Dynamic Properties of Gravelly Materials
A.
Ghalandarzadeh
Department of Civil Engineering,University of Tehran
author
A.
Aghaei Araei
Department of Civil Engineering,Iran University of Science and Technology
author
H. R.
Razeghi
Department of Civil Engineering,Iran University of Science and Technology
author
S.
Hashemi Tabatabaei
Department of Geomatics Engineering,Building and Housing Research Center
author
text
article
2010
eng
This paper studies the dynamic characteristics (i.e. shear modulus and damping ratio)
of modeled gravelly soils used as construction materials in some rock-fill dams in Iran by conducting
large-scale triaxial testing. Tested specimens were compacted to more than 95% maximum dry density,
according to Modied Proctor, and tested according to ASTM D 3999. Accurate monitoring of strains by
means of non-contact type displacement transducers to infinitesimal strains as small as 0.0001% enabled
us to obtain Gmax with some extrapolation. Based on the available experimental results the ranges for
G=Gmax ????
and D ????
are defined for materials with > 30% fine content and materials with < 15%
fine content. The results clearly indicate the need for modification in previously proposed G=Gmax ????
curves, particularly for gravels with > 30% fine content. Also, the suggested D ????
curves lay out of
the bounds of data reported by previous researchers, which may be due to the effects of testing frequency,
fine content, and confining pressure. In addition, a predictive hyperbolic model for estimating normalized
shear modulus (G=Gmax) versus shear strain (
) is presented. Effects of the number of cyclic loadings
over the shear modulus and damping ratio are also investigated.
Scientia Iranica
Sharif University of Technology
1026-3098
17
v.
4
no.
2010
https://scientiairanica.sharif.edu/article_3151_1fcf5aef1fb8c6453216d1e4ce01bd73.pdf
Effect of Internal and External Shear Wall Location on Strengthening Weak RC Frames
M.Y.
Kaltakci
Department of Civil Engineering,SeoNam University
author
M.H.
Arslan
Department of Civil Engineering,SeoNam University
author
G.
Yavuz
Department of Civil Engineering,SeoNam University
author
text
article
2010
eng
Hundreds of thousands of Reinforced Concrete (RC) buildings have been either seriously
damaged or have completely collapsed due to major earthquakes in recent years in Turkey, therefore, the
construction of RC buildings gained momentum by the aid of scientific studies on strengthening. As well
as mentioning the importance of the strengthening process using Shear Walls (SW) in RC buildings of
poor earthquake performance, an experimental study carried out to analyze the in
uence of the location of
a SW on the existing system was also mentioned in this study. A total of three, two-storey, two-bay RC
frames of 1/3 scale were produced for the experiments by expecting them to represent the behavior of the
RC frames having weak earthquake strength; two of which were strengthened with SWs. The main aim
of this study is to compare the effectiveness of internal and external SW locations on strengthened weak,
RC frame earthquake behavior. The strength, stiness and ductility of the tested frames were compared
within the light of numerical results obtained from the experiments. In the study, an overall comparison
of strengthening methods was made in terms of applicability, usability and cost.
Scientia Iranica
Sharif University of Technology
1026-3098
17
v.
4
no.
2010
https://scientiairanica.sharif.edu/article_3152_bb2bc2c857f13735f950216dc7bca1ac.pdf
Lateral-Torsional Buckling of Retrofitted Steel I-Beams Using FRP Sheets
M.Z.
Kabir
Department of Civil Engineering,Amirkabir University of Technology
author
A.E.
Seif
Department of Civil Engineering,Amirkabir University of Technology
author
text
article
2010
eng
This study intends to present an analytical solution of lateral-torsional buckling of an Ibeam,
which is retrofitted using FRP sheets. The analytical solution is based on calculating the total
potential energy and applying the Rayleigh-Ritz method. It is supposed that the FRP sheet can be used on
anges. Therefore, two cases of retrotting are the I-beam with Top-Bottom retrofitted
anges (TB) and
Bottom retrofitted
ange Only (BO). It is also assumed that the
ange and the FRP sheet are considered
as a continuous hybrid element and the Classical Lamination Theory (CLT) can be applied. Subsequently,
from the energy method, stiness parameters of retrotted sections are produced for both cases of TB and
BO and the critical moment is presented for the retrotted I-beam under positive end moments. Finally,
numerical consideration and a parametric study with various fiber angles in a [+=????] laminate sequence
are used for both simple and clamped beams under some typical loadings, to inspect the eects of FRP
sheets on the development of the lateral-torsional buckling capacity. Moreover, FEM results are produced
from numerical models made up of 2D shell elements to verify the analytical solution.
