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Showing 57 results for Location

Shooshpasha I.,
Volume 1, Issue 2 (12-2003)

This study was designed to investigate the local volume changes induced by swelling pressure in unsaturated stand-bentonite bused buffer material. A laboratory mixture of sodium bentonite (lilt/ well graded silica stool in equal proportion by do weight was used for moisture floss experiments in both ambient and elevated temperatures. Experimental results have shown that tit high water content locations within the tested specimens, the density was reduced by .3.57% from its initial values clue to swelling. The swelling pressure was calculated by 4 different models as a function of distance. The calculated results have indicated that the density distribution within the .specimen is affected by swelling potential distribution. The calculated swelling pressure values van as u function of water content, reaching I MPa at the source of water intake, i.e., at high water content, and 2 MPa cot the heater .side, i.e., cot low water content .one.
Bakhtiari Nejad F., Rahai A., Esfandiari A.,
Volume 2, Issue 2 (6-2004)

In this paper a structural damage detection algorithm using static test data is presented. Damage is considered as a reduction in the structural stiffness (Axial and/or Flexural) parameters. Change in the static displacement of a structure is characterized as a set of non-linear undetermined simultaneous equations that relates the changes in static response of the structure to the location and severity of damage. An optimality criterion is introduced to solve these equations by minimizing the difference between the load vector of damaged and undamaged structures. The overall formulation leads to a non-linear optimization problem with non-linear equality and linear inequality constraints. A method based on stored strain energy in elements is presented to select the loading location. Measurement locations are selected based on Fisher Information Matrix. Numerical and experimental results of a 2D frame represent good ability of this method in detecting damages in a given structure with presence of noise in measurements.
M.r Esfahani , M.r Kianoush, M. Lachemi ,
Volume 2, Issue 3 (9-2004)

This paper compares the results of two experimental studies on bond strength of steel and GFRP bars in the case of self-consolidating concrete (SCC). Each study included pull-out tests of thirty six reinforcing bars embedded in concrete specimens. Two types of concretes, normal concrete and self-consolidating concrete were used in different studies. Different parameters such as bar location and cover thickness were considered as variables in different specimens. The comparison between the results of GFRP reinforcing bars with those of steel deformed bars showed that the splitting bond strength of GFRP reinforcing bars was comparable to that of steel bars in both normal strength and self-consolidating concrete (SCC). The bond strength of bottom reinforcing bars was almost the same for both normal concrete and self-consolidating concrete. However, for the top bars, the bond strength of self-consolidating concrete was less than that of normal concrete.
Sabouri Ghomi S., Kharazi M.h.k., Asghari A., Javidan P.,
Volume 3, Issue 1 (3-2005)

Design and construction of efficient and economic Reinforced Concrete (R.C.) Hyperbolic Cooling Towers have driven the engineers toward the design of tall and thin-shell towers which have considerable high slenderness aspect ratio. Consequently, the shell of R.C. Cooling Towers with relative high slenderness aspect ratio is extremely prone to buckling instability due to wind loading. To increase the structural stability or buckling safety factor, one economic approach is to design and construct stiffening rings for the R.C. Hyperbolic Cooling Towers. Despite the research previously performed to determine the effect of stiffening rings on the buckling behavior of the R.C. Hyperbolic Cooling Towers, information resulting in maximum buckling stability is absent considering the optimized utilization of the quantity and dimension as well as the location of this type of stiffeners. In this paper, not only the effect of the stiffening rings on the buckling stability of the R.C. Cooling Tower is studied but also the optimized location,quantity and dimension of the stiffening rings are carried out for a sample RC Cooling Tower. The dimensions of the selected sample cooling tower are in average typical dimensions which are used in the current practice. In this study, finite element (F. E.) analyses has been carried out to define the buckling modes and resistance of this tower due to wind loading for different number of stiffening ring configurations. Based on the conducted buckling analysis, the optimized number, location and dimension of the stiffening rings that maximizes the tower.s buckling stability are defined and the methodology to achieve this information is discussed in this paper.
Mahin Roosta R., Sadaghyani M.h., Pak A.,
Volume 3, Issue 3 (9-2005)

