Fit Condition and Fit-Up Behavior - Impact on Design and Construction of Steel I-Girder Bridges

By

Thanh V. Nguyen

Advisor

Dr. Donald W. White (CEE)

Committee Members:

Dr. Barry Goodno (CEE), Dr. Abdul-Hamid Zureick (CEE), Dr. Kenneth M. Will (CEE), Dr. Richard W. Neu (ME)

Date & Time: Monday, October 5, 2015 at 12:00pm

Location: 2119 Mason Building

ABSTRACT

Tighter constraints on right-of-way, particularly in urban environments, have led to a significantly increased utilization of skewed and/or curved alignments in highway bridge construction. However, challenging attributes of the framing arrangements combined with current practices for detailing of the cross-frames and erecting these bridges can result in problems during and after construction. Substantial progress has been made in answering many of the questions associated with this research in prior NCHRP Report 725 research as well as in subsequent efforts. However, the focus of these efforts was predominantly on sufficiency of different methods of analysis and on synthesis of broad observations and experiences with respect to fit-up.

This research studies various factors and methods and proposes improved design, detailing and erection guidelines to facilitate the fit-up of skewed and/or curved steel I-girder bridges. Concepts and procedures for explicit calculation of locked-in forces due to cross-frame detailing are developed and discussed. Fit-up forces are evaluated and discussed for a suite of bridge cases analyzed in this research. Bridge cases with difficult fit-up are highlighted. Recommendations for erection procedures are provided to facilitate fit-up. The research investigates and recommends beneficial staggered cross-frame framing arrangements that are applicable to straight skewed bridges, framing arrangements with liberal offsets around bearing lines at interior pier in continuous spans bridges, and the use of staggered versus lean-on cross-frame arrangements in straight skewed bridges. The research also addresses the impacts of cross-frame detailing methods, that is, the “fit condition” of the structure, on cross-frame forces, girder elevations, girder layovers, girder stresses, and vertical reactions in the completed bridges.