitigating hazard in architectural heritage. Minaret of Tarikhanehmosque which is one of the oldest minarets and most precious historical monuments in Islamic world was built between 130 and 170 AH (750-760 AD). In the present study, this minaret is first modeled via ABAQUS finite element software considering geometric details and different seismic analysis such as pushover, modal and nonlinear time history analysis is conducted under the different earthquake frequency contents. After realizing the current state and weaknesses of the minaret, seismic strengthening is done via three different methods including FRP sheets, Ferro-cement (welded wire mesh with micro-concrete/mortar), and fiber reinforced cementitious matrix (FRCM) material. Finally, results of these three strengthening methods were evaluated and the most appropriate method was selected. According to the results, it was observed that Ferro-cement strengthening method is the most effective one among the proposed methods; so that, in comparison to the FRCM strengthening method, this method is effective by up to 100 %.","PeriodicalId":52415,"journal":{"name":"Journal of Rehabilitation in Civil Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90449895","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 : 2021-01-16DOI: 10.22075/JRCE.2021.20562.1426
N. Zandi, M. Adlparvar, Amir Lamei Javan
In order to design seismic-resistant buildings, it is necessary to get comprehensive information about their behavior against the forces induced by earthquakes. Seismic design codes have been developed to meet the requirements of a safe and economical structure. According to the structural codes, the designed structures should not be damaged against light or moderate earthquakes so that the members should be had sufficient strength and safety while they should be a ductile complex with a proper structural configuration against severe earthquakes to dissipate the forces caused by ground motions. In the design of steel buildings, the use of moment-resisting frames in combination with braces is a seismic-resistant system. One of these systems is the dual steel moment-resisting frames with zipper braces. In this research, the seismic performance of the moment-resisting frame with the zipper brace system has been studied and its performance has been compared to the performance when the chevron bracing system is used. Three 4-story, 8-story, and 12-story buildings have been selected then they have been modeled by SAP2000 software, and finally, their seismic performances have been evaluated using time history analysis. The structural responses have been compared as comparing the relative displacement of the stories (story drift), the maximum displacement of the roof, and the formation of plastic hinges in the members. The results of the current study have been shown that using a zipper member has been decreased both overall displacement of the structure by about 10 to 30 percent, and also has been reduced the damage index of 4, 8, and 12-story structures by 27, 11, and 12 percent, respectively. The formation of plastic hinges has been directed from horizontal and vertical members toward diagonal members.
{"title":"Evaluation on Seismic Performance of Dual Steel Moment-Resisting Frame with Zipper Bracing System Compared to Chevron Bracing System against Near - Fault Earthquakes","authors":"N. Zandi, M. Adlparvar, Amir Lamei Javan","doi":"10.22075/JRCE.2021.20562.1426","DOIUrl":"https://doi.org/10.22075/JRCE.2021.20562.1426","url":null,"abstract":"In order to design seismic-resistant buildings, it is necessary to get comprehensive information about their behavior against the forces induced by earthquakes. Seismic design codes have been developed to meet the requirements of a safe and economical structure. According to the structural codes, the designed structures should not be damaged against light or moderate earthquakes so that the members should be had sufficient strength and safety while they should be a ductile complex with a proper structural configuration against severe earthquakes to dissipate the forces caused by ground motions. In the design of steel buildings, the use of moment-resisting frames in combination with braces is a seismic-resistant system. One of these systems is the dual steel moment-resisting frames with zipper braces. In this research, the seismic performance of the moment-resisting frame with the zipper brace system has been studied and its performance has been compared to the performance when the chevron bracing system is used. Three 4-story, 8-story, and 12-story buildings have been selected then they have been modeled by SAP2000 software, and finally, their seismic performances have been evaluated using time history analysis. The structural responses have been compared as comparing the relative displacement of the stories (story drift), the maximum displacement of the roof, and the formation of plastic hinges in the members. The results of the current study have been shown that using a zipper member has been decreased both overall displacement of the structure by about 10 to 30 percent, and also has been reduced the damage index of 4, 8, and 12-story structures by 27, 11, and 12 percent, respectively. The formation of plastic hinges has been directed from horizontal and vertical members toward diagonal members.","PeriodicalId":52415,"journal":{"name":"Journal of Rehabilitation in Civil Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75931065","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 : 2021-01-15DOI: 10.22075/JRCE.2021.20803.1431
N. Ahmadi, M. Yazdandoust, M. Yazdani
In the current experimental work, the simultaneous effect of fineness modulus, water-to-cementitious materials [W/(C+M)], and also micro silica content were investigated on workability, mechanical and physical properties of high strength concrete. For this purpose, 45 mix-designs were made by selecting five different ratios of micro-silica, three W/(C+M) ratios, and three distributions of particle size and then the slump, compressive strength, elastic modulus, and split tensile strength of each designed concrete mixture were determined. Findings showed that increasing the micro-silica content up to 10 wt% improves the mechanical properties of concrete and then leads to a reduction in strength parameters, so that the effect of changes in the micro-silica content on mechanical parameters of concrete becomes more prominent with increasing and decreasing the fineness modulus of aggregate and W/(C+M) ratio, respectively. It was also observed that increasing the micro-silica content leads to reducing the slump and unit weight of concrete so that this reduction is more noticeable in the low fineness modulus of aggregate and water-cement ratio.
