A. Specify that all structural steel conform to AASHTO M270 (ASTM A709), Grade 36, 50, 50W or HPS 70W. The Department may approve grade 100 or 100W for use in special cases.
B. Show the AASHTO M270 or ASTM A709 designation on the contract documents.
C. Do not specify painting of weathering steel unless approved by the SDO.
D. Miscellaneous hardware, including shapes, plates, and threaded bar stock, may conform to ASTM A709, Grade 36.
Commentary: AASHTO M270 and ASTM A709 include notch toughness, weldability and other supplementary requirements for steel bridges. When these supplementary requirements are specified, they exceed the requirements of other ASTM steel specifications.
A. Fracture critical members are defined as tension members or tension components of nonredundant members whose failure would result in the collapse of the structure. Examples include:
1.) All tension components of single box superstructures.
2.) All tension components of double plate girder superstructures.
3.) All tension components in the positive moment region of double box superstructures. Negative moment regions over the piers have four top flanges and are therefore considered redundant.
B. Avoid fracture critical members. Fracture critical requirements are expensive due to the intensive welding procedures, base metal and weld tests, and inspections after fabrication. Two girder systems on non-movable structures are undesirable and must be approved by the State Structures Design Engineer.
C. Designate on the plans, all:
1.) Girder components (non-fracture critical tension components) that require CVN testing only.
2.) Fracture critical girder components (defined in A).
3.) Splice plates to be tested to the requirements of the tension components to which they are attached. See the SDM Chapter 14.