Longitudinal stiffeners are welded to the webs of slender-web Ⅰ-girders to restrict the web lateral deformations at service and construction load levels. The AASHTO 2015 equations recognize an increase in the bend-buckling resistance of girder webs reinforced by longitudinal stiffeners. However, in girders where web bend-buckling occurs prior to reaching the girder ultimate flexural resistance, a portion of the web becomes ineffective and flexural stresses are redistributed largely to the compression flange. The current Specification equations impose a penalty on the strength of the compression flange by a load shedding factor, R_b. However, this load shedding factor neglects the contribution of the longitudinal stiffener to the web post-buckling resistance. The authors have previously developed a cross-section model that can be used to estimate the flexural capacity of Ⅰ-girders for both homogenous and hybrid girders at the yield limit state. In this paper, an improved handling of combined web buckling and lateral torsional buckling of longitudinally stiffened plate girders is proposed based on finite element test simulations. In addition, the R_b calculated from the proposed model, used in conjunction with the current Specification flange local buckling equations is shown to provide a better characterization of the flange local buckling capacity of longitudinally stiffened Ⅰ-girders.
展开▼
