Determination of Discharge Coefficient in Ogee Spillways and Investigation the Effects of Submergence, Upstream Slope and Apron Elevation on Its Variations
Parvaneh
Heidary
University of Tabriz, Tabriz, Iran
author
Farzin
Salmasi
Tabriz University, Agricultural faculty, Irrigation department
author
Hadi
Arvanaghi
Associated Professor, Department of Water Engineering, Faculty of Agriculture, University of Tabriz, Tabriz-Iran
author
text
article
2021
per
Discharge over the ogee spillway is related to the length of crest, upstream total head, and discharge coefficient. Also, the discharge coefficient is influenced by several factors. In this study, some parameters that are affecting the discharge coefficient in ogee weir are investigated. These are ogee spillway upstream slope, apron elevation, and downstream submergence. In this regard, some ogee spillway physical models were fabricated. These models include (1) ogee spillway with vertical upstream face, (2) ogee spillway with inclined upstream face (18, 33, and 45 degrees), (3) ogee spillways with downstream apron elevations (3, 5, 7, and 10 cm thickness) in free flow, and (4) ogee spillway with the vertical upstream slope in submerged flow condition. Results showed that in all the ogee weirs, the discharge coefficient (C) increases with increasing (P/He) and then remain constant. The value of the discharge coefficient decreased from 2.25 (in free flow) to 2.15 (in submerged flow). For a constant value of head over ogee spillways (He), the discharge coefficient decreased with increasing downstream apron elevation and submergence. The relative discharge coefficient had a constant trend at the beginning with parameter (hd/He), then it had a decreasing trend. The threshold value for submergence (hd/He), was 0.75 in the ogee spillway in this study. With increasing relative submergence (hd/He) from 0.75 to 1, the relative discharge coefficient (Cs/C0) decreased from 0.88 to 0.24.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
53
v.
7
no.
2021
2715
2734
https://ceej.aut.ac.ir/article_3774_95408d752b2ee2098f8af3777ee3ae5c.pdf
dx.doi.org/10.22060/ceej.2020.17257.6503
A Micromechanical Inelastic Strain-Damage Constitutive Model Based on Wing- and Secondary- Cracking Mechanisms under Dynamic Loading
Mohammad Hosein
Ahmadi
دانشکده مهندسی معدن و متالورژی، دانشگاه صنعتی امیرکبیر، تهران، ایران،
author
حامد
ملاداودی
دانشگاه صنعتی امیرکبیر
author
text
article
2021
per
For most rock materials, there exists a coupling between inelastic deformations caused by crack displacements on micro-crack faces and damage evolution due to nucleation and growth of wing- and secondary cracks. While rock material is subjected to dynamic loading, the interaction between micro-cracks plays an important role in materials behavior. The self-consistent homogenization scheme is implemented in this paper to consider micro-cracks interaction and determine the equivalent mechanical properties of micro-cracked rock deteriorated by damage evolution. This article aims to develop a self-consistent based micromechanical damage model by taking into account the wing- and secondary-cracking mechanisms accompanied by inelastic strains caused by crack displacements under dynamic compressive loading. While stress intensity factors in tensile and in-plane shear modes at flaw tips exceed the material fracture toughness in modes I and II, respectively, wing- and secondary cracks are sprouted and damage evolution occurs. For closed cracks, an appropriate criterion for the secondary-crack initiation is proposed in this paper. The developed model algorithm is programmed in the commercial finite difference software environment for numerical simulation of rock material to investigate the relationship between the macroscopic mechanical behavior and the microstructure. The fracture toughness parameters of the rock samples are experimentally determined. The rock microstructure parameters (average initial length and density of flaws) are studied using scanning electron microscopy. To verify the developed model, a series of numerical simulations are carried out to numerically reproduce the Split-Hopkinson pressure bar test results. The simulation results demonstrate that the developed micromechanical model can adequately reproduce many features of the rock behavior such as softening in the post-peak region, damage induced by wing- and secondary cracks, and irreversible deformations caused by crack displacements on micro-cracks. Furthermore, the softening behavior of rock material in the post-peak region is affected by considering inelasticity and the secondary cracking mechanisms. Therefore, the rock sample simulation with the coupled inelastic-damage model can increase inelastic deformations in the post-peak region as a result of irreversible strains caused by crack displacements on micro-cracks. The simulation by considering the secondary-crack mechanism leads to an increase in the micro-cracking process, damage, and fragmentation in rock material.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
53
v.
7
no.
2021
2735
2764
https://ceej.aut.ac.ir/article_3952_20b46ec1773a8047ca9abf860b23cf00.pdf
dx.doi.org/10.22060/ceej.2020.17456.6568
Parametric Study of Kinematic Interaction in Pile-Cohesive Soil under Dynamic Loads
Mohammad Mehdi
Ahmadi
Department of Civil Engineering, Sharif University of Technology, Tehran,Iran
author
Mohammad Javad
Mashin chian
Ph.D Candidate in Geotechnical Engineering, Faculty of Civil Engineering, Sharif University of Technology, Tehran, Iran.
author
Sadjad
Hadei
Ph.D Candidate in Geotechnical Engineering, Faculty of Civil Engineering, Sharif University of Technology, Tehran, Iran.
author
text
article
2021
per
Pile foundations are widely used to ensure the stability of structures subjected to seismic excitation. Numerous structures and foundations in soil-pile-structure systems have been destroyed during the occurrence of earthquakes. Because of the complexities involved in soil-pile interaction problems and the lack of precise methods, it is necessary to use numerical methods for analyzing soil-pile interaction problems. Several factors are affecting the dynamic response of a pile in the soil-pile system. These factors can be divided into three main categories: geometrical factors, material properties, and load characteristics. Studying the effects and importance of these factors in the response of the pile will help geotechnical engineers to optimize their design. In this research, three-dimensional modeling has been developed using the FLAC3D computer program, and the effects of various soil and pile properties on the dynamic behavior of a single pile in clayey soils are evaluated. One of the most important subjects in the numerical modeling of soil-pile system dynamic response is the constitutive model considered for the soil. This strongly affects the accuracy of results. In this study, a softening model has been used for the behavior of the soil under dynamic loads. Sinusoidal harmonic loading has been applied to the model base as the acceleration time history, and the variations of bending moments, shear forces, and displacements along the pile are obtained for all analyses carried out in this study. The results showed that the kinematic interaction coefficient depends on the loading characteristics and in the high frequencies head pile response was lower than the free field.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
53
v.
