About the research
With ever-tightening budgets, states are looking for cost-effective methods of lengthening the time from initial bridge construction to its complete replacement. One common technique to make effective use of funds and to minimize the time from initial construction to replacement is to replace the deck after it has reached the end of its useful service life while keeping the original superstructure and substructure (assuming that the superstructure and substructure still have adequate strength and remaining life). However, one key element to such a deck replacement is ensuring that the deck is removed successfully without damaging the superstructure elements. The situation is especially important/difficult when the deck must be removed in large pieces without allowing concrete to fall under the bridge.
Contractors are typically using saws to segment the deck and impact equipment (breakers, chipping hammers, etc.) to then break the deck segments free from the superstructure elements. There are attributes of both steel and concrete (prestressed) girders that present difficulties in such operations. For example, steel girder bridges have a variety of shear connector types (sometimes with variable spacing) and are quite susceptible to top flange cutting; current standard concrete girders have very thin top flanges that make them vulnerable to impact and other damage.
When damage to the superstructure occurs, delays in reconstruction can be quite significant. Recent examples can be found in many locations across the US. More efficient and reliable methods for concrete deck removal are needed.
The objective of this work is to determine and/or develop new cost-effective and efficient deck removal techniques for steel superstructure bridges. The following criteria will be considered as part of the evaluation:
- Impact on the future performance of the superstructure
- Cost – including cost comparison between deck removal and complete superstructure replacement
Furthermore, the work proposed herein will include guidance on assessing and repairing steel girders that are damaged during removal of a deck.