Amirkabir University of Technology
Amirkabir Journal of Civil Engineering
2588-297X
2588-2988
52
6
2020
08
22
Evaluating Election, Imperialist Competitive Algorithms and Artificial Neural
Network Method in Investigating the Groundwater Level of Reshtkhar Plain
1333
1246
FA
Yahya
Choopan
0000-0001-6275-6717
Water Engineering Department of Gorgan university
yahyachoopan68@gmail.com
Somayeh
Emami
Water Engineering Department of Tabriz university
somayehemami70@gmail.com
Milad
Kheiri ghooje bigloo
Master of Water and Hydraulic Structures, Islamic Azad University, Pars Abad Unit Moghan
eng.miladenoor@gmail.com
10.22060/ceej.2019.15344.5888
Evaluating the groundwater level in arid and semi-arid regions of the country requires accurate prediction and efficiency of its fluctuations. The use of modern methods, including evolutionary algorithms, artificial neural networks, and fuzzy methods, is very useful for predicting the groundwater level and generating artificial water surface data due to its high efficiency. In this research, by using Election and Imperialist Competitive Algorithms, artificial neural network, monthly data for 9 years as well as groundwater level of 10 wells, predicted the 7-year the groundwater level of Reshtkhar plain in Khorasan-Razavi. To train the models, the statistic data was provided on 10 observation wells with a 9-year (2002-2014), which 70% of the data was introduced as training data to the model and 30% of the data was used as a test for calibration of the model. The results of the Election Algorithm predicted Reshtkhar groundwater level for the year 1400, between 14 to 16.5 meters in different areas of the plain. Based on the calculations and the results obtained from the statistical parameters, the Election algorithm was RMSE, R2 and NSE, 0.029, 0.90 and 0.73 respectively, compared with the two methods of artificial neural network and Imperialist Competitive Algorithm has a significant ability to predict the groundwater level.
Groundwater Level,Election Algorithm,Imperialist Competitive Algorithm,artificial neural network,Prediction
https://ceej.aut.ac.ir/article_3299.html
https://ceej.aut.ac.ir/article_3299_a8a0638d90073ae368814ccd601d66c2.pdf
Amirkabir University of Technology
Amirkabir Journal of Civil Engineering
2588-297X
2588-2988
52
6
2020
08
22
Experimental investigation of lime impact on self-healing and dispersion processes of
clay soils (Case study: Gurdyan dam)
1347
1360
FA
Kiyoumars
Roushangar
Civil Engineering Department, Tabriz University, Tabriz, Iran.
kroshangar@yahoo.com
Mohammad Taghi
Alami
Civil Engineering Department, Tabriz University, Tabriz, Iran.
mtaalami@tabrizu.ac.ir
Yagoub
Houshyar
Civil Engineering Department, Tabriz University, Tabriz, Iran.
myhoshyar@yahoo.com
10.22060/ceej.2019.15354.5893
Dispersive soils have been responsible for excessive erosion in some soil practices or structures such as dams or channels. Dispersion and high penetration of clay soils are the important factors, which can reduce the efficiency of clay soils and lead to the failure of dams and embankments. Soil stabilization is an effective technique for controlling erosion. Clay soil self-healing characteristic as one of the positive characteristics of this type of soil has been investigated in recent years. In this research, the impact of lime on self- healing capacity of clay soils was investigated. In this regard, soil samples excavated from Gordyan dam (Iran) were considered. Two samples (S2 and S3) of dispersive soils (ND3 and ND4) with 0.25, 0.5, 1, and 2 % lime were prepared. Pinhole, double hydrometer and atterberg limits tests were performed and self-healing and dispersion processes of samples were investigated. The results showed that with adding 1% of lime to clay soils, the range of soil plasticity increased and the outflow of the pinhole test and the final diameter of both samples decreased up to 28% and 67%, respectively. This issue indicated an improvement in clay soil self-healing capacity and a reduction in soil dispersivity. The results also showed that the pinhole test led to more accurate and reliable results than other tests in investigating the clay soil dispersivity.
