Performance-Based Seismic Response of Continues Buried Steel Pipelines Under Near-Field Ground Motion Effects
Alireza
Kiani
Civil Eng. Dept., Faculty Engineering, Islamic Azad University, Arak Branch, Arak, Iran.
author
Mehdi
Torabi
Civil Eng. Dept., Faculty Engineering, Islamic Azad University, Kangan Branch, Kangan, Iran
author
S. Mohammad
Mirhosseini
Civil Eng. Dept., Faculty Engineering, Islamic Azad University, Arak Branch, Arak, Iran.
author
text
article
2019
per
Performance-Based Earthquake Engineering (PBEE) attempts to improve seismic risk through assessment and design methods that are more informative than current approaches. However, little work has been performed investigating the seismic response of buried steel pipelines within a performance-based framework. In this paper the seismic response of buried steel pipelines was studied in a performance-based context. Multiple nonlinear dynamic analyses of three buried steel pipes with different diameter to thickness and burial depth to diameter ratios, steel grade and various soil characteristics carried out using an ensemble of near-field ground motion records were scaled to various intensities to capture the behavior of buried pipeline in the range of elastic response to dynamic instability. Peak axial compressive strain in critical section of the pipe was considered as engineering demand parameter (EDP) of pipelines. Several ground motion intensity measures (IMs) are considered to investigate their correlation with EDP. Using the regression analysis in logarithmic space, the efficiency and sufficiency of investigated IMs are studied. Among the models investigated in this study, it was seen that a combined IM, PGV and SMV were the most sufficient IMS. For buried steel pipelines investigated in this study, it was concluded that PGD is the most sufficient IM for near-field ground motions. It was seen that the combined IM followed by SMV were the optimal IM for buried steel pipelines under near-field ground motions based on both efficiency and sufficiency conceptions.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
51
v.
4
no.
2019
619
630
https://ceej.aut.ac.ir/article_3060_f08450e8cada7ef816e860b400bfca92.pdf
dx.doi.org/10.22060/ceej.2018.13581.5444
Investigating The Effect of Thermal Loading on Cooling Tower Shells
salman
rahimian
MSc Graduate, Yazd University
author
reza
morshed
Yazd University / member of Scientific Board
author
text
article
2019
per
Thermal load is one of important loads on the cooling towers, which reduce the final resistance of the cooling towers by creating micro Cracks at the end of the wind load. In the past, the impact of these loads has been less considered. Due to the progress of the finite element methods, nowadays it is possible to model cooling towers under thermal loads. In this research, the cooling tower of Shahid Rajaee power plant was modeled using ABAQUS finite element software. Damage plasticity model was used to model the crust of this tower. Behavior of cooling tower shell under two loading was compared. In the first loading, gravity, wind and heat, and in the second loading, the gravity and wind load were applied. The difference in shell displacement, tensile and compression cracking and ultimate strength in the shell was compared in both loading. Based on this study, the difference in the displacement of the shell in two loading was 6.4%. The difference in compression damage was about 3%, and the difference in tensile damage was about 10%. The pressure damage and tensile damage was developed in the presence of thermal loading. The difference in the bending moments in two loading was about 40% at the back side of the wind. Finally, the tower shell was reached to its ultimate strength in the presence of thermal load at a lower wind pressure.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
51
v.
4
no.
2019
631
644
https://ceej.aut.ac.ir/article_2916_74cb0106f928a870a1efa47ad6ef9bc6.pdf
dx.doi.org/10.22060/ceej.2018.13858.5493
Prediction of Flow Discharge in Compound Open Channels Using Group Method of Data Handling
Abbas
Parsaie
Ph.D. Candidate of Hydro-Structure Engineering, Water Engineering Department, Lorestan University, Khorramabad, Iran.
author
Shadi
Najafian
Ph.D. Candidate of Hydro-Structure Engineering, Water Engineering Department, Gorgan University, Golestan, Iran.
author
Abdolreza
Zahiri
Associate professor in Water Engineering, Gorgan University of Agricultural Sciences and Natural, Golestan, Iran.
