ORIGINAL_ARTICLE
Reliabilty-based Torsional Design of Reinforced Concrete Beams Strengthened with CFRP Laminate
The structural reliability of torsional concrete beams strengthened with full and strip wrapping of carbon fiber reinforced polymer (CFRP) laminate is investigated. The first order-second moment reliability method has been applied to make a reliability assessment on the torsional capacity design by technical guideline in Iran. The code No.345 published by the Management and Planning Organization of Iran (MPO 345-2006) is the first technical code in Iran for design of concrete members strengthened with CFRP laminate. In this work, the average reliability indexes for unstrengthened, strengthened with full wrap and strengthened with strip wrap beams have been found. The results indicate that the MPO design guideline are some unconservative. A reliability strengthening ratio is introduced for assessment of the variation in average reliability index before and after strengthening with different resistance factors. A parametric study on this factor reveals that if the reliability level of the strengthened reinforced concrete beams is kept to be consistent with their similar unstrengthened beams, a value of 0.89 and 0.81 for strengthened with full wrap and strengthened with strip wrap, respectively, should be applied.
https://www.ije.ir/article_72181_d8064e08200f2ee8c7eba4f987c0a584.pdf
2013-10-01
1103
1110
CFRP Laminate
Reliability Indexes
Torsion
Concrete Beams
MPO Guideline
MOHAMMAD JAVAD
FADAEE
mjfadaee@mail.uk.ac.ir
1
Civil Engineering, Shahid Bahonar University of Kerman
AUTHOR
Hamzeh
Dehghani
ham.dehghani@yahoo.com
2
Civil Engineering, Shahid Bahonar University of Kerman
AUTHOR
ORIGINAL_ARTICLE
Proposed Relationship to Design the Waffle Floor under Harmonic Vertical Loading
The design codes of building are mainly related to the strength of the building and there are no specific codes for the design of building with waffle floors for vibration sensitive equipment. The finite element model, ANSYS, is capable to consider the effects of floor thickness, the size of the bays and stiffness of the columns for analyzing the vibration of the waffle floors and vibration transmission along the waffle floor. Because the finite element analysis is time consuming and it needs enough expertise for modeling, in this study, an approximate relationship is proposed to design the waffle floor based on the comprehensive investigations of different effective parameters in the response of waffle floor and the results obtained from finite element analysis. This proposed relationship comforts the designers of industrial buildings and vibration sensitive equipment to attain a preliminary and appropriate outline to design the waffle floor considering the effective parameters on the floor vibration.
https://www.ije.ir/article_72182_e647daca3d7e03f8dd21c0ca4f6b6ffe.pdf
2013-10-01
1111
1118
Waffle floor
vibration
Harmonic loading
Finite Element
Abed
Fereydouni
fereydouni66@yahoo.com
1
Civil Engineering, Islamic Azad Universit,bushehr Branch
AUTHOR
Mohammad Mehdi
Heydari
mmhc790@gmail.com
2
Civil Engineering, University of Shiraz
AUTHOR
reza
jalili
r_jalili65@yahoo.com
3
Civil Engineering, Islamic Azad Universit,bushehr Branch
AUTHOR
ORIGINAL_ARTICLE
Non-Linear Behavior of New (FSFN) Moment Resisting Connections in Comparison to the Existing KBB Connections in Steel Frames
After Northridge (1994) and Kobe (1995) earthquakes, several studies have been conducted to improve the seismic performance of steel structures. In this investigation, new steel moment-resisting connections (FSFN) developed by the authors, were studied by the non-linear numerical analysis. These connections were single-sided beam-to-column assemblies that are representative of exterior beam-to-column connections. Seismic performance of FSFN connections in comparison to the W-series of existing KBB connections under standard and near fault load history based on AISC 341 and FEMA 355D were also studied. For this purpose, 32 analytical modeled specimens were evaluated and the results were compared. Results showed that FSFN bracket connection has a seismic performance similar to KBB connection and it is an appropriate connection for the special moment resisting frames both in far and near fault zones. More so, these connections do not have patent and due to their dimensions which are smaller than the Kaiser brackets, they can supported deeper beams up to 100 cm. Therefore, it can be considered as an appropriate alternative for the Kaiser patented connections. This paper is to present the analytical modeling, non-linear behavior and the results of the comparison studies in detail including obtained conclusions.