Clay soil, Dispersive,Double hydrometer,Lime,Pinhole Test,Self-healing
https://ceej.aut.ac.ir/article_3267.html
https://ceej.aut.ac.ir/article_3267_e8c3028bcba6652e20316286c97a7e9e.pdf
Amirkabir University of Technology
Amirkabir Journal of Civil Engineering
2588-297X
2588-2988
52
6
2020
08
22
Investigating the Effect of Loading Frequency on the Dynamic Properties of SandTire Powder Mixture Using Shaking Table Tests
1361
1378
FA
hadi
bahadori
Associate Professor, Department of Civil Engineering, Urmia University
h.bahadori@urmia.ac.ir
amin
khalili
phd student, department of civil engineering, urmia university
a.khalili@urmia.ac.ir
10.22060/ceej.2019.15362.5895
Nowadays, the use of waste tires has been expanded in various geotechnical projects to absorb and reduce the vibration caused by seismic and dynamic loads, and therefore it is crucial to study the effect of different parameters on their behavior and dynamic characteristics in combination with soil. So this study examined the effects of loading frequency on dynamic properties of sand-tire powder mixtures such as shear modulus (G) and damping ratio (D). A series of 1-g shaking table tests were performed on sand-tire powder mixture. Tire powders were added to the sand with 5%, 10%, 15% and 20% in gravimetric basis and with a relative density of zero were subjected to sinusoidal loading at frequencies of 0.5, 1, 2, 3, 5, 7 and 9 Hz and input acceleration of 0.1g and 0.3g. The results showed that in all cases, the increase in frequency in the same cycles increased the shear modulus and the damping ratio. Also, with increasing shear strain, the shear modulus of the mixture decreased, but the damping ratio increased. On the other hand, by increasing the tire powder, the value of the shear modulus is reduced, but the amount of damping ratio is increased.
Sand,Tire Powder,shaking table,Shear Modulus,Damping Ratio
https://ceej.aut.ac.ir/article_3264.html
https://ceej.aut.ac.ir/article_3264_7bffb68ef16dad3babcbaa4957876e4e.pdf
Amirkabir University of Technology
Amirkabir Journal of Civil Engineering
2588-297X
2588-2988
52
6
2020
08
22
Experimental investigation on hexagonal steel tubular columns filled with plain and
fiber reinforced concrete under eccentric compression load
1379
1404
FA
Navid
Mahdavi
Civil Structural Engineering Department, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
navid.mahdavi@mail.um.ac.ir
milad
salimi
Civil Structural Engineering Department, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
salimi.milad@mail.um.ac.ir
Mansour
Ghalehnovi
0000-0002-1667-7812
Faculty member and Secretary of Construction Management / Ferdowsi University of Mashhad
ghalehnovi@um.ac.ir
10.22060/ceej.2019.15365.5896
Due to the advantages of Concrete Filled Tube columns (CFT), their attention is increasingly on the rise. Despite the great research done in these sections, in some cases, as in the case of less frequent sections or using different types of concrete, the need for research to complete the design criteria and guidelines seems necessary. The present study was conducted with an experimental approach to study the behavior of CFT columns under eccentric load. In this study, 8 CFT columns with a hexagonal cross-section of 150 cm in length were tested. Concrete used as the core of the samples was simple concrete and fiber concrete. The displacements in two directions of the longitudinal and lateral has been recorded and the force-displacement diagram for all samples in both directions has been drawn. Parameters such as bearing capacity, ductility index, energy dissipation and effective hardness have been analyzed and compared. Based on the comparison of the results, it was found that in columns that are only under axial load, the increase in concrete core strength significantly increases the bearing capacity of the specimens, so that an increase of about 50% of the concrete core strength causes an increase of about 20% of the loaded capacity of the specimen; However, by increasing the bending moment, the effect of concrete core resistance is greatly reduced. Also, it was found that specimens filled with fiber concrete have a greater ability to maintain effective hardness. It also seems that the presence of fibers in concrete affects the ductility and energy dissipation parameters.
