18
1735-0522
671
Structure- Concrete
An experimental study on the flexural performance of agro-waste cement composite boards
Khorami
M.
^{
b
}
Sobhani
J.
^{
c
}
^{
b
}Assistant professor at Islamic Azad University, branch Eslamshahr
^{
c
}Assistant Professor of Road, Housing & Urban Development Research Center (BHRC), Tehran, Iran, 13145-1696.
1
12
2013
11
4
207
216
06
02
2012
03
07
2013
Worldwide, asbestos fibers utilized in fiber cement boards, have been recognized as harmful materials regarding the public
health and environmental pollutions. These concerns motivate the researchers to find the appropriate alternatives to substitute
the asbestos material towards the sustainability policies. In this paper, the applicability of asbestos replacement with three
types of agricultural waste fibers, including bagasse, wheat and eucalyptus fibers were experimentally investigated. To this
end, the flexural behaviour and microstructure of cement composite boards made by addition of 2 % and 4 % of waste
agricultural fibers in combination with and without 5 % replacement of silica fume by mass of cement were evaluated. The
results of this study attested the applicability of utilized waste agricultural fibers in production of cement composite boards by
improving the flexural and energy absorption characteristics, more or less, depending on the type of fibers. Moreover, it is
found that application of silica fume in production of cement composite boards led to an increase in flexural strength.
493
Structure-Earthquake
A comparison between lumped and distributed plasticity approaches in the pushover analysis results of a pc frame bridge
Rahai
A. R.
^{
d
}
Fallah Nafari
S.
^{
e
}
^{
d
}Amirkabir University of Technology
^{
e
}Amirkabir University of Technology
1
12
2013
11
4
217
225
19
10
2010
16
07
2013
The seismic behavior of frame bridges is generally evaluated using nonlinear static analysis with different plasticity
models hence this paper tends to focus on the effectiveness of the two most common nonlinear modeling approaches
comprising of concentrated and distributed plasticity models. A three-span prestressed concrete frame bridge in Tehran, Iran,
including a pair of independent parallel bridge structures was selected as the model of the study. The parallel bridges were
composed of identical decks with the total length of 215 meters supported on different regular and irregular substructures with
non-prismatic piers. To calibrate the analytical modeling, a large-scale experimental and analytical seismic study on a two-span reinforced concrete bridge system carried out at the University of Nevada Reno was used. The comparison of the results
shows the accuracy of analytical studies. In addition, close correlation between results obtained from two nonlinear modeling
methods depicts that the lumped plasticity approach can be decisively considered as the useful tool for the nonlinear modeling
of non-prismatic bridge piers with hollow sections due to its simple modeling assumption and less computational time.
938
Structure-Steel
Analysis of near-regular structures with node irregularity using SVD of equilibrium matrix
Rahami
H.
^{
f
}
Kaveh
A.
^{
g
}
Ardalan Asl
M.
^{
h
}
Mirghaderi
S. R.
^{
i
}
^{
f
}University of Tehran
^{
g
}IRAN UNIVERSITY OF SCIENCE AND TECHNOLOGY
^{
h
}University of Tehran
^{
i
}University of Tehran
1
12
2013
11
4
226
241
14
06
2013
19
10
2013
In the process of structural analysis we often come to structures that can be analyzed with simpler methods than the standard approaches. For these structures, known as regular structures, the matrices involved are in canonical forms and their eigen-solution can be performed in a simple manner. However, by adding or removing some elements or nodes, such methods cannot be utilized. Here, an efficient method is developed for the analysis of irregular structures in the form a regular structure with additional or missing nodes or with additional or missing supports. In this method, the saving in computational time is considerable. The power of the method becomes more apparent when the analysis should be repeated very many times as it is the case in optimal design or non-linear analysis.
600
Construction Management
Predicting the operation and maintenance costs of condominium properties in the project planning phase: An artificial neural network approach
Tu
K. J.
^{
j
}
Huang
Y. W.
^{
k
}
^{
j
}National Taiwan University of Science and Technology
^{
k
}National Taiwan University of Science and Technology
1
12
2013
11
4
242
250
11
09
2011
02
07
2013
The decisions made in the planning phase of a building project greatly affect its future operation and maintenance (O;M)
cost. Recognizing the O;M cost of condominiums’ common facilities as a critical issue for home owners, this research aims to
develop an artificial neural network (ANN) O;M cost prediction model to assist developers and architects in effectively
assessing the impacts of their decisions made in the planning phase of condominium projects on future O;M costs. A
regression cost prediction model was also developed as a benchmark model for testing the predictive accuracy of the ANN
model. Six critical building design attributes (building age, number of apartment units, number of floors, average sale price,
total floor area, and common facility floor area) which are usually available in the project planning phase, were identified as
the input factors to both models and average monthly O;M cost as the output factor. 55 of the 65 existing condominium
properties randomly selected were treated as the training samples whose data were used to develop the ANN and regression
models the other ten as the test samples to compare and verify the predictive performance of both models. The study results
revealed that the ANN model delivers more accurate and reliable cost prediction results, with lower average absolute error
around 7.2% and maximum absolute error around 16.7%, as compared with the regression model. This study shows that ANN
is an effective method in predicting building O;M costs in the project planning phase.
Keywords: Project management, Facility management, Common facilities, Cost modeling.
549
Water-Coastal
Laboratory study of geosynthetic cellular system (GCS) models under wave action in flume
Ghiassian
H.
^{
l
}
Jalili
M.
^{
m
}
Rahmani
I.