Existence of discontinuities causes higher deformability and lower strength in rock masses. Thus joints can change the rock mass behaviour due to the applied loads. For this reason properties and orientation of the joint sets have a great effect on the stability of rock slopes. In this paper, after introducing some numerical methods for evaluating the factor of safety for the stability of slopes, stability of jointed rock slopes in the plane strain condition is investigated with the strength reduction technique this method is modified and applied in the multilaminate framework. First of all, stability of one homogeneous rock slope is investigated and compared with the limit equilibrium method. Then stability of a layered rock slope is analyzed with some modifications in the strength reduction technique. Effects of orientation, tensile strength and dilation of layered joint sets on the factor of safety and location of the sliding block are explained.
A. Afshar, H. Abbasi, M. R. Jalali,
Volume 4, Issue 1 (3-2006)

Water conveyance systems (WCSs) are costly infrastructures in terms of materials, construction, maintenance and energy requirements. Much attention has been given to the application of optimization methods to minimize the costs associated with such infrastructures. Historically, traditional optimization techniques have been used, such as linear and non-linear programming. In this paper, application of ant colony optimization (ACO) algorithm in the design of a water supply pipeline system is presented. Ant colony optimization algorithms, which are based on foraging behavior of ants, is successfully applied to optimize this problem. A computer model is developed that can receive pumping stations at any possible or predefined locations and optimize their specifications. As any direct search method, the mothel is highly sensitive to setup parameters, hence fine tuning of the parameters is recommended.
M. Heidarzadeh, M. Dolatshahi Pirooz, N. Hadjizadeh Zaker, M. Mokhtari,
Volume 5, Issue 4 (12-2007)

Makran Subduction Zone (MSZ) offshore of Iran and Pakistan is one of the most tsunamigenic sources in the Indian Ocean. Historically, the MSZ has generated some tsunamigenic earthquakes like that of 28 November 1945 with the death tool of more than 4000 people along the coasts of Iran, Pakistan, India, and Oman. In this study, the tsunami hazard associated with the MSZ is investigated. At first, a review of historical tsunamis in the Indian Ocean basin was performed which reveals the Makran region has experienced al least 4 tsunamis including events of 326 BC, 1897, 1008, and 1945. Consequently, since the pattern and extent of vertical ground deformation from an earthquake determines whether or not a tsunami is formed, a computer program is developed to predict the seafloor deformation due to the earthquake occurrence in the MSZ. The model was verified through run of it on some actual tsunamis so far occurred. Then, using the data of the 1945 Makran tsunami, the seismic parameters of the MSZ were calibrated. Finally, we used the developed computer program to calculate seafloor deformation at the location of Makran subduction zone for several earthquake scenarios with moment magnitudes ranging between 6.5 and 8.5. The results of this research show that the risk of tsunami generation from MSZ can be classified into three main categories, as follows: (1) very little risk for tsunami generation in the case of the occurrence of an earthquake having magnitude up to 7 (2) little to medium risk for moment magnitudes ranging between 7 and 7.5 and (3) high risk for moment magnitude greater than 7.5. At the end of the paper, modeling of tsunami propagation is performed for an earthquake scenario with magnitude of 8 offshore Chabahar, in order to give preliminary information about tsunami behavior in this region.
Kourosh Behzadian, Abdollah Ardeshir, Zoran Kapelan, Dragan Savic,
Volume 6, Issue 1 (3-2008)

A novel approach to determine optimal sampling locations under parameter uncertainty in a water distribution system (WDS) for the purpose of its hydraulic model calibration is presented. The problem is formulated as a multi-objective optimisation problem under calibration parameter uncertainty. The objectives are to maximise the calibrated model accuracy and to minimise the number of sampling devices as a surrogate of sampling design cost. Model accuracy is defined as the average of normalised traces of model prediction covariance matrices, each of which is constructed from a randomly generated sample of calibration parameter values. To resolve the computational time issue, the optimisation problem is solved using a multi-objective genetic algorithm and adaptive neural networks (MOGA-ANN). The verification of results is done by comparison of the optimal sampling locations obtained using the MOGA-ANN model to the ones obtained using the Monte Carlo Simulation (MCS) method. In the MCS method, an equivalent deterministic sampling design optimisation problem is solved for a number of randomly generated calibration model parameter samples.The results show that significant computational savings can be achieved by using MOGA-ANN compared to the MCS model or the GA model based on all full fitness evaluations without significant decrease in the final solution accuracy.
M.h. Sebt, E. Parvaresh Karan, M.r. Delavar,
Volume 6, Issue 4 (12-2008)