load-displacement curve,Eccentric Axial Load,Loading Capacity,Ductility coefficient,Energy absorption rate
https://ceej.aut.ac.ir/article_3302.html
https://ceej.aut.ac.ir/article_3302_646e83f6caf073c3e836886690b4d1cc.pdf
Amirkabir University of Technology
Amirkabir Journal of Civil Engineering
2588-297X
2588-2988
52
6
2020
08
22
Investigation of Interaction of Effecting Factors in Phosphate and Nitrate Removal
from Municipal Wastewater by Electrocoagulation Process with RSM Approach
1405
1418
FA
Susan
Khoshsima
Department of environment, Hakim Sabzevari University, Sabzevar, Iran
maneager.susan.kh@gmail.com
mojtaba
hadavifar
0000000329369787
Department of environment sciences, Hakim Sabzevari University, Sabzevar, Iran
mhadavifar@yahoo.com
Ghasem
zolfaghari
Department of environment, Hakim Sabzevari University, Sabzevar, Iran
ghr_zolfaghari@yahoo.com
10.22060/ceej.2019.15377.5901
One of the environmental problems of wastewater is the presence of micro and macronutrients, the most important of which is phosphorus and nitrate. Hence, in this study removal of phosphate and nitrate from aqueous solution was conducted using electrocoagulation (EC) processes with Al electrodes. In the present study, an electrocoagulation reactor was used in a laboratory-scale with a volume of approximately 1200 ml equipped with 3 Al-electrode in a size of 5 × 12 cm2 to remove phosphate and nitrate. The effects of operating parameters such as applied voltage, initial pH of the solution, the value of FeCl2 and reaction times were evaluated. The effect of pH and FeCl2 parameters in inlet and facultative ponds were also studied. Also, pH changes in the oxidation process were investigated. Finally, it can be said that phosphate was completely eliminated in facultative and outflow ponds, but due to the low initial concentration of phosphate in the outlet, less voltage (10 V), less time (about 3 minutes), low FeCl2 dosage (0.2 mg/l) and original pH of the solution were applied compared to the facultative pond., 100 % of nitrate in optimum condition (pH=5.5, applied voltage=25 V, FeCl2=0.65 mg/l, time=11.50 min) in output pond has been removed. In the EC process, the electrocoagulation process using an aluminum electrode, as well as it’s relatively low cost and simplicity, has a good effect on phosphorus and nitrate removal compared to other methods.
Phosphate removal,Nitrate removal,municipal wastewater,electrocoagulation,Response surface methodology
https://ceej.aut.ac.ir/article_3295.html
https://ceej.aut.ac.ir/article_3295_2650e8b6114391604eea86ea9b46fdf8.pdf
Amirkabir University of Technology
Amirkabir Journal of Civil Engineering
2588-297X
2588-2988
52
6
2020
08
22
Providing a Method for Accident Severity Analysis Using Geospatial Clustering
Functions and Decision Tree, Case Study: Qazvin-Loshan Freeway
1419
1438
FA
hamid
behbahani
Department of Road and Transportion, Faculty of Civil Engineering, The University Of Elmo-Sanat,Tehran, Iran
behbahani@iust.ac.ir
Meysam
Effati
Assistant Professor, Department of Civil Engineering, Faculty of Engineering
The University of Guilan
meysameffati@guilan.ac.ir
Samane
Mortezaei
Department of Road and Transportion, Faculty of Civil Engineering, The University Of Elmo-Sanat,Tehran, Iran
samane.mortezaei1372@yahoo.com
10.22060/ceej.2019.15376.5903
Spatial analysis of accidents occurred in freeways and identifying effective parameters can help researchers and authorities to improve road safety by reducing the severity of accidents. The purpose of this study is to provide a method to analyze the accident severity and determine related effective parameters in freeways based on spatial clustering functions and regression and classification tree data mining method. Proposed method was assessed in Qazvin-Loshan freeway. In this study, to study the spatial distribution of the accidents in the aforementioned axis during the period from 2011 to 2016, the spatial functions such as Getis-Ord G* autocorrelation and Kernel Density Functions were Used. The results of spatial analysis showed that the spatial gathering of accidents in most of horizontal curves was greater. According to this achievement, in the next phase of the study, in order to study the factors affecting the severity of accidents, the Regression and Classification Tree was used on accidents that occurred in the whole axis and specifically the crashes which occurred in the horizontal curves. Results of this part of the study showed that the type of accidents (overturning and falling, exit from the road, multi-vehicle collisions, etc.) and human factors are the most important factors in the severity of accidents in this axis. Relative importance coefficients for these two independent variables are 100 and 39.7 percent for the whole axis and 100 and 65.9 percent for horizontal curves. The study of the relative importance of other variables used in the proposed model showed that the geometric design, type and date of crashes are among the most effective factors in increasing the property damage only crashes in Qazvin-Loshan Freeway. This study showed that the integration of GIS functions with non-parametric data mining algorithms such as decision tree, which is capable of simultaneous modeling of quantitative and qualitative data, is an effective approach to determine the factors affecting the severity of accidents and to analyze the spatial patterns of accidents in freeways.
