Semi-active control of the wind-excited benchmark tall building using a fuzzy controller
text
article
2009
eng
Semi-active control systems having the adaptability aspects of active control methods along with the reliability and stability of passive controllers have been recently used to control structures against natural hazards. In this paper, a fuzzy logic based controller is designed to attenuate vibrations of a tall building under cross wind excitations. The building considered is the benchmark 76-story reinforced concrete office tower proposed for the city ofMelbourne,Australia. A collection of semi-active dampers is used at the first story to apply control forces to the structure where the damping is found through the fuzzy logic controller. Higher levels of performance are achieved in mitigating structural responses, especially the average RMS displacement response through the application of the fuzzy controller. Also investigated in the present study is the robustness of the whole structure-controller system to uncertainties in the stiffness matrix in the form of multiplicative perturbations. Simulation results verify the superior performance of the semi-active fuzzy controller over the passive controller in response mitigation of the perturbed structure.
Iranian Journal of Science and Technology Transactions of Civil Engineering
Shiraz University
2228-6160
33
v.
1
no.
2009
1
18
https://ijstc.shirazu.ac.ir/article_697_278a6177302d17b8e83b3e9c7ee77145.pdf
dx.doi.org/10.22099/ijstc.2009.697
Swelling and diffusion characteristics of the experimental GCLs
text
article
2009
eng
Swelling and diffusion characteristics of GCL samples made in the laboratory were studied and the results compared with the results of an industrial GCL. A Swell-Diffusion apparatus was designed, fabricated, and used to perform the swelling and swelling-diffusion tests. Two types of available local geotextiles (Types I and II) with an available low quality Bentonite (LQB) were used to fabricate two types of GCL’s in the laboratory (Types A and B E-GCLs). The effect of stitching, applied stress, and wetting procedure, was investigated in swelling tests. For type A E-GCL, with no stitch and no applied stress, a maximum of 6 mm swell was observed. Under 12.5 kPa stress, the swell decreased to a maximum of 2 mm. When this GCL was stitched, a maximum of 1.8 mm and 1.4 mm swell with zero and 12.5 kPa stresses were shown, respectively. The swelling results showed that the wetting procedure (from top, from bottom, and both ways) has a negligible effect in maximum swell. The type B E-GCL (having better geotextile quality compared to type A) showed a maximum 2.3 mm swell with no stitch, and 1.6 mm swell when stitched. The industrial needle punched reinforced GCLs with high quality granular sodium bentonite, under 12.5 kPa stress and wetted from top and bottom, showed a maximum of 3 mm swell. The swell data obtained from these experiments are in reasonable agreement with the data reported in the literature for similar GCLs under comparable conditions
Iranian Journal of Science and Technology Transactions of Civil Engineering
Shiraz University
2228-6160
33
v.
1
no.
2009
15
30
https://ijstc.shirazu.ac.ir/article_698_496726bcaa7453ba95c5218ee9f6e81c.pdf
dx.doi.org/10.22099/ijstc.2009.698
A constitutive model for sand liquefaction under rotational shear
text
article
2009
eng
Recently, the undrained anisotropic behavior of sand subjected to rotational shear has been a subject of great interest in both fields of experimental studies and constitutive modeling. Herein, based on the critical state concept and the bounding surface plasticity framework, a unified sand model is presented that is able to simulate the liquefaction of sand subjected to various stress paths, especially rotational shear. Using two anisotropy state parameters, the effect of soil anisotropy on the location of critical state line, dilatancy, plastic modulus, and flow direction is considered in constitutive equations. Finally, the simulative capability of the presented model is illustrated by comparison with the experimental data reported by independent research teams over a wide range of densities, stress paths, and stress levels.
Iranian Journal of Science and Technology Transactions of Civil Engineering
Shiraz University
2228-6160
33
v.
1
no.
2009
31
48
https://ijstc.shirazu.ac.ir/article_699_035c9af109252a262914a00461a9d61c.pdf
dx.doi.org/10.22099/ijstc.2009.699
The effect of beach reflection on undertow
text
article
2009
eng
Based on experiments, a model is introduced to calculate the vertical and horizontal distribution of undertow in the surf zone due to monochromatic and random wave attack for reflective beaches. The present model is a modification of the original model presented by Okayasu et al., [2] for natural, non-refiective beaches in which the wave set up, radiation stress and mass flux due to breaking waves are modified as described by Mehrdad and Neshaei [6] to include the effect of partially reflected waves. The results of experimental investigation and model development show that the existence of reflective conditions on beaches results in a reduction in the magnitude of undertow and modifies its distribution across the beach profile.
Iranian Journal of Science and Technology Transactions of Civil Engineering
Shiraz University
2228-6160
33
v.
1
no.
2009
49
60
https://ijstc.shirazu.ac.ir/article_700_9f43594120fc8efc31e8d6cec4d87ad0.pdf
dx.doi.org/10.22099/ijstc.2009.700
Fuzzy and neuro-fuzzy models for short-term water demand forecasting in Tehran
text
article
2009
eng
Water demand forecasting cannot be described by any mathematical function because it is a complicated function of a large number of interacting variables. In this paper, several fuzzy and neuro-fuzzy models are presented and their results for short-term water demand forecasting inTehran are compared. Weather data from threeTehran weather stations is weighted with the Thissen method and effective input data parameters are selected with regression of weighted effective weather and consumption data. The effective parameters include daily average temperature, relative humidity percent and last day, last week and last year water consumption. Consumption of all days between last day and the last week were also used. For the construction of fuzzy models a fuzzy rule-based approach is applied. The working rules are formulated from a set of past observations such as the relation between the parameters and the given input/output data sets. For neuro fuzzy modeling the toolbox function of Adaptive Neuro-Fuzzy Inference System (ANFIS) constructs a Sugeno Inference System (SFIS). The membership function parameters are adjusted using a back propagation algorithm in combination with a least squares method. Outputs of the fuzzy and the neuro fuzzy models demonstrate that the results of fuzzy models do not show high accuracy, but neuro fuzzy models produce better results. Besides, outputs of the neuro fuzzy models with just water consumption inputs have high accuracy. A comparison of outputs with the results of the Artificial Neural Networks (ANN) approach shows the capability of the ANFIS model to predictTehranwater consumption.
