Design Considerations for Integral Abutment/ Jointless Bridges in the USA

This paper summarizes results of a major study on jointless bridges sponsored by the U.S. Federal Highway Administration. This study included extensive laboratory and field experiments as well as detailed analytical studies. A set of design recommendations were provided. Jointless bridges have reduced maintenance, improved riding quality, lower impact loads, reduced snowplow damage, and structural continuity for live load and seismic resistance. However, the thermal movements of the bridge and restraint forces from the abutments and piers must be considered and accommodated. The general design philosophy is to build flexibility into the support structures to the extent feasible while providing sufficient strength for restraint forces that cannot be completely eliminated. The experimental phase of the research addressed thermal movements and stresses; creep and shrinkage movements, including the effects of exposure to the outside environment; and pile behavior. The overall analytical program consisted of studies on abutment soil-structure interaction, pier behavior, longitudinal bridge movement, secondary continuity forces, skewed bridge behavior, and construction sequences. In some cases, the research demonstrates that existing design procedures and engineering data can be used to adequately quantify the structural response and design forces for the structure. In other cases, the results of more complex analyses were used to develop simplified design relationships and procedures. _____________ Ralph G. Oesterle, Principal, Building & Environmental Consultants, 1019 Airpark Drive, Sugar Grove, IL 60554, USA Habib Tabatabai, Associate Professor, University of Wisconsin-Milwaukee, 3200 N Cramer St., Milwaukee, WI 53211, USA