author
text
article
2019
per
Prediction of flow through the compound open channel is one of the main problems in the field of hydraulic engineering. One of the main parameter related to the flow properties in the compound open channel is shear stress. The shear stress occurs because of difference of velocities between the main channel and floodplains. The shear stress is the main causes of turbulence and vortex creation on the border of main channel and floodplains. The difference between the roughness of main channel and floodplains intensifies the shear stress in the border zone and also decreases total flow discharge. In this paper, the flow discharge in compound open channels was predicted using group method of data handling technique. To do this, related dataset was collected from literature. Involved parameters in modeling are relative hydraulic depth (Hr ), relative hydraulic radius (Rr ), relative roughness (fr ) and relative area (Ar ). To compare the performance of GMDH with other types of soft computing methods, the MLPNN as most well[1]known soft computing technique was developed as well. Results indicated that the GMDH model with coefficient of determination 0.91 and root means square error 0.057 was more accurate than the MLPNN. Reviewing the structure of developed GMDH model showed that and are the most effective parameters on prediction of flow discharge in compound open channels.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
51
v.
4
no.
2019
645
656
https://ceej.aut.ac.ir/article_2836_7d2defa3e2ddd85829db063421051415.pdf
dx.doi.org/10.22060/ceej.2018.13841.5488
Investigation of Carbonate Sand Shear Behavior Based on Manzari anid Dafalias Behavioral Model
mehgdad
hamidzadeh
Imam Khomeini International University
author
Mahmoud
Hassanlourad
Imam Khomeini International University
author
Rasoul
Mohammadpour Salout
Imam Khomeini International University
author
text
article
2019
per
Investigating soil characteristics and models for better design and performance of construction projects is very important. In this paper, the ability of the behavioral model of Manzari and dafaliais, which is an advanced model in the field of soil behavioral model, was evaluated to predict the shear behavior of carbonate sand with brittle seeds. Soil parameters were examined and their effects on soil behavior display were studied. By comparing strain stresses obtained from a tri-axial test and a model in loose and dense samples, it was observed that the results of the behavioral model are in good agreement with experimental results. However, by examining the volumetric strain graphs against the axial strain, the outcomes of the Manzari and dafaliais behavioral model were not sufficiently accurate in comparison with the experimental results. The main reason for this was the crushing of soil grains and its effect on soil volume variation in the Dafalias model. There is no perspective on the prediction of the volumetric strain. Nevertheless, the above-mentioned behavioral model predicts the trend of change. This behavioral model in high imbibed tensions had better results in comparison with the immensely low stresses in the study of strain volumes of samples.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
51
v.
4
no.
2019
657
670
https://ceej.aut.ac.ir/article_3047_41ea826110c007045935ac196b34afad.pdf
dx.doi.org/10.22060/ceej.2018.13856.5499
Evaluation of Seismic Behavior of Steel Frames Constrained with Hybrid Core Buckling-restrained Braces
Mehdi
Alborzi Verki
Civil engineering department, University of Kashan, Kashan, Iran
author
Hossein
Tahghighi
Civil Engineering Department, University of Kashan, Iran
author
text
article
2019
per
Bucking restrained braced frame (BRBF) is a special type of concentrically braced frames that the braces do not buckle in compression. As a result, it shows a desirable energy dissipation behavior. However, low post-yield stiffness of these braces causes large residual deformations at high levels of earthquake intensities. The aim of this article was evaluation of the seismic behavior of a new steel structural system known as hybrid buckling-restrained braced frame (HBRBF). Nonlinear static analysis, nonlinear time history analysis and nonlinear incremental dynamic analysis (IDA) methods were used for standard and hybrid core BRBFs with different stories. The average values of seismic behavior factor (R) for HBRBFs were obtained 10.2 and 14.7 for ultimate limit state and allowable stress design methods, respectively. In order to carry out response history analyses, past earthquakes records were used with different hazard levels. Hybrid buckling-restrained braced frames were shown to have a significant improvement over standard BRBFs in terms of behavior factor and damage measures including inter-story drift ratios and residual displacements.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
51
v.
4
no.