Iranian Journal of Science and Technology Transactions of Civil Engineering
Shiraz University
2228-6160
33
v.
1
no.
2009
61
77
https://ijstc.shirazu.ac.ir/article_701_f4ce6f85f9d97c6d22fa858942d72d20.pdf
dx.doi.org/10.22099/ijstc.2009.701
Conjunctive simulation of surface water and ground water resources under uncertainty
text
article
1999
eng
Iranian Journal of Science and Technology Transactions of Civil Engineering
Shiraz University
2228-6160
33
v.
1
no.
1999
https://ijstc.shirazu.ac.ir/article_702_d41d8cd98f00b204e9800998ecf8427e.pdf
dx.doi.org/10.22099/ijstc.1999.702
A non-hydrostatic free surface 2D vertical model using
discrete singular convolution (DSC) method
text
article
2013
eng
This paper is an extension for the efficient implicit two-dimensional vertical model presented by previous investigators for simulating unsteady non-hydrostatic free-surface flows. Discrete singular convolution is used in order to improve the accuracy order of spatial derivatives. However, the conventional projection method only uses adjacent cells’ values (as a second order finite volume scheme), DSC method employs function values over a band width of cells. Besides, second order Runge Kutta approximation is used to improve temporal accuracy. The DSC method is used for free surface flows and gravity current for the first time. Comparison between this extension, conventional projection method and experimental observations shows that the DSC method has improved gravity current velocity prediction.
Iranian Journal of Science and Technology Transactions of Civil Engineering
Shiraz University
2228-6160
33
v.
1
no.
2013
95
108
https://ijstc.shirazu.ac.ir/article_703_d41d8cd98f00b204e9800998ecf8427e.pdf
dx.doi.org/10.22099/ijstc.2013.703
Optimal flood management options with probabilistic
optimization: a case study
text
article
2013
eng
In this paper a probabilistic optimization model for determining flood management options is presented. The proposed model minimizes flood damages and costs based on optimal flood management options such as structural, non-structural, emergency and permanent actions in a probabilistic framework to consider risk in decision making. In the optimization model different discharge-elevation-damage-probability curves are used as the inputs which are developed based on routing floods with different return periods. The proposed methodology is applied to the Sefidrud river in the northern part ofIran. In this study, the HEC-RAS model is used for hydraulic routing of floods with different return periods along the river considering different types of flood management options. The estimated flood damage is the basis for comparing different options and determining appropriate actions. The results demonstrate the integration of various options in flood damage reduction and show the high potential of this approach in floodplain planning and management. The results also show the significant value of using the probabilistic approach in flood management and its applications in decision making.
Iranian Journal of Science and Technology Transactions of Civil Engineering
Shiraz University
2228-6160
33
v.
1
no.
2013
109
121
https://ijstc.shirazu.ac.ir/article_704_07dd55c509adcb9cb855258832a07e12.pdf
dx.doi.org/10.22099/ijstc.2013.704
Numerical study on seismic behaviour of precast concrete connection zone
text
article
2013
eng
Precast industrial plants in Turkey experienced considerable damage during the recent earthquakes in Turkey. The presented paper is based on a parametric study to evaluate the seismic performance of a code-designed moment-transferring scarfed connection that is widely utilized in precast industrial buildings in Turkey. Firstly, the seismic behavior of a typical symmetrically pitched double-bay precast framed system with a scarfed beam to the column connections was investigated. The coefficient of elastic rotational stiffness, Rθ,and maximum stress values were then obtained by finite element idealization with an approach of a repeated analysis. Finally, a parametric study was carried out for different values of Rθin order to evaluate the effect of joint elasticity on the behavior of a precast frame under seismic action.
Iranian Journal of Science and Technology Transactions of Civil Engineering
Shiraz University
2228-6160
33
v.
1
no.
2013
123
127
https://ijstc.shirazu.ac.ir/article_705_9596815765b3cf604fd3d2350d03d0fc.pdf
dx.doi.org/10.22099/ijstc.2013.705
Determination of "V" shaped permissible rail defect based
on WLR ratio
text
article
2013
eng
High-speed railway tracks require high quality track and accurate maintenance, but rail irregularities in main lines are inevitable. These irregularities are important sources for dynamic excitation. For the safety of trains at higher speed, the size of irregularities must be limited. In this paper, according to the Railways Standards, the wheel load reduction (WLR) ratio is introduced. Based on this ratio, the limitation for rail irregularity size is presented. Dynamic responses of track due to “V” shaped irregularity and rail corrugation is treated. A case study of rail corrugation is presented by real data measured from the Northeast district of Iranian railways.
Iranian Journal of Science and Technology Transactions of Civil Engineering
Shiraz University
2228-6160
33
v.
1
no.
2013
129
132
https://ijstc.shirazu.ac.ir/article_706_d2c4b007e7b0fe42bc5bd55e37c2c085.pdf
dx.doi.org/10.22099/ijstc.2013.706