02-02-2013, 05:36 PM
Analysis of the Strength and Stability of Prestressed Concrete Through-Girder Pedestrian Bridges Under Vehicular Impact
Author: Eray Baran | Size: 17.5 MB | Format: PDF | Quality: Unspecified | Publisher: Eray Baran | Year: 2006 | pages: 307
Two issues have been investigated regarding the prestressed concrete through-girder
pedestrian bridge system. The first issue was related with the ductility of prestressed
concrete girders used in these types of bridges. The girders are reinforced with large
amounts of prestressing strands in order to satisfy the deflection requirements with the
relatively large span lengths (125-135 ft.). Moreover, the girders do not have a composite
deck on top that would help to resist the relatively large internal tensile force caused by
the prestressing strands. As a result, the section used in these bridges (Mn/DOT Type 63
section) is considered as over-reinforced according to the AASHTO LRFD Bridge
Specifications and fails to meet the required flexural strength.
A nonlinear strain compatibility analysis of the Mn/DOT Type 63 section was performed
in order to identify the design procedures that accurately predict the section behavior.
Response of the section, including the neutral axis location, strand stress at ultimate
capacity, and the moment capacity of the section, predicted by the AASHTO Standard
and AASHTO LRFD Specifications was compared with the sectional response
determined from the strain compatibility analyses. Based on the analysis results,
modifications were proposed to the procedure used by the LRFD Specifications in order
to rectify the errors in predicting the sectional response.
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