2019
671
684
https://ceej.aut.ac.ir/article_2869_7f5c256dd00ee6d19f8645d41b78c48b.pdf
dx.doi.org/10.22060/ceej.2018.13837.5486
Experimental Investigation on the Behavior of Reinforced Concrete Beams Retrofitted with NSM-SMA/FRP
Behrouz
Farahi
M.Sc, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
author
Mohammadreza
Esfahani
Professor, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
author
javad
sabzi
Ph.D. Student, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
author
text
article
2019
per
Re-centering is an exclusive characteristic of superelastic Shape Memory Alloys (SMAs) which can be used in manufacturing and retrofitting of reinforced concrete elements. Reinforced concrete beams retrofitted with SMA bars have more ductility and higher energy dissipation compared to conventional RC beams. Furthermore, these beams experience less damage in consecutive loading-unloading cycles. The current research aims to investigate the behavior of reinforced concrete beams retrofitted with SMA bars using Near-Surface Mounted (NSM) flexural retrofitting method. Eleven RC beam specimens with the cross section of 200*150 mm and length of 1150 mm were cast. Three of the specimens had no external strengthening, four of them were retrofitted with SMA bars and other four beams were retrofitted with GFRP reinforcements. The specimens were subjected to three-point bending test under either monastic or loading-unloading. Different parameters including load-carrying capacity, energy dissipation, deformation recovery and reduction capability of crack width were investigated. The results showed that RC beams retrofitted with SMA bars had more mid-span deflection and higher energy dissipation compared to other specimens under monotonic loading. Moreover, under loading-unloading, RC beams retrofitted with SMA bars method experienced less damage.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
51
v.
4
no.
2019
685
698
https://ceej.aut.ac.ir/article_2861_8e71f1f6ecb1bd9716d160d9333c2063.pdf
dx.doi.org/10.22060/ceej.2018.13927.5512
Statistical Quality Control Based on the Process Capability Index and Control Charts with Fuzzy Approach (Case Study: Water and Wastewater Company of West Azerbaijan Province)
khosro
alinejad
MSc student, Faculty of Industrial Engineering, Urmia University of Technology, Urmia, Iran
author
rahim
dabbagh
Urmia University of technology faculty member
author
Akbar
Shirzad
Assistant Professor, Faculty of Civil Engineering, Urmia University of Technology
author
text
article
2019
per
Statistical quality control is a method for monitoring the process to identify the underlying causes of changes and carrying out corrective actions. Process and capability control charts are two important applied tools for statistical quality control. In many actual systems in which accurate and certain information is not always available and the information is vague and fuzzy, fuzzy based methods can survey production process more precisely using appropriate linguistic terms and fuzzy numbers. In this study, fuzzy control charts were developed using fuzzy rules, and then the fuzzy actual capability index of process (Cpm) was investigated in order to evaluate the precision, accuracy and performance of production process in the fuzzy state. The results of the studies performed on the quality of water flowmeters in the urban water and wastewater company of West Azerbaijan province showed that using fuzzy rules provides more decision-making options to decision- makers compared to the crisp data and provided more precise division about the product quality. Also, the fuzzy actual capability index of process could propose a more precise analysis of the process taking into account the average, target value and process variance, simultaneously. The values of the fuzzy actual capability index of process in the studied case were less than one, showing that the conditions of the production process are unfavorable.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
51
v.
4
no.
2019
699
712
https://ceej.aut.ac.ir/article_2915_8db8e09bb7435f02513f8e84412adf65.pdf
dx.doi.org/10.22060/ceej.2018.13897.5504
Experimental Study on Performance of Multi-Tiered Reinforced Soil Retaining Walls
Abas
Abedi
Civil Engineering Department, Razi University, Kermanshah, Iran
author
Jahangir
Khazaei
civil engineering, razi university, kermanshah, iran
author
hossein
moayedi
Civil Engineering Department, Kermanshah University of Technology
author
text
article
2019
per
In reinforced soil walls, if the wall divided into several sections (here called tiers) it can be called multi-tiered reinforced soil retaining walls (MRSRW). These walls are considered to be a good solution especially if the wall’s height need to increase. The main objective of the study was finding the effects of tiers horizontal distance, offset distance between adjacent tiers and number of tiers on the lateral deflection of the wall facing as well as ultimate bearing capacities of a strip footing located at top of the wall. In this study, a small scale experimental programme on MRSRW were carried out where a total of 12 experiments were performed under static loading condition. The results showed that by increasing the tiers’ width and number of tiers in MRSRW, the horizontal deflection and settlement of footing on the crest of the wall was considerably reduced. Besides, when the tires’ width increased, the lateral deflection along the wall height was significantly reduced, especially at top of the wall. The result indicated that in order to attain the highest interaction between the top and bottom sections of the MRSRWs, having four reinforcement layers and one tier (with tier’s width/wall’s height ratio equal to 0.35) can provide the best result in regard to both lowest lateral deflection and highest bearing capacity of footing installed at top of the wall.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
51
v.
