QUESTION: (SUMMER2011) What are the major differences between Welded Wide Flange sections and welded I-girders?
ANSWER: Limitations for WWF shapes versus welded I-girders
- WWF shapes are restricted to a maximum depth of 2,000 mm.
- WWF shapes are standardized sections, whereas plate girder cross-sectional dimensions may vary.
- WWF shapes are straight members.
- WWF shapes have a limit on built-in camber (though they can be quite versatile).
- The web-to-flange weld strength of WWF shapes is limited to the capacity of a 20 mm web.
- A cross-section change involves splicing 2 WWF sections, whereas a plate girder cross-section change may involve changing the size of 1, 2 or 3 plates.
- Butt-welded splices are permitted in WWF production; when fatigue is a design consideration the production splice details must be accounted for.
Dimensional tolerances:WWF shapes are supplied to the requirements of CSA G40.20, whereas welded shapes should comply with W59 requirements. These standards share essentially identical tolerance requirements for length, camber, web flatness, combined warpage and tilt and lateral deviation between centreline of web and centreline of flange at contact surface. The under-tolerances for section depth are also identical. W59 has no provision for flange width tolerances, but G40.20 does. It should also be noted that tension testing of the web-to-flange welds is part of the WWF production requirements.