Pub Date : 2021-08-11DOI: 10.22059/CEIJ.2021.311895.1716
Alireza Haji Hossein, H. Bigdeli, F. Mokhtari, Sepehr Jahantab, A. H. Korayem
This paper presents the results of an experimental investigation on three different aspects of cement mortars incorporating amorphous carbon powder; rheology, strength and water absorption. Amorphous carbon powder is a by-product of the paraffin industry and was replaced with 0, 4, 6 and 8% of aggregate. Rheological tests were conducted immediately after mixing procedure, the strength of mortars was investigated by two methods; compressive and flexural at the age of 7 and 28 days. Furthermore, the water absorption of specimens was determined. Using Amorphous carbon powder was detrimental in terms of workability. However, after 28 days compressive and flexural strengths increased and water absorption declined with the addition of amorphous carbon powder, thus reducing the risk to degradation over time in severe environments.
{"title":"The effect of hydrophobic amorphous carbon powder on the compressive strength, water absorption and rheological attributes of cement mortar","authors":"Alireza Haji Hossein, H. Bigdeli, F. Mokhtari, Sepehr Jahantab, A. H. Korayem","doi":"10.22059/CEIJ.2021.311895.1716","DOIUrl":"https://doi.org/10.22059/CEIJ.2021.311895.1716","url":null,"abstract":"This paper presents the results of an experimental investigation on three different aspects of cement mortars incorporating amorphous carbon powder; rheology, strength and water absorption. Amorphous carbon powder is a by-product of the paraffin industry and was replaced with 0, 4, 6 and 8% of aggregate. Rheological tests were conducted immediately after mixing procedure, the strength of mortars was investigated by two methods; compressive and flexural at the age of 7 and 28 days. Furthermore, the water absorption of specimens was determined. Using Amorphous carbon powder was detrimental in terms of workability. However, after 28 days compressive and flexural strengths increased and water absorption declined with the addition of amorphous carbon powder, thus reducing the risk to degradation over time in severe environments.","PeriodicalId":43959,"journal":{"name":"Civil Engineering Infrastructures Journal-CEIJ","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2021-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42450910","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-07-12DOI: 10.22059/CEIJ.2020.297661.1656
Reza Jalalkamali, Mohammad Mahdi Dibaee, M. Kamali, A. Hassani
Road accidents are one of the ten major causes of death in the world. Lack of enough friction and skid resistance of the pavement surface are known as important factors in traffic accidents. In this study, to evaluate the relationship between skid resistance and pavement surface macrotexture, five methods of creating macrotexture on concrete pavements were used. Sand Patch test, British Pendulum and Wide Wheel Abrasion tests were employed to obtain mean texture depth, skid resistance and abrasion resistance of the surface, respectively. Results showed that brushing on fresh concrete surface (parallel or perpendicular to the traffic direction) can improve frictional properties of pavement surface, drastically. This method increased British Pendulum Number (BPN) and friction coefficient by 32% and 38% (in average), respectively. Friction coefficient of parallel brushing was quite similar to perpendicular (0.2% discrepancy), while its abrasion resistance was 4% higher. Hence, as a finding, parallel brushing is the most recommended texturing technique in respect to friction. Generally, concrete pavement texturing decreases surface abrasion resistance, but burlap dragging improved this index by 2.5%. Nevertheless, burlap dragging results could be deceptive due to the high sensitivity to initial setup conditions. In other words, measurement scale of the studied testing procedures are small in respect to the scale of protuberances caused by burlap dragging method.
