Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 53 10 2021 12 22 Compressive strength prediction of ordinary concrete, fly ash concrete, and slag concrete by novel techniques and presenting their optimal mixtures Compressive strength prediction of ordinary concrete, fly ash concrete, and slag concrete by novel techniques and presenting their optimal mixtures 4105 4124 4152 10.22060/ceej.2020.17649.6631 FA Mehrdad Ehsani Amirkabir University of Technology, Tehran, Iran Hamed Naseri Department of Civil and Environmental Engineering, Amirkabir University of Technology, Tehran, Iran. Ruhollah Saeedi Nezhad Amirkabir University of Technology, Tehran, Iran Mohammadali Etebari Ghasbeh Graduate student, Department of Civil Engineering, Iran University of Science and Technology Fereidoon Moghadas Nejad Dep. of Civil Engineering, Amirkabir University of Technology 0000-0003-3830-4555 Journal Article 2020 01 02 In this study, four concrete types, including ordinary Portland cement concrete, fly ash concrete, slag concrete, and slag-fly ash concrete, are taken into account in order to estimate their compressive strength by two novel machine learning methods (genetic algorithm and soccer league competition algorithm), and four types of regressions (linear, 2nd order polynomial, exponential, and logarithmic). Subsequently, the precision of prediction models is compared based on performance indicators, and the most accurate models are applied in the optimization problem modeling. Drawing on results, the most precise model to estimate the compressive strength of ordinary Portland cement concrete is the genetic algorithm, and the soccer league competition is the most accurate model to estimate the strength of other concrete types. Afterward, a model is developed so as to design mixture proportions of 40MPa concretes. Fly ash concrete, slag-fly ash concrete, and slag concrete reduce the unit cost by 35.2%, 29.9%, and 23.1%, respectively, compared with ordinary Portland cement concrete. Fly ash concrete, slag-fly ash concrete, slag concrete, and ordinary Portland cement concrete require 217.25 kg, 150.47 kg, 102 kg, and 414.64 kg cement to be manufactured. Furthermore, slag concrete can reduce the amount of cement in the mixture proportion by 75.4%, and it is the most eco-friendly concrete. In this study, four concrete types, including ordinary Portland cement concrete, fly ash concrete, slag concrete, and slag-fly ash concrete, are taken into account in order to estimate their compressive strength by two novel machine learning methods (genetic algorithm and soccer league competition algorithm), and four types of regressions (linear, 2nd order polynomial, exponential, and logarithmic). Subsequently, the precision of prediction models is compared based on performance indicators, and the most accurate models are applied in the optimization problem modeling. Drawing on results, the most precise model to estimate the compressive strength of ordinary Portland cement concrete is the genetic algorithm, and the soccer league competition is the most accurate model to estimate the strength of other concrete types. Afterward, a model is developed so as to design mixture proportions of 40MPa concretes. Fly ash concrete, slag-fly ash concrete, and slag concrete reduce the unit cost by 35.2%, 29.9%, and 23.1%, respectively, compared with ordinary Portland cement concrete. Fly ash concrete, slag-fly ash concrete, slag concrete, and ordinary Portland cement concrete require 217.25 kg, 150.47 kg, 102 kg, and 414.64 kg cement to be manufactured. Furthermore, slag concrete can reduce the amount of cement in the mixture proportion by 75.4%, and it is the most eco-friendly concrete.

https://ceej.aut.ac.ir/article_4152_26ff6f4ca1cfca4861eb91876f706746.pdf

Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 53 10 2021 12 22 Investigation of Flow Characteristics and Pressure Parameters of Free and Submerged Hydraulic Jumps in USBR Stilling Basins Investigation of Flow Characteristics and Pressure Parameters of Free and Submerged Hydraulic Jumps in USBR Stilling Basins 4125 4142 3893 10.22060/ceej.2020.17791.6676 FA Seyed Nasrollah Mousavi Hydraulic Lab Expert, Water engineering Department, Tabriz University, Iran 0000-0002-0750-0898 Farsadizadeh Davood Prof., Dept. of Water Eng., Faculty of Agric., Univ. of Tabriz, Iran 0000-0003-1181-8767 Farzin Salmasi Assoc. Prof., Dept. of Water Eng., Faculty of Agric., Univ. of Tabriz, Iran 0000-0002-1627-8598 Ali Hosseinzadeh Dalir Dept. of Water Eng., Faculty of Agric., Univ. of Tabriz, Iran 0000-0003-2359-3921 Journal Article 2020 01 25 In this study, flow characteristics and pressure parameters of hydraulic jumps have been investigated in a laboratory flume. The results for different incident Froude numbers (Fr1), at the downstream of an Ogee spillway on a typified USBR II stilling basin bed were compared with the USBR Type I basins. Dimensions of the Ogee spillway and stilling basin were designed according to the USBR criteria. The pressure data of the points on the basin bed were recorded using pressure transmitters with 20 Hz frequency. Experimental parameters, including flow depths and velocities at the beginning and endpoint of free jumps (Y1, Y2, V1 and V2), and submerged jumps (Y3, Yt, V3 and Vt) were measured. In the present study, dimensionless parameters of energy dissipation efficiency (εt), mean pressure head (Ψ*X), the standard deviation of pressure fluctuations (Φ*X), maximum positive pressure fluctuation coefficient (CP+), maximum negative pressure fluctuation coefficient (CP‒), total pressure fluctuation coefficient (CP) and skewness coefficient (Ad) were investigated. Pressure parameters are dependent on Fr1, the dimensionless position (Γ*X), and the submergence degree (S). The results showed that by reducing the Fr1 values, the εt parameter decreases. The Φ*Xmax value in the USBR Type II basin decreases around 30% compared to the Type I basins in free jumps. The reduction of Φ*Xmax values in the submerged jump with S=1.4 is about 29% than free jumps. The CP+max and |CP‒|max coefficients in the submerged jump with S=1.4 in comparison with free jumps decrease about 15 and 17%, respectively. In this study, flow characteristics and pressure parameters of hydraulic jumps have been investigated in a laboratory flume. The results for different incident Froude numbers (Fr1), at the downstream of an Ogee spillway on a typified USBR II stilling basin bed were compared with the USBR Type I basins. Dimensions of the Ogee spillway and stilling basin were designed according to the USBR criteria. The pressure data of the points on the basin bed were recorded using pressure transmitters with 20 Hz frequency. Experimental parameters, including flow depths and velocities at the beginning and endpoint of free jumps (Y1, Y2, V1 and V2), and submerged jumps (Y3, Yt, V3 and Vt) were measured. In the present study, dimensionless parameters of energy dissipation efficiency (εt), mean pressure head (Ψ*X), the standard deviation of pressure fluctuations (Φ*X), maximum positive pressure fluctuation coefficient (CP+), maximum negative pressure fluctuation coefficient (CP‒), total pressure fluctuation coefficient (CP) and skewness coefficient (Ad) were investigated. Pressure parameters are dependent on Fr1, the dimensionless position (Γ*X), and the submergence degree (S). The results showed that by reducing the Fr1 values, the εt parameter decreases. The Φ*Xmax value in the USBR Type II basin decreases around 30% compared to the Type I basins in free jumps. The reduction of Φ*Xmax values in the submerged jump with S=1.4 is about 29% than free jumps. The CP+max and |CP‒|max coefficients in the submerged jump with S=1.4 in comparison with free jumps decrease about 15 and 17%, respectively.

https://ceej.aut.ac.ir/article_3893_e8d66338fab3727e34a9179ed8804f64.pdf

Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 53 10 2021 12 22 Effects of higher modes and degrees of freedom on energy requirement in reinforced concrete structures with steel shear wall Effects of higher modes and degrees of freedom on energy requirement in reinforced concrete structures with steel shear wall 4143 4160 4076 10.22060/ceej.2020.18001.6734 FA Seyed Reza Salimbahrami Lecturer, Technical and Vocational University, College of Imam Muhammad Baqir (AS) Majid Gholhaki teacher 0000-0002-9904-8623 Journal Article 2020 02 26 It is necessary to provide seismic design criteria for structural systems in order to optimally design bending reinforced concrete frames with steel shear wall. Researchers have used energy requirements as one of the most important and efficient tools to measure and minimize cumulative damage to structures, which depend strongly on the time and duration of the earthquake. Therefore, this study attempts to investigate the energy response properties of an equivalent single degree of freedom versus near pulse species acceleration accelerometers to estimate the maximum energy types and its relation to a multi-degree of freedom for three reinforced concrete structures with steel shear walls, low-rise, mid-rise and high-rise under ductile coefficients of 1, 2, 3, 4 and 5. The results of the study of the changes in the ratio of cyclic energy to total energy wasted in the structures show that in the multi-degree system, the period is independent of the periodicity to the extent that the effect of higher modes is negligible. Also, by increasing the ductility coefficient, this ratio for the multi-degree system is closer to the results of the one-degree system and, in a sense, increasing the ductility coefficient results in a decrease in the effects of higher modes. It is necessary to provide seismic design criteria for structural systems in order to optimally design bending reinforced concrete frames with steel shear wall. Researchers have used energy requirements as one of the most important and efficient tools to measure and minimize cumulative damage to structures, which depend strongly on the time and duration of the earthquake. Therefore, this study attempts to investigate the energy response properties of an equivalent single degree of freedom versus near pulse species acceleration accelerometers to estimate the maximum energy types and its relation to a multi-degree of freedom for three reinforced concrete structures with steel shear walls, low-rise, mid-rise and high-rise under ductile coefficients of 1, 2, 3, 4 and 5. The results of the study of the changes in the ratio of cyclic energy to total energy wasted in the structures show that in the multi-degree system, the period is independent of the periodicity to the extent that the effect of higher modes is negligible. Also, by increasing the ductility coefficient, this ratio for the multi-degree system is closer to the results of the one-degree system and, in a sense, increasing the ductility coefficient results in a decrease in the effects of higher modes.