Geographic information systems (GIS) are one of the fastest growing computer-based technologies of past two decades, yet, full potential of this technology in construction has not been realized. Based upon GIS capabilities, construction site layout is one of the areas that GIS could be applied. The layout of temporary facilities (TFs) such as warehouses, fabrication shops, maintenance shops, concrete batch plants, construction equipments, and residence facilities has an important impact on the cost savings and efficiency of construction operations, especially for large projects. The primary objectives of this paper are to describe GIS technology and to present application of GIS technology to construction site layout. The study also delineated the methods of location TFs in construction site. An example application of GIS to location optimization of tower crane and concrete batch plant is provided to demonstrate GIS capabilities as compared with previous models. The spatial and nonspatial data which used in construction site layout process are analyzed and arranged on GIS environment and results showed the GIS can solve site layout problem. Finally, areas of additional research are noted.
Shahriar Afandizadeh, Morteza Araghi,
Volume 6, Issue 4 (12-2008)

Mohammad Naisipour, Mohammad Hadi Afshar, Behrooz Hassani, Ali Rahmani Firoozjaee,
Volume 7, Issue 1 (3-2009)

A meshless approach, collocation discrete least square (CDLS) method, is extended in this paper, for solving

elasticity problems. In the present CDLS method, the problem domain is discretized by distributed field nodes. The field

nodes are used to construct the trial functions. The moving least-squares interpolant is employed to construct the trial

functions. Some collocation points that are independent of the field nodes are used to form the total residuals of the

problem. The least-squares technique is used to obtain the solution of the problem by minimizing the summation of the

residuals for the collocation points. The final stiffness matrix is symmetric and therefore can be solved via efficient

solvers. The boundary conditions are easily enforced by the penalty method. The present method does not require any

mesh so it is a truly meshless method. Numerical examples are studied in detail, which show that the present method

is stable and possesses good accuracy, high convergence rate and high efficiency.

A. Khodaii, Sh. Fallah,
Volume 7, Issue 2 (6-2009)

An experimental program was conducted to determine the effects of geosynthetic reinforcement on mitigating reflection cracking in asphalt overlays. The objectives of this study were to asses the effects of geosynthetics inclusion and its placement location on the accumulation of permanent deformation. To simulate an asphalt pavement overlaid on top of a crack in a concrete or asphalt pavement, an asphalt mixture specimen was placed on top of two discontinuous concrete or asphalt concrete blocks with 100 mm height. Four types of specimens were prepared with respect to the location of geogrid: (I) Unreinforced samples, which served as control specimen, (II) Samples with geogrid embedded on the concrete or asphalt concrete block, (III) Samples with geogrid embeded one-thired depth of asphalt concrete from bottom, (IV) Samples with geogrid embedded in the middle of the asphalt beam. Each specimen was then placed on the rubber foundation in order to be tested. Simulated- repeated loading was applied to the asphalt mixture specimens using a hydraulic dynamic loading frame. Each experiment was recorded in its entirety by a video camera to allow the physical observation of reflection crack formation and propagation. This study revealed that geosynthetic reinforced specimens exhibited resistance to reflection cracking. Placing the geogrid at the one- third depth of overlay thickness had the maximum predicted service life. Results indicate a significant reduction in the rate of crack propagation and rutting in reinforced samples compared to unreinforced samples.
Sh. Afandizadeh, M. Yadak, N. Kalantar,
Volume 9, Issue 1 (3-2011)