^{
n
}
Madani
M. M.
^{
o
}
^{
l
}IRAN UNIVERSITY OF SCIENCE AND TECHNOLOGY
^{
m
}IRAN UNIVERSITY OF SCIENCE AND TECHNOLOGY
^{
n
}Transportation Research Institute
^{
o
}Islamic Azad University, Central Branch,
1
12
2013
11
4
251
260
02
05
2011
04
09
2013
The concept of Geosynthetic Cellular Systems (GCS) has recently emerged as a new method in construction of breakwaters
and coastal protective structures. The method potentially has significant advantages compared to conventional systems from
the standpoint of constructability, cost effectiveness, and environmental considerations. This paper presents the results of
physical model testing on the hydraulic responses of GCS structures under wave action. A series of model tests were carried
out in a wave flume on GCS models with different shapes and soil types, subjected to various wave characteristics. Horizontal
wave forces acting on the models were measured at different elevations. The maximum horizontal force in each test was
calculated and compared with conventional formula of predicting wave pressure on breakwaters. The results show that Goda’s
equation overestimates the hydrodynamic water pressure on these structures. This can be attributed to the influence of seeping
water through the GCS models because of relative permeability of the GCS.
652
Water-Coastal
Investigation of the surf zone hydrodynamics in the vicinity of reflective structures by taking the nonlinearity of waves and wave-current interactions into account
Abedimahzoon
N.
^{
p
}
Lashteh Neshaei
A.
^{
}
^{
p
}Guilan University
^{
}Guilan University
1
12
2013
11
4
261
271
02
01
2012
16
07
2013
In this paper, a new approach is presented for estimating the vertical and horizontal distribution of undertow in the surf
zone for reflective beaches. The present model is a modification of the original model presented by Okayasu et al., (1990) for
natural, non-reflective beaches to include the effect of partially reflected waves. The nonlinearity of waves, wave-current
interaction and nonlinear mass drift of the incident wave are also included in the present model. The results of experimental
investigation and model development show that existence of reflective conditions on beaches results in a reduction in the
magnitude of undertow and modifies its distribution across the beach profile. Comparison of the results by those obtained from
the experiments clearly indicates that by taking the nonlinearity and wave-current interaction, the predictions of undertow in
the surf zone are much improved. In particular, due to the effect of turbulence induced by wave breaking for nonlinear waves,
the predicted results show more consistence with the measurements.
721
Environment
A pilot study for the application of one- and two-stage tube settlers as a secondary clarifier for wastewater treatment
Fraji
A.
^{
}
Asadollahfardi
Gh.
^{
}
Shevidi
A.
^{
}
^{
}Kharazmi University
^{
}Kharazmi University
^{
}Abasspour University
1
12
2013
11
4
272
280
05
06
2012
21
10
2013
Secondary clarifiers with large areas are widely applied in wastewater treatment plants. A pilot study was conducted to
examine the possibility of applying one and two-stage inclined tube settlers instead of conventional secondary clarifiers. Tube
diameter in the first stage of the two-stage settler was wide as the conventional ones, but in the second stage, it was narrow to
improve the efficiency. The results indicated that in short detention times, the tube settler was more effective in shorter
detention time than the conventional secondary sedimentation basin, and its effluent of TSS and turbidity was acceptable to
discharge into the surface waters. The average removal of TSS, BOD5, and COD, in a 20-minute detention time in the tubes, in
the one-stage tube settler pilot plants was 97.6%, 96.4%, and 96.36%, respectively, while in the conventional secondary
sedimentation basin was 98.2%, 99%, and 98.6%, respectively. There was a good agreement between theoretical analyses and
experimental results of the pilot plant. Two-stage tube settlers in the series could improve hydraulic condition and removal
efficiency of TSS, in comparison with the one-stage tube settler. The average TSS removal, in shorter detention times than that
the one-stage, was 97.8%.
800
Transportation
SA-IP method for congestion pricing based on level of service in urban network under fuzzy conditions
Soudmand
S.
^{
}
Ghatee
M.
^{
}
Hashemi
S. M.
^{
}
^{
}Amirkabir University of Technology
^{
}Amirkabir University of Technology
^{
}Amirkabir University of Technology
1
12
2013
11
4
281
291
16
11
2012
28
07
2013
This paper proposes a new hybrid method namely SA-IP including simulated annealing and interior point algorithms to
find the optimal toll prices based on level of service (LOS) in order to maximize the mobility in urban network. By considering
six fuzzy LOS for flows, the tolls of congested links can be derived by a bi-level fuzzy programming problem. The objective
function of the upper level problem is to minimize the difference between current LOS and desired LOS of links. In this level, to
find optimal toll, a simulated annealing algorithm is used. The lower level problem is a fuzzy flow estimator model with fuzzy
link costs. Applying a famous defuzzification function, a real-valued multi-commodity flow problem can be obtained. Then a
polynomial time interior point algorithm is proposed to find the optimal solution regarding to the estimated flows. In pricing
process, by imposing cost on some links with LOS F or E, users incline to use other links with better LOS and less cost. During
the iteration of SA algorithm, the LOS of a lot of links gradually closes to their desired values and so the algorithm decreases
the number of links with LOS worse than desirable LOS. Sioux Falls network is considered to illustrate the performance of SA-IP method on congestion pricing based on different LOS. In this pilot, after toll pricing, the number of links with LOS D, E and
F are reduced and LOS of a great number of links becomes C. Also the value of objective function improves 65.97% after toll
pricing process. It is shown optimal toll for considerable network is 5 dollar and by imposing higher toll, objective function
will be worse.