Title: Simplified design for positive restraint continuity moment in bridge girders
Date Published: July - August 2018 
Volume: 63 
Issue: 4 
Page Numbers: 62-78
Authors: Maher K. Tadros, Amgad M. Girgis, Christopher Y. Tuan, and Athul A. Alex
https://doi.org/10.15554/pcij63.4-04

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Abstract

Precast, prestressed concrete continuous bridges have been constructed in many countries around the world. Although these bridges have been in service for many years, there has been limited verification of the ability of the connection to provide the predicted continuity. Subsequently, many U.S. states design the girders as simple spans for both dead and live loads without considering any moments developed by the diaphragm connection. The effect of thermal expansion and contraction is hardly considered in the analysis, though it is found to have significant effects on continuity. Apart from this, there is no consensus on the best method to calculate restraint moments that develop in the continuity diaphragm or how to detail positive moment connections.

The objective of this paper is to provide a simplified spreadsheet analysis for the restraint moments and the required crack control reinforcement. Detailed numerical analysis was performed using a two-span NU-girder bridge. It is recommended that the strands already in the beam be used to meet the crack control requirements with no additional mild reinforcement.

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