- Author
- Yokel, F. Y.
- Title
- Proposed Design Criteria for Shallow Bridge Foundations.
- Coporate
- National Institute of Standards and Technology, Gaithersburg, MD
- Report
- NISTIR 90-4248, February 1990, 56 p.
- Distribution
- Available from National Technical Information Service
- Keywords
- bridges (structures) | capacity reduction factors | cohesionless soils | design criteria | design limit states | foundations | foundation settlements | load factors | sands | soil | soil exploration | spread footings
- Abstract
- Criteria for the design of spread footings for highway bridges are proposed. The criteria address working load as well as load and resistance factor design (LRFD) procedures. Importance factors to be used in conjunction with the LRFD design format are proposed. The importance factors increase the design loads as the span length increases and also otherwise account for the severity of the consequences of a structural or foundation failure. Further data on LRFD design will be available from studies presently in progress. Available information on tolerances of highway bridges and other structures to foundation displacements are reviewed. On the basis of this information, allowable foundation-displacement limits are proposed. Unconditionally allowable foundation displacements will not affect the strength and serviceability of bridges and therefore do not require structural design modifications. These allowable displacements can be doubled if it either can be demonstrated, using criteria proposed in this report, that the strength and serviceability of the bridge is comparable to that required in accordance with applicable American Association of State Highway and Transportation Officials (AASHTO) specifications, or if the design of the bridge is modified so that the predicted foundation displacements can be accommodated.