4
no.
2019
713
724
https://ceej.aut.ac.ir/article_3013_1c1f8d78a97f5a11aeccf8148c8816b7.pdf
dx.doi.org/10.22060/ceej.2018.13915.5509
Evaluation of Factors Affecting Carrying Capacity of Laboratory Flotation Column Treating Copper Sulfides
mehdi
Irannajad
Mining & Metallurgical Eng. Department
author
رحمان
سلطان پور
دانشکده مهندسی معدن و متالورژی، دانشگاه صنعتی امیرکبیر
author
فردیس
نخعی
null
author
text
article
2019
per
One of the necessary parameters in designing and scaling up flotation columns is carrying capacity (Ca ) which can be determined in terms of mass of solids per unit time per unit column cross-sectional area. The prediction of Ca for a given flotation technology has been commonly achieved using a simplified expression based on a representative particle size and density of the floatable material, regarding several assumptions in limited data ranges. In determining the Ca , the effect of operational parameters, such as particle size, pulp solids rate, bubble diameter, air flow rate, pulp solid content, frother dosage and froth height should be considered. In this study, the effect of these parameters on the Ca was investigated in column flotation. The studied sample was obtained from rougher circuit concentrate of Sungun copper complex flotation plant. It was found that when the pulp solid rate increased up to 1.4 cm/s, more surface of bubbles is covered by entering more solid particles to the column and Ca increased, but it decreased in higher rates. In lower speed of input pulp, the increase of frother dosage led to higher Ca , but in pulp rate higher than 1.2 cm/s, the maximum Ca was obtained in frother dosage of 45 ppm. By decreasing the froth height and increasing the solid percent up to 30%, Ca increased. Likewise, the results of the experiments with particles of different size distribution showed that the input pulp with size 44-63 μm had the maximum Ca.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
51
v.
4
no.
2019
725
732
https://ceej.aut.ac.ir/article_2785_a0bf1535a6dc20f37ef770ac5b39eef3.pdf
dx.doi.org/10.22060/ceej.2018.12464.5218
A Mixed Analytical Approach based on Semi-Timoshenko Planar Fiber Frame Element and Modified Compression Field Theory in RC Structures
Behrooz
Yousefi
Civil Engineering Department, Ferdowsi University of Mashhad, Mashhad, Iran
author
Mohammadreza
Esfahani
Department of Civil Engineering, Ferdowsi Unversity of Mashhad
author
Mohammad Reza
Tavakolizadeh
Civil Engineering Department, Ferdowsi University of Mashhad, Mashhad, Iran
author
text
article
2019
per
An accurate assessment of the behavior of structures by an analytical method should be able to estimate the initial stiffness of the structure, the maximum capacity and the local and global ductility. In this research, in order to simulate the nonlinear behavior of reinforced concrete structures under monotonic loading, a new fiber beam-column element was developed with a displacement control method using linearized arc-length approach. The formulation of the implemented element was based on the combination of Bernoulli and Timoshenko’s theory along with the axial, flexural, and shear interaction effects of each element. The cross-sectional area of each element in Gaussian points was equivalent to a set of discrete fibers with uniaxial constitutive behavior in the process of nonlinear solution. Also, in order to consider the elemental shear deformation, the four-way smeared cracked approach and the modified compression field theory (MCFT) was considered in nonlinear shear analysis using the direct-displacement control algorithm in the main sub-program. The reference configuration of numerical formulation was considered according to the configuration of the previous step and the initial configuration, simultaneously. The analytic approach of the algorithm had the ability to change the updated Lagrangian formulation to the total Lagrangian in accordance with the problem-solving convergence. The developed fiber element was validated by numerous experimental experiments and the evaluation of the proposed analytical method was tested. The proposed method led to an appropriate solution and an acceptable convergence process with high processing speed for problems with mixed combinational mechanisms.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
51
v.