https://www.ije.ir/article_72183_a7f4b836f64b88a668be33e99d6122d9.pdf
2013-10-01
1119
1134
FSFN brackets
Non
linear numerical analysis
Standard load history
near
Fault load history
and KBB brackets
Farhood
Shahidi
1
Civil Engineering, Islamic Azad University of Takestan
AUTHOR
Farhad
Shahidi
fr.shahidi@yahoo.com
2
Technical Office, Qazvin Sazeh
AUTHOR
F.
Nateghi
nateghi@iiees.ac.ir
3
structure, IIEES
AUTHOR
ORIGINAL_ARTICLE
Wavelet-based Analysis for Pulse Period of Earthquake Ground-motions
Pulse period of earthquake records has been known as a key parameter in seismology and earthquake engineering. This paper presents a detailed characterization of this parameter for a special class of earthquake records called pulse-like ground motions. This type of motions often resulting from directivity effects is characterized by a strong pulse in the velocity time history of motion, in normal-fault component. Wavelet analysis was used as a powerful and useful technique in the analysis of non-stationary signals in this study. The period of velocity pulses is basically determined by using the pseudo-period of the mother wavelets. The effects of three different mother wavelets on results were investigated and new empirical predictive equations for pulse period have been derived.
https://www.ije.ir/article_72184_bfb5b2a55ce609df4aca4b559aff2e55.pdf
2013-10-01
1135
1144
Pulse
like ground motions
pulse period
wavelet analysis
directivity effect
magnitude scaling
Mother wavelet
Saman
Yaghmaei-Sabegh
s_yaghmaei@tabrizu.ac.ir
1
Civil Engineering, University of Tabriz
AUTHOR
ORIGINAL_ARTICLE
Effect of the Height Increasing on Steel Buildings Retrofitted by Buckling Restrained Bracing Systems and TTD Damper
The Behavior of conventional braced frames, are not the same in tension and compression. This problem can be improved by prevention of buckling under compressive loads, which is called buckling restrained brace(BRB). In this field TTD metal damper also have much attention due to simplicity in construction and execution. This damper is recommended because of accessing to better performance than BRB brace and also having easier construction technology and consequently cheaper until possibility of making it is feasible in countries without complex technologies. In this research, three steel structures with three, five and eight stories that require to retrofitting, are retrofitted using buckling restrained brace and TTD metal damper separately, and are compared before and after the retrofitting using nonlinear dynamic analysis in Perform 3d software. Finally, the effects of this systems in reduction of structure displacement, reduction of energy dissipation due to nonlinear behavior in main members of structure, and increasing of performance level is inspected. The observation of both of systems results also imply that with increasing of the number of building stories, expressed positive effect, is reduced. Which that, indicates more effect of this energy dissapation systems in short-order structures.
