Rapid Bridge Construction Technology: Precast Elements for Substructures

Abstract

This thesis elaborates on the ongoing efforts of University of Wisconsin ? Madison and Wisconsin DOT to utilize precast technology for bridge substructures in Wisconsin as a rapid construction technique. Decreasing the negative outcomes of detours for the traveling public and freight transportation during bridge replacement projects is the main advantage of the precast construction in addition to improving work zone safety, allowing the use of innovative materials, introducing better in plant quality control and lessening the environmental impact. The use of precast concrete for bridge superstructures has long been known and practiced. Various precast substructure elements have been used throughout the world resulting in successful projects. After the better understanding of the importance of the project time in replacement projects, Wisconsin also started to shift to accelerated construction techniques. The last two projects, Baldwin Bridge on USH 63 in Croix County of Wisconsin and Mississippi Slough Bridges on Wisconsin Highway 25 which use precast substructure elements, clearly show these efforts. After evaluating the characteristics of current cast in place abutments, piers, pier caps and foundations, the components that are the most advantageous for precasting were already determined and specific systems have been developed during a first phase of research completed by Okumus46. Precast abutments and pier caps are observed to be the most suitable elements for standardizing and are the focus of this research as well, which is the extension of the first precast substructures project. Modules of reasonable weight under permissible limit for Wisconsin and sizes, accordingly, are defined. Easy to implement connection details with enough strength were identified for the systems. Standardization was ii given special attention to allow repetition, reuse of forms and provide familiarity of details for contractors. Especially for this research, it is decided that the same bent cap system will be used for piers, pile caps and in some abutments which will increase the repetitive nature of the system. Through regular interaction with DOT engineers and the precast manufacturers, alternative guidelines, design examples and standard plans are being prepared as end products. It is believed that future projects such as the ones mentioned before, with precast abutments will help improve the system more and show efficiency of precast substructure use in Wisconsin and make both design engineers and contractors more familiar with the system resulting in a lower project cost.