7
no.
2021
2765
2780
https://ceej.aut.ac.ir/article_3949_f6bd6bcd2ca3addcc1deed7c8ed44e6e.pdf
dx.doi.org/10.22060/ceej.2020.17487.6580
Pavement Maintenance and Rehabilitation Planning Considering Budget Uncertainty
Amir
Golroo
Transportation group, Civil dept, AUT
author
Amirhossein
Fani
Transportation Engineering, Department of Civil Engineering, Amirkabir University of Technology, Tehran, Iran
author
Hamed
Naseri
Department of Civil and Environmental Engineering, Amirkabir University of Technology, Tehran, Iran.
author
Seyed Ali
MirHassani
Math and computer Science Dept, Amirkabir University of Tech, Tehran
author
text
article
2021
per
Maintenance and rehabilitation planning plays a pivotal role in the implementation of an efficient pavement management system. The variables are generally considered deterministic to solve the problem. Nevertheless, this problem tackles with a high level of uncertainty. For instance, the budget, as one of the essential criteria, is fluctuated owing to resource limitation, and policy alteration. If the budget is taken into account as deterministic, the result of the problem may be considerably different from the absolute optimal solution to the problem. This investigation aims to solve a maintenance and rehabilitation problem by consideration of a novel and powerful uncertainty approach. To this end, a multi-stage integer linear uncertainty model is introduced to find a solution, which is feasible and optimal in all of the uncertainty modes. The case study of this paper is a network, including six pavements. The outcomes indicated that the proposed model is competent to consider budget fluctuation, and it introduces a solution that is optimal for all uncertainty scenarios. The comparison of deterministic and uncertainty models revealed that the number of preventative maintenance selected by the uncertainty model is more than that of the deterministic model. The number of preventative maintenance was increased from 36.67% to 40.91% via considering uncertainty in the problem. It can be postulated that the uncertainty model tries to allocate budget to more segments to reduce the likely negative impacts of budget fluctuation on the project.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
53
v.
7
no.
2021
2781
2800
https://ceej.aut.ac.ir/article_3883_9f608cfba355f3124a408a385cd705d4.pdf
dx.doi.org/10.22060/ceej.2020.17502.6583
Introducing a New Method for the Pavements’ Maintenance and Rehabilitation Planning
hamid
behbahani
Professor, Iran University of Science and Technology
author
Navid
Nadimi
Shahid Bahonar University of Kerman
author
Mostafa
Khaleghi
M.Sc. Iran University of Science and Technology
author
text
article
2021
per
Roads are considered as one of the most extensive civil infrastructures and national capitals of each country. Pavement maintenance and rehabilitation (M&R) management is one of the most important problems, which can help to reduce further costs. Two issues are important in the field of road maintenance and rehabilitation management; the first type of M&R option and then time its application. In this paper, it was attempted to combine prioritization, artificial intelligence, and optimization methods to select the optimal option for the maintenance and rehabilitation of pavement sections at any time interval. For this purpose, the analytical hierarchy process was used to prioritize the branches in the pavement network. In the next step, using a linear programming model, the probability of selecting maintenance and rehabilitation options for pavement sections was maximized considering several specific constraints. A fuzzy inference system was used to determine the probability of selecting each maintenance and rehabilitation option in pavement sections. A case study in Mahan (Kerman) was used to run the proposed model. Based on the results, it can be concluded that the proposed algorithm can consider different parameters and indices for pavement branches and sections. In addition, it offers different scenarios for the selection of M&R options in a year. The model helps to compare various scenarios based on different budgets for each year. In all, the proposed algorithm facilitates the process of selecting M&R options in the different sections of a road network and provides a scientific approach to manage maintenance roads.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
53
v.
7
no.
2021
2801
2820
https://ceej.aut.ac.ir/article_3853_bce5c86e121a819d6c394adef7f1f0c1.pdf
dx.doi.org/10.22060/ceej.2020.17506.6585
Experimental Study of the Effect of Chemical and Biological Stabilization on Clay Subgrade Soil
siamak
shafaghatian
Department of civil engineering-Geotechnical engineering,University of tabriz,Tabriz,Iran
author
gholam
moradi
Department of civil engineering-Geotechnical engineering,University of tabriz,Tabriz,Iran
author
Hooshang
Katebi
Department of civil engineering-Geotechnical engineering,University of tabriz,Tabriz,Iran
author
text
article
2021
per
Chemical stabilization of weak subgrade soil is a viable and essential method of avoiding weak soil replacement problems with selected borrow pit from an economically and environmentally point of view. Although the use of new materials such as polymers instead of traditional materials such as lime accelerates operations and reduces resource pressure, the environmental impact and long-term resistance in these methods are concerns for experts. Recently, according to the “Kyoto Environmental Protocol” recommendation on soil stabilization with geotechnical purposes, research on new biological methods of soil stabilization including "soil microbial stabilization" has been developed. In this study, the effect of clay subgrade stabilization with chemical and biological methods was investigated and compared through different experiments. Cationic polyelectrolyte as a liquid polymer and microbial-induced calcium carbonate precipitation (MICP) was used to stabilize chemically and biologically respectively. In both methods, the specific dry weight of soil decreases, and its optimum moisture content increases. Chemical stabilization increases plastic index and microbial stabilization decreases it. Both materials at low concentrations raise the pH for up to three days. Both materials increase the uniaxial compressive strength and elasticity modulus of the soil almost equally. In terms of project economy (time and cost), chemical stabilization with cationic polyelectrolyte, and terms of environmental issues, the MICP method is suitable for the studied soil.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
53
v.