https://www.ije.ir/article_72185_406223c4b859e472d45800a40684a2b0.pdf
2013-10-01
1145
1154
Seismic Retrofitting
Buckling Restrained Brace
TTD Metal Damper
Conventional Braces
Energy Dissipation Systems
Nonlinear dynamic analysis
Hossein
Shafiei seifabadi
hossein_shafiei64@yahoo.com
1
Civil Engineering, University of Kazeroon
AUTHOR
ORIGINAL_ARTICLE
Effect of Short- and Long-term Memory on Trend Significancy of Mean Annual Flow by Mann-Kendall Test
Climate variability and change is threatening water resources around the world. One hundred and fourtheen (114) stations from Reference Hydrometric Basin Network (RHBN) around Canada with at least 30 years continuous data (up to 2011) were selected to study the trend in mean annual runoff for different periods of 30 to 100 years in step 10 years by non-parametric Mann-Kendall test. Effect of short term persistant (STP) and long term persistant (LTP) on this test were made through lag 1 serial correlation (r1) and Hurst exponent (H), respectively. r1 for about one third of the total cases considered were negative. H, based on “equivalent Normal deviate” (eNv), was slightly right-skewed with minimum and maximum values of 0.20 and 0.87, respectively. About half of the data sets were anti-persistant (H0.1). The number of positive and negative trends, were nearly the same, though fluctuating for different time spans. p-value after pre-whitening was highly correlated with those of before pre-whitening, for both negatve and positive trends. There were about 16% of cases that pre-whitening decreased the p-values of the Mann-Kendall trend test, where nearly all of them were negatively trended. The effect of LTP on Mann-Kendall trend test was minor, due to inconsistancy of originally significant trend case and significant H of greater than 0.5. For recent 30 years length of record (1982-2011), British Columbia is experiencing positive trends in the west and negative trend in the east. Most parts of the New Brunswick is experincing the positive trend, while negative trend is due to Southeast of Ontario. For the more logest duration of 40 years, trend statistics and geographical pattern were changed. While the significant trends are decreased, more significant negative trends are governed over New Brunswick. There is no positive trend in British Colimbia in the past 50 years (1962-2011) while there are both negative and positive trends in New Brunswick and negative trends are switched to positive trends in south east of Ontario. For long duration of > 70 years, there are only positive trends in Southeast of Canada (South New Brunswick and South East of Ontario) while centeral and East of Canada have experinced a negative trend.
https://www.ije.ir/article_72186_463a2e4cbec8451ce3c5ba99cb0f13ac.pdf
2013-10-01
1155
1168
Climate change
Climate variablility
Hurst exponent
Hydrology
Lag 1 serial correlation
long
memory process
Bijan
Ghahraman
bijan_ghahreman@yahoo.com
1
Water Engineering, the Ferdowsi University of Mashhad
AUTHOR
ORIGINAL_ARTICLE
Semi-active Control of Building Structures using Variable Stiffness Device and Fuzzy Logic
Semi-active control devices, also called “Intelligent” control devices, constitute the positive aspects of both the passive and active control devices. A semi-active control strategy is similar to the active control strategy, but this control device has been shown to be more energy-efficient than active devices. A particular type of semi-active control device, the Variable Stiffness Device (VSD), consists of a hydraulic cylinder with a normally closed solenoid control valve inserted in the tube connecting the two cylinder chambers. This paper emphasizes on the application of Semi-active Fuzzy Logic Controller (SFLC) of this system for getting the best results in the reduction of the building responses under earthquake excitations. For the numerical example, a 12-story building, located in the city of Rasht, Iran, is modeled as 3-D frame and the problem is solved in state space. The results obtained from the proposed control scheme (SFLC) are compared with those obtained from the ON-OFF control method. It is found that the SFLC is highly effective in reducing the responses of the example building than the ON-OFF algorithm. In this study, the optimal values of the fuzzy rule bases, membership functions, and the location of the control device are determined.
https://www.ije.ir/article_72187_154d0b458e36aab73e01ed5eeb2a3eb4.pdf
2013-10-01
1169
1182
semi
Active control
variable stiffness device (VSD)
on
OFF algorithm
fuzzy logic controller (FLC)
P.
Jooei
peymanjooei@yahoo.com
1
Civil Engineering, University of Guilan
AUTHOR
S.
Pourzeynali
pourzeynali@guilan.ac.ir
2
Civil Engineering, The University of Guilan, Rasht, I. R. Iran
AUTHOR
ORIGINAL_ARTICLE
Laboratory Studies of the Effect of Recycled Glass Powder Additive on the Properties of Polymer Modified Asphalt Binders
In this paper, the effect of adding recycled glass powder (RGP) as a third component in polymer modified bitumen is studied. RGP and styrene butadiene rubber (SBR) is added to the base bitumen in order to prepare modified binders and mixtures. The initial study is performed to determine physical properties of unmodified, SBR modified and RGP-SBR modified asphalt binders which prove RGP's compatibilizing effect on asphalt and polymer as well as high compatibility between RGP and polymer leading to better dispersion of the polymer in asphalt. The results of the study showed how final rheological properties of the mentioned combination could be affected by adding RGP and SBR. Modified and unmodified binders are used for preparing the Marshall samples for the following tests: Marshall Strength, indirect tensile strength (ITS), tensile strength ratio (TSR), and indirect tensile stiffness modulus (ITSM) tests. The results of this study indicated that the combination of 3% SBR plus 2% RGP can improve mechanical properties of asphalt mixture considerably.
