A three-span continuous plate girder bridge is fully restrained against lateral buckling throughout its spans. It has spans of 33.5 m – 50 m – 38 m. Design this plate girder in accordance with the BS 5950 and EC3 Bridge Design Specifications.
Structural steel:
a) I-section: A 709 Grade 50 for web, flanges Fy = 345 MPa. A 709 Grade 36 for cross frames and stiffeners, etc. Fy = 248 MPa.

b) Trapezoidal box girder: (Self choice design parameters)
Concrete: fc= 25 MPa; Ec = 25 MPa; modular ratio n = 8
Deck: Concrete deck slab thickness = 232 mm.