Road Safety,Accidents Severity,Getis-Ord G* Autocorrelation,kernel Density Functions,Classification and Regression Tree
https://ceej.aut.ac.ir/article_3501.html
https://ceej.aut.ac.ir/article_3501_0b899fb8455a5b36faf1706dd327b0b9.pdf
Amirkabir University of Technology
Amirkabir Journal of Civil Engineering
2588-297X
2588-2988
52
6
2020
08
22
Investigating the effect of Portland cement and Nano-clay on the collapse potential
and consolidation indexes of the collapsible soil
1439
1454
FA
Mostafa
Zamanian
Department of Civil, Water, and Environmental Engineering, Shahid Beheshti University, Tehran, Iran
m_zamanian@sbu.ac.ir
Fatemeh
Qahremani
Master of Geotechnical Engineering, University of Science and Culture
fqahremani.civil@gmail.com
10.22060/ceej.2019.15386.5905
Collapse refers to a sudden decrease in the soil volume upon wetting which is attributed to a loss in the strength of the inter-particle bonds. Collapsible soils can be founded in vast areas around the word and subtropical areas of Iran. Collapse characteristics contribute to various problems to infrastructures that are constructed on loess soils. For this reason, the collapse behavior of loess soils has been the subject of interest. In this study, stabilization of Semnan loess which is composed of fine sand and silt bonded by weak clay bonds, has been investigated. The loess was mixed with Portland cement in the order of 0.5%, 1%, and 2.5% for and with nano-clay in order of 0.05%, 0.1%, and 0.25%. The specimens were prepared to achieve a dry density of 14 kN/m3 and a water content of 5%. Oedeometer tests were performed to determine the collapse potential according to ASTM D5333 after 7, 14, and 28 days. Results showed that both Portland cement and nano-clay could reduce collapse potential. Improvement performance was significantly dependent on the binder content and curing time. The best improvement performance was observed at low nano-clay content and it was reduced by increasing nano-clay content. Unlike the cement stabilization, treatment process with nano-clay was relatively fast that terminated when soil moisture content was evaporated. In addition, in this study, micromechanical soil behaviors were investigated by scanning electron microscopy (SEM) image of the treated and untreated specimens.
Collapsible soil,collapse potential,Soil improvement,Portland cement,nano-clay
https://ceej.aut.ac.ir/article_3390.html
https://ceej.aut.ac.ir/article_3390_bdb1592d56ede1faa87d4af9181a2989.pdf
Amirkabir University of Technology
Amirkabir Journal of Civil Engineering
2588-297X
2588-2988
52
6
2020
08
22
Experimental Investigation Effect of the Porosity and Angle of Permeable Obstacles
on Density Current Sedimentation
1455
1468
FA
Alireza
Jahangir
Ferdowsi University of Mashhad
ar.jahangir@mail.um.ac.ir
kazem
Esmaili
0000000153540949
Head of dept.