7
no.
2021
2821
2836
https://ceej.aut.ac.ir/article_3793_724affa95515da8bffe4ea9e7516a8f7.pdf
dx.doi.org/10.22060/ceej.2020.17493.6588
Capability Evaluation of Hybrid Wavelet-Principal Component Analysis-Random Forest Approach in Simulating the River Flow
Fariba
Azarpira
Water engineering department, Faculty of civil and surveying engineering, Graduate University of Advanced technology, Kerman, Iran
author
Sajad
Shahabi
Water Engineering Department, Civil and surveying engineering Faculty, Graduate University of Advanced Technology
author
text
article
2021
per
Simulating the flow for managing the water allocation in drought and wet periods is of great importance. According to the researches conducted during several decades in this regard, computational intelligence methods combined with wavelets are known to be effective. In this paper, Wavelet-Principal Component Analysis-Random Forest (WPCARF) hybrid approach is proposed to model the daily flow of the Polroud river. In the proposed model, first, hydrometric data is preprocessed by wavelet transform and applied to the PCA along with meteorological data. Afterward, their output vectors were entered into the random forest network. The results have shown that the PCA algorithm can improve the performance accuracy and speed of the model, despite reducing the input vectors and simplifying them. Also, it can integrate a model with increased simulation time and input vectors uncertainty having a lower impact on model capability leading to a more uniform decreasing trend. Furthermore, preprocessing the data accompanied by PCA could enhance the agreement index by 5 and 8 percent during one and three days of the simulation and increase the model ability for a more accurate simulation of river flow. On the other hand, results for the best-proposed hybrid model during the one-day-ahead simulation time were R=0.911 and RMSE=7.095 m3/s, while these values were R=0.817 and RMSE=8.681 m3/s in the best hybrid model for three-day-ahead simulation time. This indicates the adequate capacity of the proposed hybrid model for long-term simulation times.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
53
v.
7
no.
2021
2837
2850
https://ceej.aut.ac.ir/article_4116_1ee240f9d9459f80c3da305ad5edb429.pdf
dx.doi.org/10.22060/ceej.2020.17520.6589
Experimental Study of Flexural Strengthening of Two-way Reinforced Concrete Slabs Using Punched Steel Plates
saeed
sahranavard
civil engineering department, faculty of engineering, ferdowsi unversity, mashhad
author
hasan
hajikazemi
department of civil engineering, faculty of engineering, ferdowsi university of Mashhad
author
text
article
2021
per
RC slabs are the structural members responsible for carrying and transferring loads. RC slabs need to be strengthened as a result of different reasons such as changing of function and corrosion of steel bars. The most widely utilized approach in strengthening these slabs has been the usage of steel plates. However, the concerns in using these plates consist of their immense weight as well as their unreliability in being properly connected to the concrete slabs. This study focuses on using punched steel plates as a strengthening factor for concrete slabs since they have reduced weight and allow an easier and more reliable connection. For the experiment, two-way RC slabs with the dimensions of 120 cm and the thickness of 8 cm are strengthened through punched steel plates and are placed under a semi-concentrated loading effect. The effect of plates’ thickness, the arrangement and the area of the punched holes, and the connection type in the performance of the strengthening system are studied through load-displacement graphs and are analyzed in dissipated energy and ductility. The results showed that the punched strengthening plates increase loading capacity, energy absorption, and the ductility of the two-way slabs up to 62%, 253%, and 220%, respectively. Also, it was shown that the arrangement of the holes and the connection type of the strengthening plates have a significant effect on the performance of the strengthening system. Failure state control in experimental models showed that the failure mode in using epoxy resin is the debonding of the steel plate, while the failure mode in using expansive bolt is pulled out of the bolt.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
53
v.
7
no.
2021
2851
2868
https://ceej.aut.ac.ir/article_3894_5c7f748537bf0a9853ea5760ab9e02ca.pdf
dx.doi.org/10.22060/ceej.2020.17529.6591
Analytical Review of Risk Triggers in the Design Phase of D&B Contracts
Ahad
Nazari
Associate Professor, University of Shahid Beheshti/School of Architecture,tehran,iran
author
Majid
Parchami Jalal
University of Tehran/ School of Architecture
author
Omid
Ahmad soltani
Project management and constructions, civil engineering, mehralborz higher education institute,Tehran, Iran
author
text
article
2021
per
Nowadays, improvement of the project management knowledge and developing the management methods, decrease the probability of the failure of the project. One of the most important processes that affect project goals is project risk management. Identifying and managing the risk triggers is an effective method in project risk management. Many years have passed since this concept was introduced but its application is so limited yet. This research endeavors to develop and make a better understanding of this concept as the main goal. Recognition and managing of this phenomenon help the project risk management process. It makes the best decision for having the right time to adopt a strategy and ultimately it reduced the negative impact of risk-taking on the project. Moreover, the type of contract always plays an important role in the raising of the risk. Therefore, in this study, it is selected to develop a concept of risk trigger phenomenon, in D&B contract which has many benefits and client's tendency. To explain the status and importance of risk triggers, its relationship with several important risks has been qualitatively analyzed. For this purpose, through library studies and existing sources, common risks of these types of contracts and their indicators have been identified and compiled. Moreover, by interviews with experts on risk and risk triggers, some important risks are identified and validated. Finally, a functional table of risk triggers is presented that is a great help to stakeholders in being prepared to respond to the risk triggers.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
53
v.
7
no.