https://ceej.aut.ac.ir/article_4076_a3147b88259a8e5745ebd59394aee83e.pdf

Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 53 10 2021 12 22 Evaluating the Rheological and Mechanical Properties of Asphalt Mixtures Modified with Nano Copper Oxide Evaluating the Rheological and Mechanical Properties of Asphalt Mixtures Modified with Nano Copper Oxide 4161 4182 3940 10.22060/ceej.2020.18119.6773 FA Gholam Hossein Hamedi Department of Civil Engineering, Faculty of Engineering, University of Guilan, Rasht, Iran 0000-0003-4421-3721 Journal Article 2020 03 15 The performance of the asphalt mixture against damage is related to two main factors: external factors and internal factors. External factors are characteristics that are related to environmental factors such as weather conditions, drainage, and traffic. Internal factors are characteristics that are related to the asphalt mixing design, such as the properties and amount of aggregate, the properties and amount of bitumen, the properties of the filler, and the asphalt mixing mix design. Although bitumen has a small volume of asphalt mixture, its role in different temperatures on different failures of asphalt mixture is very important. The growth of the transportation network has led to a special need for the life cycle cost analysis and increase the lifespan of asphalt mixtures. There are several ways to improve the performance of asphalt mixtures, one of which is bitumen modification using modifiers. In recent years, with the invention and expansion of the production of nanomaterials, special attention has been paid to the use of nanomaterials to improve the rheological properties of bitumen. Accordingly, this study evaluates the effect of copper nano oxide on the rheological behavior of bitumen and the mechanical properties of the asphalt mixture. Therefore, the dynamic shear rheometer is used to determine the specifications of bitumens at medium and high temperatures, as well as fatigue and dynamic creep tests to investigate the performance of asphalt mixtures against fatigue cracking and rutting. The results of bitumen rheological experiments show that the use of copper nano oxide at 1 and 2 percent by weight of bitumen improves the rutting parameter in unaged and short-term aged bitumen from 49-343 and 57-257 percent, respectively, and also improves the fatigue parameter in long-term aged bitumen from 11-40 percent. The results of fatigue tests show that the fatigue life of samples containing 1 and 2 percent of this additive at 5 and 20 °C will improve by 9-16 percent and 6-31 percent, respectively. Also, the results of the rutting potential show that the use of 1 and 2 percent of nano oxide has reduced the permanent deformation change of 13-35 and 18-18 percent, respectively. The performance of the asphalt mixture against damage is related to two main factors: external factors and internal factors. External factors are characteristics that are related to environmental factors such as weather conditions, drainage, and traffic. Internal factors are characteristics that are related to the asphalt mixing design, such as the properties and amount of aggregate, the properties and amount of bitumen, the properties of the filler, and the asphalt mixing mix design. Although bitumen has a small volume of asphalt mixture, its role in different temperatures on different failures of asphalt mixture is very important. The growth of the transportation network has led to a special need for the life cycle cost analysis and increase the lifespan of asphalt mixtures. There are several ways to improve the performance of asphalt mixtures, one of which is bitumen modification using modifiers. In recent years, with the invention and expansion of the production of nanomaterials, special attention has been paid to the use of nanomaterials to improve the rheological properties of bitumen. Accordingly, this study evaluates the effect of copper nano oxide on the rheological behavior of bitumen and the mechanical properties of the asphalt mixture. Therefore, the dynamic shear rheometer is used to determine the specifications of bitumens at medium and high temperatures, as well as fatigue and dynamic creep tests to investigate the performance of asphalt mixtures against fatigue cracking and rutting. The results of bitumen rheological experiments show that the use of copper nano oxide at 1 and 2 percent by weight of bitumen improves the rutting parameter in unaged and short-term aged bitumen from 49-343 and 57-257 percent, respectively, and also improves the fatigue parameter in long-term aged bitumen from 11-40 percent. The results of fatigue tests show that the fatigue life of samples containing 1 and 2 percent of this additive at 5 and 20 °C will improve by 9-16 percent and 6-31 percent, respectively. Also, the results of the rutting potential show that the use of 1 and 2 percent of nano oxide has reduced the permanent deformation change of 13-35 and 18-18 percent, respectively.

https://ceej.aut.ac.ir/article_3940_3fa146219c48a4393aace23e8f353125.pdf

Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 53 10 2021 12 22 Experimental investigation of shear behavior of one-way reinforced slabs with high-performance fiber-reinforced cementitious composite laminates Experimental investigation of shear behavior of one-way reinforced slabs with high-performance fiber-reinforced cementitious composite laminates 4183 4204 4110 10.22060/ceej.2020.18138.6778 FA Mahdieh Sabbaghian Semnan University 0000-0003-4386-4565 Ali Kheyroddin semnan university 0000-0001-7802-2013 Journal Article 2020 03 19 It has been used to preserve structures and extend their useful life, retrofit damaged structures. Concrete slabs, as a key structural member, play an important role in the load distribution and structural behavior, and lack of resolving the damage to concrete slabs can lead to irreparable damage. In this experimental study, the one way reinforced concrete slabs were strengthened by using high-performance fiber-reinforced cementitious composite (HPFRCC) laminates in the slab's tensile side. Its lateral surfaces are then strengthened with carbon fiber reinforced polymer laminates to increase shear capacity. This study is summarized in three steps. In the first step, the mixing design and mechanical properties of fiber-reinforced cement composites were investigated. In the second step, the flexural capacity of fiber-reinforced cement composite laminates was determined separately before bonding to the slab. In the final step, shear and shear reinforced concrete slabs were tested for shear behavior investigation. The results showed that the strengthening of the lateral sides of the specimens was improved the flexural capacity, fracture pattern, stiffness, and energy absorption by examining the shear behavior of the specimens. Also, for one-way slabs strengthened with fiber-reinforced cement composite laminates, if the concentrated load is applied to the slab so that the shear Span-to-effective height ratio is less than 2.5, even If it is strengthened at the lateral surfaces to increase the shear capacity of the cross-section, the failure pattern will certainly be shear. It has been used to preserve structures and extend their useful life, retrofit damaged structures. Concrete slabs, as a key structural member, play an important role in the load distribution and structural behavior, and lack of resolving the damage to concrete slabs can lead to irreparable damage. In this experimental study, the one way reinforced concrete slabs were strengthened by using high-performance fiber-reinforced cementitious composite (HPFRCC) laminates in the slab's tensile side. Its lateral surfaces are then strengthened with carbon fiber reinforced polymer laminates to increase shear capacity. This study is summarized in three steps. In the first step, the mixing design and mechanical properties of fiber-reinforced cement composites were investigated. In the second step, the flexural capacity of fiber-reinforced cement composite laminates was determined separately before bonding to the slab. In the final step, shear and shear reinforced concrete slabs were tested for shear behavior investigation. The results showed that the strengthening of the lateral sides of the specimens was improved the flexural capacity, fracture pattern, stiffness, and energy absorption by examining the shear behavior of the specimens. Also, for one-way slabs strengthened with fiber-reinforced cement composite laminates, if the concentrated load is applied to the slab so that the shear Span-to-effective height ratio is less than 2.5, even If it is strengthened at the lateral surfaces to increase the shear capacity of the cross-section, the failure pattern will certainly be shear.

https://ceej.aut.ac.ir/article_4110_c42f891cebbc81aa59f8f183243ac2b9.pdf

Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 53 10 2021 12 22 Fusion of travel time data in Niayesh tunnel using Bayesian inference Fusion of travel time data in Niayesh tunnel using Bayesian inference 4205 4218 4061 10.22060/ceej.2020.18214.6803 FA Mahmoud Mesbah Department of Civil & Environmental Engineering, Amirkabir University of Technology, Tehran, Iran Mahan Mollajafari Department of Civil & Environmental Engineering, Amirkabir University of Technology, Tehran, Iran Amir Golroo Department of Civil & Environmental Engineering, Amirkabir University of Technology, Tehran, Iran 0000-0002-4222-9861 Zahra Pakdaman Department of Civil Engineering, the University of Science & Technology, Tehran, Iran Journal Article 2020 04 05 As data collection costs decrease, transportation systems have shifted from systems requiring data to systems requiring data analysis. Since the accuracy of these data varies with the sources of data collection, acquiring higher-accuracy data from a combination of multiple sources is the main challenge of working with such data. Data fusion is a very efficient mechanism that can interconnect data from different sources to increase the accuracy of data in line with the purpose of the study. The main goal of this article is to get the most accurate travel time possible from multiple sources. Among the data fusion methods are the Kalman filter, Bayesian inference, artificial neural networks and Dumpster-Scheffer theory, from which the Bayesian inference is used and its results are investigated. It is proposed that by combining different data sources with different temporal and spatial coverage, the most accurate travel time with maximum spatial and temporal coverage would be achieved. The Niayesh tunnel in Tehran was selected as a case study, where extensive equipment for intelligent transportation systems is installed. In this study, considering the possibility of simultaneous access to multiple data sources at the same location, the following source, Google travel time data, Bluetooth travel time data and Inductive loop detectors, were fused. The improved travel time can increase the accuracy of travel time costs in transportation planning, information on variable message signs and routing software. As data collection costs decrease, transportation systems have shifted from systems requiring data to systems requiring data analysis. Since the accuracy of these data varies with the sources of data collection, acquiring higher-accuracy data from a combination of multiple sources is the main challenge of working with such data. Data fusion is a very efficient mechanism that can interconnect data from different sources to increase the accuracy of data in line with the purpose of the study. The main goal of this article is to get the most accurate travel time possible from multiple sources. Among the data fusion methods are the Kalman filter, Bayesian inference, artificial neural networks and Dumpster-Scheffer theory, from which the Bayesian inference is used and its results are investigated. It is proposed that by combining different data sources with different temporal and spatial coverage, the most accurate travel time with maximum spatial and temporal coverage would be achieved. The Niayesh tunnel in Tehran was selected as a case study, where extensive equipment for intelligent transportation systems is installed. In this study, considering the possibility of simultaneous access to multiple data sources at the same location, the following source, Google travel time data, Bluetooth travel time data and Inductive loop detectors, were fused. The improved travel time can increase the accuracy of travel time costs in transportation planning, information on variable message signs and routing software.

