This report contains the findings of NCHRP Project 12-15(3). The objective of this study was to examine the fatigue strength of beams with web and flange lateral attachment plates. In addition to providing a more comprehensive data base for this type of detail, the program was intended to examine the influence of lateral bracing members on the out-of-plane distortion of the lateral plates. Further work also was undertaken during the experimental studies on the effectiveness of peening and gas tungsten arc remelting the fatigue-damaged connections and on the ability of drilled holes to arrest crack growth. A total of 18 beams, each with three welded gusset plate details, were tested in fatigue with stress ranges of 6 to 15 ksi. Several other details were welded to the girder web in order to simulate beam flanges framing into a web plate. The results of these tests were used to assess the adequacy of the applicable provisions of the AASHTO specifications. In addition, the influence of lateral bracing on the fatigue performance of the attachments was evaluated. Recommendations for modifications to current practice are included in the report.
Abstract