Preliminary design of precast, segmental box-girder bridges using optimization
作者:
Craig J. Miller,
Juarez Accioly,
期刊:
Canadian Journal of Civil Engineering
(NRC Available online 1979)
卷期:
Volume 6,
issue 1
页码: 120-128
ISSN:0315-1468
年代: 1979
DOI:10.1139/l79-013
出版商: NRC Research Press
数据来源: NRC
摘要:
Precast, prestressed segmental box-girder bridges are now accepted as an economical alternative for spans over 150 ft (46 m). Decisions about cross-sectional dimensions made during preliminary design can have a substantial influence on the final cost of the bridge. To help the designer obtain an economical starting point for a final design, a program was written to determine section dimensions and midspan and pier prestressing steel areas to give minimum cost. Since a preliminary design is obtained, the analysis techniques and design criteria have been simplified to reduce computation. The design produced by the program will satisfy AASHTO specification requirements and the recommendations of the PCI Bridge Committee. The optimization algorithm used is the generalized reduced gradient technique. To demonstrate the program capabilities, three example problems are discussed. The results indicate that optimum span-depth ratios are approximately 24 for the cost ratios used. The cost of the optimum design does not seem to be too sensitive to the ratio of concrete cost to prestressing steel cost.
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