Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 55 11 2024 01 21 Investigation of Viscous Damper Effect on the Behavior of Thin Steel Plate Shear Walls Investigation of Viscous Damper Effect on the Behavior of Thin Steel Plate Shear Walls 2151 2178 5270 10.22060/ceej.2023.21113.7624 FA Mohammad Jahanara MSc in Structural Engineering, Faculty of Civil Engineering of Semnan University M. Gholhaki 0000-0002-9904-8623 Journal Article 2022 02 17 Steel plate shear wall systems have attracted researchers' attention as lateral force-resisting systems, owing to their high stiffness, capacity, considerable ductility, and energy dissipation. On the other hand, retrofitting and repairing these systems is uneconomical for low and medium seismic levels. Therefore, to limit damage, a new steel plate shear wall system equipped with viscous dampers has been proposed as a system capable of resisting lateral loads. In this paper, the behavior and performance of a composite thin steel plate shear wall system with viscous dampers is investigated numerically using OpenSees software. Structures are analyzed and designed in two cases: one with steel plate shear walls alone and one with steel plate shear walls coupled with viscous dampers. Their seismic performance and collapse assessment are studied. Furthermore, the interaction between the steel shear wall and the viscous damper is examined. Results show that with the increasing number of stories and the dominance of flexural mode over the structure, the interfering deformations of the wall and damper produce interaction between the steel plate shear wall and the viscous damper bracing frame. Collapse assessment results demonstrate that utilizing viscous dampers along with the steel plate shear wall system in 8, 16, and 24-story structures leads to the significant increase in collapse margin ratio by 100%, 92%, and 66% respectively. It also reduces annual collapse probability by 75%, 79% and 58% respectively, which indicates the influence of the viscous damper and underscores the importance of using this component. Steel plate shear wall systems have attracted researchers' attention as lateral force-resisting systems, owing to their high stiffness, capacity, considerable ductility, and energy dissipation. On the other hand, retrofitting and repairing these systems is uneconomical for low and medium seismic levels. Therefore, to limit damage, a new steel plate shear wall system equipped with viscous dampers has been proposed as a system capable of resisting lateral loads. In this paper, the behavior and performance of a composite thin steel plate shear wall system with viscous dampers is investigated numerically using OpenSees software. Structures are analyzed and designed in two cases: one with steel plate shear walls alone and one with steel plate shear walls coupled with viscous dampers. Their seismic performance and collapse assessment are studied. Furthermore, the interaction between the steel shear wall and the viscous damper is examined. Results show that with the increasing number of stories and the dominance of flexural mode over the structure, the interfering deformations of the wall and damper produce interaction between the steel plate shear wall and the viscous damper bracing frame. Collapse assessment results demonstrate that utilizing viscous dampers along with the steel plate shear wall system in 8, 16, and 24-story structures leads to the significant increase in collapse margin ratio by 100%, 92%, and 66% respectively. It also reduces annual collapse probability by 75%, 79% and 58% respectively, which indicates the influence of the viscous damper and underscores the importance of using this component.

https://ceej.aut.ac.ir/article_5270_c4bbac870026694953a91cbd99149a13.pdf

Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 55 11 2024 01 21 The effect of calcium presence in limepet for clayey soil stabilization using the geopolymer method The effect of calcium presence in limepet for clayey soil stabilization using the geopolymer method 2179 2194 5263 10.22060/ceej.2023.21117.7627 FA Negin Bahrami Department of Civil Engineering, Mashhad Branch, Islamic Azad University, Mashhad, Iran DANIAL MOAZAMI Department of Civil Engineering, Mashhad Branch, Islamic Azad University, Mashhad, Iran Shahram Pourakbar Department of Civil Engineering,,Faculty of Engineering , Binaloud University Journal Article 2022 02 18 In geotechnical engineering, clay is known as problematic soil, including low compressive strength, low bearing capacity, and high swelling potential. Chemical stabilization of soil with different additives is one of the possible methods for soil improvement. Portland cement is commonly used for the soil stabilization process. Climate change and global warming a life-threatening challenges, and governments have enacted laws restricting carbon dioxide emissions. Therefore, the use of environmentally friendly additives, cheap and available in the soil stabilization process is essential. In this regard, in recent years, geopolymerization processes have been introduced as the most serious alternatives to cement. In geotechnical engineering, clay is known as problematic soil, including low compressive strength, low bearing capacity, and high swelling potential. Chemical stabilization of soil with different additives is one of the possible methods for soil improvement. Portland cement is commonly used for the soil stabilization process. Climate change and global warming a life-threatening challenges, and governments have enacted laws restricting carbon dioxide emissions. Therefore, the use of environmentally friendly additives, cheap and available in the soil stabilization process is essential. In this regard, in recent years, geopolymerization processes have been introduced as the most serious alternatives to cement.