{"title":"An Investigation of the Relationship among Skid Resistance, Mean Texture Depth and Abrasion Resistance for Different Macrotextures of Concrete Pavements","authors":"Reza Jalalkamali, Mohammad Mahdi Dibaee, M. Kamali, A. Hassani","doi":"10.22059/CEIJ.2020.297661.1656","DOIUrl":"https://doi.org/10.22059/CEIJ.2020.297661.1656","url":null,"abstract":"Road accidents are one of the ten major causes of death in the world. Lack of enough friction and skid resistance of the pavement surface are known as important factors in traffic accidents. In this study, to evaluate the relationship between skid resistance and pavement surface macrotexture, five methods of creating macrotexture on concrete pavements were used. Sand Patch test, British Pendulum and Wide Wheel Abrasion tests were employed to obtain mean texture depth, skid resistance and abrasion resistance of the surface, respectively. Results showed that brushing on fresh concrete surface (parallel or perpendicular to the traffic direction) can improve frictional properties of pavement surface, drastically. This method increased British Pendulum Number (BPN) and friction coefficient by 32% and 38% (in average), respectively. Friction coefficient of parallel brushing was quite similar to perpendicular (0.2% discrepancy), while its abrasion resistance was 4% higher. Hence, as a finding, parallel brushing is the most recommended texturing technique in respect to friction. Generally, concrete pavement texturing decreases surface abrasion resistance, but burlap dragging improved this index by 2.5%. Nevertheless, burlap dragging results could be deceptive due to the high sensitivity to initial setup conditions. In other words, measurement scale of the studied testing procedures are small in respect to the scale of protuberances caused by burlap dragging method.","PeriodicalId":43959,"journal":{"name":"Civil Engineering Infrastructures Journal-CEIJ","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2021-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47897114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-07-12DOI: 10.22059/CEIJ.2021.294057.1642
A. Miyamoto, Hugo Da Costa Ximenes
The deterioration of existing road pavement surfaces over the years due to aging and the growing number of heavy vehicles has become an important issue. Roads require appropriate maintenance to keep providing the target service. Many efforts have been made by road engineers to maintain road pavement surfaces; however, there are some problems due to costs, including vehicle running costs. Therefore, there is a need for an efficient and low-cost system to facilitate evaluation of the serviceability of existing road pavement surfaces. This study aims to develop an efficient, rational and useful method or system that can be used to perform a visual assessment of the condition of not only the pavement but also road structures, including slopes and vegetation and equipment such as guardrails, curbs, and guideposts. Such a system should be inexpensive and be IT-based by making use of new information and the latest technologies. In addition, a method based on an analytic hierarchy process is employed in the decision-making process to analyze a complicated decision problem based on video files obtained by the system.
{"title":"Development of a Road-Condition Assessment System and Application to Road Maintenance Decision-Making","authors":"A. Miyamoto, Hugo Da Costa Ximenes","doi":"10.22059/CEIJ.2021.294057.1642","DOIUrl":"https://doi.org/10.22059/CEIJ.2021.294057.1642","url":null,"abstract":"The deterioration of existing road pavement surfaces over the years due to aging and the growing number of heavy vehicles has become an important issue. Roads require appropriate maintenance to keep providing the target service. Many efforts have been made by road engineers to maintain road pavement surfaces; however, there are some problems due to costs, including vehicle running costs. Therefore, there is a need for an efficient and low-cost system to facilitate evaluation of the serviceability of existing road pavement surfaces. This study aims to develop an efficient, rational and useful method or system that can be used to perform a visual assessment of the condition of not only the pavement but also road structures, including slopes and vegetation and equipment such as guardrails, curbs, and guideposts. Such a system should be inexpensive and be IT-based by making use of new information and the latest technologies. In addition, a method based on an analytic hierarchy process is employed in the decision-making process to analyze a complicated decision problem based on video files obtained by the system.","PeriodicalId":43959,"journal":{"name":"Civil Engineering Infrastructures Journal-CEIJ","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2021-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44685612","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-07-12DOI: 10.22059/CEIJ.2020.298837.1661
Dana Samadi, H. Taghaddos, M. Nili, Mojtaba Noghabaei
Bridges play a critical role in the transportation system network; accordingly, assuring satisfaction with the service level of these structures is vital for bridge maintenance managers. Thus, it is vital to determine the optimum bridge maintenance plan (i.e., the optimum timing and type of repair activities applied to the bridge elements) considering the budget limitations. To optimize the bridge maintenance plan, some researchers have focused on developing optimization models, including the Genetic Algorithm (GA). However, a few studies have employed Bridge Information Modeling (BrIM) to enhance bridge maintenance management. This study focuses on developing an integrated framework based on BrIM and bridge maintenance optimization to utilize visualization capabilities of BrIM to assist maintenance managers in making decisions. The presented framework optimizes the bridge maintenance plan at the sub-element level. The BrIM automatically feeds into the developed GA optimization system. The introduced framework is successfully verified using a real-world case study.