The congestion pricing has been discussed as a practical tool for traffic management on urban transport networks. The traffic congestion is defined as an external diseconomy on the network in transport economics. It has been proposed that the congestion pricing would be used to reduce the traffic on the network. This paper investigates the cordon-based second-best congestion-pricing problems on road networks, including optimal selection of both toll levels and toll locations. A road network is viewed as a directed graph and the cutest concept in graph theory is used to describe the mathematical properties of a toll cordon by examining the incidence matrix of the network. Maximization of social welfare is sought subject to the elastic-demand traffic equilibrium constraint. A mathematical programming model with mixed (integer and continuous) variables is formulated and solved by use of two genetic algorithms for simultaneous determination of the toll levels and cordon location on the networks. The model and algorithm are demonstrated in the road network of Mashhad CBD.
M.h. Sebt, A. Yousefzadeh, M. Tehranizadeh,
Volume 9, Issue 1 (3-2011)

In this paper, the optimal location and characteristics of TADAS dampers in moment resisting steel structures, considering the application of minimum number of TADAS dampers in a building as an objective function and the restriction for destruction of main members is studied. Genetic algorithm in first generation randomly produces different chromosomes representing unique TADAS dampers distributions in structure and the structure corresponding to each chromosome is time history analyzed. Then the damage index for each member and the average weighted damage index for all members are determined. Genetic algorithm evaluates the fitness of each chromosome then selection and crossover as logical operators and mutation as random operator effect the current generation's chromosomes according to their fitness and new chromosomes are generated. Accordingly, successive generations are reproduced in the same way until the convergence condition is fulfilled in final generation and four distributions are suggested as better options. Since these proposed distributions are selected under the one earthquake, therefore, it is better that the four new structures are cost-benefit analyzed in different earthquakes. Finally, the optimal placement for dampers is compared and selected based on a benefit to cost ratio, drift stories and the number of different TADAS types of such structures. The increase in amount of energy dissipated via dampers located in different floors as well as the status of plastic hinges in main members of the structure strengthened with optimum option are the proof of the optimal placement and suitable characteristics for dampers.

A. Kaveh, H. Nasr Esfahani,
Volume 10, Issue 1 (3-2012)

In this paper the conditional location problem is discussed. Conditional location problems have a wide range of applications

in location science. A new meta-heuristic algorithm for solving conditional p-median problems is proposed and results are

compared to those of the previous studies. This algorithm produces much better results than the previous formulations.

R. A. Memon, G. B. Khaskheli, M. H. Dahani,
Volume 10, Issue 1 (3-2012)

Present study is an extension of earlier work carried out on two-lane two way roads in the two provinces of Pakistan i.e. N-25,

N-55 and N-5 regarding the measure of operating speed and development of operating speed prediction models. Curved sections

of two-lane rural highways are the main location of run-off road accidents. In addition to that the road alignment having

combination of geometric elements may be more harmful to the drivers than the successive features with adequate separation.

This study is carried out on two-lane two- way road along N-65 (from Sibi to Quetta). Three sections are selected for study with

thirty three horizontal curves. Continuous speed profile data was recorded with the help of VBox (GPS based device) which was

attached with a vehicle to detect vehicle position through satellite signals. VBox is new equipment with modern technology in this

field and it helps in recording continuous speed profile and saving of this information on the computer as a permanent record.

Through the regression analysis, models were developed for estimation of operating speed on horizontal curves and on tangent,

and estimation of maximum speed reduction from tangent to curve. The validation of developed model shows compatibility with

the experimental data.

K. Behzadian, M. Alimohammadnejad, A. Ardeshir, H. Vasheghani, F. Jalilsani,
Volume 10, Issue 1 (3-2012)

Compared to conventional chlorination methods which apply chlorine at water treatment plant, booster chlorination has almost

solved the problems of high dosages of chlorine residuals near water sources and lack of chlorine residuals in the remote points

of a water distribution system (WDS). However, control of trihalomethane (THM) formation as a potentially carcinogenic

disinfection by-product (DBP) within a WDS has still remained as a water quality problem. This paper presents a two-phase

approach of multi-objective booster disinfection in which both chlorine residuals and THM formation are concurrently optimized

in a WDS. In the first phase, a booster disinfection system is formulated as a multi-objective optimization problem in which the

location of booster stations is determined. The objectives are defined as to maximize the volumetric discharge with appropriate