{"title":"Simultaneous Effect of Aggregate and Cement Matrix on the Performance of High Strength Concrete","authors":"N. Ahmadi, M. Yazdandoust, M. Yazdani","doi":"10.22075/JRCE.2021.20803.1431","DOIUrl":"https://doi.org/10.22075/JRCE.2021.20803.1431","url":null,"abstract":"In the current experimental work, the simultaneous effect of fineness modulus, water-to-cementitious materials [W/(C+M)], and also micro silica content were investigated on workability, mechanical and physical properties of high strength concrete. For this purpose, 45 mix-designs were made by selecting five different ratios of micro-silica, three W/(C+M) ratios, and three distributions of particle size and then the slump, compressive strength, elastic modulus, and split tensile strength of each designed concrete mixture were determined. Findings showed that increasing the micro-silica content up to 10 wt% improves the mechanical properties of concrete and then leads to a reduction in strength parameters, so that the effect of changes in the micro-silica content on mechanical parameters of concrete becomes more prominent with increasing and decreasing the fineness modulus of aggregate and W/(C+M) ratio, respectively. It was also observed that increasing the micro-silica content leads to reducing the slump and unit weight of concrete so that this reduction is more noticeable in the low fineness modulus of aggregate and water-cement ratio.","PeriodicalId":52415,"journal":{"name":"Journal of Rehabilitation in Civil Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75443732","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 : 2021-01-15DOI: 10.22075/JRCE.2021.20557.1425
A. Nagaraj, S. Girish
Concrete is a heterogeneous, complex composite construction material. Fresh property of concrete is a critical property with significant effect on quality , cost of construction, strength, and durability. Even to this day the workability of fresh concrete is measured by empirical test, notably by slump test in spite of its drawbacks and sometimes with misleading results with less practical significance. There is an urgent need to characterize the flow of fresh concrete b y its rheological properties based on material science approach to overcome the inadequacies of the empirical test methods.Fluid rheology approach is the most fundamental one and describes the concrete flow by at least two parameters namely yield stress and plastic viscosity by considering fresh concrete as a Bingham fluid. Understanding and controlling the two fundamental fresh properties of concrete allow for more economical and better performing concrete mixes with the use of wide range of ingredients.This paper brings out the importance of rheology and advocates the use of fundamental science approach with two parameter tests along with advantages and limitations of using rheometers. Also highlights the use of concrete shear box static tests for wide range of workability requirements with the use of new and marginal materials in concrete industry.