4
no.
2019
733
748
https://ceej.aut.ac.ir/article_2904_9eeccfbab7627499362122bc821ef289.pdf
dx.doi.org/10.22060/ceej.2018.14017.5536
Laboratory Study of the Effects of Step Number, Slope and Particle Size on Energy Dissipation in Gabion Stepped Weirs
Sina
Razi
PhD candidate, University of Tabriz, Tabriz-Iran
author
Farzin
Salmasi
Tabriz University, Agricultural faculty, Irrigation department
author
Ali
Hoseinzade Dalir
Professor, University of Tabriz, Tabriz-Iran
author
text
article
2019
per
Gabion stepped weir is a simple hydraulic and environment friendly structure that can be used to dissipate flow energy in downstream of dams or to control downstream erosion of various structures. Most researches have been related to concrete and rigid stepped spillways, so studies on gabion stepped weirs are very small. In this research, using the experimental method and physical model, various components that affected the energy loss in gabion stepped weirs were studied and comparisons with other studies by researchers were also made. The flow passes in gabion stepped weir was carried out both in overflow and inflow (both simultaneously) and the amount of energy dissipation along the structure was calculated based on the energy relation. In this study, completely uniform particles with three diameters (d50) of 10, 25 and 40 mm were used. The height and width of physical models made of gabion stepped weirs were 60 cm and 40 cm respectively, with stairs of 3, 6 and 12 and height of stairs 5, 10 and 20 cm and the slope of the weirs are 1:1, 1:2 and 1:3 (2 and 3 horizontals, 1 vertical). In the gabion stepped weirs, the downward slope of the weir had a negligible impact on the energy dissipation. As the number of steps increased (for constant h/l), the energy loss was decreased. The average diameter of the particles of 10 mm for y0/Hw<0.92 and the average diameter of the particles of 40 mm for y0/Hw>0.92 had the highest of relative energy loss. Due to the fact that the stone materials used in this research are of a broken type, it is recommended that further research be carried out on round stone materials.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
51
v.
4
no.
2019
749
756
https://ceej.aut.ac.ir/article_2865_6efe898e2e642347410549ff01c044fe.pdf
dx.doi.org/10.22060/ceej.2018.13984.5527
Seismic Assessment of Steel Frame Bridges and Comparison with Damage Indices
Alireza
Rahaei
Amirkabir University of Technology, Tehran, Iran
author
Ali
Mirzazade
دانشگاه صنعتی امیرکبیر
author
Negin
Sadeghi
Civil Engineering,Amirkabir university,Tehran,Iran
author
text
article
2019
per
Vulnerability assessment and seismic retrofit of bridges as lifelines are of great importance. In recent years, performance-based procedures in bridges are taken into consideration by researchers. In this paper after evaluation of proposed methods for seismic performance assessment of bridges, a laboratory model of box-shaped steel bridge piers was analyzed for verification and results were compared with a tested model’s data. Then based on the properties of a real bridge, several bridges’ models were designed for parametric studies. The mentioned bridge is continuous and consists of steel moment frames in a longitudinal direction. Further, after evaluating performance levels of the bridges, obtained results were compared with damage indices and the difference between structural specifications and mentioned indices were indicated. The nonlinear static analysis procedure was utilized to analyze the models. Energy, effective stiffness and Park-Ang damage indices were employed to evaluate damage. Independence of indices from geometric changes of structures, the high adaptation of Park- Ang index with energy index due to use of energy as a common concept and more accurate results of energy damage index in each performance level were some of the results.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
51
v.
4
no.