esmaili@um.ac.ir
Mahmoud
Faghfour Maghrebi
Civil Engineering Department, Engineering Faculty, Ferdowsi University of Mashhad
magrebi@yahoo.com
10.22060/ceej.2019.15394.5907
Flood flow in rivers is often of density current type. Hence, recognizing and exploring these currents can solve some problems of sedimentation. In this study, the effect of porosity and the angle of permeable obstacles on the control and trapping of density current have been investigated in the laboratory. For this purpose, an expanded polystyrene (EPS) polymer was used with 1.135 g/L density and average diameter of 1.15 mm. The experiments were carried out with two concentrations (10 and 20%) and 5 porosity and 4 angles. The obstacles were made of palsy glass plates and two types of groove and cavity with 8.2 mm width of the groove and the diameter of the cavity. The results showed that, with an increase in porosity ratio, the amount of trapping to optimum porosity decreases and then increases. The optimal porosity of the cavity and groove is 22 % and 19%, respectively. In experiments, the cavity trapping was observed more than the groove, in the concentrations of 10.20% it was 0.13 and 0.14%, respectively. Also, with the increase of the angle, the amount of trapping has reduced and its value was observed in the groove more than the cavity. The correlation coefficient in the grooves and cavities was 0.996 and 0.937, respectively. The major effect of obstacles, reducing velocity and slowing flow were identified as the average velocity in the cavity was 3.62% higher than the groove. Accordingly, in the same conditions, the cavity obstacles have better performance than the groove obstacles.
Density current,Suspended Sedimentation,Permeable Obstacle,Obstacle Angle,Obstacle porosity
https://ceej.aut.ac.ir/article_3426.html
https://ceej.aut.ac.ir/article_3426_b723a92760d4e62010c73d6ad4188ee7.pdf
Amirkabir University of Technology
Amirkabir Journal of Civil Engineering
2588-297X
2588-2988
52
6
2020
08
22
Impact of surface dissolution on flotation kinetics and kinetics of collector adsorption
on ilmenite ore
1469
1484
FA
Omid
Salmani Nuri
Amirkabir University of Technology
omidnuri@aut.ac.ir
mehdi
Irannajad
0000-0002-5469-084X
Mining & Metallurgical Eng. Department
iranajad@aut.ac.ir
Akbar
Mehdilo
AUT
amehdilo@aut.ac.ir
10.22060/ceej.2019.15399.5909
In this study, the effect of surface dissolution by oxalic acid was investigated on the flotation kinetics and kinetics of collector adsorption for ilmenite in the presence of olivine-pyroxene, tremolite-clinochlore and quartz. Fitting of first-order kinetic model on the results of flotation before and after surface dissolution showed that flotation kinetic constant (K) and ultimate recovery (R∞) of ilmenite is increased after surface dissolution and they are decreased for gangue minerals. The results showed that the kinetic selectivity index of ilmenite in the presence of olivine-pyroxene, tremolite-clinochlore and quartz are increased from 1.28 to 1.98, 1.42 to 3.02, and 3.58, respectively, after surface dissolution indicating the positive effect of surface dissolution process. Investigating the kinetics of collector adsorption showed that the collector adsorption is conforming to second[1]order kinetic model. After surface dissolution, the kinetics of collector adsorption and initial rate of collector adsorption on ilmenite surface is increased from 3.85 to 8.44 g.mol-1 min-1 and it is decreased for olivine-pyroxene, tremolite-clinochlore and quartz from 6.33 to 5.03, 7.3 to 6.22 and 7.77 to 7.37 g.mol-1 min-1, respectively. These results are in good agreement with the results of collector adsorption via UV analysis which the collector adsorption on ilmenite surface is increased and it is decreased for gangue minerals after surface dissolution. The results of SEM showed that the surface of ilmenite becomes smoother and uniform and about the gangue minerals, some cavities are produced due to dissolution of surface cations.