2021
2869
2888
https://ceej.aut.ac.ir/article_3856_7de7e3ffadd378e16abc448d972ab633.pdf
dx.doi.org/10.22060/ceej.2020.17512.6592
Dynamic Behavior of Composite Floor Consisting Profiled Steel Sheet and Dry Board under Explosion Load
Farhad
Abbas Gandomkar
Department of Structure-Faculty of Civil-Jundishapur University of Technology-Dezful-Iran
author
Saeed
Parsafar
Department of Structure-Faculty of Civil-Jundishapur University of Technology-Dezful-Iran
author
vahid
razavi toosi
Department of Structure-Faculty of Civil-Jundishapur University of Technology-Dezful-Iran
author
Negar
Samimifard
Department of Structure-Faculty of Civil-Jundishapur University of Technology-Dezful-Iran
author
text
article
2021
per
One of the kinds of structural floor systems is consisting of profiled steel sheet and dry board which is connected by self-drilling and self-tapping screws. This research aims to study the behavior of mentioned floor under explosion load. For this purpose, effects of various parameters such as the thickness of the dry board and profiled steel sheet, kind of dry board, screw spacing, boundary conditions, floor dimensions, using of double profiled steel sheet and dry board, and also weight and distance of explosive material from the center of the floor, on the nonlinear dynamic behavior of the mentioned floor are studied. This study was performed by using the numerical finite element method taking advantage of ABAQUS software. The research results showed by varying parameters such as thickness and kind of dry board, dimensions and boundary conditions of the floor, using of double profiled steel sheet and dry board, and also distance and weight of explosive materials, significant changes are created in maximum displacement and strain energy of floor. But, varying other above-mentioned parameters did not create important changes in them. The profiled steel sheet and dry board reached their yield stresses under various conditions, though in many conditions they did not reach their yield stresses. The results of current research present great help to researchers and designers in identification effective and ineffective parameters on the behavior of studied floor under explosion load.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
53
v.
7
no.
2021
2889
2908
https://ceej.aut.ac.ir/article_3888_00e1fb29448401b81ad0cbafafd88e98.pdf
dx.doi.org/10.22060/ceej.2020.17546.6595
Site Selection of Construction Waste Landfill Based on Combination of Fuzzy AHP and Geospatial Information System (GIS) (Case Study: Qazvin, Iran)
Mozaffar
Khademi Shiraz
M.Sc. of Islamic Azad University of Science Research Branch
author
Mehdi
Ravanshadnia
Associated Professor of Islamic Azad University Tehran Science and Research Branch
author
Afshin
Khoshand
Assistant Professor at K N Toosi University of Tech.
author
Hamidreza
Abbasianjahromi
Assistant Professor at K. N. Toosi University of Technology
author
text
article
2021
per
Today, with the increasing urban development, construction waste is a major problem for urban life. The city of Qazvin is no exception to this, and researching an optimum landfill site is an important necessity. The purpose of this research is to optimum site selection areas for landfill Construction wastes using the geospatial information system (GIS) in a boundary area of Qazvin County which taking into account the terms and conditions of organizations such as the Municipality, Waste Management, and Environmental Protection Organization. In this study, 16 layers of information including geology, soil type, and permeability, landuse, climate, river distance, distance from protected areas, aspect, etc. in the boundary of Qazvin County were used. After producing the preliminary maps, the sub-criteria of each information layer are classified and evaluated and the values are converted to fuzzy values between zero and one. Then, the fuzzy analytic hierarchy process (FAHP) method has been used to determine the absolute weight of each information layer and by integrating and overlapping weighted layers, a suitability mapof the construction landfill site for Qazvin city is produced.According to the suitability map, sites for landfill were identified in five distinct zones, and fields with high area among fields of the fifth zone (with value 9) were suggested as the best landfill site for 40 years. The results showed that northwest of Qazvin due to good soil type, suitable landuse, distance from rivers, faults, and access to communication road and dry climate could be the most suitable site for landfill.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
53
v.
7
no.
2021
2909
2920
https://ceej.aut.ac.ir/article_3945_03d8da6d1152c25aee6b0a72b11f9508.pdf
dx.doi.org/10.22060/ceej.2020.17555.6599
The Effect of Shrinkage Reducing Admixture on the Behavior of Concrete used in Concrete Pavements
masood
gholami
highway and transportation engineering, department of civil and environmental engineering, amirkabir university of technology
author
Fereidoon
Moghadas Nejad
Dep. of Civil Engineering, Amirkabir University of Technology, tehran, iran
author
Aliakbar
Ramezanianpor
department of civil and environmental engineering, amirkabir university of technology, tehran, iran
author
Amir mohammad
Ramezanianpour
Tehran university, tehran, iran
author
text
article
2021
per
Concrete pavements are widely used by pavement engineers due to their advantages over flexible pavements such as long lifetime, good performance and durability, etc. However, concrete pavements represent some drawbacks such as shrinkage that increases the tensile stress in concrete, which may lead to cracking, warping, etc. Drying shrinkage is the most important type of shrinkage in concrete pavements. To prevent or reduce the amount of cracking, shrinkage reducing admixture (SRA) can be used. This admixture controls shrinkage by reducing water surface tensile in capillary tubes. In this study, the effect of shrinkage reducing admixture on the behavior of concrete used in concrete pavements was investigated. Slump, compressive strength, third-point flexural strength, electrical resistance, skid resistance, free shrinkage, and restrained shrinkage by ring test were performed. Two water-cement ratios of 0.35 & 0.4 were used for mix design and the percentage of shrinkage reducing admixture used in mixtures was 2% by weight of cement. The results showed that the use of SRA had a negligible effect on workability. Also, the use of SRA caused about a 10% reduction in compressive and flexural strength and electrical resistance. Furthermore, a reduction of 10% and 20% was observed in free and restrained shrinkages, respectively, followed by a 40% reduction in crack width and more than one-week delay in the occurrence of the first crack. Finally, no certain relationship was observed between the usage of SRA and variations of the skid resistance of concrete pavements.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
53
v.
7
no.
