Optimal Design for Prestressed Structures Based on Continuous and Discrete Variables

2011 ◽  
Vol 243-249 ◽  
pp. 1003-1007
Author(s):  
Yong Hua Yang ◽  
Jie Wu
Keyword(s):  
Optimal Design ◽  
Search Algorithm ◽  
Relative Difference ◽  
Continuous Variable ◽  
Difference Quotient ◽  
Cross Sectional ◽  
Design Variables ◽  
Continuous And Discrete Variables ◽  
The Mathematical Model ◽  
Prestressed Structures

The mathematical model of optimal design for prestressed structures is established and a two-level algorithm based on hybrid variables is proposed. At the first level, the prestressed forces are chosen to be the design variables and the optimal design for prestressed forces based on continuous variable is carried out. At the second level, the cross-sectional areas are chosen to be the design variables and the discrete sizing optimization is carried out under fixed prestressed forces, the local constrains are satisfied with one-dimensional search algorithm, the integral constrains are satisfied with the relative difference quotient algorithm, and the efficiency of the relative difference quotient algorithm is greatly improved by introducing the assumption of statically determinant structures. The numerical example shows the correctness and effectiveness of the method.

Comparison of four meta-heuristic algorithms for optimal design of double-layer barrel vaults

2018 ◽  
Vol 33 (3-4) ◽  
pp. 115-123
Author(s):  
Ali Kaveh ◽  
Majid Ilchi Ghazaan ◽  
Soroush Mahjoubi
Keyword(s):  
Optimal Design ◽  
Double Layer ◽  
Heuristic Algorithms ◽  
Size Optimization ◽  
Community Centers ◽  
Cross Sectional ◽  
Long Span ◽  
Design Variables ◽  
Rail Station ◽  
Barrel Vaults

Barrel vaults are effective semi-cylindrical forms of roof systems that are widespread for multipurpose facilities including warehouse, rail station, pools, sports center, airplane hungers, and community centers because of providing long-span and economical roof with significant amount of space underneath. In the present study, size optimization of double-layer barrel vaults with different configurations is studied. Four recently developed algorithms consisting of the CBO, ECBO, VPS, and MDVC-UVPS are employed and their performances are compared. The structures are subjected to stress, stability, and displacement limitations according to the provisions of AISC-ASD. The design variables are the cross-sectional areas of the bar elements which are selected from steel pipe sections. The numerical results indicate that the MDVC-UVPS outperforms the other algorithms in finding optimal design in all examples.

Optimal design of nonlinear large-scale suspendome using cascade optimization

2017 ◽  
Vol 33 (1) ◽  
pp. 3-18 ◽  
Author(s):  
Ali Kaveh ◽  
Masoud Rezaei ◽  
MR Shiravand
Keyword(s):  
Optimal Design ◽  
Large Scale ◽  
Simple Procedure ◽  
Geometry Optimization ◽  
Steel Structures ◽  
Optimization Method ◽  
Scale Space ◽  
Cross Sectional ◽  
Colliding Bodies Optimization ◽  
Design Variables

Large-scale suspendomes are elegant architectural structures which cover a vast area with no interrupting columns in the middle. These domes have attractive shapes which are also economical. Domes are built in a wide variety of forms. In this article, an algorithm is developed for optimum design of domes considering the topology, geometry, and size of member section using the cascade-enhanced colliding bodies optimization method. In large-scale space steel structures, a large number of design variables are involved. The idea of cascade optimization allows a single optimization problem to be tackled in a number of successive autonomous optimization stages. The variables are the optimum height of crown and tubular sections of these domes, the initial strain, the length of the struts, and the cross-sectional areas of the cables in the tensegrity system of domes. The number of joints in each ring and the number of rings are considered for topology optimization of ribbed and Schwedler domes. Weight of the dome is taken as the objective function for minimization. A simple procedure is defined to determine the configuration of the domes. The design constraints are considered according to the provisions of Load and Resistance Factor Design–American Institute of Steel Constitution. In order to investigate the efficiency of the presented method, a large-scale suspendome with more than 2266 members is investigated. Numerical results show that the utilized method is an efficient tool for optimal design of large-scale domes. Additionally, in this article, a topology and geometry optimization for two common ribbed and Schwedler domes are performed to find their optimum graphs considering various spans.

Shape Optimal Design of Elastic Planar Frames With Elastic and Skew-Sliding Supports

1997 ◽  
Author(s):  
M. M. Oblak ◽  
M. Kegl ◽  
D. Dinevski
Keyword(s):  
Optimal Design ◽  
Linear Response ◽  
Frame Structure ◽  
Design Element ◽  
Cross Sectional ◽  
Design Elements ◽  
Beam Elements ◽  
Design Variables ◽  
Planar Frames ◽  
Gradient Based

Abstract This paper describes an approach to shape optimal design of elastic, statically loaded, planar frames with kinematically non-linear response where special attention is focused on consideration of elastic and skew-sliding supports. A frame structure is treated as to be assembled from several design elements each of them being defined as a Bézier curve. The design variables may influence the position and the shape of each design element, the cross-sectional properties of beam elements, the elastic properties of the supports as well as the angles of inclination of sliding supports. Highly accurate, locking-free and initially curved beam elements are employed to ensure accurate and reliable results. The optimal design problem is defined in a general form and its solution, by employing gradient based methods of mathematical programming, is discussed briefly. The theory is illustrated with a numerical example.