https://ceej.aut.ac.ir/article_5263_cc638784cf213986ec75983a4aa08cdb.pdf

Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 55 11 2024 01 21 Determining the Spectral Ratio of the Vertical and Horizontal Components of Near-Field Earthquakes Determining the Spectral Ratio of the Vertical and Horizontal Components of Near-Field Earthquakes 2195 2206 5298 10.22060/ceej.2023.21204.7650 FA Milad Mohammadian Department of Civil, Water and Environmental Engineering, Faculty of Engineering, University of Shahid Beheshti, Tehran, Iran Abbas Mahdavian Department of Civil, Water and Environmental Engineering, Faculty of Engineering, University of Shahid Beheshti, Tehran, Iran Nemat Hassani Department of Civil, Water and Environmental Engineering, Faculty of Engineering, University of Shahid Beheshti, Tehran, Iran Journal Article 2022 03 10 Based on studies conducted in recent decades, it has been determined that the characteristics of earthquakes in the near-field zone are different from those of earthquakes far from faults[1], Among these differences, we can mention the effect of the vertical component of the earthquake. Earthquakes near faults have unique features that neglecting them can increase the damages and human and environmental disasters caused by these types of earthquakes, and their effects on the environment and existing structures can be several times greater. Most of these damages occur in the short distance from the epicenter, especially in the horizontal components of long-span bridges, structures, and buildings.The effects of the vertical component of the earthquake in the past were considered negligible, so in past researches and the old versions of some regulations, the effect of the vertical component of the earthquake was ignored or it was considered as a coefficient (two-thirds) of the horizontal component. Therefore, one of the simple methods to determine the design spectrum of the vertical earthquake component is to use empirical relationships such as the V/H spectral ratio (vertical to horizontal component). Based on studies conducted in recent decades, it has been determined that the characteristics of earthquakes in the near-field zone are different from those of earthquakes far from faults[1], Among these differences, we can mention the effect of the vertical component of the earthquake. Earthquakes near faults have unique features that neglecting them can increase the damages and human and environmental disasters caused by these types of earthquakes, and their effects on the environment and existing structures can be several times greater. Most of these damages occur in the short distance from the epicenter, especially in the horizontal components of long-span bridges, structures, and buildings.The effects of the vertical component of the earthquake in the past were considered negligible, so in past researches and the old versions of some regulations, the effect of the vertical component of the earthquake was ignored or it was considered as a coefficient (two-thirds) of the horizontal component. Therefore, one of the simple methods to determine the design spectrum of the vertical earthquake component is to use empirical relationships such as the V/H spectral ratio (vertical to horizontal component).