2021
2921
2936
https://ceej.aut.ac.ir/article_3886_efa2ea6aa073312a1d7bd75b051cbd61.pdf
dx.doi.org/10.22060/ceej.2020.17542.6600
Numerical and Experimental Investigation of Optimal Soil Improvement with Lime and Cement and Its Impact on Reduction of Settlement in West Tehran Wastewater Treatment Plant
Masoud
Zabihi-Samani
Iran University of Science and Technology: Tehran, Tehran
author
seyed mostafa
daryabari
Master of Science Parand Branch, Islamic Azad University, Parand, Iran.
author
Seyed Aboulfazl
Daryabari
Master of Science, Tarbiat Modares University
author
Alireza
Mirhabibi
Islamic Azad University,Parand Branch
author
text
article
2021
per
In this research, lime and cement additives were used to stabilize clay and therefore to reduce the settlement in raft foundations. Lime and cement were mixed with clay and the effect of the use of these two additives on the stabilization of fine clay soil in the laboratory was investigated. Soil samples in normal state and combination with different percentages of lime and cement equal to 3%, 6%, and 8% dry weight of soil for laboratory tests including Atterberg limits test, grading test, standard compaction test, uniaxial compressive strength test, and California bearing ratio test. Also, the consolidated undrained triaxial compression strength test (CU) and direct shear tests were used. The results showed a decrease in the plasticity and maximum dry density of soil and an increase in optimum moisture content, compressive strength, and also the California bearing ratio of clay by adding these two materials. The cohesion and internal friction angle obtained from consolidated undrained triaxial compression strength tests (CU) and direct shear tests increase with increment of cement and lime percentages. After laboratory tests, the effects of the use of soil improvement with depths of 1m, 2m, 4m, 6m, 8m, and 10m using Plaxis2D software suggests that as the depth of improvement increases, the number of settlement decreases, which is a lot different from that of the plate loading test before improvement while the difference between the results obtained from Plaxis2D and plate loading test after improvement is negligible.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
53
v.
7
no.
2021
2937
2956
https://ceej.aut.ac.ir/article_4131_d822efdc2b7c581245ebe47d415770b0.pdf
dx.doi.org/10.22060/ceej.2020.17574.6607
Code Investigation and Experimental Study of Wide Beam-Column Connections
Ali
Pakzad
PHD candidate,school of Civil Engineering, University of Tehran, Tehran, Iran
author
Khan Mohammadi
Mohammad
Associate professor, school of Civil Engineering, University of Tehran, Tehran, Iran
author
text
article
2021
per
In this paper, the seismic behavior of wide beams was investigated. First, code provisions and results of previous tests on reinforcement concrete wide beam-column connections were reviewed. After a precise investigation of previous test results and a detailed study of the behavior of wide joints, 4 specimens of exterior wide beam-column connections on a scale of 3:5 were cast and tested under constant axial and cyclic lateral loads. The specimens were designed and detailed under ACI 318-14 and ACI 352R-02. In tested specimens, different geometries for columns (square, rectangular or circular) and spandrel beams (wide or conventional) were considered. During the tests, the formation of the full-width flexural plastic hinge of wide beams was observed in all the specimens without any shear or torsional failure. Energy absorption of specimens was relatively high and that is because of using stirrups at the joint area and axial loads applied to columns. The width of the spandrel beam and geometry of columns influenced the seismic performance of tested specimens. A comparison between experimental results and ACI provisions showed that dimensional limitations of ACI 318 on wide beams can be violated. Also, in wide joints with an axial load ratio greater than 15%, the bond performance of column longitudinal bars is improved, and ACI 352R provisions in this context can be relaxed.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
53
v.
7
no.
2021
2957
2976
https://ceej.aut.ac.ir/article_4144_d0d080010329341f09559416921fcd0f.pdf
dx.doi.org/10.22060/ceej.2020.17588.6612
Nonlinear Free Vibration Analysis of Granular Soil Layer Using Perturbation Technique
Ali
Shirzad
Civil engineering, engineerin,kharazmi,Tehran,Iran
author
Amir
Hamidi
civil engineering department, Kharazmi University, Tehran, Iran
author
S.A.A.
Hosseini
Mechanical engineering department, faculty of engineering, Kharazmi University, Tehran, Iran.
author
text
article
2021
per
In this study, an experimental model has been proposed to determine the dynamic deformation properties of cemented and non-cemented granular soils and then the natural frequency of one-layered, homogeneous and horizontal surface alluvium under the influence of one-dimensional harmonic vibrations was studied. The proposed model is very compatible with laboratory results in a wide range of grain soils. The natural frequency of a one-degree-of-freedom system was determined analytically, and the results showed that it has careful accuracy. The analytical method to determine the response of a one-degree-of-freedom system has a very good agreement with the numerical method such as the Runge-Kutta method. In the present study, considering the one-layered alluvium as a lumped mass system and nonlinear spring and nonlinear damping, a clear solution of this system of a one-degree-of-freedom has been proposed. On the other hand, the natural frequency can not only be a function of the depth of the alluvium layer and can be considered as a function of time.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
53
v.
7
no.
2021
2977
2994
https://ceej.aut.ac.ir/article_4120_d1d2706d495cf5c81dc81c3c09e76a1b.pdf
dx.doi.org/10.22060/ceej.2020.17605.6614
Effect of Structural Parameters on Failure Probability of Piers in Seismic Isolated Concrete Bridges
Mahmoud R.
Shiravand
Shahid Beheshti University
author
Mohammad
Vasef
Shahid beheshti Un.
author
text
article
2021
per
Bridges are a critical part of the urban and suburban transportation network, so they are supposed to be designed to sustain earthquake-induced damages to be utilized after the earthquake. Various parameters can affect the behavior and probability of failure of a bridge and the present work aims to evaluate the effects of structural parameters on the probability of failure in isolated concrete bridges. OpenSees software is used for simulating and analyzing 16 different bridge models. Incremental dynamic analysis is conducted using this software and IDA and fragility curves of models are derived and presented. The results showed that the probability of failure decreases with the increase of the pier diameter, concrete compressive strength, yield strength of longitudinal rebar, and diameter of longitudinal bars. Also increasing the stiffness of the elastic isolator and decreasing the confined diameter of the pier resulted in increasing the probability of failure. Furthermore, results revealed that the probability of failure is more sensitive to the variation of pier confined diameter, yield strength of longitudinal rebar, the diameter of longitudinal bars, and the stiffness of elastic isolators in comparison with the variation of concrete compressive strength.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
53
v.