Single Spur Gear Reducer Optimization Design Mathematical Modeling

2013 ◽  
Vol 273 ◽  
pp. 198-202
Author(s):  
Yu Xia Wang
Keyword(s):  
Mathematical Modeling ◽  
Mathematical Model ◽  
Optimal Design ◽  
Objective Function ◽  
Optimization Design ◽  
Spur Gear ◽  
Design Parameters ◽  
Constraint Function ◽  
Design Variables ◽  
The Mathematical Model

In a given power P, number of teeth than u, input speed and other technical conditions and requirements, find out a set of used a economic and technical indexes reach the optimal design parameters, realize the optimization design of the reducer, This paper determined unipolar standard spur gear reducer design optimization of the design variables, and then determine the objective function, determining constraint function, so as to establish the mathematical model.

scholarly journals CO2 and Cost Optimization of Reinforced Concrete Cantilever Soldier Piles: A Parametric Study with Harmony Search Algorithm

2020 ◽  
Vol 12 (15) ◽  
pp. 5906 ◽  
Author(s):  
Zülal Akbay Arama ◽  
Aylin Ece Kayabekir ◽  
Gebrail Bekdaş ◽  
Zong Woo Geem
Keyword(s):  
Co2 Emission ◽  
Search Algorithm ◽  
Cost Optimization ◽  
Harmony Search ◽  
Minimum Cost ◽  
Objective Evaluation ◽  
Harmony Search Algorithm ◽  
Parametric Modelling ◽  
Cross Sectional ◽  
Design Variables

This paper presents the parametric modelling process of cantilever soldier pile walls based on CO2 and cost optimization with the Harmony Search Algorithm. The study attempted to fulfil the geotechnical and structural design requirements and sustainable usage necessities simultaneously. The variants of the optimum design process are selected as the cross-sectional characteristics of cantilever soldier piles such as the length and diameter of the pile, and the other design variables are the reinforcement detailing of the pile such as the diameter and the number of reinforcement bars. Besides the volume of the concrete, the unit prices of both reinforcement and concrete are evaluated as another part of the variants. The shear and flexural strength necessities, minimum cross section of the reinforcing bars and factor of safety values are identified as the constraints of the optimization. Different objective functions are defined to provide the minimum cost, the minimum CO2 emission and the integrated multi-objective evaluation of cost and CO2. In addition, the type of steel and concrete reinforcement on the optimum CO2 emission is investigated with the use of different material emission values that are selected from current literature studies. Consequently, the results of the optimization analyses are interrogated to investigate if the attainment of both minimum CO2 and cost balance can be achieved.

scholarly journals Size and Shape Optimization of Space Trusses Considering Geometrical Imperfection-Sensitivity in Buckling Constraints

2018 ◽  
Vol 3 (12) ◽  
pp. 1314 ◽  
Author(s):  
Fardad Haghpanah ◽  
Hamid Foroughi
Keyword(s):  
Optimal Design ◽  
Structural Engineering ◽  
Real Life ◽  
Imperfection Sensitivity ◽  
Cross Sectional ◽  
Design Variables ◽  
Geometrical Imperfection ◽  
Discrete Design Variables ◽  
Teaching Learning ◽  
Space Trusses

Optimal design considering buckling of compressive members is an important subject in structural engineering. The strength of compressive members can be compensated by initial geometrical imperfection due to the manufacturing process; therefore, geometrical imperfection can affect the optimal design of structures. In this study, the metaheuristic teaching-learning-based-optimization (TLBO) algorithm is applied to study the geometrical imperfection-sensitivity of members’ buckling in the optimal design of space trusses. Three benchmark trusses and a real-life bridge with continuous and discrete design variables are considered, and the results of optimization are compared for different degrees of imperfection, namely 0.001, 0.002, and 0.003. The design variables are the cross-sectional areas, and the objective is to minimize the total weight of the structures under the following constraints: tensile and compressive yielding stress, Euler buckling stress considering imperfection, nodal displacement, and available cross-sectional areas. The results reveal that higher geometrical imperfection degrees significantly change the critical buckling load of compressive members, and consequently, increase the weight of the optimal design. This increase varies from 0.4 to 119% for different degrees of imperfection in the studied trusses.

