Framework for maintenance management of shield tunnel using structural performance and life cycle cost as indicators

2018 ◽  
pp. 44-54
Author(s):  
Jianhong Wang ◽  
Atsushi Koizumi ◽  
Hiroshi Tanaka
2020 ◽  
Vol 153 ◽  
pp. 1100-1110
Author(s):  
J. Izquierdo ◽  
A. Crespo Márquez ◽  
J. Uribetxebarria ◽  
A. Erguido

2011 ◽  
Vol 255-260 ◽  
pp. 3933-3937
Author(s):  
Yu Meng Wu ◽  
Jun Chang

In this paper, decision-making tree and Markov process are used to select maintenance strategies of in-service bridges with the minimum LCC (life-cycle cost). Other costs in life cycle are considered comprehensively when establish the model to find the optimal maintenance strategy. Finally, an example is given to verify the efficiency of the model. The research methodology can provide effective support to bridge maintenance management decision-maker for making management strategies.


Author(s):  
B. H. Cameron ◽  
E. W. Grald ◽  
T. M. Conboy ◽  
C. H. Passow ◽  
N. T. Kattamis ◽  
...  

Abstract A methodology is presented for the re-design of a large centrifugal impeller used for the lift fan on an air cushion vehicle. The design is driven by stringent requirements for aerodynamic and structural performance. It is also desired to minimize the fan’s life cycle cost, by reducing both the manufacturing cost and on-going maintenance burden. Improving the fan efficiency will increase the vehicle’s endurance and range, and minimizing life cycle cost will reduce the overall operational expenses. The lift fan assembly has a double-inlet impeller and an offset double-discharge volute. The new impeller design provides increased air flow with similar aerodynamic efficiency when compared to the prior design. To reduce the manufacturing cost, the new fan blade design can be produced by an aluminum extrusion process. The manufacturing process dictates that the blade cross-section be two-dimensional across the entire span, which poses structural challenges for attachment of the blades to the shroud and center disk. Analysis of the aerodynamic and structural performance of the lift fan was carried out using computational fluid dynamics (CFD) and structural finite element analysis (FEA) models. The fabrication of full-scale lift fan components is described. Plans for final assembly and for conducting full-scale, full-power aerodynamic testing will also be explained.


Energies ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7515
Author(s):  
Bertrand Teodosio ◽  
Francesco Bonacci ◽  
Seongwon Seo ◽  
Kasun Shanaka Kristombu Baduge ◽  
Priyan Mendis

The need for advancements in residential construction and the hazard induced by the shrink–swell reactive soil movement prompted the development of the prefabricated footing system of this study, which was assessed and compared to a conventional waffle raft using a multi-criteria analysis. The assessment evaluates the structural performance, cost efficiency, and sustainability using finite element modelling, life cycle cost analysis, and life cycle assessment, respectively. The structural performance of the developed prefabricated system was found to have reduced the deformation and cracking by approximately 40%. However, the cost, GHG emission, and embodied energy were higher in the prefabricated footing system due to the greater required amount of concrete and steel than that of the waffle raft. The cost difference between the two systems can be reduced to as low as 6% when prefabricated systems were installed in a highly reactive sites with large floor areas. The life cycle assessment further observed that the prefabricated footing systems consume up to 21% more energy and up to 18% more GHG emissions. These can significantly be compensated by reusing the developed prefabricated footing system, decreasing the GHG emission and energy consumption by 75–77% and 55–59% with respect to that of the waffle raft.


1994 ◽  
Vol 11 (1) ◽  
pp. 47-56
Author(s):  
Virginia C. Day ◽  
Zachary F. Lansdowne ◽  
Richard A Moynihan ◽  
John A. Vitkevich

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