{"title":"Rheology of Fresh Concrete - A Review","authors":"A. Nagaraj, S. Girish","doi":"10.22075/JRCE.2021.20557.1425","DOIUrl":"https://doi.org/10.22075/JRCE.2021.20557.1425","url":null,"abstract":"Concrete is a heterogeneous, complex composite construction material. Fresh property of concrete is a critical property with significant effect on quality , cost of construction, strength, and durability. Even to this day the workability of fresh concrete is measured by empirical test, notably by slump test in spite of its drawbacks and sometimes with misleading results with less practical significance. There is an urgent need to characterize the flow of fresh concrete b y its rheological properties based on material science approach to overcome the inadequacies of the empirical test methods.Fluid rheology approach is the most fundamental one and describes the concrete flow by at least two parameters namely yield stress and plastic viscosity by considering fresh concrete as a Bingham fluid. Understanding and controlling the two fundamental fresh properties of concrete allow for more economical and better performing concrete mixes with the use of wide range of ingredients.This paper brings out the importance of rheology and advocates the use of fundamental science approach with two parameter tests along with advantages and limitations of using rheometers. Also highlights the use of concrete shear box static tests for wide range of workability requirements with the use of new and marginal materials in concrete industry.","PeriodicalId":52415,"journal":{"name":"Journal of Rehabilitation in Civil Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91226231","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 : 2020-11-10DOI: 10.22075/JRCE.2020.13379.1243
M. Nikoo, A. H. Akhaveissy, A. Permanoon
The current article seeks to investigate the behavior of masonry wall reinforced with timber lumbers and effect of timbers on increasing the shear strength and ductility of wall. To determine the mechanical properties of the timbers, two experiments according to ASTM D143 were performed. All of the mechanical properties required for timber simulation were determined via tensile and compressive tests, and using parametric equations. The behavior of the timbers under tensile force was brittle, and under pressure was semi-ductile. Hill yield criterion was utilized for timber behavior modelling. Predictably, the location of the plastic strain formation in the tensile and compressive specimen was consistent with the location of the fracture in the experimental specimens. In the next parts of the research, the obtained parameters were used to model the mechanical behavior of the timbers. Macro and meso approaches were used for the numerical modeling of the masonry wall. The Willam–Warnke yield criterion was used on the macro scale, and the cohesive-frictional interface constitutive model was utilized on the meso scale. Both numerical models were in good agreement with the laboratory results. However, due to the gap and sliding of the masonry wall in the numerical model, the Meso scale was used in the research. The masonry wall was retrofitted and strengthened by three different patterns of timber placement. An examination of the analysis results showed that by placing the timbers, the wall cracking pattern tends to change, and the ductility and shear capacity of the wall considerably enhances.
{"title":"An Investigation of Performance of Masonry Wall Reinforced with Timber lumbers","authors":"M. Nikoo, A. H. Akhaveissy, A. Permanoon","doi":"10.22075/JRCE.2020.13379.1243","DOIUrl":"https://doi.org/10.22075/JRCE.2020.13379.1243","url":null,"abstract":"The current article seeks to investigate the behavior of masonry wall reinforced with timber lumbers and effect of timbers on increasing the shear strength and ductility of wall. To determine the mechanical properties of the timbers, two experiments according to ASTM D143 were performed. All of the mechanical properties required for timber simulation were determined via tensile and compressive tests, and using parametric equations. The behavior of the timbers under tensile force was brittle, and under pressure was semi-ductile. Hill yield criterion was utilized for timber behavior modelling. Predictably, the location of the plastic strain formation in the tensile and compressive specimen was consistent with the location of the fracture in the experimental specimens. In the next parts of the research, the obtained parameters were used to model the mechanical behavior of the timbers. Macro and meso approaches were used for the numerical modeling of the masonry wall. The Willam–Warnke yield criterion was used on the macro scale, and the cohesive-frictional interface constitutive model was utilized on the meso scale. Both numerical models were in good agreement with the laboratory results. However, due to the gap and sliding of the masonry wall in the numerical model, the Meso scale was used in the research. The masonry wall was retrofitted and strengthened by three different patterns of timber placement. An examination of the analysis results showed that by placing the timbers, the wall cracking pattern tends to change, and the ductility and shear capacity of the wall considerably enhances.","PeriodicalId":52415,"journal":{"name":"Journal of Rehabilitation in Civil Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88850064","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 : 2020-11-01DOI: 10.22075/JRCE.2020.17480.1332
A. Dalvand, E. Sharififard, F. Omidinasab
Cementitious composites are one of the most consumed construction materials in the world. The use of cementitious composites is increasing due to their special characteristics. The behavior of high strength cementitious composites is improved by increasing the fiber percentage. In the present paper, the effects of steel microfibers and polypropylene fibers on mechanical properties and impact resistance of high strength cementitious composites are investigated. The percentage of fibers used in the study was 0, 0.5, and 1.5% in seven separate and three combined mix designs. Experiments were carried out on 120 specimens in 10 mix designs. Compressive strength, tensile strength, flexural strength, and dynamic impact tests were carried out on 10 mix designs manufactured in this research. The dynamic impact strength of the disc specimen was investigated by a drop hammer test machine with a capacity of 7500J. After testing the samples, it was shown that using a high percentage of steel and polypropylene fibers reduces the compressive strength and increases tensile strength, flexural strength, and impact strength. The effects of steel microfibers on the reduction of the crush displacement resulting from the dynamic impact were higher than that of polypropylene fibers.