Scientia Iranica
Sharif University of Technology
1026-3098
17
v.
4
no.
2010
https://scientiairanica.sharif.edu/article_3153_22346c19e70e93adac9602e52c90b73f.pdf
A New Approach for Estimating the Seismic Soil Pressure on Retaining Walls
S.
Maleki
Department of Civil Engineering,Sharif University of Technology
author
S.
Mahjoubi
Department of Civil Engineering,Sharif University of Technology
author
text
article
2010
eng
The model incorporates nonlinearity in the behavior of near wall soil, wall
exibility and
elastic free eld soil response. This model can be employed in nonlinear modeling of retaining walls and
bridge abutments. The advantages of this model are simplicity and
exibility in addition to acceptable
precision. Using this nite element model, an analytical study is conducted on several soil-wall systems
using nonlinear time-history analysis by applying real earthquake records. Based on the results of these
analyses, new seismic soil pressure distributions are proposed for dierent soil and boundary conditions.
These distributions are shown to be more accurate than the popular Mononobe-Okabe equations.
Scientia Iranica
Sharif University of Technology
1026-3098
17
v.
4
no.
2010
https://scientiairanica.sharif.edu/article_3154_e48d2e3b69756c315d282a9f5c6dafd3.pdf
Experimental and Numerical Investigations on Flooding System of Iranian South-Coast Dry Docks
A.
Najafi-Jilani
Department of Civil Engineering,Tarbiat Modares University
author
M.
Monshizadeh
Department of Civil Engineering,Tarbiat Modares University
author
A.
Naghavi
Department of Civil Engineering,Tarbiat Modares University
author
text
article
2010
eng
Experimental investigations were carried out on the
ooding system of the Bandar-Abbas
dry dock, located on the southern coast of Iran. The main goal of the investigation was to evaluate
the
ooding time, as well as the seawater
ow specications, in the intake channels. The time variable
upstream and downstream boundary conditions were simulated. The eects of tidal
uctuations on water
discharge through the intake channels were inspected. The
ow pattern around the bed over
ow weirs
of the intake channel was also investigated. The air trapping at the top of the main intake channel
was recognized as an eective phenomenon on the
ooding rate. A numerical model is simultaneously
developed to evaluate the
ow pattern and the velocity and pressure domain in the watering channels.
Applicable guidance about selection of the element type and optimization of the convergence rate of the
numerical modeling was presented especially for
ow simulation under unsteady boundary conditions and
complex geometry. Numerical results were compared with corresponding laboratory measured data and a
good agreement was obtained.
Scientia Iranica
Sharif University of Technology
1026-3098
17
v.
4
no.
2010
https://scientiairanica.sharif.edu/article_3155_cb41be9a68bcb567ea7037a510c07adb.pdf
A Shortest Path Problem in an Urban Transportation Network Based on Driver Perceived Travel Time
Y.
Shafahi
Department of Civil Engineering,Sharif University of Technology
author
H.
Ramazani
Department of Civil Engineering,Sharif University of Technology
author
S.E.
Seyedabrishami
Department of Civil Engineering,Sharif University of Technology
author
text
article
2010
eng
This paper proposes a method to solve shortest path problems in route choice processes when
each link's travel time is a fuzzy number, called the Perceived Travel Time (PTT). The PTT is a subjective
travel time perceived by a driver. The algorithm solves the fuzzy shortest path problem (FSPA) for drivers
in the presence of uncertainty regarding route travel time. For congested networks, the method is able to
nd the shortest path in terms of perceived travel time and degree of saturation (congestion) along routes
at the same time. The FSPA can be used to support the fuzzication of trac assignment algorithms. The
applicability of the resulting FSPA for the trac assignment was tested in conjunction with incremental
trac loading and was applied to a large-scale real network. The results of the trac assignment based on
the FSPA, User Equilibrium (UE) and a stochastic loading network model (Dial's assignment algorithm)
were compared to the observed volume for certain links in the network. We conclude that the proposed
method oers better accuracy than the UE or Dial's assignment algorithm for the network under testing.
Scientia Iranica
Sharif University of Technology
1026-3098
17
v.
4
no.
2010
https://scientiairanica.sharif.edu/article_3156_2f3258a15b2c100b37fa528c8a825949.pdf