Research Spotlight: Behavior and Design of Non-Composite Non-Longitudinally Stiffened Welded Steel Box Section Beams

2017 Annual Stability Conference Presentation

Session S1 – Stability of Steel Bridges
Wednesday, March 22, 2017
8:30 am

Behavior and Design of Non-Composite Non-Longitudinally Stiffened Welded Steel Box Section Beams

The current AASHTO LRFD provisions for flexural resistance of non-composite non- longitudinally stiffened, welded steel box section members have a number of limitations. The current AASHTO Article does not address general singly symmetric box section members. It does not have provisions for flange local buckling, web bend buckling and general yielding of welded box section beams. It also does not address box section beams with hybrid webs. This paper explains the development of design provisions for any general singly or doubly symmetric non-composite non-longitudinally stiffened, homogeneous or hybrid welded box section beam, covering all ranges of web and flange plate slenderness and addressing all relevant limit states. An extensive parametric study via test simulations was performed to evaluate the performance of the proposed equations. The finite element model was validated using existing experimental data and a good agreement, within 5% of experimental test results, was obtained. From the results of the parametric study, it was observed that for box section beams with compact or noncompact webs the cross section resistance is larger than yield moment and up to the plastic moment capacity of the effective cross section based on the effective width of the compression flange taking into account its post-buckling resistance. It was also found that for box section members the limit state of tension flange yielding is not required and the resistance is captured accurately by the general yielding strengths up to the plastic moment of the effective cross-section. The mean, median and standard deviation of the ratio of the beam strength from test simulations to the strength predicted by the proposed equations were 1.05, 1.04 and 0.06 respectively; thus showing that the proposed equations give a good prediction of the flexural resistance.

Ajinkya M. Lokhande and Donald W. White, Georgia Institute of Technology, Atlanta, GA