2020-11-29T20:09:29Z
http://scientiairanica.sharif.edu/?_action=export&rf=summon&issue=151
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2013
20
5
Relationships of yield-capacity-risk in a multiple reservoir system: The Munzur River Basin in Turkey
M.
Opan
The aim of this study is to determine the relationships of yield-capacity-risk in a multiple reservoir system. In this study, yield, capacity and risk have been defined as the average energy production, storage volume of reservoir and obtaining the same yield with lower capacity, respectively. Then, an optimization model using dynamic programming with successive approximations (DPSA) for a multi-reservoir system for energy production has been developed. The objective function used in the model has the objective of the maximization of the total energy. A multi-reservoir system in the Munzur River Basin of Turkey has been selected for the application. The results of the proposed approach have been evaluated with regard to relationships of yield-capacity-risk. As a result, the capacity was increased when the yield was raised, and the same yield has been obtained in a different capacity by reducing the capacity under a certain yield risk. The yield risk has been raised in the direction of the yield coordinate of the yield-capacity-yield risk curve.
Yield
Capacity
Risk
Multiple Reservoirs
Dynamic programming
2013
10
01
1311
1319
http://scientiairanica.sharif.edu/article_1508_807ded9422a333a8cc892195f366ed4c.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2013
20
5
Experimental Study on Water-wing characteristics induced by piers in Flood Drainage Culverts
Chen
Sheng
Zhang
Jian
Hu
Ming
Arash
Hazrati
Setting piers is an effective way to overcome the limits of manufacture and operation of the gates for large span culverts or tunnels. However, the piers, if designed improperly, will bring about water-wing to strike the top and the side walls, and hence affect the operation of hydraulic structures. This present study deals with the water-wing caused by the obstruction of the pier placed in front of a flood drainage culvert. Based on the dimension analysis, the influencing factors of water-wing were analyzed, the hydraulic characteristics were experimentally investigated, and finally a kind of new piers was proposed. The results showed that, it is the initial height of piers that is the key factor, as well as the radius and inclination angle of piers, approached flow velocity and depth.
water-wing
pier
flood drainage culvert
South-to-North Water Diversion Project
dimension analysis
2013
10
01
1320
1326
http://scientiairanica.sharif.edu/article_1509_bcafec675ed15507be42be0273498083.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2013
20
5
Method of Fundamental Solution (MFS) coupled with particle swarm optimization (PSO) to determine optimal phreatic line in unconfined seepage problem
Sh.
Shahrokhabadi
Ali R .
Ahmadi
In this research, Method of Fundamental Solution (MFS) is coupled with Particle Swarm Optimization (PSO) technique to determine the optimal phreatic line in unconfined seepage problems. To model the unconfined boundary (phreatic line), a formulation with floating geometry is derived. Regarding the use of fundamental solution of the Laplace equation, expressed in the Radial Basis Functions (RBF), a boundary type of the mesh-free method can be established. In this research an objective function, based on principle of minimum potential energy, is formed to control the position of unconfined boundary. MFS and PSO are utilized simultaneously to fit the phreatic line using 4thdegree polynomials, satisfying the flow continuity and energy principle. Efficiency and accuracy of the proposed method are verified through examples. The obtained results are in a good agreement with other numerical and experimental models.
mesh-free
particle swarm optimization (PSO)
Method of Fundamental Solution (MFS)
Radial Basis Function (RBF)
2013
10
01
1327
1336
http://scientiairanica.sharif.edu/article_1510_30f0e7712e8203476638bf11a10981b2.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2013
20
5
Comparison of the Drift Spectra Generated Using Continuous and Lumped-Mass Beam Models
Fayaz
R. Rofooei
Amir H.