2019
757
766
https://ceej.aut.ac.ir/article_3098_90d2e6fe96ab3a816c9dee0348ad7ca5.pdf
dx.doi.org/10.22060/ceej.2018.10095.4825
Damage Detection of Cable-Stayed Bridges Using Frequency Domain Analysis and Clustering
Ehsan
Darvishan
Assistant Professor, Department of Civil Engineering, Roudehen Branch, Islamic Azad University, Roudehen, Iran
author
text
article
2019
per
Cable-stayed bridges are vital structures which need significant maintenance and repair costs every year. Therefore, health monitoring of such structures can mitigate human and financial losses. In this paper, a damage detection method for cable-stayed bridges was proposed using signal processing and clustering. Since the accuracy of signal processing can considerably affect the accuracy of damage detection results, in the first part of the paper, a comparison was carried out between the popular FDD method and two newer AFDD and TDD methods, which were improved some of the FDD drawbacks. Then, the most effective method was selected. Among these procedures, FDD was successfully implemented in signal-based procedures. However, the two newer ones had not adequately investigated in comparison to FDD. In the second part, by using competitive neural network for clustering, a new damage index was introduced by calculation of the Euclidian distances of cluster centers. Results showed that the proposed damage detection algorithm can differentiate healthy and damage states with acceptable accuracy.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
51
v.
4
no.
2019
767
780
https://ceej.aut.ac.ir/article_2960_661b13e0da35db50fefc957711d8c900.pdf
dx.doi.org/10.22060/ceej.2018.14141.5568
1D Numerical Modeling of Sediment Pattern in Settling Basins
Hamed
Sarveram
Department of Civil engineering, Zanjan Branch, Islamic Azad University, Zanjan, Iran.
author
Fatemeh
Rostami
Department of Civil engineering, North Tehran Branch, Islamic Azad University, Tehran, Iran.
author
Mehdi
Shahrokhi
Department of Civil engineering, Ghiaseddin Jamshid Kashani Higher Education, Iran
author
text
article
2019
per
Settling basins are one of the most important structures, which are commonly used for deposition of sediment particles in water and wastewater systems in order to prevent the damage of sediment particles. The purpose of this study was to provide a one-dimensional numerical model for simulating flow and sediment in a rectangular settling basin. The governing equations are depth averaged equations of flow and sediment transport. In order to the numerical solution, the finite difference method has been used. The model can be used for non-uniform flow and non-uniform particles and may predict important information such as removal efficiency, thickness, and distribution of particle size of sludge. Comparison of the results of the proposed numerical model with the results of other researchers stated the acceptable accuracy of the proposed model, so that in all cases the error rate was less than 3%. The results of the sensitivity analysis showed that more than 50% of suspended sediment was deposited at the first 5 meters of the basin; therefore, the increase in the dimensions of the rectangular reservoir was not the best way to improve the performance of the pond. In fact, increasing the removal efficiency can be achieved by reducing the depth of the settling basin, increasing the cross-sectional area of flow and reducing the surface loading rate.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
51
v.
4
no.
2019
781
792
https://ceej.aut.ac.ir/article_2940_34f79e5fbe357e149122bd79fff6be6b.pdf
dx.doi.org/10.22060/ceej.2018.13948.5517
Prediction of the Stress-Strain Behavior of MSW Materials Using Hyperbolic Model and Evolutionary Polynomial Regression (EPR)
Mohsen
Keramati
Assistant professor, Faculty of Civil Engineering, Shahrood University of technology
author
Hossain
Moradi Moghaddam
M.Sc. Student, Faculty of civil engineering, Shahrood university of technology
author
Amin
Ramesh
M.Sc. Student, Faculty of civil Engineering, Shahrood University of Technology
author
text
article
2019
per
In recent years, the rupture of landfill centers has resulted in the importance of studying the behavior of municipal solid waste (MSW). MSW as the main constituent element in landfills has a complicated performance. In this study, by using the results of large–scale direct shear experiments with dimensions of 300 mm*300 mm*150 mm, 2 models to predict the behavior of MSW with ages of fresh and 3 months were presented. The purpose of this investigation was prediction of MSW stress-strain behavior for kahrizak landfill as a sample of developing countries landfills under aging and by structural models. These models were Hyperbolic model and Evolutionary Polynomial Regression (EPR). In these collection of experiments, aging process up to 3 months was artificially applied to samples. Three normal stresses 20, 50 and 100 kpa along with three shear displacement rates of 0.8, 8 and 19 mm/min were used for samples with different ages. The results of these two models showed high accordance with experimental results by direct shear apparatus, in addition to predict MSW behavior under aging and degradation. Finally, this study stated the advantage of EPR model relative to Hyperbolic model in higher accuracy for all experiments.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
51
v.