{"title":"Development of a Bridge Maintenance System Using Bridge Information Modeling","authors":"Dana Samadi, H. Taghaddos, M. Nili, Mojtaba Noghabaei","doi":"10.22059/CEIJ.2020.298837.1661","DOIUrl":"https://doi.org/10.22059/CEIJ.2020.298837.1661","url":null,"abstract":"Bridges play a critical role in the transportation system network; accordingly, assuring satisfaction with the service level of these structures is vital for bridge maintenance managers. Thus, it is vital to determine the optimum bridge maintenance plan (i.e., the optimum timing and type of repair activities applied to the bridge elements) considering the budget limitations. To optimize the bridge maintenance plan, some researchers have focused on developing optimization models, including the Genetic Algorithm (GA). However, a few studies have employed Bridge Information Modeling (BrIM) to enhance bridge maintenance management. This study focuses on developing an integrated framework based on BrIM and bridge maintenance optimization to utilize visualization capabilities of BrIM to assist maintenance managers in making decisions. The presented framework optimizes the bridge maintenance plan at the sub-element level. The BrIM automatically feeds into the developed GA optimization system. The introduced framework is successfully verified using a real-world case study.","PeriodicalId":43959,"journal":{"name":"Civil Engineering Infrastructures Journal-CEIJ","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2021-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45476119","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-07-12DOI: 10.22059/CEIJ.2020.295339.1647
M. Hajiazizi, Mohammad Hossein Taban, R. Ghobadian
The determination of tunnel support, required for tunnel stability and safety, is an important debate in tunnel engineering field. Q-system classification is a technique used to determine the support system of a tunnel in rock. The problem is that all required parameters of support system are not accessible. On the other hand, such accesses are very costly and time consuming. Therefore, it is impossible to determine the Q-value in all cases. This paper identifies the most influential parameters of Q-system using SPSS program. Then, it adopts multi-variable regression (MVR) and genetic algorithm (GA) methods to propose a relation for predicting the Q-value using three influential parameters. To this end, 140 experimental data are used. To assess the obtained models, 34 new experimental data, which are not in the primary dataset, are used. The innovation of this paper is that instead of six parameters, the Q-value is determined using three parameters with the highest impact on it instead of six parameters. In this study, the MVR model, with RMSE=2.68 and correlation coefficient=0.81 for train data and RMSE=2.55 and correlation coefficient=0.80 for test data, showed better performance than GA model, with RMSE=2.90 and correlation coefficient=0.82 for train data and RMSE=2.61 and correlation coefficient=0.84 for test data.
{"title":"Prediction of Q-Value by Multi-Variable Regression and Novel Genetic Algorithm Based on the Most Influential Parameters","authors":"M. Hajiazizi, Mohammad Hossein Taban, R. Ghobadian","doi":"10.22059/CEIJ.2020.295339.1647","DOIUrl":"https://doi.org/10.22059/CEIJ.2020.295339.1647","url":null,"abstract":"The determination of tunnel support, required for tunnel stability and safety, is an important debate in tunnel engineering field. Q-system classification is a technique used to determine the support system of a tunnel in rock. The problem is that all required parameters of support system are not accessible. On the other hand, such accesses are very costly and time consuming. Therefore, it is impossible to determine the Q-value in all cases. This paper identifies the most influential parameters of Q-system using SPSS program. Then, it adopts multi-variable regression (MVR) and genetic algorithm (GA) methods to propose a relation for predicting the Q-value using three influential parameters. To this end, 140 experimental data are used. To assess the obtained models, 34 new experimental data, which are not in the primary dataset, are used. The innovation of this paper is that instead of six parameters, the Q-value is determined using three parameters with the highest impact on it instead of six parameters. In this study, the MVR model, with RMSE=2.68 and correlation coefficient=0.81 for train data and RMSE=2.55 and correlation coefficient=0.80 for test data, showed better performance than GA model, with RMSE=2.90 and correlation coefficient=0.82 for train data and RMSE=2.61 and correlation coefficient=0.84 for test data.","PeriodicalId":43959,"journal":{"name":"Civil Engineering Infrastructures Journal-CEIJ","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2021-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45817105","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-07-12DOI: 10.22059/CEIJ.2020.294512.1644