https://ceej.aut.ac.ir/article_4061_f3a3a63a79eb1831b0a2776bfd20d838.pdf

Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 53 10 2021 12 22 Study of water flow drainage in sandy soil due to surface recharge conditions using a laboratory model Study of water flow drainage in sandy soil due to surface recharge conditions using a laboratory model 4219 4230 4059 10.22060/ceej.2020.18247.6808 FA Mansour Parvizi Assistant Professor, PhD in Geotechnical Engineering, Faculty of Engineering, Yasouj University, Yasouj, Iran. Masoud Rabeti Moghadam Assistant Professor, PhD in Geotechnical Engineering, Faculty of Engineering, Yasouj University, Yasouj, Iran. Jahanpour Monfared M.Sc in Geotechnical Engineering, Faculty of Engineering, Yasouj University, Yasouj, Iran Mohammad Sedghi-Asl Associate Professor, Department of Soil Science, Faculty of Agriculture, Yasouj University, Yasouj, Iran Journal Article 2020 04 10 In the present study, laboratory methods were used to investigate the drainage conditions of the steady-state with the surface recharging. In the study, fine and coarse sandy soil samples were used to study changes in groundwater level. The test specimen was poured into a large-scale flume, with 5.4 m long, which led to uniform vertical precipitation and vertical drains on both sides. The parameters of precipitation rate, soil gradation and water level within the drains were investigated as variables in this study. The results showed that the maximum change in water height in coarse sand due to increasing water height in drains from 0 to 40 cm is equal to 56.9 cm and 72.5 cm, respectively, which caused an increase of 15.6 cm. However, in fine sand, these changes are very small (2 cm) and equal to 87.2 cm in free drainage conditions and 89.2 cm in the conditions of 40 cm of water height inside the drains. The obtained laboratory results were compared with the Dupuit-Forchheimer analytical relationship. It was concluded that this relationship is able to accurately predict the level of water in the fine sand, but in coarse sand, the relationship underestimates the water table height in the soil. In the present study, laboratory methods were used to investigate the drainage conditions of the steady-state with the surface recharging. In the study, fine and coarse sandy soil samples were used to study changes in groundwater level. The test specimen was poured into a large-scale flume, with 5.4 m long, which led to uniform vertical precipitation and vertical drains on both sides. The parameters of precipitation rate, soil gradation and water level within the drains were investigated as variables in this study. The results showed that the maximum change in water height in coarse sand due to increasing water height in drains from 0 to 40 cm is equal to 56.9 cm and 72.5 cm, respectively, which caused an increase of 15.6 cm. However, in fine sand, these changes are very small (2 cm) and equal to 87.2 cm in free drainage conditions and 89.2 cm in the conditions of 40 cm of water height inside the drains. The obtained laboratory results were compared with the Dupuit-Forchheimer analytical relationship. It was concluded that this relationship is able to accurately predict the level of water in the fine sand, but in coarse sand, the relationship underestimates the water table height in the soil.

https://ceej.aut.ac.ir/article_4059_75806e8a1c04cad241934a374c1359c0.pdf

Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 53 10 2021 12 22 Experimental and Numerical Investigation on Discharge Coefficient Relationships sharp-crested U Shape Plan Form Weirs Experimental and Numerical Investigation on Discharge Coefficient Relationships sharp-crested U Shape Plan Form Weirs 4231 4252 4117 10.22060/ceej.2020.18289.6819 FA Firouz Mohammadi Management / Technical School of Ahar Boys Yousef Hassanzadeh Professor, Dept. of Water Eng., Center of Excellence in Hydroinformatics, Faculty of Civil Eng., Univ. of Tabriz, Tabriz, Iran 0000-0003-4272-4667 Kiyoumars Roushangar Professor, Dept. of Civil-Water Eng., Faculty of Civil Eng., Univ. of Tabriz, Tabriz, Iran Journal Article 2020 04 18 In this research, the relationships of the discharge coefficient of the sharp-crested U shape plan form labyrinth weirs (one cycle) have been investigated experimentally and numerically. Also, from 3 groups of weirs with heights of 10, 12.5, and 15 cm and at each height, the length of different arches to the values of 40.82, 45 and 48.10 cm have been tested. The main purpose of the present study is to determine the overflow discharge from the weir by providing relationships for the discharge coefficient experimentally. Dimensional analysis was used by 𝜋 Buckingham method to extract the relationship. Three-dimensional simulation of weirs was performed numerically with equations governing the finite volume method using FLOW-3D software, then compared with laboratory results. The results of the present study show that the proposed relationship can predict discharge values with very high accuracy and an error of 4.79% in the ratio of the head-to-height weir of 0.1 to 1.2. As the length of the weirs arch increases, the flow interference increases, and the discharge efficiency decreases. Although with increasing the length of the weirs, the length of the crest increases, the weirs efficiency decreases, the maximum throughput efficiency decreases in this case, it is at 7.01%. With constant arc length and increase in weirs height, it was observed that the throughput efficiency decreases significantly, which shows a maximum volume of flow through the weirs of 4.82%. In this research, the relationships of the discharge coefficient of the sharp-crested U shape plan form labyrinth weirs (one cycle) have been investigated experimentally and numerically. Also, from 3 groups of weirs with heights of 10, 12.5, and 15 cm and at each height, the length of different arches to the values of 40.82, 45 and 48.10 cm have been tested. The main purpose of the present study is to determine the overflow discharge from the weir by providing relationships for the discharge coefficient experimentally. Dimensional analysis was used by 𝜋 Buckingham method to extract the relationship. Three-dimensional simulation of weirs was performed numerically with equations governing the finite volume method using FLOW-3D software, then compared with laboratory results. The results of the present study show that the proposed relationship can predict discharge values with very high accuracy and an error of 4.79% in the ratio of the head-to-height weir of 0.1 to 1.2. As the length of the weirs arch increases, the flow interference increases, and the discharge efficiency decreases. Although with increasing the length of the weirs, the length of the crest increases, the weirs efficiency decreases, the maximum throughput efficiency decreases in this case, it is at 7.01%. With constant arc length and increase in weirs height, it was observed that the throughput efficiency decreases significantly, which shows a maximum volume of flow through the weirs of 4.82%.

https://ceej.aut.ac.ir/article_4117_c1aeb6517a1c7f33514f7ff69047e74e.pdf

Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 53 10 2021 12 22 Association between route walkability measures and children’s walking to school Association between route walkability measures and children’s walking to school 4253 4278 4006 10.22060/ceej.2020.18293.6821 FA Mehdi Barati Graduated Master of Science in Highway Engineering, Kharazmi University, Tehran, Iran Mohsen Fallah Zavareh Assistant professor, Dept. of Civil Engineering, Engineering Faculty, Kharazmi University, Tehran, Iran 0000-0001-6841-5876 Amir Reza Mamdoohi Department of Transportation Planning, Faculty of Civil Engineering and Environment, Tarbiat Modares University, Tehran, Iran 0000-0002-5339-9807 Journal Article 2020 04 19 Increasing active school trips is a strategy for children’s health. Although route features may associate with higher amounts of walking school trips, the majority of previous studies have focused on buffer-level characteristics of the built environment. Moreover, the role of children’s interests has not been widely examined in previous studies. The present study investigates the associations between the route-level features of the built environment, socio-economic, and cognitive characteristics on children’s walk to school. A total of 340 questionnaires were distributed among 7-12 year-old pupils across three primary schools in a neighbourhood in Tehran. For each route to school the environmental features were collected per Pedestrians First (PF) instrument, a tool for measuring walkability. Results reveal that number of motorcycles, and distance from home to school are negatively, and non-residential land use and proportion of favourable sidewalks are positively related to children’s walk to school. Parental worry about children’s walking to school is negatively associated with children’s walk to school. It is also found that children’s interest in walking is not significant. Results have important ramifications for planning the walk to school programs in the neighbourhood level. Furthermore, findings underscored the provision of multi-facet long-term policies such as land use changes and school location patterns across the neighbourhood, when preparing master and land use plans, to enhance walking school travels for health reasons. Increasing active school trips is a strategy for children’s health. Although route features may associate with higher amounts of walking school trips, the majority of previous studies have focused on buffer-level characteristics of the built environment. Moreover, the role of children’s interests has not been widely examined in previous studies. The present study investigates the associations between the route-level features of the built environment, socio-economic, and cognitive characteristics on children’s walk to school. A total of 340 questionnaires were distributed among 7-12 year-old pupils across three primary schools in a neighbourhood in Tehran. For each route to school the environmental features were collected per Pedestrians First (PF) instrument, a tool for measuring walkability. Results reveal that number of motorcycles, and distance from home to school are negatively, and non-residential land use and proportion of favourable sidewalks are positively related to children’s walk to school. Parental worry about children’s walking to school is negatively associated with children’s walk to school. It is also found that children’s interest in walking is not significant. Results have important ramifications for planning the walk to school programs in the neighbourhood level. Furthermore, findings underscored the provision of multi-facet long-term policies such as land use changes and school location patterns across the neighbourhood, when preparing master and land use plans, to enhance walking school travels for health reasons.

