Impact of Construction Loads on Steel Diaphragm Bridge Design
Sponsor: Georgia Department of Transportation
Project Information
PI: Lauren Stewart, Co-PI: Yang Wang
Students: Nadine Fahed and Peter Lander
Dates: Sept 25, 2018 - June 24, 2020
Funding: $98,500
Summary
Bridges are critical structures, serving an important function vital to the safe and economical conveyance of people and goods throughout Georgia. They are designed to carry loads including their self-weight and a design vehicle load, among others, when they are completed. Satisfying all design specifications is crucial to the strength, stiffness, stability, and durability of the structure throughout its lifetime. In addition to the in service dead and live load conditions, bridges are also designed to accommodate various loading conditions during the construction process. In some cases, these construction load and associated stability requirements are the governing load conditions for some of the bridges’ components.
Georgia Department of Transportation (GDOT) has recently allowed the substitution of steel diaphragms in lieu of concrete diaphragms in its bridges. This substitution is gaining popularity amongst contractors due to the ease of construction and subsequent reduction of cost. Currently, there is no standardized design for GDOT steel diaphragms and contractors are allowed to produce their own designs based on loading scenarios currently specified in the GDOT Bridge and Structures Design Manual, revision 2.6. These scenarios include full long-term wind loadings and are not well characterized, mainly due to the lack of understanding of the actual loads and load transfer mechanisms that the bridges are subjected to during the construction process. This project seeks to provide the data and recommendations for a more efficient, yet safe, steel diaphragm design. Specifically, this project will: (1) observe and measure GDOT construction practices through visual observations by experts and by electronic sensors, (2) quantify the effects of the construction practices in terms of loadings via observations and computational models, (3) assess the overall impact of construction load variations on bridge designs, and (4) make recommendations to GDOT for loading specifications and for a standardized steel diaphragm design. .