We propose a practical and fast finite element (FE) model updating method in which the response surface method and fmincon algorithm (FA) are used to modify the FE model of a new, improved box girder bridge with corru...
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We propose a practical and fast finite element (FE) model updating method in which the response surface method and fmincon algorithm (FA) are used to modify the FE model of a new, improved box girder bridge with corrugated steel webs. Two three-dimensional FE bridge design models were compared to develop a reasonable initial FE model for updating this bridge. The response surface method (RSM) was used in our method for the optimal experimental design of the updated parameters, which were used as the basis of the numerical analyses performed to obtain the explicit relationships between the structural responses from the FE results and the parameters themselves. A comparison of the two optimisation methods - genetic algorithm and FA - revealed that FA provides more stable optimised results with higher efficiency. Using FA, parameters can be updated by minimising an objective function, which is constructed from residuals between measured and predicted structural responses using the expressed relationships. A numerical example of a simply supported composite girder was discussed to illustrate the effectiveness of our procedure. The method was applied to the FE model updating of the Jingzhong Bridge using in situ static and dynamic results;satisfactory agreement was observed between measured and predicted bridge responses.
An inverted syphon is a hydraulic structure utilized to convey open channel flow under obstructions. This study focuses on identifying the safest and optimum design of a sewage inverted syphon to avoid intersection pr...
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An inverted syphon is a hydraulic structure utilized to convey open channel flow under obstructions. This study focuses on identifying the safest and optimum design of a sewage inverted syphon to avoid intersection problems with immovable infrastructures. Hydraulic design requirements, inlet and outlet distribution rooms features and protection of expected loads on syphons' pipes were taken under consideration in formulation the optimization model. Further, different pipes' material, many levels of the design variables and parameters were incorporated in the model to highlight the effect of each variable on the optimum design. The objective function was the minimum construction cost, and the design requirements were presented as constraints in the model. Results demonstrated that the optimum design for discharges ranging from 0.38 m(3)/sec to 0.95 m(3)/sec was Poly Vinyl Chloride (PVC) syphon, but for other discharges the reinforced concrete type was the optimum. Compared to traditional design, the optimum solutions provide a significant cost reduction. Concrete inverted syphon was the optimum possible solution to solve intersection problem of Al-Hashmea sewer project to pass sewage flow under the railway.
To improve the precision of traditional response surface methods, an updated response surface method is proposed. Combining the updated response surface method and fmincon algorithm, the accuracy of the finite-element...
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To improve the precision of traditional response surface methods, an updated response surface method is proposed. Combining the updated response surface method and fmincon algorithm, the accuracy of the finite-element model of a certain prestressed concrete continuous beam bridge is improved using the data of in situ dynamic testing. First, on the basis of specific configurations of a certain prestressed concrete continuous beam bridge, three specific design parameters that need to be updated were preselected. Eigenvalues of 15 samples were calculated using the central composite design method. The response surface method was updated by obtaining the internal relationship between specific design parameters and response eigenvalues. Fifteen response eigenvalues were calculated by finite-element analysis. Using the lsqcurvefit algorithm, undetermined coefficients of the updated response surface model were calculated, and the updated design parameters and response eigenvalues were obtained using the fmincon algorithm from the MATLAB toolbox. Numerical examples show that the updated design parameters and response eigenvalues are reasonable when compared with original parameters. Using the updated response surface method and fmincon algorithm, the numerical model of a prestressed concrete continuous beam bridge was updated effectively.
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