https://ceej.aut.ac.ir/article_4006_671d8d05d795091118b1344f715307c4.pdf

Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 53 10 2021 12 22 Calculating the cost of time loss in traffic accidents by different types of roads and vehicles(Case Study: Khorasan Razavi rural roads) Calculating the cost of time loss in traffic accidents by different types of roads and vehicles(Case Study: Khorasan Razavi rural roads) 4279 4290 4044 10.22060/ceej.2020.18308.6827 FA Aliasghar Sadeghi Department of civil engineering, Faculty engineering, Hakim Sabzevari university Morteza Jalili Qazizadeh Civil Engineering, Engineering Faculty, Quchan University of Technology Journal Article 2020 04 22 In cost-benefit analysis and prioritization of safety countermeasure, it is necessary to estimate the social costs of accidents. One of the crash costs is the cost of users' time loss due to delays caused by accidents. In most studies, this factor has been ignored or considered only as a general estimate and no specific method has been considered for it. In this research, an analytical method has been proposed to calculate the cost of the delay caused by accident and the factors affecting it have been investigated. Another objective of this paper is to investigate and compare the cost of time loss to road users in different types of accidents according to the type of vehicles and roads. In a case study, the total time loss of users in various accidents is calculated. The results show that accidents on freeways-highways and especially heavy vehicle accidents cause the most wasted time for users. Total time loss in each injury or fatal accident on the freeway-highway, major road and secondary road is 2039.65, 700.39 and 95.90, respectively. Also, it is found that the share of freeway-highway, major and secondary roads from the total time lost in rural accidents is 43.69, 54.92 and 1.39 percent, respectively. The average time lost in each rural accident is 869 people - hour and its cost in 2016 is equal to 27.3 million Rials, which is about 0.6% of the total cost of rural accidents. The results show that although the cost of time lost in accidents on low-traffic roads can be neglected, it is still significant on expressways and highways. In cost-benefit analysis and prioritization of safety countermeasure, it is necessary to estimate the social costs of accidents. One of the crash costs is the cost of users' time loss due to delays caused by accidents. In most studies, this factor has been ignored or considered only as a general estimate and no specific method has been considered for it. In this research, an analytical method has been proposed to calculate the cost of the delay caused by accident and the factors affecting it have been investigated. Another objective of this paper is to investigate and compare the cost of time loss to road users in different types of accidents according to the type of vehicles and roads. In a case study, the total time loss of users in various accidents is calculated. The results show that accidents on freeways-highways and especially heavy vehicle accidents cause the most wasted time for users. Total time loss in each injury or fatal accident on the freeway-highway, major road and secondary road is 2039.65, 700.39 and 95.90, respectively. Also, it is found that the share of freeway-highway, major and secondary roads from the total time lost in rural accidents is 43.69, 54.92 and 1.39 percent, respectively. The average time lost in each rural accident is 869 people - hour and its cost in 2016 is equal to 27.3 million Rials, which is about 0.6% of the total cost of rural accidents. The results show that although the cost of time lost in accidents on low-traffic roads can be neglected, it is still significant on expressways and highways.

https://ceej.aut.ac.ir/article_4044_df5354693177e83e8ba089e94b7b6b55.pdf

Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 53 10 2021 12 22 Investigation of foam volume on the penetration parameters of foamed concrete Investigation of foam volume on the penetration parameters of foamed concrete 4291 4304 4042 10.22060/ceej.2020.18311.6828 FA Alireza Bagheri ِDepartment of Civil Engineering K. N. Toosi university of Technology Tehran Iran 0000-0002-6045-0885 Mohammad Mahdi Rastegar Department of civil engineering K. N. Toosi university of technology Journal Article 2020 04 23 In this study performance of mixes with w/c ratio of 0.5 and foam contents of 20, 35 and 50%, with regards to absorption, capillary absorption and chloride ingress, were determined and compared to those of a base mix with the same proportions but without foam incorporation. A structural grade foam concrete with w/c ratio of 0.4 and foam content of 20% was also considered together with a conventional concrete of equal strength level. The results show that foam incorporation results in decreased absorption and capillary absorption and increased chloride diffusion. The discrepancy is due to the presentation of absorption results on a total concrete volume basis. By considering these results on paste volume basis, which is the penetrable phase, absorption results show the same trend as the chloride diffusion results. Incorporation of 20, 35 and 50 percent foam into the base mix resulted in increases of 12, 27 and 50 percent in paste absorption and 18, 55 and 155 percent in chloride diffusion values, respectively. Increased foam volume resulted in larger and more connected air voids. Although foamed porosity has a negative effect on penetration characteristics, the structural grade foam concrete with its lower w/c ratio achieved similar levels of performance as the base mix and performed better than the conventional concrete of equal strength level. In this study performance of mixes with w/c ratio of 0.5 and foam contents of 20, 35 and 50%, with regards to absorption, capillary absorption and chloride ingress, were determined and compared to those of a base mix with the same proportions but without foam incorporation. A structural grade foam concrete with w/c ratio of 0.4 and foam content of 20% was also considered together with a conventional concrete of equal strength level. The results show that foam incorporation results in decreased absorption and capillary absorption and increased chloride diffusion. The discrepancy is due to the presentation of absorption results on a total concrete volume basis. By considering these results on paste volume basis, which is the penetrable phase, absorption results show the same trend as the chloride diffusion results. Incorporation of 20, 35 and 50 percent foam into the base mix resulted in increases of 12, 27 and 50 percent in paste absorption and 18, 55 and 155 percent in chloride diffusion values, respectively. Increased foam volume resulted in larger and more connected air voids. Although foamed porosity has a negative effect on penetration characteristics, the structural grade foam concrete with its lower w/c ratio achieved similar levels of performance as the base mix and performed better than the conventional concrete of equal strength level.

https://ceej.aut.ac.ir/article_4042_d3f5d4de09ea19461dab00590df91e4f.pdf

Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 53 10 2021 12 22 Experimental investigation and statistical analysis on structural design and impact strengths of fiber geopolymer mortar Experimental investigation and statistical analysis on structural design and impact strengths of fiber geopolymer mortar 4305 4324 4031 10.22060/ceej.2020.18317.6831 FA Mohammad Hossein Dalvand Faculty of Civil Engineering, Semnan University, Semnan, Iran 0000-0001-9459-4847 Mohammad Kazem Sharbatdar Semnan University 0000-0001-6106-1235 Ahmad Dalvand Lorestan University Journal Article 2020 04 24 Due to the high consumption of mortar and concrete, especially in structures and the increasing demand for cement production, considering the environmental degradation effects of this substance, it seems necessary. One of the solutions is to produce environmentally friendly materials and reduce the damaging effects of Portland cement production, Such as slag geopolymer mortar and concrete. The purpose of this paper is to experimentally investigate the statistical approach of the mechanical and resistive properties of cement mortar and geopolymer fibers mortar. Four mix designs, including three geopolymer mix designs with 0, 0.5, and 1% steel micro-fibers and a conventional mortar mix design, were considered. A total of 320 specimens were made, each consisting of 20 cubic specimens, 20 cylindrical specimens, 20 small beam specimens, and 20 small disc specimens. The results indicated that by increasing the percentage of steel microfibers up to 1% in geopolymer samples, the compressive strength, tensile strength and modulus of rupture increased by 6.39, 60.86, and 63.40%, respectively. The number of destruction resistance blows was also about 25 times higher. In all compressive, tensile, flexural, and impact strengths tests, the non-fiber geopolymer specimens had better behavior than conventional cement mortar specimens. In all geopolymer specimens with increasing fiber percentage, standard deviation and coefficient of variation increased as a result of data dispersion. Due to the high consumption of mortar and concrete, especially in structures and the increasing demand for cement production, considering the environmental degradation effects of this substance, it seems necessary. One of the solutions is to produce environmentally friendly materials and reduce the damaging effects of Portland cement production, Such as slag geopolymer mortar and concrete. The purpose of this paper is to experimentally investigate the statistical approach of the mechanical and resistive properties of cement mortar and geopolymer fibers mortar. Four mix designs, including three geopolymer mix designs with 0, 0.5, and 1% steel micro-fibers and a conventional mortar mix design, were considered. A total of 320 specimens were made, each consisting of 20 cubic specimens, 20 cylindrical specimens, 20 small beam specimens, and 20 small disc specimens. The results indicated that by increasing the percentage of steel microfibers up to 1% in geopolymer samples, the compressive strength, tensile strength and modulus of rupture increased by 6.39, 60.86, and 63.40%, respectively. The number of destruction resistance blows was also about 25 times higher. In all compressive, tensile, flexural, and impact strengths tests, the non-fiber geopolymer specimens had better behavior than conventional cement mortar specimens. In all geopolymer specimens with increasing fiber percentage, standard deviation and coefficient of variation increased as a result of data dispersion.

