جستجو در تالارهای گفتگو

OPTIMIZATION OF I-SECTION PROFILE DESIGN BY THE FINITE ELEMENT METHOD ABSTRACT: This paper discusses the problem of design optimization for an I-section profile. The optimization process was performed using the Abaqus program. The numerical analysis of a strictly static problem was based on the finite element method. The scope of the analysis involved both determination of stresses and displacements in the profile and structure topology optimization. The main focus of the numerical analysis was put on reducing profile volume while maintaining the same load and similar stresses prior to and after optimization. The solution of the optimization problem is just an example of the potential of using this method in combination with the finite element method in the Abaqus environment. Nowadays numerical analysis is the most effective cost-reducing alternative to experimental tests and it enables structure examination by means of a computer. منبع دانلود OPTIMIZATION OF I-SECTION.pdf

OPTIMAL DESIGN AND BENEFIT/COST ANALYSIS OF RESERVOIR DAMS BY GENETIC ALGORITHMS CASE STUDY: SONATEH DAM, KORDISTAN PROVINCE, IRAN M. Monadia, H. M. V. Samanib and M. Mohammadi Abstract This paper presents a method concerning the integration of the benefit/cost analysis and the real genetic algorithm with various elements of reservoir dam design. The version 4.0 of HEC-RAS software and Hydro-Rout models have been used to simulate the region and flood routing in the reservoir of the dam, respectively. A mathematical programming has been prepared in MATLAB software and linked with the optimal programming then employed to maximize the benefit/cost ratio of the reservoir dam construction. After a sensitivity analysis, mutation and crossover probability are assumed to be 0.05 and 0.7, respectively. The objective function of the study is benefit/cost ratio. The combined methodology has been provided to help to compute the optimal normal water level, length of spillway and downstream levee height of a reservoir dam considering flood control and cost of construction. This is the first attempt to optimize these important parameters, in the construction of a reservoir dam, together considering flood control and economical aspects. It has been displayed that the proposed method provides strong and suitable solutions to determine these parameters. The results showed that there is potential for application of genetic algorithms to such optimization problems, where the objective function is nonlinear and other optimization techniques may be troublesome to apply and find the global optimum. Keywords Optimization, Normal Water Level , Spillway Length, Genetic Algorithms, Matlab Software, Reservoir Dam, Sonateh Dam چکیده در این مقاله از یک روش که در آن تحلیل سود بر هزینه و الگوریتم ژنتیک پیوسته با هم ترکیب شده­اند برای طراحی سد مخزنی استفاده شده است. برای شبیه­سازی محدوده مورد نظر و روندیابی سیلاب در مخرن سد به ترتیب از نرم افزار4.0 HEC-RAS و Hydro-Rout استفاده شده است. برای یافتن حداکثر مقدار نسبت سود به هزینه ساخت سد یک برنامه کامپیوتری در نرم­افزار MATLAB نوشته شده و با برنامه بهینه­سازی پیوند داده شده است. پس از تحلیل حساسیت برنامه بهینه­سازی، مقادیر جهش و تولید مثل به ترتیب برابر با 05/0 و 7/0 به دست آمدند. در تحقیق حاضر تابع هدف نسبت سود به هزینه ساخت سد مخزنی است. برنامه یاد شده امکان محاسبه مقادیر بهینه رقوم نرمال، طول سرریز و ارتفاع خاکریزپایین­دست سد مخزنی، با در نظر گرفتن کنترل سیلاب و هزینه ساخت سد مخزنی، را فراهم می­سازد. روش معرفی شده در این مقاله اولین تلاش برای به دست آوردن مقادیر بهینه پارامترهای یاد شده با در نظر گرفتن موضوع کنترل سیلاب و جنبه­های اقتصادی سد مخزنی و همچنین روشی قدرتمند برای محاسبه مقادیر پارامترهای یاد شده است. نتایج به دست آمده نشان می­دهد که برای چنین مسائلی که تابع هدف غیرخطی بوده و استفاده از روش­های دیگر بهینه­سازی با مشکلاتی روبه­رو خواهند بود، الگوریتم ژنتیک ابزاری دقیق و قدرتمند خواهد بود. 29-4-6.pdf

An Optimization Model for Financial Resource Allocation Towards Seismic Risk Reduction Elnaz Peyghaleh; M.R. Zolfaghari; P. Vaziric This paper presents a study on determining the degree of effectiveness of earthquake risk mitigation measures and how to prioritize such efforts in developing countries. In this paper a model is proposed for optimizing funds allocation towards risk reduction measures (building retrofitting) and reconstruction process after potential earthquakes in a regional level. The proposed model seeks optimized strategy towards risk reduction based on minimizing or maximizing various criteria such as retrofitting costs, economic damages including business interruption losses, number of human casualties and other seismic hazard consequences. The main objective of this model is to find optimum strategy for maximizing the benefits of available economic resources for retrofitting and reconstructions. Regional seismic hazard and building stocks and their vulnerability functions are used to model probabilistic seismic risk for a given region. The proposed model is adjusted for developing countries exposed to high seismic sources like Iran. In order to present the application of the proposed method, the approach is applied for a pilot area in Tehran. Results illustrate the variation of mitigation in particular, structural retrofitting expenditures and reconstruction expenditures by structural type for buildings in this region. In addition, recommended expenditures by year for the case study are obtained according to the results. منبع دانلود JSEG301354307400.pdf