https://ceej.aut.ac.ir/article_5298_70821a40b06f8751781d5a895357da67.pdf

Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 55 11 2024 01 21 Coupled DEM-SPH Modeling of Saturated Sand Coupled DEM-SPH Modeling of Saturated Sand 2207 2226 5299 10.22060/ceej.2023.21590.7772 FA Younes Khalili Department of Civil and Environmental Engineering, Shahid Beheshti University, Tehran, Iran Ahmad Mahboubi Department of Civil and Environmental Engineering, Shahid Beheshti University, Tehran, Iran 0000-0002-7468-5140 Mohammad Haji-Sotoiudeh Department of Civil and Environmental Engineering, Shahid Beheshti University, Tehran, Iran Journal Article 2022 07 13 DEM (Discrete Element Method) is a particle-based method for modeling the granular materials. SPH (Smoothed Particle Hydrodynamics) is also a particle-based method to analyze fluids using a limited number of integration points. These mesh-free methods are suitable to analyze geotechnical problems with large deformations or complicated geometries. Coupling DEM and SPH for simulating multi-phase media, resolves the need for the spatial mesh and prepares a more realistic understanding of the saturated granular materials. In this study by coupling both DEM and SPH methods, a novel DEM-SPH model was developed to simulate saturated granular media such as saturated sand. The particles were modeled using DEM and the inter-particle fluid was simulated using SPH. The fluid flow and the particle-fluid interactions were included in the model. The model was validated by comparing the numerical results to experimental data. The evolution of the fluid pressure distribution was investigated. Three phases were observed in fluid pressure distribution. After starting loading, a pressure wave appeared adjacent to the top wall that formed a “transient phase”. After finishing the transient phase, a “stable phase” of the fluid pressure distribution started, during which the pressure gradient changed gradually. There was an “instable phase” at large axial stains. The pressure gradient changed randomly in this phase. The results showed that the model could satisfactorily predict the undrained behavior of the saturated granular materials and capture the local parameters of the inter-particle fluid e.g. the local variations of the fluid pressure. DEM (Discrete Element Method) is a particle-based method for modeling the granular materials. SPH (Smoothed Particle Hydrodynamics) is also a particle-based method to analyze fluids using a limited number of integration points. These mesh-free methods are suitable to analyze geotechnical problems with large deformations or complicated geometries. Coupling DEM and SPH for simulating multi-phase media, resolves the need for the spatial mesh and prepares a more realistic understanding of the saturated granular materials. In this study by coupling both DEM and SPH methods, a novel DEM-SPH model was developed to simulate saturated granular media such as saturated sand. The particles were modeled using DEM and the inter-particle fluid was simulated using SPH. The fluid flow and the particle-fluid interactions were included in the model. The model was validated by comparing the numerical results to experimental data. The evolution of the fluid pressure distribution was investigated. Three phases were observed in fluid pressure distribution. After starting loading, a pressure wave appeared adjacent to the top wall that formed a “transient phase”. After finishing the transient phase, a “stable phase” of the fluid pressure distribution started, during which the pressure gradient changed gradually. There was an “instable phase” at large axial stains. The pressure gradient changed randomly in this phase. The results showed that the model could satisfactorily predict the undrained behavior of the saturated granular materials and capture the local parameters of the inter-particle fluid e.g. the local variations of the fluid pressure.