Hamed Teimouri, M. Davoodi, S. Mostafavian, L. Khanmohammadi
Change in modal strain energy is one of the indicators used to detect damage in structures. However, in structures with high degrees of freedom, such as double-layer grids, this method requires a relatively large number of mode shapes which in practice is difficult to determine. Therefore, it is necessary to reduce the number of required mode shapes. In this study, a damage detection technique based on modal strain energy and Dempster-Shafer evidence theory is presented for locating damage in double layer grids using only a few number of mode shapes. First, by calculating mode shapes of the grid in undamaged and damaged states, the modal strain energy based index for each mode shape is determined. Then, the results obtained from separate mode shapes are combined using Dempster-Shafer theory to achieve better results. In order to investigate the effect of noise on damage detection, 3% random noise is added to mode shapes. To demonstrate the performance of the proposed method, different single and multiple damage cases with different damage intensities are considered. Numerical results show that using 5 mode shapes, the presented technique can detect up to 3 damaged elements with different damage intensities in different parts of the grid with good accuracy (probability of 92.3%). Considering the fact that the classical modal strain energy method fails to distinguish even 1 damaged element in the double layer grid, the result shows significant improvement.
{"title":"Damage Detection in Double Layer Grids with Modal Strain Energy Method and Dempster-Shafer Theory","authors":"Hamed Teimouri, M. Davoodi, S. Mostafavian, L. Khanmohammadi","doi":"10.22059/CEIJ.2020.294512.1644","DOIUrl":"https://doi.org/10.22059/CEIJ.2020.294512.1644","url":null,"abstract":"Change in modal strain energy is one of the indicators used to detect damage in structures. However, in structures with high degrees of freedom, such as double-layer grids, this method requires a relatively large number of mode shapes which in practice is difficult to determine. Therefore, it is necessary to reduce the number of required mode shapes. In this study, a damage detection technique based on modal strain energy and Dempster-Shafer evidence theory is presented for locating damage in double layer grids using only a few number of mode shapes. First, by calculating mode shapes of the grid in undamaged and damaged states, the modal strain energy based index for each mode shape is determined. Then, the results obtained from separate mode shapes are combined using Dempster-Shafer theory to achieve better results. In order to investigate the effect of noise on damage detection, 3% random noise is added to mode shapes. To demonstrate the performance of the proposed method, different single and multiple damage cases with different damage intensities are considered. Numerical results show that using 5 mode shapes, the presented technique can detect up to 3 damaged elements with different damage intensities in different parts of the grid with good accuracy (probability of 92.3%). Considering the fact that the classical modal strain energy method fails to distinguish even 1 damaged element in the double layer grid, the result shows significant improvement.","PeriodicalId":43959,"journal":{"name":"Civil Engineering Infrastructures Journal-CEIJ","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2021-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43780974","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-07-12DOI: 10.22059/CEIJ.2020.295522.1649
J. M. Sardroud, A. Fakhimi, A. Mazroi, S. R. Ghoreishi, S. Azhar
The implementation of Building Information Modeling (BIM) in the Architecture, Engineering and Construction (AEC) industry is growing rapidly. The Oil, Gas and Petrochemical industry (OGPi), however, is still lagging in harnessing the BIM capabilities. Therefore, the main question of this research is: How and what actions should be adopted for deploying BIM in the OGPi? The research is divided into three parts as an action research. This study investigates the second part, namely preparation of an adoption roadmap for deploying BIM in collaboration with Integrated Project Delivery (IPD) in the OGPi. To achieve this goal, the extensive literature review including the most established roadmaps in the AEC industry and also the semi-structured interviews with the OGPi's experts were conducted. In this part of the research, an adoption roadmap is derived for OGPi via Innovation Diffusion Theory (IDT), ‘Why, How, What’ questions (Sink model), strategic planning and innovation roadmap as well as the iterative process in the studies and interviews. The prepared roadmap validated by triangulation through focus group meetings and oils the wheels of BIM implementation alongside with IPD in the OGPi firms to grabs BIM merits and harness its challenges. Finally, the major limitations and the required future studies are addressed.
