TIMBER SUBSTRUCTURES FOR BRIDGE APPLICATIONS. FINAL REPORT

Timber bridges have become a viable alternative for new bridge construction on low-volume roads, where it is imperative that the bridges be economical and long-lasting. Considerable research on superstructural systems has been completed in the U.S. and has provided design, construction, and inspection guidelines for innovative timber bridges. Guidelines for the design of stress-laminated timber decks have been published by AASHTO. However, practical recommendations concerning timber substructural systems are not readily available. Therefore, the objectives of this booklet are: (1) to present background information on timber substructures, (2) to present practical design guidelines for various systems, (3) to recommend guidelines for construction and inspection procedures, and (4) to present sources of additional information on timber substructures for bridge applications. The following five systems were selected: timber piles, steel bent-pile abutments, culverts, crib-wall abutments, and stub abutments. This publication is part of a collection of three booklets for the study Education and Technology Transfer, under the Timber Bridge Research Program. The other two booklets are: FHWA-RD-92-044 - Corrosion Protection of Steel Hardware Used in Modern Timber Bridges (TRIS 636308); and FHWA-RD-91-120 - Design, Construction, and Quality Control Guidelines for Stress-Laminated Timber Bridge Decks (TRIS 636334).