Application of a Compact Genetic Algorithm to Pipe Network Optimization Problems
M.H.
Afshar
Department of Civil Engineering,Iran University of Science and Technology
author
text
article
2009
eng
Abstract. This paper presents the application of a compact Genetic Algorithm (cGA) to pipe network
optimization problems. A compact genetic algorithm is proposed to reduce the storage and computational
requirements of population-based genetic algorithms. A compact GA acts like a standard GA, with a
binary chromosome and uniform crossover, but does not use a population. Instead, the cGA represents
a virtual population for a binary GA by a vector of probabilities representing the chance that the optimal
solution has a one at each bit position. The application of the cGA to pipe network optimization problems
is considered in this paper and the results are presented for two benchmark examples and compared with
existing solutions in the literature. The results show the ability of the cGA to locate the optimal solution
of problems, considered with a computational eort, comparable to improved population-based GAs and
with much fewer storage requirements.
Scientia Iranica
Sharif University of Technology
1026-3098
16
v.
3
no.
2009
http://scientiairanica.sharif.edu/article_3103_f84c8dd6b5651dd658e959bc5ab46594.pdf
Implementation and Comparison of a Generalized Plasticity and Disturbed State Concept for the Load-Deformation Behavior of Foundations
S. A.
Sadrnejad
Department of Civil Engineering,Khajeh Nasire Toosi University of Technology
author
H.
Shakib
Department of Civil Engineering,Tarbiat Modares University
author
C. S.
Desai
Department of Civil Engineering,Arizona State University
author
A. H.
Akhaveissy
Department of Civil Engineering,Razi University
author
text
article
2009
eng
Abstract. A nonlinear nite element method with an eight-noded isoparametric quadrilateral element
is used for the prediction of load-deformation behavior including the bearing capacity of foundations.
A Disturbed State Concept (DSC) with a Hierarchical Single-Surface (HISS) plasticity model with an
associated
ow rule, and a Generalized Plasticity Model (GPM) with a non-associated
ow rule are used
to characterize the constitutive behavior of soils. The DSC model, however, can allow for non-associative
behavior through the use of disturbance. Both models are able to simulate load-deformation including
softening behavior. However, the GPM is based on the continuum approach while the DSC can allow
for discontinuity due to factors such as microcracking. Predictions by both models show good agreement
with laboratory data. A comparison between the DSC/HISS and generalized plasticity model is presented
and it is found that the DSC/HISS model has certain advantages over the generalized plasticity model. A
modied Terzaghi theory is developed for the bearing capacity based on the dependence of material behavior
and in-situ stress; it can be used to compute the bearing capacity aected by in-situ stress.
Scientia Iranica
Sharif University of Technology
1026-3098
16
v.
3
no.
2009
http://scientiairanica.sharif.edu/article_3104_9166c80d597cf7ef34e9d2d1d1542050.pdf
Second-Order Displacement Functions for Three-Dimensional Discontinuous Deformation Analysis (3-D DDA) S.A.
A.
Jafari
Department of Mining and Metallurgical Engineering,University of Tehran
author
S. A. R.
Beyabanaki
Department of Mining and Metallurgical Engineering,University of Tehran
author
M. R.
Yeung
Department of Civil Engineering,University of California
author
text
article
2009
eng
Abstract. The development of second-order displacement functions for a Three-Dimensional Discontinuous
Deformation Analysis (3-D DDA) is made by incorporating the complete second order terms.
Formulations of stiness and force matrices in second-order due to elastic stress, initial stress, point load,
body force, inertia force and xed point are derived. Two illustrative examples of 3-D beams subjected to
various loads are used to validate the new formulations and code. By contrast, the results calculated for
the same model by use of the original rst-order 3-D DDA are far from the theoretical solutions.
Scientia Iranica
Sharif University of Technology
1026-3098
16
v.
3
no.
2009
http://scientiairanica.sharif.edu/article_3105_34a797fb82508aaa2e904d8b298a4443.pdf
Uniform Hazard Response Spectra and Ground Motions for Tabriz
H.
Moghaddam
Department of Civil Engineering,Sharif University of Technology
author
N.
Fanaie
Department of Civil Engineering,Sharif University of Technology
author
H.
Hamzehloo
Department of Civil Engineering,International Energy Foundation
author
text
article
2009
eng
Abstract. Tabriz has experienced several large destructive historical earthquakes in the past. Due
to the absence of ground motion records in this area, a simulation of future events based on a regional
seismicity information and ground motion model is necessary. Based on a maximum likelihood method,
earthquake magnitude is estimated for a 10% probability of exceedance within 50 years (475-year return
period) and its corresponding strong ground motions have been simulated using stochastic nite fault
modeling. Using dierent stress parameters, suites of ground motions have been simulated for a return
period of 475 years and their spectral accelerations have been compared with the corresponding uniform
hazard spectrum. It is observed that the t between simulated spectra and its corresponding uniform hazard
spectrum has been improved including the directivity eect especially at high periods.
Scientia Iranica
Sharif University of Technology
1026-3098
16
v.
3
no.
2009
http://scientiairanica.sharif.edu/article_3106_904c8829efa78d26410aa552e1422557.pdf
Semi-Active Control of Structures Using a Neuro-Inverse Model of MR Dampers
A.
Khaje-karamodin
Department of Civil Engineering,Ferdowsi University of Mashhad
author
A.
Rowhanimanesh
Department of Civil Engineering,Ferdowsi University of Mashhad
author
M.R.
Akbarzadeh-Tootoonchi
Department of Civil Engineering,Sharif University of Technology
author
H.
