ABSTRACT
ABSTRACT: Many steel bridges built decades ago have redundancy issues since redundancy was not accommodated in the design. These major non-redundant steel bridges are in various forms, such as two-girder bridges, tied arch bridges with tension ties, and truss bridges. With the lack of redundancy, failure from one member of the bridge would lead to the failure of the entire bridge. Serious attention is necessary for this structural performance, structural reliability, and, most importantly, public safety issue. Instead of replacement of the entire bridge, rehabilitation might be favorable for some steel bridges due to their historical significance, materials viability for continuous service, cost effectiveness of rehabilitation over bridge replacement, etc. This paper provides a discussion on the structural reliability improvement using a post-tensioned concrete floor system for major non-redundant steel bridges rehabilitation. A non-redundant structure can be represented as a series system, in the reliability engineering aspect, in which when one of the system components fails, the entire system fails. A structure with redundancy, on the other hand, is considered as a combination system made of series and parallel configurations, where a parallel configuration is one that does not fail unless all the components fail. Illustrative examples are provided in this paper for further demonstration of the structural reliability improvement.