https://www.ije.ir/article_72188_bb982e58c260c5a41378eab5c7456275.pdf
2013-10-01
1183
1190
Bitumen
recycled glass powder
SBR
ITS
TSR
ITSM
Seyed Morteza
Marandi
marandi@uk.ac.ir
1
Civil Engineering, Shahid Bahonar University of Kerman
AUTHOR
Mojtaba
Ghasemi
mghasemi59@eng.uk.ac.ir
2
Civil Engineering, Shahid Bahonar University
AUTHOR
ORIGINAL_ARTICLE
The Performance of an Hexahedron C* Element in Finite Element Analysis
The performance of an 8-noded hexahedron C1* element in elasticity is investigated. Three translational displacements and their derivatives as strain in each direction are considered as degrees of freedom (d.o.f.’s) at each node. The geometric mapping is enforced using a C0 element with no derivative as nodal d.o.f.’s . The stiffness matrix of the element is also computed using a transformation matrix obtained from an equivalent C0 element. The results obtained from elastic stress analysis of a cantilever show that: (i) the convergence rate of 8-noded C1* element is nearly equal to its equivalent C0 element, while it consumes less CPU time with respect to the C0 element; (ii) the element has successfully passed the patch and distortion tests; (iii) the condition number of the stiffness matrix for C1* element is less than the C0 element; (iv) the directly computation of strains as derivative degrees of freedom at the nodes along with excellent convergence makes the C1* element superior compared with its equivalent C0 element.
https://www.ije.ir/article_72189_73edefd51f680e6ecf064031d4a2186e.pdf
2013-10-01
1191
1202
elasticity
Finite element method
elements
Convergence
Bahman
Sharifi Hamadani
bah.sharifi@gmail.com
1
Mechanical Engineering, Islamic Azad university
AUTHOR
ORIGINAL_ARTICLE
Plasticity Effect on Residual Stresses Measurement Using Contour Method
Residual stresses have become an important player in the field of the structural integrity for many years. Having an exact knowledge of residual stress distributions can be essential in designing the engineering components as unexpected failures are inevitable where such stresses are ignored. There are many residual stresses measurement techniques including destructive and non-destructive ones. Among the mechanical strain relief (MSR) techniques, contour method is one of the youngest. Contour Method relies on the material removal similar to other MSR techniques. In this method a part is carefully cut into two pieces along a flat plane, causing the residual stress normal to the cutting plane to relax. However, similar to other MSR techniques, plasticity can have a great influence on the accuracy of the results. In the present work, effect of plasticity on the residual stress measurement using contour method is investigated. Quenching is employed to induce residual stresses within the samples. To create different levels of plasticity, the samples were quenched at three different temperatures, 500°C, 700°C and 850°C. The residual stresses were then measured using contour method. Furthermore, the contour method procedure is simulated using finite element analysis to compare with the experimental results.
https://www.ije.ir/article_72190_26546a1198ebf57bca84a0674bc4aac7.pdf
2013-10-01
1203
1212
Contour method
Residual Stress
plasticity
Finite Element
Mohammad
Jooya
jooya6767@gmail.com
1
Mechanical Engineering Department, Bu-Ali Sina University
AUTHOR
Amir Reza
Hosseinzadeh
amirreza.hosseinzade@gmail.com
2
Mechanical Engineering Department, Bu-Ali Sina University
AUTHOR
A.H.
