1,720,964 research outputs found
Optimal design of steel skeletal structures using the enhanced genetic algorithm methodology
No full textThis study concerns with the design optimization of steel skeletal structures thereby utilizing both a real-life specification provisions and ready steel profiles named hot-rolled I sections. For this purpose, the enhanced genetic algorithm methodology named EGAwMP is utilized as an optimization tool. The evolutionary search mechanism of EGAwMP is constituted on the basis of generational genetic algorithm (GGA). The exploration capacity of EGAwMP is improved in a way of dividing an entire population into sub-populations and using of a radial basis neural network for dynamically adjustment of EGAwMP's genetic operator parameters. In order to improve the exploitation capability of EGAwMP, the proposed neural network implementation is also utilized for prediction of more accurate design variables associating with a new design strategy, design codes of which are based on the provisions of LRFD_AISC V3 specification. EGAwMP is applied to determine the real-life ready steel profiles for the optimal design of skeletal structures with 105, 200, 444, and 942 members. EGAwMP accomplishes to increase the quality degrees of optimum designations Furthermore, the importance of using the real-life steel profiles and design codes is also demonstrated. Consequently, EGAwMP is suggested as a design optimization tool for the real-life steel skeletal structures
A comparative study of multi-objective evolutionary metaheuristics for lattice girder design optimization
No full textThe geometric nonlinearity has been successfully integrated with the design of steel structural system. Thus, the tubular lattice girder, one application of steel structural systems have already been optimized to obtain an economic design following the completion of computationally expensive design procedure. In order to decrease its computing cost, this study proposes to employ five multi-objective metaheuristics for the design optimization of geometrically nonlinear tubular lattice girder. Then, the employed multi-objective optimization algorithms (MOAs), NSGAII, PESAII, SPEAII, AbYSS and MoCell are evaluated considering their computing performances. For an unbiased evaluation of their computing performance, a tubular lattice girder with varying size-shape-topology and a benchmark truss design with 17 members are not only optimized considering the geometrically nonlinear behavior, but three benchmark mathematical functions along with the four benchmark linear design problems are also included for the comparison purpose. The proposed experimental study is carried out by use of an intelligent optimization tool named JMetal v5.10. According to the quantitative results of employed quality indicators with respect to a statistical analysis test, MoCell is resulted with an achievement of showing better computing performance compared to other four MOAs. Consequently, MoCell is suggested as an optimization tool for the design of geometrically nonlinear tubular lattice girder than the other employed MOAs
DESIGN OPTIMIZATION OF LATTICE GIRDERS ACCORDING TO MEMBER AND JOINT-RELATED DESIGN CONSTRAINTS
No full textThis study concerns with the design optimization of geometrically nonlinear lattice girders. The novelty of this study comes from simultaneously using the member and joint related design constraints, which are borrowed from the provisions of API RP2A-LRFD specification and defined depending on both member and joint strengths. A multi-objective design optimization approach named ImpNSGAII, which was improved in way of integrating both a neural network implementation and an automatic generating lattice girder tool for the search mechanism of NSGAII, is utilized in this study. Hence, this study purposes to investigate how to vary the optimality quality depending on the presence of joint strength-related design constraints. Thus, it is demonstrated that the presence of the joint strength-related design constraints causes to a divergence in the construction cost of optimal designs. Consequently, it is proved that the ImpNSGAII has a higher capability of exploring a conceptual lattice girder configuration in order to obtain an optimal design satisfying the economy, load-resistance and serviceability-related design conditions at the same time. Copyright (C) 2021 by The Hong Kong Institute of Steel Construction. All rights reserved
A Unified Optimal Design Approach for Geometrically Nonlinear Skeletal Dome Structures
Get PDFIn this study, a unified optimal design approach is proposed for the design of skeletal dome structure (SDS). Thus, this study has three objectivities, i) presenting the emergence of proposed design integrity, ii) applying the proposed optimal design approach for the design optimization geometrically nonlinear SDS with both ellipse and sphere-shaped forms considering both the shape, size and topology-related design variables, iii) determining the dominant design criteria in the design of SDS. In this framework, the design of SDS is optimized thereby minimizing its entire weight and joint displacements and maximizing its member forces at the same time. The design constraints are borrowed from the provisions of American Petroleum Institute (API RP2A-LRFD) specification. A multi-objective optimization algorithm (MOA) named Pareto Archived Genetic Algorithm (PAGA), as an optimization tool is integrated by an automatic dome generating tool. Therefore, the novelty of this study comes from being the first attempt to obtain the optimal design in a way of integrating both member and joint-related design constraints by the geometrically nonlinear structural analysis. Consequently, it is displayed that that the proposed optimal design approach facilitates to determine an appropriate optimal design through a tradeoff analysis for designers depending on their preferences. The design concepts concerned with buckling, axial stress, combination of axial & bending, and yielding have the higher dominant effects in the optimal design of SDS. Furthermore, it is also demonstrated that the inclusion of diagonal members into the design of SDS provides a reduction in the violation of dominant design constraints
Optimal dome design considering member-related design constraints