https://ceej.aut.ac.ir/article_4031_3be0214185d6177a9aa6adea5a720b09.pdf

Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 53 10 2021 12 22 Discrete Element Method Simulation of Dynamic Behavior of Granular Materials Discrete Element Method Simulation of Dynamic Behavior of Granular Materials 4325 4344 4058 10.22060/ceej.2020.18320.6833 FA Nazanin Mahbubi Motlagh Faculty of Civil, Water and Environmental Eng. Shahid Beheshti University Tehran, Iran Ali Noorzad Faculty of Civil, Water and Environmental Eng. Shahid Beheshti University Journal Article 2020 04 29 The granular soil has a complex macroscopic response under seismic loading. Due to the many uses of the results of cyclic triaxial tests, the numerical modeling of these tests is needed to facilitate the prediction of soil behavior and reducing the cost of laboratory tests. The aim of the present research is to evaluate the ability of the discrete element method to investigate the dynamic behavior of sand by simulating a number of drained stress-controlled cyclic triaxial tests under three-dimensional conditions. In addition, the effect of parameters such as the number of loading cycles, soil relative density, cyclic stress ratio, particle shape and loading paths on the dynamic properties of soil (shear modulus and damping ratio) is also considered. The results indicate that numerical simulation by the discrete element method can accurately represent the variations of soil dynamic properties with the considered variables. The comparison of experimental results from the literature and numerical models carried out in this study shows that the rate of decreasing in shear modulus and increasing in damping ratio of the samples with non-spherical particles with shear strain is higher in the given cyclic stress ratio and porosity. The cyclic stress ratio does not significantly affect the shear modulus, damping ratio and the coordinate number of samples. The coordinate number of the sample with spherical and non-spherical particles (e=0.3) is obtained 7.7 and 6.4, respectively, at the end of the simulation test. In the same condition, the samples with non - spherical particles have undergone more deformations. The granular soil has a complex macroscopic response under seismic loading. Due to the many uses of the results of cyclic triaxial tests, the numerical modeling of these tests is needed to facilitate the prediction of soil behavior and reducing the cost of laboratory tests. The aim of the present research is to evaluate the ability of the discrete element method to investigate the dynamic behavior of sand by simulating a number of drained stress-controlled cyclic triaxial tests under three-dimensional conditions. In addition, the effect of parameters such as the number of loading cycles, soil relative density, cyclic stress ratio, particle shape and loading paths on the dynamic properties of soil (shear modulus and damping ratio) is also considered. The results indicate that numerical simulation by the discrete element method can accurately represent the variations of soil dynamic properties with the considered variables. The comparison of experimental results from the literature and numerical models carried out in this study shows that the rate of decreasing in shear modulus and increasing in damping ratio of the samples with non-spherical particles with shear strain is higher in the given cyclic stress ratio and porosity. The cyclic stress ratio does not significantly affect the shear modulus, damping ratio and the coordinate number of samples. The coordinate number of the sample with spherical and non-spherical particles (e=0.3) is obtained 7.7 and 6.4, respectively, at the end of the simulation test. In the same condition, the samples with non - spherical particles have undergone more deformations.

https://ceej.aut.ac.ir/article_4058_8133415ea4647b6345849fb38311cf32.pdf

Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 53 10 2021 12 22 Comparison of carbonate and quartz sand shear strength parameters with triaxial and simple shear tests Comparison of carbonate and quartz sand shear strength parameters with triaxial and simple shear tests 4345 4358 4231 10.22060/ceej.2021.18313.6834 FA Kourosh Zargar Department of Civil engineering Imam Khomeini International University,Qazvin, Iran. Alireza Ardakani Department of civil engineering, Imam Khomeini International University, Qazvin, Iran. Journal Article 2020 04 25 Carbonate sediments are among the problematic soils in geotechnical engineering. These soils are different from quartz soils both in terms of production origin and engineering behavior. In this paper, for comparison of shear strength parameters, Bandar Abbas carbonate sand and Firoozkooh quartz sand were studied by common triaxial and simple shear tests. Experiments were performed under the same conditions of grain size, relative density and stress level. Parameters such as physical properties, shear behavior, stress path, modulus of elasticity, shear modulus, internal friction angle and dilation angle were compared. The results showed that Bandar Abbas carbonate sand had higher shear strength than quartz sand. The maximum internal friction angle of carbonate sand was higher than quartz sand due to its intrinsic interlocking in both triaxial and shear tests. The dilation angle decreases with increasing stress level for both experiments. Also, the internal friction angle obtained from the triaxial test was higher than the simple shear test for about 10 to 15% due to different stresses paths and the presence of a pre-shear in the simple shear test. Also, the presence of shear stress in simple shear tests reduces more the internal friction angle versus stress level compared to the triaxial test. Carbonate sediments are among the problematic soils in geotechnical engineering. These soils are different from quartz soils both in terms of production origin and engineering behavior. In this paper, for comparison of shear strength parameters, Bandar Abbas carbonate sand and Firoozkooh quartz sand were studied by common triaxial and simple shear tests. Experiments were performed under the same conditions of grain size, relative density and stress level. Parameters such as physical properties, shear behavior, stress path, modulus of elasticity, shear modulus, internal friction angle and dilation angle were compared. The results showed that Bandar Abbas carbonate sand had higher shear strength than quartz sand. The maximum internal friction angle of carbonate sand was higher than quartz sand due to its intrinsic interlocking in both triaxial and shear tests. The dilation angle decreases with increasing stress level for both experiments. Also, the internal friction angle obtained from the triaxial test was higher than the simple shear test for about 10 to 15% due to different stresses paths and the presence of a pre-shear in the simple shear test. Also, the presence of shear stress in simple shear tests reduces more the internal friction angle versus stress level compared to the triaxial test.

https://ceej.aut.ac.ir/article_4231_dd1016d687d5960a8f279198a94d0cc5.pdf

Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 53 10 2021 12 22 Feasibility Study on Utilizing Self-centering Structural System for Typical Highway Bridges in Iran Feasibility Study on Utilizing Self-centering Structural System for Typical Highway Bridges in Iran 4359 4378 4009 10.22060/ceej.2020.18323.6835 FA Akbar Vasseghi International Institute of Earthquake Engineering and Seismology, Tehran, Iran Babak Mansouri International Institute of Earthquake Engineering and Seismology, Tehran, Iran Sadaf Rointan International Institute of Earthquake Engineering and Seismology, Tehran, Iran Journal Article 2020 04 26 Recently, in developed countries, a variety of self-centering structural systems have been developed using precast concrete bends and the Accelerated Bridge Construction (ABC) method to reduce construction time, increase safety, reduce seismic damage, reduce repair and reconstruction costs, and increase seismic resiliency. In this system, bridge bents are constructed by precast elements tied together with post-tensioned tendons such that under the effect of lateral seismic forces, they are able to rock and self-center back to their original configuration. The use of this system greatly reduces the residual displacements and the seismic damage. Also, due to the use of prefabricated elements, the construction speed of the bridge is significantly increased. This paper compares the seismic performance of one type of self-centering structural system with the conventional structural system for three typical highway bridges constructed in Iran. An analytical model for simulating nonlinear behavior due to the rocking motion in the self-centering system is first developed and verified by comparing the analytical response with the experimental results. Then, the concrete bends of the three typical bridges in Iran are modeled and analyzed once as a conventional system and once as a self-centering system, and the seismic performance of these two systems is compared with each other. The results of this study indicate that despite the modest increase in maximum lateral drifts, the residual drifts are substantially reduced when the conventional system is replaced by the self-centering system. Recently, in developed countries, a variety of self-centering structural systems have been developed using precast concrete bends and the Accelerated Bridge Construction (ABC) method to reduce construction time, increase safety, reduce seismic damage, reduce repair and reconstruction costs, and increase seismic resiliency. In this system, bridge bents are constructed by precast elements tied together with post-tensioned tendons such that under the effect of lateral seismic forces, they are able to rock and self-center back to their original configuration. The use of this system greatly reduces the residual displacements and the seismic damage. Also, due to the use of prefabricated elements, the construction speed of the bridge is significantly increased. This paper compares the seismic performance of one type of self-centering structural system with the conventional structural system for three typical highway bridges constructed in Iran. An analytical model for simulating nonlinear behavior due to the rocking motion in the self-centering system is first developed and verified by comparing the analytical response with the experimental results. Then, the concrete bends of the three typical bridges in Iran are modeled and analyzed once as a conventional system and once as a self-centering system, and the seismic performance of these two systems is compared with each other. The results of this study indicate that despite the modest increase in maximum lateral drifts, the residual drifts are substantially reduced when the conventional system is replaced by the self-centering system.

https://ceej.aut.ac.ir/article_4009_cb5f984421c93f1efb42b53a43f83c3a.pdf

Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 53 10 2021 12 22 Assessing the compressive strength and permeability of protective coating layers applied to CFRP sheets, under harsh environmental conditions Assessing the compressive strength and permeability of protective coating layers applied to CFRP sheets, under harsh environmental conditions 4379 4396 4056 10.22060/ceej.2020.18324.6836 FA Mahmood Naderi Department of civil engineering, Faculty of engineering, International Imam Khomeini university, Qazvin, Iran Roza Rahbari Department of Civil Engineering, Engineering Faculty, International Imam Khomeini University, Qazvin, Iran Journal Article 2020 04 26 In this paper, the results of the effect of exposure of CFRP strengthened and coated 150mm concrete cubes to harsh environments are presented. The harsh environment included: wet-dry, freeze-thaw and different temperature change cycles. It is anticipated that the intended environmental conditions harm the performance of the CFRP sheet by reducing the compressive strength of concrete and, at the same time, increase its permeability. The test specimens used in this investigation included 150mm CFRP strengthened concrete cubes with and without protective coating layers. The methods employed were "Cylindrical Chamber" permeability, mortar capillary water absorption and mortar compressive strength tests. The results obtained tend to indicate that the proper selection of protective coating has a significant impact on the performance of the CFRP-coated concrete cubes that were under harsh environmental conditions. Application of suitable coatings onto the CFRP layer caused respective reductions of about 28%, 34%, and 36%, on the permeability of specimens after being exposed to specified wet-dry, freeze-thaw and temperature change cycles. In this paper, the results of the effect of exposure of CFRP strengthened and coated 150mm concrete cubes to harsh environments are presented. The harsh environment included: wet-dry, freeze-thaw and different temperature change cycles. It is anticipated that the intended environmental conditions harm the performance of the CFRP sheet by reducing the compressive strength of concrete and, at the same time, increase its permeability. The test specimens used in this investigation included 150mm CFRP strengthened concrete cubes with and without protective coating layers. The methods employed were "Cylindrical Chamber" permeability, mortar capillary water absorption and mortar compressive strength tests. The results obtained tend to indicate that the proper selection of protective coating has a significant impact on the performance of the CFRP-coated concrete cubes that were under harsh environmental conditions. Application of suitable coatings onto the CFRP layer caused respective reductions of about 28%, 34%, and 36%, on the permeability of specimens after being exposed to specified wet-dry, freeze-thaw and temperature change cycles.

