AASHTO GPEB

Description / Abstract: PREFACE: These Guide Specifications give alternative fatigue design procedures that are intended to be used in place of Articles 10.3.1 and 10.3.2 of the Standard Specifications. They accurately reflect the actual conditions in bridges subjected to traffic loadings and provide the following additional advantages: (1) They permit more flexibility in accounting for differing traffic conditions at various sites. (2) They permit designs for any desired design life. (3) They provide reasonable and consistent levels of safety over a broad range of design conditions. (4) They are based on extensive recent research and can be conveniently modified in the future if needed to reflect new research results. (5) They are consistent with recently developed fatigue evaluation procedures for existing bridges.

The Guide Specifications use the same detail categories and corresponding fatigue strength data as the Standard Specifications; they also use methods of calculating stress ranges that are similar to those used with the Standard Specifications.

The Guide Specifications for the fatigue design of new steel bridges, and comparable procedures for the fatigue evaluation of existing steel bridges, were developed in NCHRP Project 12-28(3). The development of both is described in detail in NCHRP Report 299. The evaluation procedures are being considered for inclusion in the Manual for Maintenance Inspection of Bridges.

Commentaries on the provisions of the Guide Specifications are given in Appendix A. A simplified six-step design procedure based on the Guide Specifications is given in Appendix B; it can be used for most rolled beam and plate girder bridges. Examples of the application of the Guide Specifications in the design of (1) a simple-span plate-girder bridge and (2) a two-span continuous plate-girder bridge are given in Appendix C.