A welded steel plate girder consisting of two flange plates of 350 mm x 16 mm and a web plate of 1000 mm x 6 mm, requires-A-nostiffenersB-vertical stiffenersC-intermediate vertical stiffenersD-vertical and horizontal stiffeners-C-intermediate vertical stiffeners

C intermediate vertical stiffeners Here d/tw=1000/6 = 166.66 which is between 67 200 so intermediate stiffener required.