Surface dissolution,Kinetics,Flotation,Collector adsorption,Ilmenite
https://ceej.aut.ac.ir/article_3327.html
https://ceej.aut.ac.ir/article_3327_0d8da99e40d798b486b241729260fa5a.pdf
Amirkabir University of Technology
Amirkabir Journal of Civil Engineering
2588-297X
2588-2988
52
6
2020
08
22
Analytical simulation of passive and pre-tensioned grouted rockbolts performances in
bedding rock slopes
1485
1498
FA
Mir Mahdi
Rashedi
Department of geotechnical engineering, Faculty of civil engineering, university of Tabriz
mahdicivil72@yahoo.com
Masoud
Ranjbarnia
0000-0003-3995-3258
Department of Geotechnical Engineering, Faculty of Civil Engineering, University of Tabriz, Tabriz, Iran
m.ranjbarnia@tabrizu.ac.ir
10.22060/ceej.2019.15415.5914
Rockbolts are one of the best systems to stabilize plane failure of rock slopes. The passive bolts are loaded and activated when rock block slides while pre-tensioned types are initially loaded before any rock sliding. The pre-tensioned rock bolts make the rock layers pressed together and the friction between them is activated before slipping, and probably no displacement between the layers is occurred. If a slippage occurs after the installation of a pre-tensioned rock-bolt, an excessive load is applied. In this paper, the bolt contribution generated by the pre-tensioned and passive rock-bolt in discontinuity is analytically simulated, and the effect of roughness angle, inclination of the bolt to the joint plane, pre-tensioned force, and strength of the rock are evaluated. For modeling, it is assumed the sliding imposes a bending moment to the rockbolt, which leads two plastic hinges to be created. The part of the bolt between two hinges (located on either side of the joint) is considered a beam with two cantilever supports, which is loaded by a uniform distribution generated by surrounding grout/ rock. The results showed that the pre-tensioned rock-bolts are effective when the resistance of the rock or grout around the bolt is high.
Rock slope,Active and passive rock-bolt,Inclination of the bolt,Pre-tensioned force,Analytical modeling
https://ceej.aut.ac.ir/article_3276.html
https://ceej.aut.ac.ir/article_3276_e8be7bcec5e859de2a33c5ce5a0477f9.pdf
Amirkabir University of Technology
Amirkabir Journal of Civil Engineering
2588-297X
2588-2988
52
6
2020
08
22
Numerical finite element parametric study to investigate the performance of SPSW in
RC frame
1499
1520
FA
Benyamin
Kioumarsi
Department of Civil Engineering, Structural engineering, Semnan University, Semnan, Iran
benyamin.kioumarsi@semnan.ac.ir
majid
gholhaki
0000-0002-9904-8623
عضو هیات علمی دانشگاه سمنان
mgholhaki@semnan.ac.ir
Ali
Kheyroddin
0000-0001-7802-2013
استاد دانشگاه سمنان
kheyroddin@semnan.ac.ir
10.22060/ceej.2019.15418.5916
Studies conducted on the performance of Steel Plate Shear Walls (SPSWs) indicate high stiffness, capacity, ductility and significant potential of energy absorption of this lateral seismic system. In this regard, using SPSWs in Reinforced Concrete (RC) structures has recently been considered by researchers. In this paper, two different connection types have been proposed and numerically investigated to connect SPSW to RC frame (RCF). In the first type connection, SPSW has been connected to RCF by a few studs through fish plates. However, in the second type, it has been connected to RCF by additional stirrups, which has been welded to the endplate. The behavior of connections has been evaluated using non-linear finite element analysis (NLFEA). A parametric study has been conducted on the thickness of SPSWs and the placement of studs and stirrups through the length of columns. Results of the specimens with different types of connections demonstrated that using both connection types leads to a prominent increase in stiffness and capacity comparing to the reference RCF. Investigating the placement of studs and stirrups showed that there is no need to use studs and stirrups in whole column height. Similar results can be obtained by connection in a length of 0.3 or 0.2 of the column clear height. The dual system behavior factor of special RCF with SPSW was estimated to be 8.