Mahmoudi
a.h.mahmoudi@gmail.com
3
Mechanical Engineering, Bu-Ali Sina University
AUTHOR
ORIGINAL_ARTICLE
Numerical Investigation of Magnetic Field Effects on Mixed Convection Flow in a Nanofluid-filled Lid-driven Cavity
In this work, the stencil adaptive method is applied to investigate the effects of a magnetic field on mixed convection of Al2O3-water nanofluid in a square lid-driven cavity. The incompressible Navier-Stokes equations are solved by an adaptive mesh method which has superior numerical advantages compared to the traditional method on the uniform fine grid. The main objective of this study is to investigate the influence of several pertinent parameters such as the Reynolds number, the Hartmann number and the solid particle volume fraction on the heat transfer performance of the nanofluid. Based on the obtained numerical results, the heat transfer rate increases with an increase of the Reynolds number but, it decreases with an increase of the Hartmann number. Also, the results indicate that heat transfer of the nanofluid could be either enhanced or mitigated with respect to that of the base fluid depending on the Reynolds number.
https://www.ije.ir/article_72191_bff772ee0ee2e93bed40d982b84abed7.pdf
2013-10-01
1213
1224
Mixed convection
Nanofluids
Hartmann number
Reynolds Number
Stencil adaptive method
Mohammad
Kalteh
mkalteh@guilan.ac.ir
1
faculty of engineering, university of guilan
AUTHOR
Ali
Ramezani
ramezaniua@alum.sharif.edu
2
Faculty of Aerospace Engineering, K.N. Toosi University of Technology
AUTHOR
Javad
Rahmannezhad
j.rahmannezhad@gmail.com
3
Mechanical Engineering, University of Birjand
AUTHOR
ORIGINAL_ARTICLE
Multi-objective Optimization of a Projectile Tip for Normal Penetration
The main purpose of the present work is multi-objective shape optimization of a projectile tip for impacting and normal penetrating. Velocity drop, weight and inner volume of projectile have been considered as three conflicting objective functions. For this purpose, at the first step, finite element modeling was done using ABAQUS/Explicit and projectile penetration was examined in different geometric dimensions. Hammersley sequence sampling was employed for designing computer experiments. In the next step, results of the FEM were employed as raw data for MLF-type neural network training to achieve a mathematical model which is able to describe velocity drop behavior. Projectile weight and Inner volume were also expressed in explicit mathematical form using geometric relations. Obtained mathematical models were used as conflicting objective functions for multi-objective optimization of projectile tip using modified NSGA-II. Finally, it is shown that some interesting and important relationships as useful optimal design principles involved in the performance of projectile impact have been discovered by Pareto based multi-objective optimization.
https://www.ije.ir/article_72192_2a8e9f11a64ada86aab058ec96fd7697.pdf
2013-10-01
1225
1234
projectile
Impact
Finite element method
Neural Networks
multi
objective optimization
NSGA
II
Shadi
Roshanfekr
shadi.roshanfekr@yahoo.com
1
School of Mechanical Engineering, Islamic Azad University, Takestan Branch
AUTHOR
Mansour
Torabi
mtoraabi@auto.iust.ac.ir
2
School of Mechanical Engineering, Sharif University of Technology
AUTHOR
Abolfazl
Khalkhali
ab_khalkhali@iust.ac.ir
3
automotive engineering, Iran University of Science and Technology
AUTHOR
ORIGINAL_ARTICLE
Artificial Neural Network Involved in the Action of Optimum Mixed Refrigerant (Domestic Refrigerator) (TECHNICAL NOTE)
This analysis principally focuses on the implementation of Radial basis function (RBF) and back propagation (BPA) algorithms for training artificial neural network (ANN) to get the optimum mixture of Hydro fluorocarbon (HFC) and organic compound (Hydrocarbons) for obtaining higher coefficient of Performances (COPs). The thermodynamical properties of mixed refrigerants are observed using REFPROP 9 software system that contains details of refrigerants. Totally different mixtures of the refrigerants along with their COP are obtained by the REFPROP 9. This task consumes time in getting the right combination of refrigerants as lot of menu choices have to be compelled to be chosen within the REFPROP 9. In order to form the method of checking out the correct mixed refrigerants with minimum manual intervention, RBF is trained and tested with the different patterns of mixed refrigerants. The RBF / BPA mixed refrigerant analysis software has been developed by using MATLAB 11a.