Shodja
The drift spectrum as a new measure of earthquake induced demands in structures, was developed using a uniform-stiffness continuous beam model. Practical limitations in the procedures based on such models have caused structural engineers to pay little attention to drift spectra. In this paper, a method is proposed to estimate the seismic-induced inter-story drift demands using the modal analysis technique of lumped mass, non-uniform beam models. The proposed approach is simple and can overcome many deficiencies of the previous methods. It can take into account the very important effect of height-wise stiffness reduction on drift demands, without the numerical difficulties usually encountered in computing the drift spectra. The Drift spectra for high-rise shear buildings are computed using both continuous and lumped mass beam models. The comparisons indicate that the results of the continuous uniform-stiffness beam models in some cases are not acceptable. The effect of various parameters such as the structural system, the height-wise variation of structural stiffness, the number of stories, higher modes and damping ratios, on inter-story drift demands are investigated. Also, the importance of the structural system and height-wise variation of structural stiffness on the height-wise distribution of maximum inter-story drift demands is evaluated using a number of building models.
Time history analysis
Near-field records
Drift spectrum, Approximation Methods
2013
10
01
1337
1348
http://scientiairanica.sharif.edu/article_1511_6c88ed55318558cc4b83d83772f0d217.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2013
20
5
DETERMINING SOIL SHEAR STRENGTH PARAMETERS FROM CPT AND CPTu DATA
Hossein
Motaghedi
Abolfazl
Eslami
Determining the soil shear strength parameters, i. e., cohesion (C), internal friction angle (ϕ)is done by means of laboratory tests and the in situ testing data. The cone penetration test, cone penetrometer test (CPT) is not only quick and economical, but also is repeatable and shows continuous records of soil parameters with depth. The common approaches for shearing strength parameters determination from CPT data are on the basis of bearing capacity and cavity expansion theories. In this study, different methods of soil shear strength parameters determination from CPT and CPTu results, qc,fs anduwere reviewed and investigated. A new method is proposed for C, ϕprediction on the basis of all quantities, qc, u and fs from CPTu considering bearing capacity mechanism of failure. One advantage of this method is improvement accuracy in the case of erroneous data by using all three output of CPTu. The proposed, current and experimental test results of an information bank including 32 CPT and CPTu results were assessed in five sites. The comparison of predicted and measured C and ϕangle values indicates good consistency and low scatter for the proposed method. This can be led to more accurate and apply continuous soil parameters in optimized geotechnical design.
Effective shearing strength parameters
Cohesion
internal friction angle
sleeve friction
CPT and CPTu
In situ tests
2013
10
01
1349
1360
http://scientiairanica.sharif.edu/article_1512_37baa4c01a273db19659be0799a257b5.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2013
20
5
Experimental Investigation of Square RC Column Strengthened with Near Surface Mounted GFRP Bars Subjected to Axial and Cyclic lateral Loads
N.
Dayhim
A.
Nicknam
M.A.
Barkhordari
A.
Hosseini
S.
Mehdizad
This article is intended to highlight the effectiveness of longitudinal Glass Fiber Reinforced Polymer (GFRP) bars in combination with GFRP sheets on the flexural capacity of Reinforced Concrete (RC) columns. Seven half-scale RC columns including five strengthened and two control unstrengthened specimens were experimentally tested under axial and cyclic lateral loads. The strengthened columns with two different longitudinal GFRP bar ratios were tested under three different axial load levels. The flexural strength and ductility parameters of the specimens were calculated by obtaining their deformations and measuring the loads from load cells. The experimental results indicate significant increase in the flexural strength of the RC specimens. The results of this study can be reliably utilized to enhance the flexural strength of RC columns in the regions with high seismicity.