https://ceej.aut.ac.ir/article_5299_56a3107cad6611c8337ee36d178ca129.pdf

Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 55 11 2024 01 21 Presenting a Model for Integrated Crisis Management in Smart Cities from the Viewpoint of Passive Defense Based on AHP and ANFIS Presenting a Model for Integrated Crisis Management in Smart Cities from the Viewpoint of Passive Defense Based on AHP and ANFIS 2227 2242 5300 10.22060/ceej.2023.21679.7793 FA Seyed Azim Hosseini Associate Professor, Department of Civil Engineering, South Tehran Branch, Islamic Azad University, Tehran, Iran. 0000-0002-3691-0204 Hossein Maleki Toulabi Ph. D. Student, Department of Civil Engineering, South Tehran Branch, Islamic Azad University, Tehran, Iran. 0000-0002-6815-9005 Journal Article 2022 08 11 Currently, the ever-increasing population growth coupled with the people’s tendency toward urbanization, especially in developing countries, has led to a number of environmental, economic, social, and security problems, to a point where continuation of the current trends is likely to prevent sustainable urban development. On the other hand, passive defense has gained lots of attention in many countries in the recent past. This is where the concept of smart cities emerges as an ideal solution for tackling the challenges of urbanization. In this research, we began by identifying the most significant factors of integrated crisis management in smart cities with a focus on passive defense, with the importance of each factor further evaluated. The results were then analyzed. In this work, data gathering was performed through a descriptive-analytic method based on library studies. The required qualitative data was collected by library studies by completing a checklist. Subsequently, numerical analyses were conducted using opinions from experts in the passive defense and smart cities studies. Afterward, an analytic hierarchical process (AHP) was utilized to appraise and rank different factors. Next, an adaptive neuro-fuzzy inference system (ANFIS) was coded in MATLAB R2021b, which ended up presenting an integrated model of crisis management in smart cities from the viewpoint of passive defense. Based on the AHP and ANFIS, our findings highlighted the importance of securing the Internet of things (IoT), securing the environment, securing the network, network acceptance control, developing visualization software at the level of operating system (container), suppressing the threats and modification, and the analysis and action-taking when it came to the integrated crisis management in smart cities from the viewpoint of passive defense. Considering the importance of building smart cities, it can be stipulated that comprehensive attention to integrated crisis management in smart cities considering the principles of passive defense can boost urban protection, security, and sustainable development. Therefore, we considered all important factors separately to come up with a final model. The presented model exhibited a final compatibility ratio of 0.059, which is pretty acceptable. Moreover, the trained ANFIS ended up with an RMSE of 0.0179 coupled with an R2 value of 0.9897, indicating the high accuracy of the proposed model. Currently, the ever-increasing population growth coupled with the people’s tendency toward urbanization, especially in developing countries, has led to a number of environmental, economic, social, and security problems, to a point where continuation of the current trends is likely to prevent sustainable urban development. On the other hand, passive defense has gained lots of attention in many countries in the recent past. This is where the concept of smart cities emerges as an ideal solution for tackling the challenges of urbanization. In this research, we began by identifying the most significant factors of integrated crisis management in smart cities with a focus on passive defense, with the importance of each factor further evaluated. The results were then analyzed. In this work, data gathering was performed through a descriptive-analytic method based on library studies. The required qualitative data was collected by library studies by completing a checklist. Subsequently, numerical analyses were conducted using opinions from experts in the passive defense and smart cities studies. Afterward, an analytic hierarchical process (AHP) was utilized to appraise and rank different factors. Next, an adaptive neuro-fuzzy inference system (ANFIS) was coded in MATLAB R2021b, which ended up presenting an integrated model of crisis management in smart cities from the viewpoint of passive defense. Based on the AHP and ANFIS, our findings highlighted the importance of securing the Internet of things (IoT), securing the environment, securing the network, network acceptance control, developing visualization software at the level of operating system (container), suppressing the threats and modification, and the analysis and action-taking when it came to the integrated crisis management in smart cities from the viewpoint of passive defense. Considering the importance of building smart cities, it can be stipulated that comprehensive attention to integrated crisis management in smart cities considering the principles of passive defense can boost urban protection, security, and sustainable development. Therefore, we considered all important factors separately to come up with a final model. The presented model exhibited a final compatibility ratio of 0.059, which is pretty acceptable. Moreover, the trained ANFIS ended up with an RMSE of 0.0179 coupled with an R2 value of 0.9897, indicating the high accuracy of the proposed model.

https://ceej.aut.ac.ir/article_5300_bd380c81db012b113b6ab112b847e52b.pdf

Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 55 11 2024 01 21 Durability of geopolymer mortars with suggested percentages of slag and kaolin containing polymer Durability of geopolymer mortars with suggested percentages of slag and kaolin containing polymer 2243 2262 5301 10.22060/ceej.2023.21710.7803 FA Seyed Hosein Ghasemzadeh Mosavinejad Faculty of Engineering, University of Guilan, Rasht, Iran 0000-0002-8023-7694 Arian Darvishalinezhad Faculty of Engineering, University of Guilan, Rasht, Iran 0000-0002-6215-7789 Journal Article 2022 08 21 Geopolymers as cement-free concrete have attracted the attention of researchers in recent years. In making this type of concrete, instead of cement, various materials such as micro silica, metakaolin, zeolite, etc., and chemical solutions are used to complete the geopolymerization process to form the binding adhesive substance. The present study examines the durability of geopolymeric mortars based on blast furnace slag (GGBFS) with different replacement percentages of kaolin in several molar amounts. The GGBFS was used as a substitute for cement, and sodium hydroxide solution with a concentration of 4 and 8 M and sodium silicate (glass water) were used as chemical solutions. For this purpose, kaolin ceramic powder was mixed with GGBFS at 50% and 75%, and a total of 12 mixing plans were made. Compressive strength, rapid chloride migration test (RCMT), electrical resistance, water absorption percentage, loss of compressive strength, and weight after exposure to sulfuric acid solution were studied. The results of kaolin powder and slag reduced the compressive strength, and the lowest value of 33% was observed in BSC50-4; Also, the results of the penetration of chlorine ions in concrete and the weight loss of mortar samples in sulfuric acid solution indicate that the use of kaolin powder and slag increases the durability of BSC50-8 concrete samples by 38% under the conditions of chloride attack caused by Permeability decreases. Geopolymers as cement-free concrete have attracted the attention of researchers in recent years. In making this type of concrete, instead of cement, various materials such as micro silica, metakaolin, zeolite, etc., and chemical solutions are used to complete the geopolymerization process to form the binding adhesive substance. The present study examines the durability of geopolymeric mortars based on blast furnace slag (GGBFS) with different replacement percentages of kaolin in several molar amounts. The GGBFS was used as a substitute for cement, and sodium hydroxide solution with a concentration of 4 and 8 M and sodium silicate (glass water) were used as chemical solutions. For this purpose, kaolin ceramic powder was mixed with GGBFS at 50% and 75%, and a total of 12 mixing plans were made. Compressive strength, rapid chloride migration test (RCMT), electrical resistance, water absorption percentage, loss of compressive strength, and weight after exposure to sulfuric acid solution were studied. The results of kaolin powder and slag reduced the compressive strength, and the lowest value of 33% was observed in BSC50-4; Also, the results of the penetration of chlorine ions in concrete and the weight loss of mortar samples in sulfuric acid solution indicate that the use of kaolin powder and slag increases the durability of BSC50-8 concrete samples by 38% under the conditions of chloride attack caused by Permeability decreases.