https://www.ije.ir/article_72193_b0eb5cf66cc15793648b80a85352b2ff.pdf
2013-10-01
1235
1242
ANN
Artificial Neural Network
Back propagation algorithm
COP
radial basis function
Mixed refrigerant
Natesan
Kanthavelkumaran
kanthavelpriya@yahoo.com
1
Mechanical Engineering, Arunachala College of Engineering for Women, Kanyakumari, Tamilnadu, India
AUTHOR
Senthil
kumar
cryosenthil@yahoo.com
2
Head, Mechanical Engg., KSR College of Engg.
AUTHOR
Austin
N
austinmdmk@yahoo.co.in
3
Mechanical Engineering, Mar Ephraem College of Engineering and Technology
AUTHOR
ORIGINAL_ARTICLE
Receding Horizon Based Control of Disturbed Upright Balance with Consideration of Foot Tilting(RESEARCH NOTE)
In some situations, when an external disturbance occurs, humans can rock stably backward and forward by lifting the toe or the heel to keep the upright balance without stepping. Many control schemes have been proposed for standing balance control under external disturbances without stepping. But, in most of them researchers have only considered a flat foot phase. In this paper a framework is presented that includes the foot tilting. This is done by hybrid modeling of the humanoid robot and also using a receding horizon based approach. The decision for the recovery pattern is done based on the evaluation of the Vertical Forces criterion. If the method predicts the tilting of the foot under disturbance, then the optimum trajectories are obtained for upper segments to return the robot to the secure posture in which the foot is flat (home posture). The obtained optimum trajectories are then tracked by a feedback controller. In the context of receding horizon approach the Extrapolated Center of Mass position has been used as the stability constraint. The results demonstrate the success of method to reproduce human-like balance recovery reactions under impulsive disturbances. The simulated results are compared with experimental data reported in the biomechanics literature.
https://www.ije.ir/article_72194_de5cd0d1850172e311ee71345ea9f417.pdf
2013-10-01
1243
1254
Hybrid Model
Receding Horizon Approach
Upright Balance
External Disturbances
Ahad
Sedaghatkish Khoshkbijari
sedaghatkish@msc.guilan.ac.ir
1
Mechainical Engineering Department, Guilan University
AUTHOR
Ahmad
Bagheri
bagheri@guilan.ac.ir
2
Mechanical Engineering, University of Guilan
AUTHOR
Behanm
Miripour Fard
behnam_miripur@yahoo.com
3
Department of Robotics Engineering, Hamedan University of Technology
AUTHOR
ORIGINAL_ARTICLE
Optimization of Low Pressure Vortex Tube via Different Axial Angles of Injection Nozzles
In this article, a Ranque–Hilsch Vortex Tube has been optimized utilizing axial angles for nozzles. Effect of nozzles angles on the flow behavior has been investigated by computational fluid dynamics (CFD) techniques. A finite volume approach with the standard k–ε turbulence model has been used to carry out all the computations. The dimensions of studied vortex tubes are kept the same for all models and the performance of machine is studied under 5 different angles (β) including 0, 2, 4, 6 and 8 degree adjusted to the nozzles. Achieving to a minimum cold exit temperature is the main goal of this numerical research. The results show that utilizing this kind of nozzle improves the cooling capacity of device for most of inlet mass flow rates. Finally, some results of the CFD models are validated by the available experimental data which show reasonable agreement, and other ones are compared qualitatively.
https://www.ije.ir/article_72195_b38fe6250332005152f675851da67e05.pdf
2013-10-01
1255
1266
Vortex tube
numerical simulation
axial angle
Energy separation
Total pressure
alireza
izadi
alireza.izadi1225@gmail.com
1
Faculty of Engineering, Urmia University
AUTHOR
ashkan
jahangir amini
ajahangiramini@yahoo.com
2
Faculty of Engineering, Urmia University
AUTHOR
nader
pourmahmoud
n.pourmahmoud@urmia.ac.ir
3
mechanical engineering, Urmia University
AUTHOR