https://ceej.aut.ac.ir/article_4056_9529fbba677729d3206b3b9073d1e9ca.pdf

Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 53 10 2021 12 22 Optimal water utilization policy with sustainable aquifer approach with simulation and decentralized optimization Optimal water utilization policy with sustainable aquifer approach with simulation and decentralized optimization 4397 4412 4105 10.22060/ceej.2020.18345.6841 FA Atena Khajeem Moghadam Department of Civil Engineering, Islamic Azad University Arak Branch, Arak, Iran Bahram Saghafian Professor of Water Resources Engineering, Science and Research Branch, Islamic Azad University. Tehran, Iran. 0000-0003-2846-2840 Mohsen Najarchi Department of Civil Engineering, Arak Branch, Islamic Azad University, Arak, Iran Majid Delavar Department of Water Resources Engineering, Tarbiat Modares University, Tehran, Iran. Journal Article 2020 05 02 Nowadays, providing optimum solutions to water resources exploitation problems has become one of the major concerns of decision-makers. In this study, a multi-objective model was developed for coupled surface and groundwater resources allocation, considering different interactive scenarios between stakeholders and the ecosystem. The general algorithm for water resources allocation was based on an optimization model coupled with the environmental-agricultural model. The optimization approach reduced the irrigation water allocation to 78%. While the 7% reduction was allocated to meet the aquifer and agricultural demands of the study area, the cultivation cost was raised by only ~1.3%. Nowadays, providing optimum solutions to water resources exploitation problems has become one of the major concerns of decision-makers. In this study, a multi-objective model was developed for coupled surface and groundwater resources allocation, considering different interactive scenarios between stakeholders and the ecosystem. The general algorithm for water resources allocation was based on an optimization model coupled with the environmental-agricultural model. The optimization approach reduced the irrigation water allocation to 78%. While the 7% reduction was allocated to meet the aquifer and agricultural demands of the study area, the cultivation cost was raised by only ~1.3%.

https://ceej.aut.ac.ir/article_4105_77143919d1234297079f075357988f3b.pdf

Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 53 10 2021 12 22 Study on the effect of reclaimed asphalt pavement and rejuvenator on fracture behavior of WMA Study on the effect of reclaimed asphalt pavement and rejuvenator on fracture behavior of WMA 4413 4432 4030 10.22060/ceej.2020.18351.6842 FA Sadjad Pirmohammad Faculty member of mechanical engineering, university of Mohaghegh Ardabili, Ardabil, Iran Saeid Sobhi Babol Noshirvani University of Technology 0000-0001-6254-4829 Afshar Yusefi iust 0000-0002-1840-1887 Journal Article 2020 05 02 Recycling or, in other words, reuse of pavement is one of the latest technologies in the field of road construction that is now more accepted than other pavement construction methods. In addition to better environmental protection, this technology results in significant cost savings. Still, one of the major concerns of its use is the creation of undesirable properties in asphalt mix, such as bitumen aging and reduced cracking resistance. The use of rejuvenation agent and WMA (warm mix asphalt) additive are the solutions to improve the performance of asphalt mixers containing RAP (reclaimed asphalt pavement) materials. Hence, in this research, in order to evaluate the effect of using RAP on the fracture resistance of WMA mixtures, the RAP materials with two dosages of 25% and 50%, one type of rejuvenation agent and Sasobit, as a WMA additive, were employed. To study the fracture resistance of the mixtures at the temperatures of -15 °C and 25 °C under mode I loading, semi-circular bending test was selected, and different fracture parameters including critical fracture load, fracture energy, flexibility index, cracking resistance index and fracture toughness were calculated. The results exhibited that the addition of RAP material to the mixture had a negative effect on the fracture parameters at different temperatures and resulted in the reduction of these parameters. While the mixtures containing rejuvenator showed more elastic behavior than those without rejuvenator. Therefore, the use of a rejuvenator led to the improvement of the fracture parameters. Recycling or, in other words, reuse of pavement is one of the latest technologies in the field of road construction that is now more accepted than other pavement construction methods. In addition to better environmental protection, this technology results in significant cost savings. Still, one of the major concerns of its use is the creation of undesirable properties in asphalt mix, such as bitumen aging and reduced cracking resistance. The use of rejuvenation agent and WMA (warm mix asphalt) additive are the solutions to improve the performance of asphalt mixers containing RAP (reclaimed asphalt pavement) materials. Hence, in this research, in order to evaluate the effect of using RAP on the fracture resistance of WMA mixtures, the RAP materials with two dosages of 25% and 50%, one type of rejuvenation agent and Sasobit, as a WMA additive, were employed. To study the fracture resistance of the mixtures at the temperatures of -15 °C and 25 °C under mode I loading, semi-circular bending test was selected, and different fracture parameters including critical fracture load, fracture energy, flexibility index, cracking resistance index and fracture toughness were calculated. The results exhibited that the addition of RAP material to the mixture had a negative effect on the fracture parameters at different temperatures and resulted in the reduction of these parameters. While the mixtures containing rejuvenator showed more elastic behavior than those without rejuvenator. Therefore, the use of a rejuvenator led to the improvement of the fracture parameters.

https://ceej.aut.ac.ir/article_4030_084a8a9aa8cced9175bd07bc44998e75.pdf

Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 53 10 2021 12 22 Seismic Assessment of Reinforced Concrete Skewed Bridges under Near-Fault Ground Motions with Considering Soil-Structure Interaction- Case Study of Jack Tone Road On-Ramp Overcrossing Located in California Seismic Assessment of Reinforced Concrete Skewed Bridges under Near-Fault Ground Motions with Considering Soil-Structure Interaction- Case Study of Jack Tone Road On-Ramp Overcrossing Located in California 4433 4458 4064 10.22060/ceej.2020.18336.6845 FA Hanieh Soltani Department of Civil Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran Fereshteh Emami Department of Civil Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran 0000-0002-5410-7992 Pasha Javadi Department of Civil Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran Journal Article 2020 05 10 Seismic behavior of skewed bridges, the backbone of modern transportation networks, has not been well studied compared to their ordinary straight counterparts. Investigating past earthquakes, it can be evident that such bridges have experienced intensive damages specially due to girder unseating under the torsional effects of seismic responses coupling in longitudinal and transverse directions, which will be aggravated by local crushing of deck concrete due to pounding between the abutments and adjacent spans. Additionally, bridges are usually supported on Cast-In-Drilled-Hole extended pile-shafts. The inelastic behavior of the superstructure during an earthquake is profoundly dependant on soil strength due to the effect of surrounding soil properties on substructure stiffness. So, the main purpose of the present research is to evaluate the seismic responses of R.C skewed overcrossing to variations in some structural parameters by applying analytical models capturing backfill-abutment and soil-pile nonlinearities under near-fault ground motions with high-velocity pulses, especially in their strike-normal component, comparing the results with fixed-base model and finally obtain the most efficient ground motion intensity measure. A set of nonlinear time history analyses was conducted using seven pulse-like ground motions containing horizontal and vertical components on a two-span skewed bridge. Then, the effects of abutment skew angle, base condition modeling approach and soil strength on the revision of various demands were assessed and compared for both flexible- and rigid-base conditions. Furthermore, various analyses were carried out with respect to possible changes in soil properties ranging from soft to stiff for clayey and loose to dense for sandy soils besides the skew angle variations. It was observed that most of the demands, despite the changes in soil strength, were sensitive to an increase in abutment skew angle as a factor of structural stiffness and will often increase incrementally with that, but deck rotation was significantly affected by these variations. Considering foundation flexibility by a set of nonlinear springs can refine structural responses in most cases, particularly by applying Direct Method, based on precise modeling of structural components besides a vast region of encompassed soil around, which will impose an improving effect on various demands relative to the fixed-base condition. Seismic behavior of skewed bridges, the backbone of modern transportation networks, has not been well studied compared to their ordinary straight counterparts. Investigating past earthquakes, it can be evident that such bridges have experienced intensive damages specially due to girder unseating under the torsional effects of seismic responses coupling in longitudinal and transverse directions, which will be aggravated by local crushing of deck concrete due to pounding between the abutments and adjacent spans. Additionally, bridges are usually supported on Cast-In-Drilled-Hole extended pile-shafts. The inelastic behavior of the superstructure during an earthquake is profoundly dependant on soil strength due to the effect of surrounding soil properties on substructure stiffness. So, the main purpose of the present research is to evaluate the seismic responses of R.C skewed overcrossing to variations in some structural parameters by applying analytical models capturing backfill-abutment and soil-pile nonlinearities under near-fault ground motions with high-velocity pulses, especially in their strike-normal component, comparing the results with fixed-base model and finally obtain the most efficient ground motion intensity measure. A set of nonlinear time history analyses was conducted using seven pulse-like ground motions containing horizontal and vertical components on a two-span skewed bridge. Then, the effects of abutment skew angle, base condition modeling approach and soil strength on the revision of various demands were assessed and compared for both flexible- and rigid-base conditions. Furthermore, various analyses were carried out with respect to possible changes in soil properties ranging from soft to stiff for clayey and loose to dense for sandy soils besides the skew angle variations. It was observed that most of the demands, despite the changes in soil strength, were sensitive to an increase in abutment skew angle as a factor of structural stiffness and will often increase incrementally with that, but deck rotation was significantly affected by these variations. Considering foundation flexibility by a set of nonlinear springs can refine structural responses in most cases, particularly by applying Direct Method, based on precise modeling of structural components besides a vast region of encompassed soil around, which will impose an improving effect on various demands relative to the fixed-base condition.