https://ceej.aut.ac.ir/article_5301_b27d5296bede63b1493a5d321d4e8092.pdf

Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 55 11 2024 01 21 Investigating the Freezing Strength and Durability of Lightweight Concrete With Different Weight Ratios of Nano Montmorillonite and Microsilica Investigating the Freezing Strength and Durability of Lightweight Concrete With Different Weight Ratios of Nano Montmorillonite and Microsilica 2263 2284 5285 10.22060/ceej.2023.21730.7809 FA Babak Mansoori Assistant Professor, Department of Civil Engineering, Firoozabad Branch, Meymand center, Islamic Azad University, Meymand, Iran 0009-0006-6635-8760 Hamed Yousefinezhad Department of Engineering, Shiraz Branch, Islamic Azad University, Shiraz, Iran Farhad Avaznejad Instructor, Department Of Architecture And Urban Planning, Technical And Vocational University (TVU), Tehran, Iran Amirhossein Bazaee Instructor, Department Of Civil Engineering, Technical And Vocational University (TVU), Tehran, Iran 0000-0001-5504-7103 Journal Article 2022 08 28 One of the effective ways to reduce the specific weight of concrete is to use mineral pumice instead of aggregate, which can reduce the specific weight of concrete. However, due to the high porosity of mineral pumice, the strength and durability of concrete decrease and increase its permeability. While some of the disadvantages of concrete can be specially corrected by using nanomaterials. Nano montmorillonite quickly swells and increases its volume by absorbing water. This property increases density in lightweight concrete. In this research, to make lightweight concrete from mineral pumice, and to increase its density, nano montmorillonite was used in different weight ratios of 0.5%, 1%, 1.5%, 2%, and 2.5% cement. Also, to increase the quality and reduce the cost of consumable materials, micro silica was used in the amount of 10% by weight of the grade of cement used in concrete. The conducted tests include compressive strength, tensile strength, water absorption in hardened concrete, durability against the freezing cycle, economic index, and examination of concrete microstructure. The results of this research showed that the use of 2.5% nano montmorillonite instead of cement along with 10% micro silica in lightweight concrete can increase the 90-day compressive strength by 65% compared to the control sample. But due to the high cost of preparing nanomaterials, the optimal amount of using nano montmorillonite in lightweight concrete was determined to be 1.5% maximum. Because adding amounts more than that has no noticeable effect on increasing the compressive and tensile strength of concrete and the failure of concrete mainly occurs in the light-grained area. One of the effective ways to reduce the specific weight of concrete is to use mineral pumice instead of aggregate, which can reduce the specific weight of concrete. However, due to the high porosity of mineral pumice, the strength and durability of concrete decrease and increase its permeability. While some of the disadvantages of concrete can be specially corrected by using nanomaterials. Nano montmorillonite quickly swells and increases its volume by absorbing water. This property increases density in lightweight concrete. In this research, to make lightweight concrete from mineral pumice, and to increase its density, nano montmorillonite was used in different weight ratios of 0.5%, 1%, 1.5%, 2%, and 2.5% cement. Also, to increase the quality and reduce the cost of consumable materials, micro silica was used in the amount of 10% by weight of the grade of cement used in concrete. The conducted tests include compressive strength, tensile strength, water absorption in hardened concrete, durability against the freezing cycle, economic index, and examination of concrete microstructure. The results of this research showed that the use of 2.5% nano montmorillonite instead of cement along with 10% micro silica in lightweight concrete can increase the 90-day compressive strength by 65% compared to the control sample. But due to the high cost of preparing nanomaterials, the optimal amount of using nano montmorillonite in lightweight concrete was determined to be 1.5% maximum. Because adding amounts more than that has no noticeable effect on increasing the compressive and tensile strength of concrete and the failure of concrete mainly occurs in the light-grained area.