Efficient Optimum Design of Structures with Discrete Design Variables

1993 ◽  
Vol 8 (3) ◽  
pp. 199-208 ◽  
Author(s):  
E. Salajegheh ◽  
G.N. Vanderplaats
Keyword(s):  
Optimum Design ◽  
Main Idea ◽  
Continuous Variable ◽  
Test Cases ◽  
Cross Sectional ◽  
Design Variables ◽  
Discrete Design Variables ◽  
Design Values ◽  
Structural Responses ◽  
Approximate Expressions

A method is presented for optimum design of structures, where some or all design variables can be chosen from a set of prescribed values. The main idea is to reduce the number of structural analyses in the process of optimization. First the structural responses such as forces and displacements are approximated as functions of cross-sectional properties, thus high quality explicit functions are generated for the responses. Employing these approximate expressions in the optimization process, the continuous optimum design can be achieved rapidly. Using the results obtained from the continuous variable optimization and with the help of the approximated responses, a branch and bound method is used to obtain the discrete design values. The results indicate that after the completion of the continuous variable optimization, only one or two extra detailed analyses of the structure is needed to complete the discrete variable optimization. In this work, a dome and a grillage are presented as test cases.

Study on the Optimal Design of the Members of Contaniner Building with Building Materials II: Joint and Corner Column Optimization

2013 ◽  
Vol 859 ◽  
pp. 266-269 ◽  
Author(s):  
Xiao Xiong Zha ◽  
Yang Zuo ◽  
Shi Yun Chen
Keyword(s):  
Optimal Design ◽  
Software Package ◽  
Optimization Design ◽  
Building Materials ◽  
Element Analysis ◽  
Cross Sectional ◽  
Design Variables ◽  
The Finite Element Analysis ◽  
Cross Sectional Size ◽  
Strength And Stiffness

Containers are widely used for building, in order to promote the use of container building, it is necessary to do the research on optimal design. The corresponding optimal design has been achieved through the software package of HyperWorks, the lightest total weight is taken as the objective function, and the strength and stiffness are taken as the constraint conditions. Based on the finite element analysis of the joint and corner column, the cross-sectional size is taken as design variables, and then the optimization design of joint and corner column of container building is made.

scholarly journals Prediction of Optimal Design and Deflection of Space Structures Using Neural Networks

2012 ◽  
Vol 2012 ◽  
pp. 1-18 ◽  
Author(s):  
Reza Kamyab Moghadas ◽  
Kok Keong Choong ◽  
Sabarudin Bin Mohd
Keyword(s):  
Neural Networks ◽  
Optimal Design ◽  
Double Layer ◽  
Optimization Problem ◽  
Computational Cost ◽  
Space Structures ◽  
Maximum Deflection ◽  
Cross Sectional ◽  
Design Variables ◽  
Low Computational Cost

The main aim of the present work is to determine the optimal design and maximum deflection of double layer grids spending low computational cost using neural networks. The design variables of the optimization problem are cross-sectional area of the elements as well as the length of the span and height of the structures. In this paper, a number of double layer grids with various random values of length and height are selected and optimized by simultaneous perturbation stochastic approximation algorithm. Then, radial basis function (RBF) and generalized regression (GR) neural networks are trained to predict the optimal design and maximum deflection of the structures. The numerical results demonstrate the efficiency of the proposed methodology.

scholarly journals Prevalence of internalizing disorders, symptoms, and traits across age using advanced nonlinear models

2021 ◽  
pp. 1-10
Author(s):  
Hanna M. van Loo ◽  
Lian Beijers ◽  
Martijn Wieling ◽  
Trynke R. de Jong ◽  
Robert A. Schoevers ◽  
...  
Keyword(s):  
Internalizing Symptoms ◽  
Nonlinear Models ◽  
Generalized Additive Models ◽  
Population Sample ◽  
Internalizing Disorders ◽  
Relative Difference ◽  
Additive Models ◽  
Point Prevalence ◽  
Cross Sectional ◽  
The Impact

Abstract Background Most epidemiological studies show a decrease of internalizing disorders at older ages, but it is unclear how the prevalence exactly changes with age, and whether there are different patterns for internalizing symptoms and traits, and for men and women. This study investigates the impact of age and sex on the point prevalence across different mood and anxiety disorders, internalizing symptoms, and neuroticism. Methods We used cross-sectional data on 146 315 subjects, aged 18–80 years, from the Lifelines Cohort Study, a Dutch general population sample. Between 2012 and 2016, five current internalizing disorders – major depression, dysthymia, generalized anxiety disorder, social phobia, and panic disorder – were assessed according to DSM-IV criteria. Depressive symptoms, anxiety symptoms, neuroticism, and negative affect (NA) were also measured. Generalized additive models were used to identify nonlinear patterns across age, and to investigate sex differences. Results The point prevalence of internalizing disorders generally increased between the ages of 18 and 30 years, stabilized between 30 and 50, and decreased after age 50. The patterns of internalizing symptoms and traits were different. NA and neuroticism gradually decreased after age 18. Women reported more internalizing disorders than men, but the relative difference remained stable across age (relative risk ~1.7). Conclusions The point prevalence of internalizing disorders was typically highest between age 30 and 50, but there were differences between the disorders, which could indicate differences in etiology. The relative gap between the sexes remained similar across age, suggesting that changes in sex hormones around the menopause do not significantly influence women's risk of internalizing disorders.

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