4
no.
2019
793
804
https://ceej.aut.ac.ir/article_2993_fe0f79ce4d46bdc03cf79163f175be02.pdf
dx.doi.org/10.22060/ceej.2018.13955.5519
Mapped Moving Least Squares Approximation Used in Mixed Discrete Least Squares Meshfree Method
Morteza
Kolahdoozan
دانشکده عمران
author
Ehsan
Amani
Department of Mechanical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Tehran, Iran
author
Saeb
Faraji
Department of Civil and Environmental Engineering, Amirkabir University of Technology (Tehran Polytechnic), Tehran, Iran
author
text
article
2019
per
The Mixed Least Squares Meshfree (MDLSM) method has shown its appropriate efficiency for solving Partial Differential Equations (PDEs) related to the engineering problems. The method is based on the minimizing the residual functional. The residual functional is defined as a summation of the weighted residuals on the governing PDEs and the boundaries. The Moving Least Squares (MLS) is usually applied in the MDLSM method for constructing the shape functions. Although the required consistency and compatibility for the approximation function are satisfied by the MLS, the method loses its appropriate efficiency when the nodal points cluster become too much. In the current study, the mentioned drawback is overcome using the novel approximation function called Mapped Moving Least Squares (MMLS). In this approach, the cluster of closed nodal was pointed maps to standard nodal distribution. Then the approximation function and its derivatives were computed incorporating some consideration. The efficiency of suggested MMLS for overcoming the drawback of MLS was evaluated by approximating the mathematical function. The obtained results showed the ability of suggested MMLS method to solve the drawback. The suggested approximation function was applied in MDLSM method, and used for solving the Burgers equations. Obtained results approved the efficiency of suggested method.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
51
v.
4
no.
2019
805
816
https://ceej.aut.ac.ir/article_3018_ee45eb8b3e1064f8e1d86fc332a70338.pdf
dx.doi.org/10.22060/ceej.2018.13861.5505
Study of Geotechnical Parameters Uncertainties in Analysis of New Tunnel Construction Over the Existing Tunnel
Mahsa
Tajdid Khaje
Department of Geotechnical Engineering, Faculty of Civil Engineering, University of Tabriz
author
Masoud
Ranjbarnia
Department of Geotechnical Engineering, Faculty of Civil Engineering, University of Tabriz, Tabriz, Iran
author
Vahid
Nourani
Department of Water Engineering , Faculty of civil Engineering, University of Tabriz
author
text
article
2019
per
This paper aims to study the problem of a new tunnel construction over – crossing the existing tunnel through the probabilistic point of view. Metro line-7 tunnel above-crossing line-6 tunnel in Tehran was chosen as a case study project. The numerical modeling of the problem was carried out by the FLAC3D software. The parameters of the cohesion and the friction angle of the third layer as well as the surcharge on the ground level were assumed as random variables. Generating the random numbers and fitting the probabilistic distributions to these variables was carried out by the Monte – Carlo method. The displacements at four points of the existing tunnel (line 6) were recorded due to new tunneling, and the appropriate probabilistic distribution was fitted based on the mean, median and skewness of each set of random numbers. According to these probabilistic distributions, the probability of the displacements more or less than a specific displacement can be determined. The results indicate that although input parameters have normal distributions, not all of the outputs have symmetric or normal distributions, and the results of the deterministic method are not the same as the mean values of stochastic approach. As well, the probability of displacements greater than the mean value at the bottom and right side of the existing tunnel is 56 % and 55/5 %, respectively.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
51
v.
4
no.
2019
817
830
https://ceej.aut.ac.ir/article_2918_228bdf4315b416637649ead35916470d.pdf
dx.doi.org/10.22060/ceej.2018.13969.5522