https://ceej.aut.ac.ir/article_5285_151de84cca69258b17375e2f44239191.pdf

Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 55 11 2024 01 21 Numerical investigation of flow behavior over arced trapezoidal piano key weirs Numerical investigation of flow behavior over arced trapezoidal piano key weirs 2285 2310 5278 10.22060/ceej.2023.22005.7879 FA Adel Edalati Shahrood University of Technology Ramin Amini Shahrood university of Technology Journal Article 2022 12 11 Weir is one of the most common artificial hydraulic structures that are used to measure flow in canals, divert flow, store water, change the flow regime in canals, and control floods during rainfall. One of the most important advantages of piano key weirs compared to linear weirs is the improvement of flow transfer capacity by increasing the length of the crest and as a result, increasing the length of the water passage in a fixed width of the construction without increasing the upstream water load. The purpose of this research is to numerically model the flow and investigate the effect of simultaneous changes in the number of cycles and the angle of the weir on the flow coefficient by trying to keep the total length of the weir crest and other geometric parameters constant for all models. After the investigations, it was found that increasing the weir angle of the piano key at a fixed length for all models increases the discharge coefficient, while increasing the number of cycles at a fixed length for all models due to the reduction of the inlet key water tank area, increasing the contraction of the current streamlines and then intensifying the local submergence in the outlet key, the current permeability coefficient will decrease significantly. Among all the weirs modeled in this research, the ATPK135-2 is known as the best model and was able to increase the discharge coefficient by 47% compared to the linear state (without curvature). Weir is one of the most common artificial hydraulic structures that are used to measure flow in canals, divert flow, store water, change the flow regime in canals, and control floods during rainfall. One of the most important advantages of piano key weirs compared to linear weirs is the improvement of flow transfer capacity by increasing the length of the crest and as a result, increasing the length of the water passage in a fixed width of the construction without increasing the upstream water load. The purpose of this research is to numerically model the flow and investigate the effect of simultaneous changes in the number of cycles and the angle of the weir on the flow coefficient by trying to keep the total length of the weir crest and other geometric parameters constant for all models. After the investigations, it was found that increasing the weir angle of the piano key at a fixed length for all models increases the discharge coefficient, while increasing the number of cycles at a fixed length for all models due to the reduction of the inlet key water tank area, increasing the contraction of the current streamlines and then intensifying the local submergence in the outlet key, the current permeability coefficient will decrease significantly. Among all the weirs modeled in this research, the ATPK135-2 is known as the best model and was able to increase the discharge coefficient by 47% compared to the linear state (without curvature).

