Title: New LRFD-based prestressed concrete bulb-tee girders in Colorado
Date Published: May - June 2020
Volume: 65
Issue: 3
Page Numbers: 53 - 63
Authors: Yail J. Kim and Thushara Siriwardanage
https://doi.org/10.15554/pcij65.3-03  

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Abstract

This paper presents a methodology to develop prestressed concrete bulb-tee girders based on load- and resistance-factor design, particularly for addressing the immediate needs of Colorado. A historical overview of bulb-tee girders in the United States is provided along with important considerations and detailed endeavors, which give the reason for employing state-specific girders. The structural efficiency of the BT618 girders currently used in Colorado is examined and, through an optimization technique, prototype girder sections are established for parametric investigations. With the web thickness varying from 6 to 8 in. (152.4 to 203.2 mm), physical properties of the prototype girders alter, leading to a change in serviceability. Following practical suggestions from the Colorado Department of Transportation, the prototype girders were adjusted to a proposed girder series. Using bridge modeling software, the theoretical performance of the proposed girders was comparatively evaluated against the prototype and BT618 girders with an emphasis on efficiency, stress, achievable span length, time-dependent camber and deflection, and stability for hanging and during shipping.