No full textThis study proposes to optimize the design of geometrically nonlinear dome structures. A new Multi-objective Optimization Algorithm named Pareto Archived Genetic Algorithm (PAGA), which has an ability of integrating the nonlinear structural analysis with the provisions of American Petroleum Institute specification is employed to optimize the design of ellipse and sphere-shaped dome configurations. Thus, it is possible to investigate how the qualities of optimal designations vary considering the shape, size, and topology-related design variables. Furthermore, the computing efficiency of PAGA is evaluated considering six multi-objective optimization algorithms and eight quality measuring indicators. It is shown that PAGA has a capability of both exploring an increased number of pareto solutions and predicting a pareto front with a higher convergence degree. Moreover, the inclusion of shape-related design variables leads to a decrease in both the weights of dome structures and their load-carrying capacities. However, the designer easily determines the most requested optimal design through the archiving feature of PAGA. Thus, it is also demonstrated that the proposed optimal design procedure increases the correctness degree in the evaluation of optimal dome designs through the tradeoff analysis. Consequently, PAGA is recommended as an optimization tool for the design optimization of geometrically nonlinear dome structures
Multi-objective design optimization of geometrically nonlinear truss structures
No full textThe design optimization of geometrically nonlinear truss structures has been carried out generally by utilizing a single objective function (weight of truss structure and etc.) and an optimality criterion (uniform strain density distribution among truss members and etc.) as a design constraint. However, the interaction between optimality criteria and objective function prevents a correct and complete evaluation about optimal designations. In this study, three conflicted design criteria (weight of truss structure, critical load and uniform strain density distribution among truss members) and one design constrain (a pre-defined yielding limit) are simultaneously involved into the size and shape optimization of truss structures. For this purpose, an arc-length method as a nonlinear structural analysis is incorporated into search mechanism of a traditional pareto-ranking based multi-objective optimization method. Thus, a designer easily examines the entire solution space and makes a trade-off analysis between optimal designations (pareto solutions). Furthermore, this traditional multi-objective optimization method is improved by incorporating the multiple populations into its optimization procedure. Consequently, it is demonstrated that the computing efficiency of improved pareto-ranking based multi-objective optimization method is higher compared to both the traditional one and existing optimization approaches in Literature considering both the quality degrees of pareto solutions and the values of quality indicators named spread and inverted generational distance
Multiobjective size and topolgy optimization of dome structures
No full textThe size and topology of geometrically nonlinear dome structures are optimized thereby minimizing both its entire weight & joint (node) displacements and maximizing load-carrying capacity. Design constraints are implemented from provisions of American Petroleum Institute specification (API RP2A-LRFD). In accordance with the proposed design constraints, the member responses computed by use of arc-length technique as a nonlinear structural analysis method are checked at each load increment. Thus, a penalization process utilized for inclusion of unfeasible designations to genetic search is correspondingly neglected. In order to solve this complex design optimization problem with multiple objective functions, Non-dominated Sorting Genetic Algorithm II (NSGA II) approach is employed as a multi-objective optimization tool. Furthermore, the flexibility of proposed optimization is enhanced thereby integrating an automatic dome generating tool. Thus, it is possible to generate three distinct sphere-shaped dome configurations with varying topologies. It is demonstrated that the inclusion of brace (diagonal) members into the geometrical configuration of dome structure provides a weight-saving dome designation with higher load-carrying capacity. The proposed optimization approach is recommended for the design optimization of geometrically nonlinear dome structures
Investigation of column axial load effect for bolted-end-plate type steel connections
No full textSteel moment resisting frames (MRFs) experience not only lateral movements but also vertical ones during a seismic event. Particularly, the vertical deflections in the members of the structural system cause an increase in the possibility of high column axial compressive loads (CACLs) and correspondingly the bending moment value in the beam-to-column joints. Thus, the beam-to-column joint fails in an unanticipated form. Unfortunately, the available literature about this problem is limited and inconclusive. To help bridge the gap, this study examines the effects of the CACL on the structural behavior of bolted end-plate beam-to-column connections. In this context, this study has three purposes: verifying the experimental tests by the numerical models and evaluating the CACL effect both purely and depending on the variation of fundamental parameter values governing the joint components on the verified numerical models. The numerical analyses of the reference test specimens which are borrowed from the experimental tests in the literature are conducted utilizing a finite element (FE) model including material, geometry, and contact nonlinearities. It is concluded that a possible increase in CACL causes a deterioration in the structural behavior of the beam-to-column connection depending on the moment level transferred from the connection to the column and the shear stiffness of the panel zone.providing test data and Professor I. Serkan Misir from DEU-Turkiye for providing access to a strong computer
Incomplete-type welding imperfection on fatigue assessment of tubular T-joints
Get PDFT-joints are structural parts of tubular steel skeletal structural systems. The connection of these joints is assembled by seam-welding. The fatigue strength of the seam-welded T-joint is one of the most determinative factors for sustainable performance. Manufacturing-related incomplete-type welding imperfections affect this strength parameter. In this study, the influence of incomplete-type welding imperfection on the fatigue life of tubular T-joint is investigated for the different loading conditions with the equivalent structural stress-based approach. A total of 7 numerical models are established, including a reference model of a tubular T-joint and its variants with incomplete welding imperfections in the crown and saddle regions. Each numerical model is subjected to 14 static analyses including combinations of axial tension, in-plane bending, and out-of-plane bending loads. The results are evaluated in terms of fatigue life and the location of the damage. It is demonstrated that incomplete welding causes a decrease in the fatigue life and a change of location of the fatigue
- …