Cyclic Lateral Load
GFRP Bar
Near-Surface Mounted Technique
GFRP Wrap
ductility
Flexural strengthening
2013
10
01
1361
1371
http://scientiairanica.sharif.edu/article_1513_3a46cbce50628fcb429b140e3fa298fc.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2013
20
5
Combined Effect of Silica Fume and Polypropylene Fiberon Drying Shrinkage Properties of Concrete Composites Containing Fly Ash
Peng
Zhang
Qing-fu
Li
A parametric experimental study has been conducted to investigate the combined effect of silica fume and polypropylene fiber onthe workability and dryingshrinkage of concrete composite containing fly ash. Four contents of fly ash, four silica fume contents and four different fiber volume fractions were used. The results indicate thatfly ash can not only improve the workability but also lower the dryingshrinkage of the concrete composite.The workability of the concrete compositebecomes better and betterand the dryingshrinkage strain is decreasing gradually with the increase of fly ash content. Besides, silica fume has adverse effect on both of the workability and dryingshrinkage property of concrete composite containing fly ash. With the increase of silica fume content, both of the slump and slump flow of the concrete containing fly ash are decreasing gradually, while the dryingshrinkage strainhas an increasing tendency. In addition, polypropylene fiber can greatly restrict the dryingshrinkage of concrete composite containing fly ash and silica fume, and there is a tendency of decrease in the dryingshrinkage strain with the increase of fiber volume fraction.However, polypropylene fiber has a little adverse effect on the workability of concrete composite.
Concrete composite
Workability
Dryingshrinkage property
Fly ash
Silica Fume
Polypropylene fiber
2013
10
01
1372
1380
http://scientiairanica.sharif.edu/article_1514_aeb5ccc6622f68909404a2fd3d8d5a4c.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2013
20
5
Study of Rotational Kinematic Hardening Model: A General Plasticity Formula and Model Implement
Kuangmin
WEI
Sheng
ZHU
Theories of the rotational kinematic hardening model are introduced in detail. This model is used to predict soil behaviors under large stress reversals by incorporating the rotation and intersection of isotropic hardening yield surfaces in principal stress space. During the monotonic loading, the model behaves the same as isotropic hardening model, but once stress reversals occurs, new kinematic yield surfaces will generate, then these yield surfaces evolve (e.g. rotate, shrink, expand, vanish etc.) obeying the rotational kinematic hardening rule in the process of loading. A general plasticity formula of rotated yield surface or plastic potential surface in the principal stress space is given in this research, which is the basis of the rotational kinematic hardening model. It is also a very integral part to design logical procedures to determine the load mode of soil element during surfaces’ evolution. New logical procedures developed by this paper have been successfully used within the framework of Lade-Kim model, test results and model predictions showed a good consistency in stress reversal triaxial tests using loose Santa Monica beach sand. Source codes of logical procedures to implement the rotational kinematic hardening model within the framework of Lade-Kim model are provided at the end of this paper to give readers a further understanding.
Elastoplasticity
Rotational kinematic hardening model
Stress reversal
General plasticity formula
Logical procedures
2013
10
01
1381
1394
http://scientiairanica.sharif.edu/article_1515_6e68f3edd555efd1f31b7f978f6871a5.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2013
20
5
INVESTIGATION OF CARBON AND ACRYLIC FIBRE– REINFORCED MORTARS
Hanifi
BINICI
Hasan
KAPLAN
Osman
U.BAYRAK
This paper presents an experimental study on the compressive, flexure, toughness and abrasion behaviours of acrylic and carbon fibre–reinforced mortars. The mechanical and physical properties of seven different composite mortars samples containing different amounts of textile fibres were compared with reference samples preparedwith standard sand, cement and water. The characteristic properties of the mortars were improved by adding fibre. However, this improvement is directly related to the type and length of fibre used for reinforcing the concrete structure. Mortarscontaining both carbon and acrylic fibre had more compressive strength. In particular, mortars containing acrylic and carbon had 32% higher compression strength than control mortars. Sample AC1 produced with both carbon filaments and acrylic fibreshas the highest compressive strength. The brittle property of mortarscan be improved by reinforcing it with carbon filaments or acrylic fibres. The toughnessof specimens depending on both the fibre type and the length of fibres were observed.
