scholarly journals Multiobjective Design Optimization of Grillage Systems according to LRFD-AISC

2011 ◽  
Vol 2011 ◽  
pp. 1-24 ◽  
Author(s):  
Tugrul Talaslioglu
Keyword(s):  
Multiobjective Optimization ◽  
Design Optimization ◽  
Optimization Algorithms ◽  
Grid Structure ◽  
American Institute ◽  
Design Constraints ◽  
Factor Design ◽  
Computational Procedures ◽  
Load And Resistance Factor ◽  
Multiobjective Design

Both the entire weight and joint displacements of grid structures are minimized at the same time in this study. Four multiobjective optimization algorithms, NSGAII, SPEAII, PESAII, and AbYSS are employed to perform computational procedures related to optimization processes. The design constraints related to serviceability and ultimate strength of grid structure are implemented from Load and Resistance Factor Design-American Institute of Steel Constructions (LRFD-AISC Ver.13). Hence, while the computational performances of these four optimization algorithms are compared using different combinations of optimizer-related parameters, the various strengths of grid members are also evaluated. For this purpose, multiobjective optimization algorithms (MOAs) employed are applied to the design optimization of three application examples and achieved to generate various optimal designations using different combinations of optimizer-related parameters. According to assessment of these optimal designations considering various quality indicators, IGD, HV, and spread, AbYSSS shows a better performance comparatively to the other three proposed MOAs, NSGAII, SPEAII, and PESAII.

scholarly journals Multiobjective Design Optimization Framework for Multicomponent System with Complex Nonuniform Loading

2020 ◽  
Vol 2020 ◽  
pp. 1-19
Author(s):  
Hong Zhang ◽  
Guangchen Bai ◽  
Lukai Song
Keyword(s):  
Genetic Algorithm ◽  
Multiobjective Optimization ◽  
Design Optimization ◽  
Optimal Algorithm ◽  
Multicomponent System ◽  
Kriging Model ◽  
Surface Model ◽  
Optimization Framework ◽  
Comparison Results ◽  
Multiobjective Design

To improve the accuracy and efficiency of multiobjective design optimization for a multicomponent system with complex nonuniform loads, an efficient surrogate model (the decomposed collaborative optimized Kriging model, DCOKM) and an accurate optimal algorithm (the dynamic multiobjective genetic algorithm, DMOGA) are presented in this study. Furthermore, by combining DCOKM and DMOGA, the corresponding multiobjective design optimization framework for the multicomponent system is developed. The multiobjective optimization design of the carrier roller system is considered as a study case to verify the developed approach with respect to multidirectional nonuniform loads. We find that the total standard deviation of three carrier rollers is reduced by 92%, where the loading distribution is more uniform after optimization. This study then compares surrogate models (response surface model, Kriging model, OKM, and DCOKM) and optimal algorithms (neighbourhood cultivation genetic algorithm, nondominated sorting genetic algorithm, archive microgenetic algorithm, and DMOGA). The comparison results demonstrate that the proposed multiobjective design optimization framework is demonstrated to hold advantages in efficiency and accuracy for multiobjective optimization.

scholarly journals Perancangan Kolom Struktur Gable Frame Untuk Berbagai Bentang Lebar Bangunan

2020 ◽  
Vol 23 (1) ◽  
Author(s):  
Marsiano Marsiano ◽  
Fajar Fajar
Keyword(s):  
Resistance Factor ◽  
American Institute ◽  
Factor Design ◽  
Load And Resistance Factor

Struktur Gable Frame merupakan salah satu alternatif didalam mendesain bangunan baja. Strukturdengan bentang lebar antara 40 - 60 meter mengakibatkan harus menempatkan kolom tambahan di tengah. Halini menjadikan perlunya dilakukan penelitian terhadap penempatan kolom tengah. Dengan bentang bangunanyang berbeda, sudut kemiringan atap ditentukan sebesar 3 derajat, serta menggunakan Atap Metal sebagaipenutup atapnya. Studi dilakukan dengan mengamati lima variasi bentang (40, 45, 50, 55 dan 60 meter), sertaalternatif penempatan kolom tengah pada setengah bentang, pada sepertiga bentang dan pada seperempatbentang. Mutu baja yang digunakan adalah ST 37 dan profil WF. Yang akan diamati pada penelitian ini adalahdesain yang ekonomis dan mudah dalam pelaksanaannya. Digunakan program perhitungan struktur ETABSdalam mencari gaya-gaya yang bekerja pada setiap batangnya. Serta peraturan AISC (American Institute of SteelConstruction) untuk perhitungan perencanaan rangka atap tersebut. Proses perhitungan dilakukan berdasarkanprinsip desain keadaan batas yang diacu oleh AISC sebagai LRFD (Load and Resistance Factor Design) sertaperaturan SNI (Standar Nasional Indonesia). Dalam analisa perbandingan ini dapat disimpulkan bahwa lebihbaik menggunakan desain ketiga yaitu desain dengan jarak seperempat bentang, dimana desain tersebut lebihekonomis dari segi berat struktur 1 portalnya dengan nilai yang lebih kecil dibandingkan dengan desain pertamadan kedua. Dari segi berat struktur 1 portal dapat dirata-ratakan bahwa Tipe 1 lebih ekonomis 11,6 % jikadibandingkan dengan Tipe 2, dan Tipe 2 lebih boros 21,7 % jika dibandingkan dengan Tipe 3 serta Tipe 1 lebihboros 7,3 % jika dibandingkan dengan Tipe 3.

