EVALUATION OF CONTINUITY IN PRESTRESSED CONCRETE JOINTLESS BRIDGES

This paper presents the results of an experimental and analytical research program that was funded by the Federal Highway Administration in order to provide a better understanding of the behavior of jointless and integral abutment bridges and also to develop a rational basis for the analysis and design of such bridges. Jointless bridges, which have been constructed by several states, promote reduced maintenance costs, improved riding quality, lower impact loads, reduced snowplow damage to decks and approaches, and improved seismic resistance. In spite of many of these recognized benefits, the behavior of such structures is not yet fully understood, and nationally adopted criteria for their design are still lacking. The experimental work presented includes testing and monitoring of bridge models and a bridge structure under construction, tests of bridge components; and a field survey of fifteen jointless bridges. Experimental results have resolved many questions regarding environmental effects, and long-term and time-dependent loading in combination with live and dead load effects. Results indicated that the live load continuity of the bridge can be reduced significantly with long-term and time dependent loading effects. In the analytical phase, the response of a jointless bridge was evaluated with respect to various design parameters. The research indicated that analysis procedures can be used to adequately quantify the structural response if accurate material and environmental parameters are known. However, in lieu of complex analyses, simplified design procedures are recommended.