https://ceej.aut.ac.ir/article_4064_8430b32b5bac908e765df8813d4405c5.pdf

Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 53 10 2021 12 22 Application of Lime and Nano Lime in Control of Failure in Side Slope of Earth Channel Application of Lime and Nano Lime in Control of Failure in Side Slope of Earth Channel 4459 4472 4277 10.22060/ceej.2021.18360.6848 FA Saeid Najjarzadeh Master's graduate, Water engineering department, Shahrood University of Technology Roozbeh Moazenzadeh Assistant professor, Water engineering department, Shahrood University of Technology Sayyedhossein Hosseini Assistant professor, Water engineering department, Shahrood University of Technology Khalil Azhdary Associate professor, Water engineering department, Shahrood University of Technology Journal Article 2020 05 04 The instability of earth slopes in open channels has always been considered by hydraulic engineering. In the present study, the application of lime and nano lime in control of failure in the side slope of the earth channel has been investigated experimentally. Results showed lining of 20% lime and 5% nano lime increased the angle of internal friction 31.8% and 35.5%, respectively and cohesion reached a value of 3.3 kPa. In feeding, for slopes of 26.5, 33, 45 and 53-degree failure occurred in water levels of 560 mm, 460 mm, 460 mm and 410 mm, respectively. For the seepage situation, the slope of 26.5 degree was stable and slopes of 33 and 45 became instable in a water level of 510 mm. Slopes of 45 degree with 10% lime and 53 degree with 20% lime were stable in the maximum level of 660 mm. Potential variation behind the slope showed curve procedure with lime percent. The lining of the side slop with lime and nano lime decreased seepage discharge in the same water level. Also, the application of lime and nano lime changed the shape of the failure zone and using nano lime decreased cracks in size. In feeding, without and with lime lining, curved failure surface and crack were observed on the slope. The instability of earth slopes in open channels has always been considered by hydraulic engineering. In the present study, the application of lime and nano lime in control of failure in the side slope of the earth channel has been investigated experimentally. Results showed lining of 20% lime and 5% nano lime increased the angle of internal friction 31.8% and 35.5%, respectively and cohesion reached a value of 3.3 kPa. In feeding, for slopes of 26.5, 33, 45 and 53-degree failure occurred in water levels of 560 mm, 460 mm, 460 mm and 410 mm, respectively. For the seepage situation, the slope of 26.5 degree was stable and slopes of 33 and 45 became instable in a water level of 510 mm. Slopes of 45 degree with 10% lime and 53 degree with 20% lime were stable in the maximum level of 660 mm. Potential variation behind the slope showed curve procedure with lime percent. The lining of the side slop with lime and nano lime decreased seepage discharge in the same water level. Also, the application of lime and nano lime changed the shape of the failure zone and using nano lime decreased cracks in size. In feeding, without and with lime lining, curved failure surface and crack were observed on the slope.

https://ceej.aut.ac.ir/article_4277_18a010d2a9813e91907ce88cd9143fdf.pdf

Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 53 10 2021 12 22 Experimental Investigation of Nappe Flow Domain on Stepped Spillways Experimental Investigation of Nappe Flow Domain on Stepped Spillways 4473 4488 4232 10.22060/ceej.2021.18376.6856 FA Abdollah Ghasempour Feremi Research Expert / water research ins Institute Shervin Faghihirad Hydro-Environment Department, Water Research Institute Mohammad Reza Kavianpour Faculty of Civil Engineering, K. N. Toosi University of Technology 0000-0003-3546-6663 Journal Article 2020 05 06 Stepped spillways are used to discharge the floods flow entering the reservoirs. Along these spillways, the energy is highly dissipated. It consists of a series of arranged steps along the spillway to ensure a uniform flow depth and velocity. Stepped spillways improve the rate of longitudinal energy dissipation on the spillway. The energy dissipation affects the flow characteristics and the energy dissipaters at downstream. The flow over stepped spillways is divided into three regimes of nappe, transition and skimming flows. So far, limited numbers of studies have been performed on the basis of analytical and empirical information to check the features and complicated nature of nappe flows. Limitations on physical model studies are also important to mention. As a result, few relationships have been suggested to describe nappe flow characteristics over stepped spillways. In this study, a set of experiments were performed on three large-scales hydraulic spillway models of Siahbisheh upper and lower dams and Zhaveh spillway dam. The data cover six spillway slopes and 24 flow rates. Measurements of depth, velocity, and static pressure were made at 40 different cross sections along the chutes. Major effective geometrical and hydraulic parameters on energy dissipation in nappe flow regime over stepped spillways were analyzed, based on present measurements. A relationship was then suggested to calculate the rate of energy dissipation in nappe flow regime. This study showed that the ratio of critical depth to height of spillway is the most important dimensionless parameter in predicting energy dissipation, the increase of which reduces the relative energy dissipation in the nappe flow regime. Stepped spillways are used to discharge the floods flow entering the reservoirs. Along these spillways, the energy is highly dissipated. It consists of a series of arranged steps along the spillway to ensure a uniform flow depth and velocity. Stepped spillways improve the rate of longitudinal energy dissipation on the spillway. The energy dissipation affects the flow characteristics and the energy dissipaters at downstream. The flow over stepped spillways is divided into three regimes of nappe, transition and skimming flows. So far, limited numbers of studies have been performed on the basis of analytical and empirical information to check the features and complicated nature of nappe flows. Limitations on physical model studies are also important to mention. As a result, few relationships have been suggested to describe nappe flow characteristics over stepped spillways. In this study, a set of experiments were performed on three large-scales hydraulic spillway models of Siahbisheh upper and lower dams and Zhaveh spillway dam. The data cover six spillway slopes and 24 flow rates. Measurements of depth, velocity, and static pressure were made at 40 different cross sections along the chutes. Major effective geometrical and hydraulic parameters on energy dissipation in nappe flow regime over stepped spillways were analyzed, based on present measurements. A relationship was then suggested to calculate the rate of energy dissipation in nappe flow regime. This study showed that the ratio of critical depth to height of spillway is the most important dimensionless parameter in predicting energy dissipation, the increase of which reduces the relative energy dissipation in the nappe flow regime.

https://ceej.aut.ac.ir/article_4232_3b24156ad560a696116454056bc88ab4.pdf

Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 53 10 2021 12 22 Investigation of major heavy metal concentration in urban runoff (case study: North and east catchment of Tehran city) Investigation of major heavy metal concentration in urban runoff (case study: North and east catchment of Tehran city) 4489 4504 4039 10.22060/ceej.2020.18384.6859 FA Ali Ghadiri Shahid Beheshti University Seyed Hossein Hashemi Department of Environmental Technology, Environmental Sciences Institute, Shahid Beheshti University, Tehran, Iran 0000-0002-5351-3630 Touraj Nasrabadi Faculty of Environment, University of Tehran, Tehran, Iran Journal Article 2020 05 07 Urban runoff, as one of the most important emission sources of heavy metal to the environment, has potential environmental and health risks. This study aimed to evaluate the content of ten heavy metals in the runoff of the Sorkheh Hesar catchment, Tehran. For this purpose, Runoff samples were taken from the outlet of Sorkheh Hesar catchment during three flood events in 2018-19 and the total concentration of heavy metals was determined by ICP-MS. Fe, Mn, Zn, Pb, Cu, Cr, Ni, As, Mo and Cd had the highest abundance in all samples, respectively. The results of Spearman's rank correlation coefficient showed a strong correlation (0.71-0.98) between most metals, especially Fe, Mn, Zn, Pb, Ni, Cd and Cu, which indicating the same input sources and similar geochemical behavior. Also, the mean values of Contamination Index, Heavy Metal Evaluation Index and Heavy Metal Pollution Index were 24.7, 30.1 and 130.2, respectively, which indicated most of the samples were in contaminated and high contaminated levels due to high concentrations of three elements including Fe, Mn and Pb in compare to the standard permissible values. Urban runoff, as one of the most important emission sources of heavy metal to the environment, has potential environmental and health risks. This study aimed to evaluate the content of ten heavy metals in the runoff of the Sorkheh Hesar catchment, Tehran. For this purpose, Runoff samples were taken from the outlet of Sorkheh Hesar catchment during three flood events in 2018-19 and the total concentration of heavy metals was determined by ICP-MS. Fe, Mn, Zn, Pb, Cu, Cr, Ni, As, Mo and Cd had the highest abundance in all samples, respectively. The results of Spearman's rank correlation coefficient showed a strong correlation (0.71-0.98) between most metals, especially Fe, Mn, Zn, Pb, Ni, Cd and Cu, which indicating the same input sources and similar geochemical behavior. Also, the mean values of Contamination Index, Heavy Metal Evaluation Index and Heavy Metal Pollution Index were 24.7, 30.1 and 130.2, respectively, which indicated most of the samples were in contaminated and high contaminated levels due to high concentrations of three elements including Fe, Mn and Pb in compare to the standard permissible values.