Columns in partially restrained construction: analytical studies

1987 ◽  
Vol 14 (4) ◽  
pp. 485-497 ◽  
Author(s):  
David A. Nethercot ◽  
Patrick A. Kirby ◽  
Abdussalam M. Rifai
Keyword(s):  
Structural Design ◽  
Analytical Procedure ◽  
Load Path ◽  
American Institute ◽  
Load Paths ◽  
Factor Design ◽  
Definition Of ◽  
Partially Restrained ◽  
Load And Resistance Factor ◽  
End Restraint

The American Institute of Steel Construction Proposed Load and Resistance Factor Design Specification recognizes the ability of connections that function as less than fully rigid to transmit limited moments and to provide some measure of end restraint to columns in its definition of partially restrained (PR) construction. An analytical procedure for determining the response up to collapse of subassemblages in which semirigid beam-to-column connections are present is derived. This employs a nonlinear finite element column analysis together with analytical representation of experimentally determined connection moment–rotation [Formula: see text] curves. To trace the full response under any load path produced by a combination of beam loads and direct column load, it is necessary to allow for possible reversal in the direction of rotation of any of the connections. The program is used to study the effect of different connection types (ranging from very flexible web cleats to almost rigid extended end plates) and different load paths on column behaviour in nonsway subassemblages. It is found that the degree of rotation required from each connection is an important parameter in determining column response. Key words: buckling, columns, connections, frames, stability, steel, structural design, structures.

Multiobjective Optimization Dealing With Uncertainty

1989 ◽  
Author(s):  
S. U. Mohandas ◽  
E. Sandgren
Keyword(s):  
Multiobjective Optimization ◽  
Natural Language ◽  
Design Optimization ◽  
Fuzzy Sets ◽  
Fuzzy Set ◽  
Optimization Problem ◽  
Objective Functions ◽  
Fuzzy Goals ◽  
Box Method ◽  
Multiobjective Design

Abstract An algorithm to handle uncertainty in a multiobjective design optimization problem is developed. The procedure is applied to three examples where objective functions in each of them compete against each other. The uncertainty in the description of objective functions is modeled by using fuzzy goals and the terms of natural language. Multiobjective function is formulated as a fuzzy set. The minimization is carried out using a combination of the Complex Box method and a technique of ranking of fuzzy sets.

Multiobjective Design Optimization of a Biconcave Mobile-Bearing Lumbar Total Artificial Disk Considering Spinal Kinematics, Facet Joint Loading, and Metal-on-Polyethylene Contact Mechanics

2019 ◽  
Vol 142 (4) ◽  
Author(s):  
Chaochao Zhou ◽  
Ryan Willing
Keyword(s):  
Multiobjective Optimization ◽  
Design Optimization ◽  
Performance Metrics ◽  
Facet Joint ◽  
Pareto Frontier ◽  
Mobile Bearing ◽  
Ultrahigh Molecular Weight Polyethylene ◽  
Joint Force ◽  
Multiobjective Design ◽  
Single Objective