7
no.
2021
2995
3016
https://ceej.aut.ac.ir/article_4130_b8b211b591295b2629b3eee70fdce6be.pdf
dx.doi.org/10.22060/ceej.2020.17505.6617
The behavior of Oil-Contaminated Sands in CBR Test
Masoud
Nasiri
Razi University
author
mohammad
hajiazizi
Razi University/Dep. of Engineering/Civil Eng.
author
ahmad reza
Mazaheri
Civl Eng./University of Ayatollah Borujerdi
author
text
article
2021
per
Several factors affect the bearing of a load of natural and engineered embankments and slopes including the crude oil leakage, leading to a severe decrease in resistance. This is especially important for oil-rich countries, such as Iran, which have several crude oil resources. The main purpose of this study is to investigate the load-bearing (i.e., load versus settlement) and strain-stress behavior of crude oil contaminated sandy soils using the California bearing ratio (CBR) test. In this paper, 10 different types of sand with different characteristics were used. At first, a series of CBR experiments were performed for natural sands (i.e. clean sands) and then contaminated sands with 6% crude oil tested under similar conditions and densities to obtain the reduction in bearing a load of crude oil-contaminated sands quantitatively. Experimental results showed that bearing the load of sand containing 6% of crude oil decreased at least 50% compared to clean sands and the stress-strain diagram of these contaminated soils would decrease significantly. Based on the results of the investigation, it can be stated that particle shape (sharpness or roundness), coarse particle ratio, and finally the type of aggregation influences the resistance of crude oil contaminated sands. It was also found that standard Ottawa sand had an 83% reduction in strength and sand with a coarse particle had a 57% decrease in strength. Sand contaminated with crude oil experienced a severe loss of bearing capacity, so in designing foundations and engineering structures, greater safety factors should be considered, where there is a risk of crude oil leakage.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
53
v.
7
no.
2021
3017
3028
https://ceej.aut.ac.ir/article_3991_d1ba83414b35b9835edfc45ef2a2333d.pdf
dx.doi.org/10.22060/ceej.2020.17628.6625
Analyzing the Use of Molasses as an Alternate and Optimal Culture Medium in MICP Process of Sandy Soils
Jafar
Bolouri Bazaz
Civil Engineering Dept. Ferdowsi University of Mashhad
author
Mohammad Taghi
Bolouri Bazaz
Ferdowsi University of Mashhad
author
Seyyed mohsen
karrabi
Department Of Civil Engineering, Faculty Of Engineering, Ferdowsi University Of Mashhad
author
text
article
2021
per
The use of different soil improvement methods has always been accompanied by an assessment of the effect on strength parameters, costs, and environmental impacts. Since the new and eco-friendly methods are associated with a high initial cost, optimizing these methods to commercialize them is the priority of research projects. The use of biological methods for soil improvement, despite its high environmental compatibility, has not been welcomed from the economic point of view in most parts of the world and is still being considered as an academic and not an executive method. Soil improvement, using calcium carbonate sedimentation is one of the most environmentally friendly biological methods. One of the most influential bacterial suspension parameters for calcium carbonate treatment is its culture medium, usually Nutrient Broth or Yeast extract. One of the ways to reduce the cost of biodiversity in the soil is an alternative culture medium. In this research, the use of sugar beet molasses, which is a waste of sugar and sugar factories, has been investigated as a suitable culture medium for biological improvement along with other culture media. It can reduce the cost of producing a suitable culture medium by up to 500 times. The success of soil regeneration after bacterial cultivation has been also evaluated in the present research.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
53
v.
7
no.
2021
3029
3050
https://ceej.aut.ac.ir/article_4136_d108189b1cb23c8bb71f1b138cf58bf3.pdf
dx.doi.org/10.22060/ceej.2020.17631.6630
Seismic Behavior Assessment of RC Precast Frame Damaged in Bojnord Earthquake 2017 Considering Soil-Structure Interaction Effects
Mahdi
Adibi
School of Civil Engineering, Faculty of Engineering, University of Bojnord, Bojnord, Iran
author
Alialbar
Yahyaabadi
School of Civil Engineering, Faculty of Engineering, University of Bojnord, Bojnord, Iran
author
Roozbeh
Talebkhah
Department of Civil Engineering, Faculty of Engineering, University of Bojnord, Bojnord, Iran
author
text
article
2021
per
Experiences of previous earthquakes show the effects of soil-structure interaction and behavior of beam-column connections on the seismic behavior of the building structures. In this research, seismic vulnerability assessment of RC precast Frames is investigated by consideration of the effect of soil-structure interaction and nonlinear behavior of beam-column connections. The RC precast building represented in this study, damaged in the Bojnord earthquake 2017 and located on the soil type II of Iranian seismic design code. The soil-structure interaction is modeled using the Beam-on-Nonlinear-Winkler foundation. In this procedure, an array of vertical q–z springs are used to capture vertical and rotational resistance of the foundation, while two springs, namely p–x and t–x, are placed horizontally to capture the passive and sliding resistance of the foundation, respectively. The seismic vulnerability and performance of RC precast frames are evaluated using nonlinear static pushover, nonlinear dynamic time-history analyses, and incremental dynamic analyses (IDA). The numerical models are developed using OpenSees software by consideration of the nonlinear behavior of the beam-column joints. The numerical results showed the significant role of soil-structure interaction and beam-column connections on the seismic vulnerability and performance of RC precast buildings. In fact, seismic vulnerability of RC precast buildings was increased by considering soil-structure interaction and beam-column connections effects.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
53
v.