Steel plate shear wall (SPSW),Non-linear finite element analysis (NLFEA),Reinforced concrete frame (RCF),behavior factor,Ductility
https://ceej.aut.ac.ir/article_3306.html
https://ceej.aut.ac.ir/article_3306_ebed5a11655e85ae0bd29ad5f572b934.pdf
Amirkabir University of Technology
Amirkabir Journal of Civil Engineering
2588-297X
2588-2988
52
6
2020
08
22
Static behavior of ring footing based on geogrid-rubber reinforced sand bed
1521
1538
FA
Mohammad Hossein
Keyghobadi
Department of civil engineering, Faculty of Engineering, University of Hormozgan, Bandar Abbas, Iran.
mhkeyghobadi@yahoo.com
ADEL
ASAKEREH
0000-0003-4706-2957
Department of Civil Engineering, Faculty of Engineering, University of Hormozgan, Bandar Abbas, Iran.
asakereh@hormozgan.ac.ir
Behzad
Kalantari
0000-0003-0277-2576
Department of civil engineering, Faculty of Engineering, University of Hormozgan, Bandar Abbas, Iran.
kalantari@hormozgan.ac.ir
Masoud
Dehghani
Department of civil engineering, Faculty of Engineering, University of Hormozgan, Bandar Abbas, Iran.
m.dehghani@hormozgan.ac.ir
10.22060/ceej.2019.15429.5917
Ring footings have been used in various industries, like oil and gas. So this kind of footings is very important and doing some works to improve their behavior can be very important. In the present study, the behavior of ring footings with a constant outer diameter of 300 mm based on reinforced bed with granular rubber particles alone and also in combination with a geogrid layer, subjected to static loads, has been investigated by experimental tests. The results showed in both unreinforced and rubber-reinforced bed, the ring footing with inner to outer diameter ratio of 0.4 had the maximum bearing capacity. Also, the optimum thickness of rubber-reinforced layer is equal to 0.5 times the outer diameter of ring footing; in this case, the bearing capacity can be increased by 41.5% compared with the unreinforced bed; more increases than optimum value, have reverse results and lead to decrease in bearing capacity and increase in settlement. Using the geogrid layer can activate reinforcing effects of rubber-reinforced layer with high thicknesses, but its value is not big enough to overcome the negative effects of using rubber-reinforced layers with higher thicknesses than optimum value. At last, using geogrid reinforcement in combination with rubber particles can be more effective than using each of them alone. In geogrid-rubber reinforced bed, the bearing capacity can be increased by 62.7% compared with the unreinforced bed.
Ring footing,rubber particle,Geogrid,Bearing Capacity,Settlement
https://ceej.aut.ac.ir/article_3328.html
https://ceej.aut.ac.ir/article_3328_ff87197d28b7349e3e5a1cf7f7279fcc.pdf
Amirkabir University of Technology
Amirkabir Journal of Civil Engineering
2588-297X
2588-2988
52
6
2020
08
22
Proposed Damage Index for Seismic Evaluation of RC Bridge Shear keys
1539
1554
FA
Shima
Mahboubi
Ph.D. Student, Faculty of Civil, Water and Environmental Engineering. Shahid Beheshti University, Tehran, Iran
sh_mahboubi@sbu.ac.ir
Mahmoud R.
Shiravand
Shahid Beheshti University
m_shiravand@sbu.ac.ir
10.22060/ceej.2019.15421.5920
Shear keys are bridge components that support the superstructure in transverse direction and may experience large displacements and extensive damages during earthquakes. Shear keys are designed to limit damage to abutment walls and piles by restraining the transverse movements. The shear force transferred to the abutments is controlled by design and detailing of the shear keys. Damage to shear keys during earthquakes may affect significantly on seismic behavior of the abutments and consequently, the bridge system. In this paper, a damage index is proposed for damage assessment of the bridge shear keys. The proposed damage index is defined based on the friction behavior and the ratio of the energy dissipation capacity to input energy. To evaluate the reliability of the damage index in damage assessment of the shear keys, finite element models of shear keys units, previously tested under cyclic loadings, are developed and the proposed damage index is calculated. Also, seismic response of shear key specimens are obtained under seven earthquake records using incremental dynamic analysis and the damage index is calculated for the shear keys in different PGA values of earthquakes. The results indicate that the proposed damage index can predict the damage progression in shear keys throughout loading histories and can provide reliable values for damage levels of shear keys with respect to the experimental observations.