https://ceej.aut.ac.ir/article_4039_1cd73be1e256a7405516501e94e892ac.pdf

Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 53 10 2021 12 22 Experimental investigation of using reclaimed asphalt pavement aggregate in scrap tire encased stone column Experimental investigation of using reclaimed asphalt pavement aggregate in scrap tire encased stone column 4505 4518 4109 10.22060/ceej.2020.18232.6860 FA Hoora Bikdeli Qom university of technilogy Baitollah Badarloo Qom university of technology Ali Golabchifard Islamic Azad university of Technology Journal Article 2020 05 07 The stone column is one of the cost-effective techniques for improving soft soil layers. Since in the construction process of stone column, weak soil is replaced with the stiffer material, appropriate method to bury the waste materials, e.g. reclaimed asphalt pavement (RAP) and scrap tires, is to use as stone column materials. The aim of this study is the application of scrap tires for enclosing stone columns and RAP mixed with gravel for the stone column to provide an environmental friendly and cost-effective improvement method for weak layers. In order to investigate the behavior of such stone columns, experimental modeling of the unit cell consisting of a single stone column with reclaimed asphalt pavement as filler material and encasing it by scrap tires has been carried out. RAP contents of 0%, 25%, 50%, 75% and 100% are selected to investigate effects of different mixing ratios. Loading capacity tests were performed on encased and non-encased stone column specimens. Results of loading capacity tests show that the encasing of stone columns with scrap tires improves the loading capacity significantly. On the other hand, by increasing the RAP ratio from 0% to 100%, the stone column loading capacity changes. However, no significant change in the bearing capacity has not been observed and therefore, the use of a stone column made of 100% or any percentage of RAP is reasonable. The stone column is one of the cost-effective techniques for improving soft soil layers. Since in the construction process of stone column, weak soil is replaced with the stiffer material, appropriate method to bury the waste materials, e.g. reclaimed asphalt pavement (RAP) and scrap tires, is to use as stone column materials. The aim of this study is the application of scrap tires for enclosing stone columns and RAP mixed with gravel for the stone column to provide an environmental friendly and cost-effective improvement method for weak layers. In order to investigate the behavior of such stone columns, experimental modeling of the unit cell consisting of a single stone column with reclaimed asphalt pavement as filler material and encasing it by scrap tires has been carried out. RAP contents of 0%, 25%, 50%, 75% and 100% are selected to investigate effects of different mixing ratios. Loading capacity tests were performed on encased and non-encased stone column specimens. Results of loading capacity tests show that the encasing of stone columns with scrap tires improves the loading capacity significantly. On the other hand, by increasing the RAP ratio from 0% to 100%, the stone column loading capacity changes. However, no significant change in the bearing capacity has not been observed and therefore, the use of a stone column made of 100% or any percentage of RAP is reasonable.

https://ceej.aut.ac.ir/article_4109_6f67057b6a3671fe882f6d4f27d547be.pdf

Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 53 10 2021 12 22 Punching shear behavior of flat slabs composed of normal concrete and ECC under the unbalanced moment Punching shear behavior of flat slabs composed of normal concrete and ECC under the unbalanced moment 4519 4534 4126 10.22060/ceej.2020.18378.6865 FA Mohammad Amiri Civil, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran Journal Article 2020 05 10 Load capacity and ductility are the two main characteristics of flat slab-column connections in highly seismic areas. To date, different methods have been employed to strengthen the connection against shear punching, including column capital, drop panel, high strength concrete, and shear reinforcement. In the current experimental study, the effect of using Engineered Cementitious Composite (ECC) on upgrading the punching shear strength of flat slabs under an unbalanced moment was investigated. ECC can provide the composite with features such as the ability to spread multiple cracks under load, strain hardening, shear force, scabbing strength, and high deformation. To this end, seven reinforced concrete flat slab specimens with the dimensions of 1000mm*1000mm*100 mm under the load with the eccentricity of 150mm were examined. The slabs were made from two layers of normal concrete and ECC in their thicknesses. The variable parameters included the unbalanced moment effect, improved interaction of the two materials, and ECC thickness. It was observed that improving the contact surface of normal concrete and ECC increased the shear capacity. In addition, the replacement of slab concrete with ECC increases the punching capacity and post-punching strength of the slab without a large and sudden drop in load. The change in failure mechanism was observed from a sudden and abrupt failure to a formable failure with high-energy absorption when using more ECC layer thicknesses. Load capacity and ductility are the two main characteristics of flat slab-column connections in highly seismic areas. To date, different methods have been employed to strengthen the connection against shear punching, including column capital, drop panel, high strength concrete, and shear reinforcement. In the current experimental study, the effect of using Engineered Cementitious Composite (ECC) on upgrading the punching shear strength of flat slabs under an unbalanced moment was investigated. ECC can provide the composite with features such as the ability to spread multiple cracks under load, strain hardening, shear force, scabbing strength, and high deformation. To this end, seven reinforced concrete flat slab specimens with the dimensions of 1000mm*1000mm*100 mm under the load with the eccentricity of 150mm were examined. The slabs were made from two layers of normal concrete and ECC in their thicknesses. The variable parameters included the unbalanced moment effect, improved interaction of the two materials, and ECC thickness. It was observed that improving the contact surface of normal concrete and ECC increased the shear capacity. In addition, the replacement of slab concrete with ECC increases the punching capacity and post-punching strength of the slab without a large and sudden drop in load. The change in failure mechanism was observed from a sudden and abrupt failure to a formable failure with high-energy absorption when using more ECC layer thicknesses.

https://ceej.aut.ac.ir/article_4126_84f74ce4511e0c9531af1182fb636f0f.pdf

Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 53 10 2021 12 22 Analytical Extension of Higher Modes Participation in The Estimation of Seismic Response of Tall Hybrid Framed Tube Structures comprising Mega Zipper Elements Analytical Extension of Higher Modes Participation in The Estimation of Seismic Response of Tall Hybrid Framed Tube Structures comprising Mega Zipper Elements 4535 4554 4156 10.22060/ceej.2020.18400.6866 FA Mahboobeh Aboutalebi Kharazmi University, Alborz, Iran Afshin Meshkat-Dini Kharazmi University, Alborz, Iran Jafar Jafar Keyvani Kharazmi University, Alborz, Iran Journal Article 2020 05 10 This paper presents a computational approach to the analytical performance of the modal pushover method (MPA) in predicting nonlinear response parameters of tall buildings comprising hybrid framed tube with large-scale zipper elements. The accuracy of the results based on MPA is evaluated by comparing the benchmark responses obtained through conducting two sets of nonlinear time history analyses (NLRHA). Also, the effects of higher modes on the structural response parameters are measured by considering three computational vectors of the ordered lateral loading prepared according to the participation of the basic mode, as well as the first 3 and 5 transitional modes, separately. In this study, the determination of the target displacement in MPA was set based on the results of NLRHA under two groups of near and far-field records. The variation range of response parameters of the three high-rise 30-story studied structures was evaluated based on conducting a series of MPA as well as NLRHA analyses. The structural system of the first studied model is a combined framed tube structure. The second and third introduced studied models contain a multi-story arrangement of large-scale zipper elements on the basic skeleton by connecting the aforementioned zipper elements to the columns on the ground floor. The multi-story arrangement of large-scale zipper elements has been aimed at preventing the formation of an intensive expanded plastic mechanism and avoiding the possible buckling mode in the columns of the lower floors. The computational outputs of the MPA are compared with the results of the NLRHA (as exact values) and the standard error percentage is estimated. Evaluation of the results presented in this study demonstrates the relatively desirable computational capability of the MPA method in predicting the behavior characteristics of tall building structures with a symmetric and regular rigid skeleton at plan and height. Moreover, it was observed that the presence of large-scale zipper elements in the resistant system could reduce the seismic response parameters and also relatively increases the overall dynamic stability of the high-rise structural skeleton. This paper presents a computational approach to the analytical performance of the modal pushover method (MPA) in predicting nonlinear response parameters of tall buildings comprising hybrid framed tube with large-scale zipper elements. The accuracy of the results based on MPA is evaluated by comparing the benchmark responses obtained through conducting two sets of nonlinear time history analyses (NLRHA). Also, the effects of higher modes on the structural response parameters are measured by considering three computational vectors of the ordered lateral loading prepared according to the participation of the basic mode, as well as the first 3 and 5 transitional modes, separately. In this study, the determination of the target displacement in MPA was set based on the results of NLRHA under two groups of near and far-field records. The variation range of response parameters of the three high-rise 30-story studied structures was evaluated based on conducting a series of MPA as well as NLRHA analyses. The structural system of the first studied model is a combined framed tube structure. The second and third introduced studied models contain a multi-story arrangement of large-scale zipper elements on the basic skeleton by connecting the aforementioned zipper elements to the columns on the ground floor. The multi-story arrangement of large-scale zipper elements has been aimed at preventing the formation of an intensive expanded plastic mechanism and avoiding the possible buckling mode in the columns of the lower floors. The computational outputs of the MPA are compared with the results of the NLRHA (as exact values) and the standard error percentage is estimated. Evaluation of the results presented in this study demonstrates the relatively desirable computational capability of the MPA method in predicting the behavior characteristics of tall building structures with a symmetric and regular rigid skeleton at plan and height. Moreover, it was observed that the presence of large-scale zipper elements in the resistant system could reduce the seismic response parameters and also relatively increases the overall dynamic stability of the high-rise structural skeleton.

https://ceej.aut.ac.ir/article_4156_bba6bca05fecde04c682328e44b974b7.pdf