7
no.
2021
3051
3066
https://ceej.aut.ac.ir/article_3890_17a9c07ec20ab7084012c4331dde3b24.pdf
dx.doi.org/10.22060/ceej.2020.17608.6633
Using Pile Group to Mitigate Lateral Spreading in Uniform and Stratified Liquefiable Sand Strata: Three-Dimensional Numerical Simulation
Ali
Asgari
Assistant Professor of Geotechnical Engineering, Faculty of Engineering and Technology, University of Mazandaran, Babolsar, Iran.
author
Faramarz
Ranjbar
University of Mazandaran
author
Habib
Akbarzadeh Bengar
Associate Professor, Faculty of Engineering and Technology, University of Mazandaran, Babolsar, Iran
author
text
article
2021
per
According to reports from past earthquakes around the world, the phenomenon of liquefaction is one of the main hazards of earthquakes that causes damage to structures and infrastructures. The risk of liquefaction and associated lateral spreading can be reduced by various ground improvement techniques, including densification, solidification (e.g., cementation), Vibro-compaction, drainage, explosive compaction, deep soil mixing, deep dynamic compaction, permeation grouting, jet grouting, pile-pinning, and gravel drains or SCs. In this research, the effects of pile groups on reducing the potential for liquefaction during earthquakes are investigated parametrically, using three-dimensional finite element (FE) simulations via OpenSees. Saturated uniform and stratified loose sand are subjected to two realistic destructive events with different characteristics. A multi-yield-surface plasticity model, Drucker–Prager yield criterion, is considered for the dynamic analysis conducted in this study based on constitutive laws applicable to all types of soils. The objective of this research is to assess the effectiveness of the pile group based on several different factors, including area replacement ratio ( ), piles diameter, number of piles, thickness and position of liquefiable soil, and earthquake characteristics. This parametric study evaluates the effect of each of these factors on soil acceleration, lateral displacement, and excess pore pressure. The results showed that the lateral displacement and excess pore pressure decrease, as the area replacement ratio, number, and diameter of the pile increase. Besides, the responses of the saturated stratified sand strata are not only dependent on the thickness of the liquefiable layer but are also highly influenced by its position. The presence of a liquefiable layer at lower depths, although acting as an isolate relative to the acceleration, can increase lateral displacements. Also, according to the results, there is an appropriate correlation between the variations of lateral displacement rate of piles and soil and earthquake parameters including Arias intensity, the time corresponding to the PGA, and the number of significant excitation cycles. Therefore, the results of this study may be applicable for other earthquakes.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
53
v.
7
no.
2021
3067
3086
https://ceej.aut.ac.ir/article_4008_d6ab47e60cf105c05f148b70ac1caeb8.pdf
dx.doi.org/10.22060/ceej.2020.17657.6639
Effect of Minor Variations in Characteristics of Beam on the Safety of 2D Steel Moment Frame under Dynamic Loads
Ehsan
Dehghani
University of Qom
author
Zeinab
Aryani
Civil Engineering, University of Qom, Qom, Iran
author
text
article
2021
per
Increasing the strength of members or enhancing the redundancy does not jeopardize the overall safety of the structure. This can be proved under static loads by the safe theorem, which is one of the fundamental theories of plastic analysis. Although this theorem has not been proved in the case of dynamic loads, it has been widely applied to the design of systems under dynamic loads. Therefore, this paper aims to make use of the results of this theorem in the numerical analysis of structures subjected to dynamic loads. Since the structural instability mechanism and collapse do not occur under transient loads, an adequate level of ductility demand has been assigned to the structural components to ensure the safety of the structure. For this purpose, the plastic rotation of the members is determined after a minor variation in strength and stiffness of the beams in a 2D five-story steel moment-frame structure by performing dynamic analysis. To compare the ductility demand obtained by the dynamic analysis with the criteria values, the performance of the structure is also evaluated by conducting nonlinear static analysis. The analysis results showed that the increase in the strength of the beam members generally leads to a lower ductility demand; however, in some cases, the maximum ductility demand increased by about 7.3%. With the increase in the stiffness of the beams, the ductility demand increased by up to 16%. It can be concluded that with the increase in the stiffness and strength of the beams, a lower ductility demand is obtained by the dynamic analysis compared to the static analysis, and thus the structural collapse has not occurred under dynamic loads.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
53
v.
7
no.
2021
3087
3100
https://ceej.aut.ac.ir/article_4043_2201d9bb71a3c723d4ef80686c3c9b45.pdf
dx.doi.org/10.22060/ceej.2020.17672.6643
Dynamic Analysis of Earth Dams under De-Noised Earthquake Records
Fatemeh
Nasiri
Department of Civil Engineering, Shahrekord University, Shahrekord, Iran.
author
Hamed
Javdanian
Assistant Professor, Department of Civil Engineering, Shahrekord University, Shahrekord, Iran.
author
Ali
Heidari
Department of Civil Engineering, Shahrekord University, Shahrekord, Iran.
author
text
article
2021
per
In this study, the dynamic behavior of earth dams with clay core was analyzed using the finite element method. The seismic responses of earth dams under main and wavelet-based decomposed earthquake records were investigated. Earthquake records were decomposed up to five stages by using the wavelet de-noising method. The ratio of acceleration response spectrum to maximum acceleration, ratio of velocity response spectrum to maximum velocity, ratio of displacement response spectrum to maximum displacement, Fourier amplitude spectrum and time history of Arias intensity of earth dam crest under main and wavelet-based decomposed earthquake records were analyzed. The results demonstrated that the acceleration response spectrum ratio of dam crest under de-noised records up to 3rd level and the velocity and displacement spectrum ratios of dam crest up to 4th level has an acceptable accuracy in comparison to the responses under main earthquake records. Results of the dynamic analysis indicated that Fourier amplitude spectra and Arias intensity of earth dam crest under de-noising based records up to 4th level are compatible with main earthquake records. The results also showed that the wavelet-based decomposed earthquake records can be a reliable alternative for main earthquake records in the dynamic analysis of earth dams.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
53
v.