Shear key,Friction behavior,Dissipated Energy,input energy,damage index
https://ceej.aut.ac.ir/article_3297.html
https://ceej.aut.ac.ir/article_3297_09db89b8d4da554d02c41345275c2c2e.pdf
Amirkabir University of Technology
Amirkabir Journal of Civil Engineering
2588-297X
2588-2988
52
6
2020
08
22
Effects of Freedom Degrees on Behavior Factor in Reinforced Concrete Moment Resisting Frames with Steel Plate Shear Wall
1555
1576
FA
seyyed reza
salim bahrami
Semnan university
salimbahrami@semnan.ac.ir
majid
gholhaki
0000-0002-9904-8623
عضو هیات علمی دانشگاه سمنان
mgholhaki@semnan.ac.ir
10.22060/ceej.2019.15456.5925
The influence of the strength reduction factor due to nonlinear behavior (Rμ) on the lateral strength of Single-Degree-Of-Freedom (SDOF) structures causes to limit the displacement ductility demand to the predetermined maximum tolerable ductility. In addition, Rμ is used for determining the behavior factor in Multi-Degree-Of-Freedom (MDOF) structures. Following this, in this paper, Rμ and the inelastic displacement ratio (CR) for equivalent SDOF systems under strike[1]parallel (NF-SP) and strike-normal (NF-SN) components of near-field ground motion, and also far[1]field (FF) ground motion were assessed. Furthermore, CR obtained by this study was compared with C1 proposed by FEMA440. The deflection amplification factor-to-behavior factor ratio (Cd/Ru) for different ductility levels was computed. After evaluating the nonlinear effects of SDOF structures based on Rμ factors, these factors for MDOF structure were modified considering higher mode effects, and a simplified practical expression was proposed to estimate the base shear modification factor. The results indicated that Rμ, corresponds to near and far-field ground motions can be different. In addition, CR does not depend on the type of earthquake, and it converges to 1 by increasing the period of vibration. In addition, the modification factor can be increased with period and ductility demand.
behavior factor,Modification Factor,SDOF Structure,MDOF,Base Shear
https://ceej.aut.ac.ir/article_3265.html
https://ceej.aut.ac.ir/article_3265_9b7c6d7832bfcb521afb75941c5128b9.pdf
Amirkabir University of Technology
Amirkabir Journal of Civil Engineering
2588-297X
2588-2988
52
6
2020
08
22
Seismic analysis of prestressed concrete cylindrical tanks
1577
1592
FA
Ahmad
Shokoohfar
Department of civil engineering, Azad University of Qazvin, Qazvin, Iran
ahmad.shokoohfar@qiau.ac.ir
mohammad
rahai
....
rahai.m@alum.sharif.edu
ALI
Sahrai
Civil Engineering and Environment, Amirkabir University of Technology, Tehran , Iran.
ali90@aut.ac.ir
10.22060/ceej.2019.15441.5935
The seismic responses of the water-filled prestressed concrete cylindrical tanks have been investigated under earthquake inputs. A series of dynamic-explicit analyses have been performed to study water sloshing phenomena effects on the prestressed concrete tank behavior using ABAQUS software. A shaking table test program has been conducted to validate the numerical analysis. Additionally, the numerical analysis capability to simulate the sloshing waves has been verified using mathematical results. Several numerical models have been prepared with different radius to water height ratios (R/H). The recorded El-Centro, Tabas and Bam accelerations have been employed as the seismic loading in the numerical models. The comparison between the experimental and theoretical results with numerical outcomes demonstrates a reasonable agreement. The seismic excitation effect on the prestressed tendons loss is negligible in the investigated numerical models.
Seismic nonlinear analysis,Concrete damage plasticity,Prestressed tendon,Prestressed concrete cylindrical tanks
https://ceej.aut.ac.ir/article_3420.html
https://ceej.aut.ac.ir/article_3420_a345d36a78a858911dfb06d490266ba8.pdf