Abstract Total disk arthroplasty (TDA) using an artificial disk (AD) is an attractive surgical technique for the treatment of spinal disorders, since it can maintain or restore spinal motion (unlike interbody fusion). However, adverse surgical outcomes of contemporary lumbar TDAs have been reported. We previously proposed a new mobile-bearing AD design concept featuring a biconcave ultrahigh-molecular-weight polyethylene (UHMWPE) mobile core. The objective of this study was to develop an artificial neural network (NN) based multiobjective optimization framework to refine the biconcave-core AD design considering multiple TDA performance metrics, simultaneously. We hypothesized that there is a tradeoff relationship between the performance metrics in terms of range of motion (ROM), facet joint force (FJF), and polyethylene contact pressure (PCP). By searching the resulting three-dimensional (3D) Pareto frontier after multiobjective optimization, it was found that there was a “best-tradeoff” AD design, which could balance all the three metrics, without excessively sacrificing each metric. However, for each single-objective optimum AD design, only one metric was optimal, and distinct sacrifices were observed in the other two metrics. For a commercially available biconvex-core AD design, the metrics were even worse than the poorest outcomes of the single-objective optimum AD designs. Therefore, multiobjective design optimization could be useful for achieving native lumbar segment biomechanics and minimal PCPs, as well as for improving the existing lumbar motion-preserving surgical treatments.

scholarly journals The new 2005 AISC specification

2007 ◽  
Vol 60 (2) ◽  
pp. 241-250
Author(s):  
Roberto T. Leon
Keyword(s):  
Structural Steel ◽  
Resistance Factor ◽  
Practical Significance ◽  
Steel Buildings ◽  
American Institute ◽  
Framed Structures ◽  
Composite Columns ◽  
Factor Design ◽  
Load And Resistance Factor ◽  
Hollow Structural Sections

In late 2005, the American Institute of Steel Construction issued its most recent Specification for Structural Steel Buildings (ANSI/AISC 360-05). This specification includes updated design provisions in both allowable strength design (ASD) and load and resistance factor design methods (LRFD), and incorporates the design provisions for hollow structural sections and single angles. Amongst the major changes are a complete revamping of the methodologies for assessing stability of framed structures, new provisions for composite columns and updated material requirements. This paper will describe the changes and highlight those of practical significance.

Integrated Design and Multi-Objective Optimization of a Single Stage Heat-Pump Turbocompressor

2013 ◽  
Author(s):  
J. Schiffmann
Keyword(s):  
Design Optimization ◽  
High Efficiency ◽  
Integrated Design ◽  
Heat Pumps ◽  
Small Scale ◽  
Multi Objective Optimization ◽  
Design Constraints ◽  
Multi Objective ◽  
Wide Range ◽  
Standard Design

Small scale turbomachines in domestic heat pumps reach high efficiency and provide oil-free solutions which improve heat-exchanger performance and offer major advantages in the design of advanced thermodynamic cycles. An appropriate turbocompressor for domestic air based heat pumps requires the ability to operate on a wide range of inlet pressure, pressure ratios and mass flows, confronting the designer with the necessity to compromise between range and efficiency. Further the design of small-scale direct driven turbomachines is a complex and interdisciplinary task. Textbook design procedures propose to split such systems into subcomponents and to design and optimize each element individually. This common procedure, however, tends to neglect the interactions between the different components leading to suboptimal solutions. The authors propose an approach based on the integrated philosophy for designing and optimizing gas bearing supported, direct driven turbocompressors for applications with challenging requirements with regards to operation range and efficiency. Using previously validated reduced order models for the different components an integrated model of the compressor is implemented and the optimum system found via multi-objective optimization. It is shown that compared to standard design procedure the integrated approach yields an increase of the seasonal compressor efficiency of more than 12 points. Further a design optimization based sensitivity analysis allows to investigate the influence of design constraints determined prior to optimization such as impeller surface roughness, rotor material and impeller force. A relaxation of these constrains yields additional room for improvement. Reduced impeller force improves efficiency due to a smaller thrust bearing mainly, whereas a lighter rotor material improves rotordynamic performance. A hydraulically smoother impeller surface improves the overall efficiency considerably by reducing aerodynamic losses. A combination of the relaxation of the 3 design constraints yields an additional improvement of 6 points compared to the original optimization process. The integrated design and optimization procedure implemented in the case of a complex design problem thus clearly shows its advantages compared to traditional design methods by allowing a truly exhaustive search for optimum solutions throughout the complete design space. It can be used for both design optimization and for design analysis.

Multiobjective design optimization of CFRP isogrid tubes using sunflower optimization based on metamodel

2021 ◽  
Vol 249 ◽  
pp. 106508
Author(s):  
Matheus Brendon Francisco ◽  
João Luiz Junho Pereira ◽  
Guilherme Antônio Oliver ◽  
Fernando Helton Sanches da Silva ◽  
Sebastião Simões da Cunha ◽  
...  
Keyword(s):  
Design Optimization ◽  
Multiobjective Design
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