Carbon and acrylic fibres
Mortar
ductility
2013
10
01
1395
1400
http://scientiairanica.sharif.edu/article_1516_b2daf84221595105a0024346a19f0d35.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2013
20
5
Control volume finite element modeling of free convection inside an inclined porous enclosure with a sinusoidal hot wall
Asskar
Janalizadeh
Saman
Soleimani kutanaei
Saman
Soleimani kutanaei
E.
Ghasemi
In this study, the effects of different governing parameters on natural convection heat transfer
between an inclined hot basement roof and a cold environment are investigated numerically
using the Control Volume based Finite Element Method (CVFEM). The medium between the
cold and hot surfaces is filled by soil which can be considered as a porous media. The
physical model can be approximated as an enclosure with various inclination angles. The cold
wall of the enclosure is assumed to mimic a sinusoidal profile with different dimensionless
amplitudes. The numerical investigations are conducted at the Prandtl number (Pr 1) and
various values of non-dimensional governing parameters namely: the porosity ( ), Darcy
number (Da ) and Rayleigh number ( Ra ). The geometrical variables in this study are the
inclination angle ( ) and dimensionless amplitude (a ) of the sinusoidal cold wall. The
obtained results show the significant effects of and a on the streamlines and isotherms as
well as the local and average Nusselt numbers at various values ofDa , andRa . Effects of
the governing parameters on heat transfer and fluid flow in the upper and lower parts of the
enclosure are also investigated.
Porous enclosure, Natural convection, Sinusoidal wall
Inclination angle
CVFEM
2013
10
01
1401
1414
http://scientiairanica.sharif.edu/article_1517_e4a4ec93ad2297c9279ca4904bcc083b.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2013
20
5
An Enhanced Particle Swarm Optimization for Design of Pin Connected Structures
A.
Baghlani
M.H.
Makiabadi
In this paper, a new technique in weight optimization of pin connected structures is proposed. Using some principles of structural analysis, the concepts of similar trusses in structural analysis and optimum similar trusses in optimization of truss structures are introduced. Based on these definitions, the technique searches for one of the optimum similar trusses to map it into boundary and find the optimum truss. The technique is referred to as searching optimum similar trusses (SOST). It is general and its implementation in standard particle swarm optimization (PSO) is developed in this article which is called PSOST. Rapid convergence with few numbers of analyses and accurate constraint handling is achieved by the technique and absolutely feasible solutions are obtained. Several benchmark planar and spatial truss structures have been optimized using this approach. The results show remarkable improvement both in accuracy and particularly in convergence rate of the design.
pin connected structures
trusses
Structural Analysis
weight optimization
particle swarm optimization (PSO)
2013
10
01
1415
1432
http://scientiairanica.sharif.edu/article_1518_9fbff77fd746430a7e73c5eb7ffd74bc.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2013
20
5
Prediction of unsaturated soils effective stress parameter using gene expression programming
A.
Johari
G.
Habibagahi
M.
Nakhaee
G.
Habibagahi
Unsaturated soil shear strength can be determined using effective stress relation that depends on the effective stress parameter. Several models have been developed in past few years to estimate this parameter. In this research, the Gene Expression Programming (GEP) is used as an Artificial Intelligence (AI) method for developing a model to predict the effective stress parameter using efficient parameters. The principal advantage of the GEP approach is its ability to generate powerful prediction equations without any prior assumption on the possible form of the functional relationship.The input terminal set consistsof net confining pressure, suction, Soil Water Characteristic Curve (SWCC) fitting parameter, bubbling pressure, residual and saturated volumetric water content. The output terminal set has one member, which is the effective stress parameter. An experimental database obtained from the literature is employed to develop the model. Comparison of the model prediction with the actual data as well as other investigators indicates a very good performance and ability of model. Sensitivity and parametric analyses are conducted to verify the results. It is also shown that soil suction is the most influential parameter in the effective stress parameter of unsaturated soils.
unsaturated soil
Effective stress parameter
gene expression programming
Soil suction
2013
10
01
1433
1444
http://scientiairanica.sharif.edu/article_1519_df97f9b282bf5e132de108d2ceba3d74.pdf