01553798

Component

Two-girder steel bridges are classified as fracture critical bridges in which a failure of a tension member would be expected to cause a portion of or entire bridge to collapse based on the definition given in the American Association of State Highways and Transportation Officials (AASHTO) LRFD Bridge Design Specifications. However, a number of such bridges with a partial or even full-depth crack in one girder have been reported. The main objective of this research project is to understand the behavior of two-girder steel bridges and evaluate their capacity in the event that one tension member is fractured. This can be achieved by investigating and identifying the factors that control whether a two-girder steel bridge will survive a girder fracture without collapse. Once identified, these factors may be used to evaluate the redundancy of existing in-service bridges and remove them from “fracture critical” list. In this research, laboratory testing of two scaled models of two-girder steel bridges and detailed finite element analyses were carried out. It was observed that the capacity of the specimens was dependent upon the level of damage. In the event of fracture of tension flange of one girder, the specimen 1 has its strength decreased 44% while this number is only 6% for the specimen 2. However, when the initial fracture involved at least half of the web, a significantly reduced capacity was observed and the crack rapidly propagated. Finally, this research recommends a new equation to calculate LTB capacity of two-girder system.

This paper was sponsored by TRB committee AFF20 Steel Bridges.

01550057

15-4860

English

18p

2015

Transportation Research Board 94th Annual Meeting

Digital/other

Figures; Photos; References; Tables

Box girder bridges; Collapse; Failure; Finite element method; Redundancy; Scale models; Steel bridges

AASHTO LRFD Bridge Design Specifications

Fracture critical members

Bridges and other structures; Design; Highways; I24: Design of Bridges and Retaining Walls

Transportation Research Board Annual Meeting 2015 Paper #15-4860

TRIS, TRB, ATRI

Dec 30 2014 1:37PM