Evaluation of web compactness limits for singly and doubly symmetric steel I-girders

Abstract

This paper presents the results of research aimed at evaluating the web compactness limit for steel I-girders. Specifically, the paper tests the implications of a new web compactness limit equation provided in the 2003 AASHTO LRFD specifications [AASHTO LRFD bridge design specifications. 3rd ed. Washington (DC): AASHTO; 2003 [in press]] versus the web compactness limit in the 2001 AASHTO LRFD specifications [AASHTO LRFD bridge design specifications. 2nd ed. Washington (DC): AASHTO; 1998 [with 2001 interims]] and 1999 AISC LRFD specifications [AISC. Manual of steel construction, load and resistance factor design, Chicago (IL); 2001]. In both the AASHTO and AISC specifications, these limits are required for the nominal moment capacity to equal the plastic moment capacity of the girder, provided other requirements are also satisfied. The origins of the AASHTO [AASHTO LRFD bridge design specifications. 3rd ed. Washington (DC): AASHTO; 2003 [in press]; AASHTO LRFD bridge design specifications. 2nd ed. Washington (DC): AASHTO; 1998 [with 2001 interims]] web compactness limits are presented along with a performance evaluation of these equations. Specifically, resulting moment capacities from a comprehensive suite of finite element analyses are compared to the capacities that the respective limits are intended to provide. Results indicate the AASHTO (2003) web compactness provisions provide a more accurate representation of girder strength than those in the AASHTO (2001) and AISC (1999) Specifications.