Haji-Kazemi
Department of Civil Engineering,Sharif University of Technology
author
text
article
2009
eng
Abstract. A semi-active controller-based neural network for a 3 story nonlinear benchmark structure
equipped with a Magneto Rheological (MR) damper is presented and evaluated. An inverse neural network
model (NIMR) is constructed to replicate the inverse dynamics of the MR damper. A Linear Quadratic
Gaussian (LQG) controller is also designed to produce the optimal control force. The LQG controller
and the NIMR models are linked to control the structure. The eectiveness of the NIMR is illustrated
and veried using the simulated response of a full-scale, nonlinear, seismically excited, 3-story benchmark
building excited by several historical earthquake records. The semi-active system using the NIMR model
is compared to the performance of an active LQG and a Clipped Optimal Control (COC) system, which is
based on the same nominal controller as used in the NIMR damper control algorithm. Two passive control
systems are also considered and compared. The results demonstrate that by using the NIMR model, the
MR damper force can be commanded to follow closely the desirable optimal control force. The results
also show that the control system is eective, and achieves better performance than active LQG and COC
system. The optimal passive controller performs better than the NIMR. However, the performance of
NIMR will be improved if a more eective active controller is replaced by a LQG controller.
Scientia Iranica
Sharif University of Technology
1026-3098
16
v.
3
no.
2009
http://scientiairanica.sharif.edu/article_3107_efed08191e37db60a9d281333208cab3.pdf
Shaking Table Test of a 1:2.35 Scale 4-Story Building Constructed with a 3D Panel System
A.
Bakhshi
Department of Civil Engineering,Sharif University of Technology
author
M.Z.
Kabir
Department of Civil Engineering,Amirkabir University of Technology
author
O.
REZAIFAR
Department of Civil Engineering,Semnan University
author
text
article
2009
eng
Abstract. The seismic behaviour of a 4-story building is investigated under horizontal excitation of
simulated earthquakes. The model has been constructed with a 3D sandwich panel system without any
conventional frame system in four storeys on a shaking table. The building has been modelled before
construction. Due to the table limit, the scale factor of the model is chosen as 1:2.35 of a prototype. The
shaking table test of the scaled model of the building is carried out under several ground motions to verify
the safety of the system. The simulated motions were applied to the model in two-perpendicular directions,
simultaneously. The failure mechanism and dynamic behaviour of the model, as a 3D-panel building, is
investigated in this study. Also, the objective of the study is to obtain the seismic performances of the
described structural system under dynamic loading such as linear and non-linear structural characteristics,
hysteretic behaviour, deformability and failure mechanism. Using these shaking tests, structural responses
such as seismic capacity and damage mechanics, the distribution of seismic forces and weak points in
the structures are evaluated. In addition, the lateral deformations, e.g. storey drifts are measured
experimentally in the time domain. Accelerometers are mounted to measure accelerations in both vertical
and horizontal directions. The results indicate that the 3D-panel system, due to its being well-conned
and its integrity, can resist mainly in the linear domain and has an adequate load bearing potential against
moderate-intense seismic excitation.
Scientia Iranica
Sharif University of Technology
1026-3098
16
v.
3
no.
2009
http://scientiairanica.sharif.edu/article_3108_9d80632e335c868eb021653a1e56fbcf.pdf
A Plate on Winkler Foundation with Variable Coecient
M.
Mofid
Department of Civil Engineering,Sharif University of Technology
author
M.
Noroozi
Department of Mechanical Engineering,Sharif University of Technology
author
text
article
2009
eng
Abstract. Plates on elastic foundations have attracted the attention of many researchers. Some
elementary models have been introduced to consider interactions between the plate and its foundation.
Other improved models have been proposed to develop basic models. In this work, a model based on the
Winkler-foundation theory is proposed, while the constant parameter of Winkler is assumed to be variable;
such as non-uniform springs with the functionality of the domain position, along with the plate and beam
span in order to consider the non-uniform behavior of the foundation. The governing equation on the
system is solved by using the Galerkin method and eects such as the presence of rigid points in the
foundation are considered.
Scientia Iranica
Sharif University of Technology
1026-3098
16
v.
3
no.
2009
http://scientiairanica.sharif.edu/article_3109_140a8394e942d87696c5a3c23e129273.pdf
Estimating Crash Risk Using a Microscopic Trac Model
S.M.
Sadat Hoseini
Department of Civil Engineering,Sharif University of Technology
author
text
article
2009
eng
Abstract. In this research, a microscopic model is developed that combines car following and lane
changing models, describing driver behavior as a utility maximization process of drivers for reducing crash
risk and increasing speed. This model is simulated by a cellular automata simulator and compared with
the real data. It is shown that there is no reason to consider the model invalid for driver behavior in
basic segments of the freeways in Iran, under non-congested conditions. Considering that the uncertain
position of vehicles is caused by their acceleration or deceleration, a probability function is calibrated
for calculating the presence probability of vehicles in their feasible cells. By multiplying the presence
probability and impact of a crash, the crash risk of cells is calculated. An idea for estimating the crash
risk of vehicles is introduced, named total risk. Total risk is the sum of risks on the path of the considered
vehicles. It is shown that, when the dierence between vehicle characteristics such as brake deceleration
increases, crash risk also increases, and vice versa.
Scientia Iranica
Sharif University of Technology
1026-3098
16
v.
3
no.
2009
http://scientiairanica.sharif.edu/article_3110_8ae6d55a2a967d301d940fbbb0f08abf.pdf