{"title":"Building Information Modeling Deployment in Oil, Gas and Petrochemical Industry: An Adoption Roadmap","authors":"J. M. Sardroud, A. Fakhimi, A. Mazroi, S. R. Ghoreishi, S. Azhar","doi":"10.22059/CEIJ.2020.295522.1649","DOIUrl":"https://doi.org/10.22059/CEIJ.2020.295522.1649","url":null,"abstract":"The implementation of Building Information Modeling (BIM) in the Architecture, Engineering and Construction (AEC) industry is growing rapidly. The Oil, Gas and Petrochemical industry (OGPi), however, is still lagging in harnessing the BIM capabilities. Therefore, the main question of this research is: How and what actions should be adopted for deploying BIM in the OGPi? The research is divided into three parts as an action research. This study investigates the second part, namely preparation of an adoption roadmap for deploying BIM in collaboration with Integrated Project Delivery (IPD) in the OGPi. To achieve this goal, the extensive literature review including the most established roadmaps in the AEC industry and also the semi-structured interviews with the OGPi's experts were conducted. In this part of the research, an adoption roadmap is derived for OGPi via Innovation Diffusion Theory (IDT), ‘Why, How, What’ questions (Sink model), strategic planning and innovation roadmap as well as the iterative process in the studies and interviews. The prepared roadmap validated by triangulation through focus group meetings and oils the wheels of BIM implementation alongside with IPD in the OGPi firms to grabs BIM merits and harness its challenges. Finally, the major limitations and the required future studies are addressed.","PeriodicalId":43959,"journal":{"name":"Civil Engineering Infrastructures Journal-CEIJ","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2021-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43878962","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-07-12DOI: 10.22059/CEIJ.2021.298632.1659
H. Shahir, S. Delfan
In this paper, the performance of soil nailed walls with various nail patterns has been studied to find an optimum layout based on the deformation criterion. To this end, parametric analysis on soil nailed walls with various nailing patterns was performed. Nine patterns including one uniform and eight variable nails length were considered. For each pattern, parametric analysis on different parameters including wall height, surcharge, nails spacing was done to find an optimum pattern based on the deformation criterion. The simulation results indicate that using the variable layout with long nails at the top of the wall not only reduces the lateral deformation of soil nailed wall but also decreases the density of nails.
{"title":"Numerical Investigation of Nailing Pattern Effect on Nailed Wall Performance","authors":"H. Shahir, S. Delfan","doi":"10.22059/CEIJ.2021.298632.1659","DOIUrl":"https://doi.org/10.22059/CEIJ.2021.298632.1659","url":null,"abstract":"In this paper, the performance of soil nailed walls with various nail patterns has been studied to find an optimum layout based on the deformation criterion. To this end, parametric analysis on soil nailed walls with various nailing patterns was performed. Nine patterns including one uniform and eight variable nails length were considered. For each pattern, parametric analysis on different parameters including wall height, surcharge, nails spacing was done to find an optimum pattern based on the deformation criterion. The simulation results indicate that using the variable layout with long nails at the top of the wall not only reduces the lateral deformation of soil nailed wall but also decreases the density of nails.","PeriodicalId":43959,"journal":{"name":"Civil Engineering Infrastructures Journal-CEIJ","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2021-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44617482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-07-12DOI: 10.22059/CEIJ.2020.297941.1657
J. Sobhani, A. Pourkhorshidi
A bonded concrete overlay consists of a new concrete overlay placed directly on top of an existing concrete pavement. The properties of such layer have a distinguished factor for reliable service-life extending of concrete pavements repairing systems. In this paper, the engineering properties of cold-drawn crimped-end steel fiber reinforced (CFCSF) concrete mixtures as overlays are evaluated. To this end, CFCSF mixtures were made with fiber contents of 15 and 25 kg/m3 with diameters of 0.8 and 1 mm and water-cement ratio of 0.5 in comparison with reference concrete. The engineering properties of these types of concrete in the properties of the fresh and the hardened concrete including compressive strength (CS), tensile strength (TS), flexural strength (FS), modulus of elasticity (ME), depth of water penetration (WP), impact (IR) and abrasion resistance (AR) were investigated. The results showed that at an early age, the addition of fibers had no significant effects on the CS but at higher ages, the samples containing steel fibers had higher compressive TS and FS than the control ones. Also, the use of steel fibers increased the ME, IR and AR of CFCSF specimens. Moreover, models developed to correlate the mechanical properties of mixtures with AR and IR. The comparison between the relation of AR and IR to other mechanical properties, made of the linear regression and polynomial relationships in aspects of R2, indicated that stronger relations were available between TS with IR and AR with ME.
