Optimization of a trussed steel portal frame
Helminen, Mika (2017)
Helminen, Mika
2017
Rakennustekniikka
Talouden ja rakentamisen tiedekunta - Faculty of Business and Built Environment
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Hyväksymispäivämäärä
2017-12-07
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tty-201711202181
https://urn.fi/URN:NBN:fi:tty-201711202181
Tiivistelmä
The goal of this study was to develop a sizing optimization method for a trussed steel portal frame that meets strength and stability criteria presented in Eurocode 3. In addition to strength and stability of the frame members, the strength and geometrical restrictions of welded truss joints were also taken into account. The method was required to find a feasible solution of good quality within appropriate calculation time. Optimization and the finite element model of the frame were both implemented in MATLAB.
A four-stage optimization procedure was developed. This procedure includes two subproblems which are both solved first with continuous variables and then with discrete variables. The cross-sectional dimensions of square hollow section profiles were treated as design variables of the optimization problem. An interior-point algorithm was used to solve the continuous problem. The discrete problem was solved by Genetic Algorithm.
The method was tested with different structural setups in which the loading conditions and the geometry of the frame were changed. Both minimum-mass and minimum-cost solutions were searched. The distribution of total mass and cost was studied by the structural components. Additionally, the conflict of mass and cost was studied. High-strength steels were also considered in the study. Based on the results of optimization it was concluded that the four-stage procedure seems to be well-suited for the optimization problem of a trussed steel portal frame.
A four-stage optimization procedure was developed. This procedure includes two subproblems which are both solved first with continuous variables and then with discrete variables. The cross-sectional dimensions of square hollow section profiles were treated as design variables of the optimization problem. An interior-point algorithm was used to solve the continuous problem. The discrete problem was solved by Genetic Algorithm.
The method was tested with different structural setups in which the loading conditions and the geometry of the frame were changed. Both minimum-mass and minimum-cost solutions were searched. The distribution of total mass and cost was studied by the structural components. Additionally, the conflict of mass and cost was studied. High-strength steels were also considered in the study. Based on the results of optimization it was concluded that the four-stage procedure seems to be well-suited for the optimization problem of a trussed steel portal frame.