levels of disinfectant residuals throughout all demand nodes and to minimize the total mass of disinfectant applied with a specified

number of booster stations. The most frequently selected locations for installing booster disinfection stations are selected for the

second phase, in which another two-objective optimization problem is defined. The objectives in the second problem are to

minimize the volumetric discharge avoiding THM maximum levels and to maximize the volumetric discharge with standard levels

of disinfectant residuals. For each point on the resulted trade-off curve between the water quality objectives optimal scheduling of

chlorination injected at each booster station is obtained. Both optimization problems used NSGA-II algorithm as a multi-objective

genetic algorithm, coupled with EPANET as a hydraulic simulation model. The optimization problems are tested for different

numbers of booster chlorination stations in a real case WDS. As a result, this type of multi-objective optimization model can

explicitly give the decision makers the optimal location and scheduling of booster disinfection systems with respect to the tradeoff

between maximum safe drinking water with allowable chlorine residual levels and minimum adverse DBP levels.

Jiuping Xu, Pei Wei,
Volume 10, Issue 1 (3-2012)

In this paper, a location allocation (LA) problem in construction and demolition (C&D) waste management (WM) is studied. A bi-level model for this problem under a fuzzy random environment is presented where the upper level is the governments who sets up the processing centers, and the lower level are the administrators of different construction projects who control C&D waste and the after treatment materials supply. This model using an improved particle swarm optimization program based on a fuzzy random simulation (IPSO-based FRS) is able to handle practical issues. A case study is presented to illustrate the effectiveness of the proposed approach. Conclusions and future research directions are discussed.

M. A. Khan,
Volume 11, Issue 1 (5-2013)

Owing to the proximity of certain locations to the thermal power stations, it has always been efforts of Engineers to enhance

the flyash utilization rate in various Civil Engineering Constructions adopting suitable strategies. In the present study, a soilflyash

interface mechanism has been evolved using different soil-flyash ratios to upgrade significantly stabilization of supporting

medium based on CBR tests. The study confirms soundness of approach when a particular interface arrangement gives high

flyash utilization rate along with many fold increase CBR values. A study was carried out to investigate the interface effect of

soil-flyash layered system in terms of CBR values so that an optimum arrangement can be achieved by using flyash in

combination with soil. In this study, 18 samples of different ratios of soil and flyash (1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:3) with three

sets of interfaces N = 2, 4 and 6 were tested to arrive at the most optimized combination of soil and flyash. The results indicate

that the CBR value optimized at soil-flyash ratio 1:2.5 and number of interface N = 4. The present study reveals that soil with

flyash when used in layered system with various numbers of interfaces gives considerable improvement in CBR values. In the

above arrangement about 71 % of flyash and 29 % of soil thus contributing significantly in utilization of flyash in subgrade of

flexible pavements. In the overall study, three equations for number of interfaces N = 2, 4 and 6 have also been developed in

terms of soil-flyash ratio and CBR value, so that CBR value can directly be obtained by substituting the value of soil-flyash ratio

at a particular number of interfaces.

M. Gharouni Nik, M. Fathali,
Volume 11, Issue 1 (5-2013)

Geometrical profile (roughness) of joint surfaces influences the behaviour of rock joints under shear loading. With regard to the

dilation, there are two models of direct shear test that may simulate the original loading condition existing in the location from

where the specimens have been sampled. The first model in which the normal load is constant (CNL) and the discontinuity is free

to dilate in shearing, represents typical situations such as movement of a block on a surface slope as a result of its own weight.

The second model in which the dilatancy is prohibited (VNL), simulates the condition of a block confined in a rock mass in an

underground opening. A shear test conducted under restricted normal displacement (dilation) will generally yield considerably

higher shear strength than one conducted under constant normal stress. In this research, both types of tests were conducted on

smooth and rough surfaces of specimens made from rock like material. The results of the VNL and the CNL direct shear tests on

regular teeth-shaped profile discontinuities indicates that at all levels of normal load, the linear Mohr-Coulomb criterion was not

valid for rough surfaces that subscribed to the power law equations. Increasing normal load emphasized the difference between

the results obtained from two methods, although for lower normal loads the results were nearly similar.

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