{"title":"Experimental Investigation of Mechanical and Dynamic Impact Properties of High Strength Cementitious Composite Containing Micro Steel and PP Fibers","authors":"A. Dalvand, E. Sharififard, F. Omidinasab","doi":"10.22075/JRCE.2020.17480.1332","DOIUrl":"https://doi.org/10.22075/JRCE.2020.17480.1332","url":null,"abstract":"Cementitious composites are one of the most consumed construction materials in the world. The use of cementitious composites is increasing due to their special characteristics. The behavior of high strength cementitious composites is improved by increasing the fiber percentage. In the present paper, the effects of steel microfibers and polypropylene fibers on mechanical properties and impact resistance of high strength cementitious composites are investigated. The percentage of fibers used in the study was 0, 0.5, and 1.5% in seven separate and three combined mix designs. Experiments were carried out on 120 specimens in 10 mix designs. Compressive strength, tensile strength, flexural strength, and dynamic impact tests were carried out on 10 mix designs manufactured in this research. The dynamic impact strength of the disc specimen was investigated by a drop hammer test machine with a capacity of 7500J. After testing the samples, it was shown that using a high percentage of steel and polypropylene fibers reduces the compressive strength and increases tensile strength, flexural strength, and impact strength. The effects of steel microfibers on the reduction of the crush displacement resulting from the dynamic impact were higher than that of polypropylene fibers.","PeriodicalId":52415,"journal":{"name":"Journal of Rehabilitation in Civil Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90275232","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 : 2020-11-01DOI: 10.22075/JRCE.2020.19189.1380
A. Farahani, H. Taghaddos
Chloride-induced corrosion is a key factor in the premature corrosion of concrete structures exposed to a marine environment. Fick's second law of diffusion is the dominant equation to model diffusion of chloride ions. This equation is traditionally solved by Finite Element Method (FEM) and Finite Difference Method (FDM). Although these methods are robust and efficient, they may face some numerical issues due to discretization process. This study solves the Fick's equation using the Element-Free Galerkin (EFG) method as well as traditional FEM and FDM. The results of these numerical methods are compared together, and validated with the analytical solution in special cases. The results show that the EFG method predicts the service life of the concrete structures, more accurately than the other methods, and exhibits the lowest displacement error and energy error for a constant diffusion coefficient problem. FDM can be performed very efficiently for simple models, and the displacement errors produced by this method do not differ considerably from the EFG results. Therefore, FDM could compete with the EFG method in simple geometries. FEM can be used with a sufficient number of elements while the convergence of the results should be controlled. However, in complicated models, FEM and especially the EFG method are much more flexible than FDM.
{"title":"Prediction of Service Life in Concrete Structures based on Diffusion Model in a Marine Environment Using Mesh Free, FEM and FDM Approaches","authors":"A. Farahani, H. Taghaddos","doi":"10.22075/JRCE.2020.19189.1380","DOIUrl":"https://doi.org/10.22075/JRCE.2020.19189.1380","url":null,"abstract":"Chloride-induced corrosion is a key factor in the premature corrosion of concrete structures exposed to a marine environment. Fick's second law of diffusion is the dominant equation to model diffusion of chloride ions. This equation is traditionally solved by Finite Element Method (FEM) and Finite Difference Method (FDM). Although these methods are robust and efficient, they may face some numerical issues due to discretization process. This study solves the Fick's equation using the Element-Free Galerkin (EFG) method as well as traditional FEM and FDM. The results of these numerical methods are compared together, and validated with the analytical solution in special cases. The results show that the EFG method predicts the service life of the concrete structures, more accurately than the other methods, and exhibits the lowest displacement error and energy error for a constant diffusion coefficient problem. FDM can be performed very efficiently for simple models, and the displacement errors produced by this method do not differ considerably from the EFG results. Therefore, FDM could compete with the EFG method in simple geometries. FEM can be used with a sufficient number of elements while the convergence of the results should be controlled. However, in complicated models, FEM and especially the EFG method are much more flexible than FDM.","PeriodicalId":52415,"journal":{"name":"Journal of Rehabilitation in Civil Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77207273","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 : 2020-11-01DOI: 10.22075/JRCE.2020.19803.1384
Shahin Lale Arefi, A. Gholizad, S. M. Seyedpoor
The subject of structural health monitoring and damage identification of structures at the earliest possible stage has been a noteworthy topic for researchers in the last years. Modal strain energy (MSE) based index is one of the efficient methods which are commonly used for detecting damage in structures. It is also more effective and economical to employ some methods for reducing the degrees of freedom in large-scale structures having a large number of degrees of freedom. The purpose of this study is to identify structural damage via an index based on MSE and reconstructed mode shapes. The Guyan reduction method (GRM) is utilized here to reconstruct the mode shapes. Therefore, in the first step by employing GRM, mode shapes in slave degrees of freedom are estimated by those of master degrees of freedom. In the second step, the modal strain energy based index (MSEBI) is used to find the location of damaged elements. In order to assess the efficiency of the method, two standard examples are considered. Damage is identified with considering complete mode shapes and reconstructed mode shapes, and the results are compared together. The outcomes show that the combination of MSE and GRM can be useful for the structural damage detection, when considering the noise.