A Mathematical Modeling for Plastic Analysis of Planar Frames by Linear Programming and Genetic Algorithm Leila Shahryari In this paper, a mathematical modeling is developed for plastic analysis of planar frames. To this end, the researcher tried to design an optimization model in linear format in order to solve large scale samples. The computational result of CPU time requirement is shown for different samples to prove efficiency of this method for large scale models. The fundamental concept of this model is obtained from moment distribution method which is a safe theorem based method, so in this mathematical modeling, the objective is finding the largest load which ensures equilibrium and yield conditions. Contrary to moment distribution method, calculation of load factor and the value of moments in the elements are completely automatic and not to need user decision. As the objective function and constraints of this model are linear so it can be solved by linear programming (LP) software such as LINGO that is shown in this paper and also the model is solved by genetic algorithm (GA) to compare two solutions منبع دانلود JSEG81313868600.pdf

Introducing a modified gradient vector method for optimization of accident prediction non-linear functions Shahriar Afandizadeh, Mahmud Ameri, Mohammad Hassan Mirabi Moghaddam ⇑ Department of Civil Engineering, Iran University of Science and Technology, Tehran, Iran a b s t r a c t In this paper, a new optimization method has been proposed for accident prediction nonlinear models. This has been achieved by eliminating the Hessian matrix from the equation of optimal pace length in the gradient vector method. One advantage is that it is independent of the starting point in optimization processes and it provides convergence at the highest top as well. This method has been tested on an accident prediction model and its preference over the gradient vector method has been proven. 2011 Elsevier Inc. All rights reserved. Keywords: Accident prediction model Optimization Gradient vector Convergence Optimal pace length Hessian matrix 1-s2.0-S0307904X11002137-main.pdf

Optimization of Clay Core Dimensions in Earth Fill Dams Using Particle Swarm Algorithm Original Article, B31 Roshani E, Farsadizadeh D. Journal. Civil Eng. Urban. 2(5): 176-181. 2012. ABSTRACT: The flow rate from earth fill dam body mainly depends on the dimensions and characteristics of the clay core. Thus, finding the optimized dimensions for clay core in non-homogeneous earth fill dam is essential. In order to decrease water loss, the clay core should be expanded this leads to dramatic increment in construction volume and costs. The novelty of this issue could be expressed as an optimization material in which the total cost of lost water and earthwork should be minimized. The method serves us a simpler and an accurate solution for an earth fill dam to be in optimised dimensions. The objective function is consisting of two parts. The first part is to calculate the water seepage volume through the dam core with a combination of finite element method and artificial neural network (ANN) and the second part encounters the costs regarding to the volume of earth works. Finally the best answer from the economical view will be chosen according to the amount of seepage and core volume. Since calculating water seepage through soil using finite element method is time consuming, first a combination of 600 different potential shapes of the core has been modelled by finite element and then the result have been used to train an artificial neural network. Comparing this model with linear and logarithmic regression models proved that ANN evaluates water flow rate with more precession. Output data, including flow rate, entered to the particle swarm optimization (PSO) algorithm and the optimized dimensions were achieved. The proposed model for optimizing the clay core dimension can be applied for non-homogeneous earth fill dams with impervious foundation. Allavian earth fill dam was chosen to show the benefit of using the proposed optimization method in a real world case study. The results indicated that the construction cost could be dramatically less than what has been already spent on the case study. Keywords:Optimization, Clay core, Artificial neural network, Particle swarm optimization منبع: [Hidden Content] دانلود: [Hidden Content],%20B%2031%20176-181.pdf JCEU, B 31 176-181.pdf

Optimum parameters of tuned liquid column–gas damper for mitigation of seismic-induced vibrations of offshore jacket platforms Seyed Amin Mousavi*,†, Khosrow Bargi and Seyed Mehdi Zahrai University of Tehran, School of Civil Engineering, Tehran, Iran, Islamic Republic of Iran SUMMARY The effectiveness of tuned liquid column–gas damper, TLCGD, on the suppression of seismic-induced vibrations of steel jacket platforms is evaluated in this study. TLCGD is an interesting choice in the case of jacket platforms because it is possible to use the structural elements as the horizontal column of the TLCGD. In this study, optimum parameters of the TLCGD are obtained, considering nonlinear damping of the TLCGD and water–structure interaction between jacket platform and sea water. Equation of motions and other related formulas are derived, and using a SIMULINK model, the frequency and the head loss coefficient of the TLCGD are optimized. Results are in general agreement with those obtained in earlier studies for typical building structures. However, effects of period of the structure and ground motion characteristics on the optimum parameters are also evaluated in this study. Results show that until a particular threshold for the mass ratio, the higher the mass ratio, the higher the efficiency of the damper. After that, by increasing the mass ratio, there is no improvement on the damper efficiency. It is also found that PGA and frequency content of a ground motion have no important effect on the optimum frequency ratio, but they have a noticeable effect on the optimum head loss coefficient. Besides, frequency content has some effect on the TLCGD efficiency. It is shown that the optimum frequency of a TLCGD is uncoupled with the area ratio and the head loss coefficient, and they have no effect on the optimum frequency ratio. Copyright © 2011 John Wiley & Sons, Ltd. Received 23 November 2010; Revised 6 July 2011; Accepted 14 October 2011 KEY WORDS: passive control; tuned liquid column–gas damper; TLCD; offshore platform; seismic excitation; optimization STRUCTURAL CONTROL AND HEALTH MONITORING Struct. Control Health Monit. 2013; 20:422–444 Published online 19 December 2011 in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/stc.505 منبع: [Hidden Content] دانلود: [Hidden Content] iQ5EJ2eG.pdf