7
no.
2021
3101
3114
https://ceej.aut.ac.ir/article_3951_88647f9dfbfa1d09014ca4f60623f3bb.pdf
dx.doi.org/10.22060/ceej.2020.17687.6648
An Investigation of the Dilation Effect of Soil on Liquefaction-Induced Settlement
MohammadHossein
Nakhaee
Graduate student, Department of Civil Engineering, Shahrood University of Technology, Shahrood, Iran
author
Amir
Bazrafshan Moghaddam
Assistant professor, Department of Civil Engineering, Shahrood University of Technology
author
text
article
2021
per
In this paper, the effect of the amount of dilation angle on the settlement of the structure due to the occurrence of liquefaction has been investigated. In this research, the dilation effect related to the density and confining stresses during liquefaction on structural settlement is investigated using OpenSEES. Therefore, a sand layer with different dilation angles and surface load is considered. The numerical model presented in this research calculated the excess pore water pressure based on fully coupled effective stress analysis during seismic loading. Model parameters were selected and verified using the results of VELACS centrifuge tests. The results showed that by increasing the dilation angle, the pore water pressure decreases, and the liquefaction-induced settlements decrease. The decreasing trend of settlement with increasing dilation angle tends to a constant value, so that at high densities with increasing dilation angle, little changes in the settlement were observed. Also, the dilation angle was calculated based on the pre-shear mean effective stresses and compared with the dilation angle caused by the stresses during liquefaction. The comparison shows that for relative densities less than 60%, the dilation angle obtained from pre-shear effective stress is more than the confining stress-based method during liquefaction.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
53
v.
7
no.
2021
3115
3128
https://ceej.aut.ac.ir/article_4297_cc7152d5ddd4c11187d940d167f51b73.pdf
dx.doi.org/10.22060/ceej.2021.17718.6650
Experimental Investigation of Composite (Steel-Concrete) Walls under Pure Out-of-plane Load
Saeid
Sabouri-Ghomi
Professor / Civil Engineering Department / K.N Toosi University of Technology / Tehran , Iran
author
Arman
Nasri
Civil Engineering Department, K.N. Toosi University of Technology, Tehran, Iran
author
Younes
Jahani
Analysis and Advanced Materials for Structural Design (AMADE), Polytechnic School, University of Girona
author
text
article
2021
per
This paper presents a new structural system for retaining walls. In civil works, in general, there is a trend to use the traditional reinforced concrete (RC) retaining walls to resist soil pressure. Despite their good resistance, RC retaining walls have some disadvantages such as the need for huge temporary formworks, high dense reinforcing, low construction speed, etc. In the present work, a composite wall with only one steel plate (steel-concrete) was proposed to cover the disadvantages of the RC walls. In this system, a steel plate was utilized not only as tensile reinforcement but also as permanent formwork for the concrete. To evaluate the efficiency of the proposed SC composite system, an experimental program that included six specimens was performed. In this experimental campaign, effects of different parameters such as length of shear connectors, use of compressive steel plate, concrete ultimate strength, the distance between shear connectors, and compressive steel reinforcement were investigated. The results showed that with proper design, the composite walls have very good and ductile behavior under out-of-plane loads. Furthermore, it was observed that even with a large distance between the shear connectors, a short length of the shear connectors, etc., this system is capable to keep the flexural performance and shows semi-ductile behavior. Furthermore, the design equations based on the ACI code for calculating out-of-plate flexural and shear strength of SC composite walls were presented and compared to the experimental database.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
53
v.
7
no.
2021
3129
3148
https://ceej.aut.ac.ir/article_3941_802a3011f4931ab0e2422c6b5aaa7784.pdf
dx.doi.org/10.22060/ceej.2020.17704.6651
Laboratory Investigation of Effect of Flat Submerged Vanes on Scour at Bridge Piers Group and Abutment
Maryam
Karimi
MSc Water structure, Department of Water Engineering, Faculty of Agriculture, University of Shahid Bahonar Kerman
author
Kourosh
Qaderi
water engineering department, faculty of agriculture, shahid bahonar university of kermen
author
Majid
Rahimpour
Water Engineering, Agriculture, Shahid Bahonar University of Kerman, Kerman, Iran
author
Mohammad Mehdi
Ahmadi
water engineering, Agriculture, Shahid Bahonar University of Kerman, Kerman, Iran
author
text
article
2021
per
Local scour involves the removal of material from around piers and abutments as the flow accelerates around the obstructed flow area. Various methods have been suggested for the control and reduction of local scour around the bridge piers and abutment. Using submerged vanes is one of these methods. Vanes change the regime of bedload movement that led to control places of deposition and erosion. The function of vanes to reduce scour around the bridge piers and sediment movement in the region of vanes due to downflow in front of them are affected by arrays of the vanes. In the present study, different layouts of arrangements (parallel rows, two parallel rows, and two zigzag rows) flat submerged vanes with the ratio of length to height (L/H=3) at an angle of 20 degrees relative to the direction of flow on the protection of local scour around abutment and piers group with rectangular debris were investigated. All experiments conducted in uniform flow with clear water were being done. The results showed that the zigzag arrangement of the two-three rows had the greatest effect on the protection of local scour around the abutment. In this case, the vane distance from the abutment and the row spacing with the relative spacing is 0/5 and 1, respectively, (the distance of the vanes from the abutment was La and the distance of the rows was 2La) that reduced the scour depth by 81%.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
53
v.
7
no.
2021
3149
3166
https://ceej.aut.ac.ir/article_4051_82888548240c78184ec6513e4d53eb16.pdf
dx.doi.org/10.22060/ceej.2020.17729.6654