{"title":"Damage Detection of Structures Using Modal Strain Energy with Guyan Reduction Method","authors":"Shahin Lale Arefi, A. Gholizad, S. M. Seyedpoor","doi":"10.22075/JRCE.2020.19803.1384","DOIUrl":"https://doi.org/10.22075/JRCE.2020.19803.1384","url":null,"abstract":"The subject of structural health monitoring and damage identification of structures at the earliest possible stage has been a noteworthy topic for researchers in the last years. Modal strain energy (MSE) based index is one of the efficient methods which are commonly used for detecting damage in structures. It is also more effective and economical to employ some methods for reducing the degrees of freedom in large-scale structures having a large number of degrees of freedom. The purpose of this study is to identify structural damage via an index based on MSE and reconstructed mode shapes. The Guyan reduction method (GRM) is utilized here to reconstruct the mode shapes. Therefore, in the first step by employing GRM, mode shapes in slave degrees of freedom are estimated by those of master degrees of freedom. In the second step, the modal strain energy based index (MSEBI) is used to find the location of damaged elements. In order to assess the efficiency of the method, two standard examples are considered. Damage is identified with considering complete mode shapes and reconstructed mode shapes, and the results are compared together. The outcomes show that the combination of MSE and GRM can be useful for the structural damage detection, when considering the noise.","PeriodicalId":52415,"journal":{"name":"Journal of Rehabilitation in Civil Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81960232","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 : 2020-11-01DOI: 10.22075/JRCE.2018.724.1093
O. Poursaeidi, H. Naderpour
This study develops a new approach for forecasting shear Strength of concrete beam without stirrups based on the artificial neural networks (ANN). Proposed ANN considers geometric and mechanical properties of cross section and FRP bars, and shear span-depth ratio. The ANN model is constructed from a set of experimental database available in the past literature. Efficiency of the ANN model was compared with existing approaches in the literature using comprehensive database. ANN is powerful tools in solving complex problems of civil engineering. The Levenberg–Marquardt (LM) method was applied for training algorithm. These existing approach include the American Concrete Institute design guide (ACI 440.1R-06), ISIS Canadian design manual (ISIS-M03-07), the British Institution of Structural Engineers guidelines (BISE), JSCE Design Recommendation, CNR-DT 203-06 Task Group, and Kara. The results demonstrate that ANN method has good agreement in calculating the shear strength of concrete beam reinforced with FRP bar among existing equations in recent decades.
提出了一种基于人工神经网络(ANN)的无箍筋混凝土梁抗剪强度预测新方法。提出的人工神经网络考虑了截面和FRP筋的几何和力学性能，以及剪切跨深比。该人工神经网络模型是根据过去文献中的一组实验数据库构建的。利用综合数据库与文献中已有的方法进行了效率比较。人工神经网络是解决复杂土木工程问题的有力工具。采用Levenberg-Marquardt (LM)方法进行训练算法。这些现有的方法包括美国混凝土学会设计指南(ACI 440.01 r -06)、ISIS加拿大设计手册(ISIS- m03 -07)、英国结构工程师学会指南(BISE)、JSCE设计建议、CNR-DT 203-06任务组和Kara。结果表明，人工神经网络方法在计算FRP筋混凝土梁抗剪强度方面与近几十年来已有的计算公式具有较好的一致性。
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