https://ceej.aut.ac.ir/article_5278_82f292a22966b857d968fb578ccbead9.pdf

Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 55 11 2024 01 21 Sulfate removal from water using TiO2 nanoparticles Sulfate removal from water using TiO2 nanoparticles 2311 2326 5260 10.22060/ceej.2023.22046.7888 FA Shahriar Mahdavi Malayer University Behnaz Taherinia Malayer University Amir Hossein Sayyahzadeh Malayer University Journal Article 2022 12 24 In this study, titanium dioxide nanoparticles were used for the removal of sulfate ions. The initial properties of the nanoparticles before and after sulfate adsorption were examined using instrumental techniques. The effects of parameters such as concentration, pH, time, and temperature on sulfate removal were measured, and the optimal conditions for each parameter were applied in the adsorption isotherm. The calculation of thermodynamic constants revealed a negative ΔG° (free energy of gypsum), indicating a spontaneous reaction that does not require energy input. The ΔH° (enthalpy) of the reaction was positive, suggesting an endothermic nature of the removal process, while the positive ΔS° (entropy) indicated an increase in disorder during the reaction. The Freundlich and Langmuir isotherm models were fitted to the experimental data under optimal conditions, with the Langmuir isotherm equation providing a better fit with an R2 value of 0.994. EDX analysis confirmed that the titanium dioxide nanoparticles primarily consisted of titanium and oxygen before sulfate adsorption, while sulfur was observed after adsorption, indicating surface adsorption of sulfate. Furthermore, the maximum adsorption capacity of titanium dioxide nanoparticles for sulfate was calculated as 10.24 mg/g based on the Langmuir equation. By comparing this adsorbent with others, it can be concluded that these nanoparticles are effective in sulfate removal from water. In this study, titanium dioxide nanoparticles were used for the removal of sulfate ions. The initial properties of the nanoparticles before and after sulfate adsorption were examined using instrumental techniques. The effects of parameters such as concentration, pH, time, and temperature on sulfate removal were measured, and the optimal conditions for each parameter were applied in the adsorption isotherm. The calculation of thermodynamic constants revealed a negative ΔG° (free energy of gypsum), indicating a spontaneous reaction that does not require energy input. The ΔH° (enthalpy) of the reaction was positive, suggesting an endothermic nature of the removal process, while the positive ΔS° (entropy) indicated an increase in disorder during the reaction. The Freundlich and Langmuir isotherm models were fitted to the experimental data under optimal conditions, with the Langmuir isotherm equation providing a better fit with an R2 value of 0.994. EDX analysis confirmed that the titanium dioxide nanoparticles primarily consisted of titanium and oxygen before sulfate adsorption, while sulfur was observed after adsorption, indicating surface adsorption of sulfate. Furthermore, the maximum adsorption capacity of titanium dioxide nanoparticles for sulfate was calculated as 10.24 mg/g based on the Langmuir equation. By comparing this adsorbent with others, it can be concluded that these nanoparticles are effective in sulfate removal from water.

https://ceej.aut.ac.ir/article_5260_6018df1842f7130f1b85a6f8e911b96b.pdf

Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 55 11 2024 01 21 Calibration of unsteady flow in Crump Weir Calibration of unsteady flow in Crump Weir 2327 2342 5279 10.22060/ceej.2023.22166.7918 FA Mohammadhosein Badiei Department of Civil Engineering, Isfahan (Khorasgan) Branch, Islamic Azad University, Isfahan, Iran Ali Khoshfetrat Department of Civil Engineering, Isfahan (Khorasgan) Branch, Islamic Azad University, Isfahan, Iran Mohsen Saadat Department of Civil Engineering, Najafabad Branch, Islamic Azad University, Najafabad, Iran Journal Article 2023 02 05 Crump weir is widely used to measure flow rate in open channels. In this study, flow rate calibration is experimentally investigated for an unsteady free flow. To consider the effect of flow rate on flow coefficient, increasing and decreasing flow rate regimes were considered. Experimental tests were performed in a laboratory flume equipped with real-time data acquisition and recording system. The behavior of the flow rate coefficient was investigated as a function of three dimensionless parameters containing weir height to the upstream water height ratio, the weir length to upstream water height ratio, and the weir width to upstream water height ratio. Results show that the flow rate coefficient is in reverse correspondence with all dimensionless parameters so that with an increase in each of these parameters, the flow rate coefficient decreases. Finally using genetic algorithm, the optimization of the flow rate coefficient was performed. It was shown that the calibrated flow rate coefficient lies between 0.4 and 0.7. Crump weir is widely used to measure flow rate in open channels. In this study, flow rate calibration is experimentally investigated for an unsteady free flow. To consider the effect of flow rate on flow coefficient, increasing and decreasing flow rate regimes were considered. Experimental tests were performed in a laboratory flume equipped with real-time data acquisition and recording system. The behavior of the flow rate coefficient was investigated as a function of three dimensionless parameters containing weir height to the upstream water height ratio, the weir length to upstream water height ratio, and the weir width to upstream water height ratio. Results show that the flow rate coefficient is in reverse correspondence with all dimensionless parameters so that with an increase in each of these parameters, the flow rate coefficient decreases. Finally using genetic algorithm, the optimization of the flow rate coefficient was performed. It was shown that the calibrated flow rate coefficient lies between 0.4 and 0.7.

https://ceej.aut.ac.ir/article_5279_10cd8cca7d33d4526cf4c264654762c6.pdf