{"title":"The Effects of Cold-Drawn Crimped-End Steel Fibers on the Mechanical and Durability of Concrete Overlay","authors":"J. Sobhani, A. Pourkhorshidi","doi":"10.22059/CEIJ.2020.297941.1657","DOIUrl":"https://doi.org/10.22059/CEIJ.2020.297941.1657","url":null,"abstract":"A bonded concrete overlay consists of a new concrete overlay placed directly on top of an existing concrete pavement. The properties of such layer have a distinguished factor for reliable service-life extending of concrete pavements repairing systems. In this paper, the engineering properties of cold-drawn crimped-end steel fiber reinforced (CFCSF) concrete mixtures as overlays are evaluated. To this end, CFCSF mixtures were made with fiber contents of 15 and 25 kg/m3 with diameters of 0.8 and 1 mm and water-cement ratio of 0.5 in comparison with reference concrete. The engineering properties of these types of concrete in the properties of the fresh and the hardened concrete including compressive strength (CS), tensile strength (TS), flexural strength (FS), modulus of elasticity (ME), depth of water penetration (WP), impact (IR) and abrasion resistance (AR) were investigated. The results showed that at an early age, the addition of fibers had no significant effects on the CS but at higher ages, the samples containing steel fibers had higher compressive TS and FS than the control ones. Also, the use of steel fibers increased the ME, IR and AR of CFCSF specimens. Moreover, models developed to correlate the mechanical properties of mixtures with AR and IR. The comparison between the relation of AR and IR to other mechanical properties, made of the linear regression and polynomial relationships in aspects of R2, indicated that stronger relations were available between TS with IR and AR with ME.","PeriodicalId":43959,"journal":{"name":"Civil Engineering Infrastructures Journal-CEIJ","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2021-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44224742","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-07-12DOI: 10.22059/CEIJ.2020.300273.1663
Ghasem Gorji Bandpey, G. Abdollahzadeh, A. Rahmani
Over the previous years, the use of structure roof systems which can be implemented with long column spans has been welcomed by manufacturers. One of the most widely used roofs is the waffle slab system. Therefore, by reviewing previous studies in the field of roof collapse in reinforced concrete structures under blast, the absence of studies on the performance of waffle slab and comparing its behavior with blast affected RC slabs is observed. Laboratory simulation of this problem requires high cost, high accuracy in model building and much time. In this study, after preliminary model validation with experimental research and two numerical studies in LS-DYNA software, the behavior of waffle slab subjected to blast load and compare its performance with RC slab is investigated. It should be noted that because the blast load is applied to the structure in a very short time, it has a high loading rate. Therefore, the strain rate effects on concrete and reinforcement are considered for achieving real material behavior. The identical volume of concrete and reinforcement used in all roofs is considered in order to evaluate and compare the behavior of the roofs reasonably. Then, the effect of the geometric dimension of waffle molds and the effect of the supporting condition on the Waffle slab responses are studied. Other parameter investigated in this study includes the effect of concrete compressive strength on the behavior of roof under blast load. The mass of the explosive and its distance from the roof surface are other parameters considered in this study. The effect of bar size on the behavior of the roof is also investigated. The results of this study are presented as diagrams and tables showing that given the same volume of concrete and reinforcement in the RC slab and the waffle slab, the central displacement of Waffle slab are reduced to a desirable level. This shows the better behavior of the waffle slab in comparison with the RC slab with the same volume of material under the blast load.
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