Idea Transcript
By: G. Kinchen State Bridge Load Rating Engr. Date: 02-2013 dfdfdfdf
Steel Bridge Modeling in BrR (formerly Virtis) Program 1.
Shop drawings – The NMDOT will, in some cases, furnish steel beam/girder fabrication shop drawings as part of the bridge documentation. Whether the drawings are included is dependant of several factors including: availability, legibility, & whether they will help to increase the model accuracy. On older rolled beam bridges it was common to provide optional fabrication details in the bridge plans. Examples of this include riveted versus welded cover-plate connections, stud versus channel shear connectors, & steel type substitutions. When so indicated by the NMDOT & shop drawings are furnished, verify the final asfabricated optional details for input into the bridge rating model using the shop drawings. Also, verify other non-optional steel details, such as rolled beam shape sizes, diaphragm details, etc., as permitted by the drawing quality. Plate girder details are more complex than rolled beam details. Plate girder details include more dimensions, member (plate) sizes, stiffener configurations, cross-frame configurations, & welds. Moreover, sometimes it is necessary to detail each individual girder separately, resulting in numerous pages of details. Given the above, along with variations in the legibility of the available drawings, it is the intent that the shop drawings be reviewed to the extent that is possible & reasonable. Even where some sheets are not legible, the shop drawings are valuable to supplement information, such as weld sizes, that may be vague on the bridge plans. Where such information is legible on only certain girder sheets, it is reasonable to assume the same for all similar locations. When included as part of the documentation provided for bridge load rating model development, & where details are legible, it is expected that the modeler will verify beam/girder data from the bridge plans. Where differences occur between the two documents, use the shop drawings information.
2.
Materials, Structural Steel Types – Information regarding steel types is found in the “Structural Steel” general note, under “Design Data”, & in various details in the bridge plans, & in the shop drawings (if available). Refer to the following table for selecting applicable BrR library steel definitions for the common steel types: AASHTO Designation on Plans
ASTM Equivalent
BrR Library Item
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ASTM A7
“1936 to 1963”
AASHTO M183
ASTM A36
“ASTM A36"
AASHTO M188
ASTM A572, Grade 45
"ASTM A572 - 1 1/2" max., Fy = 45 ksi" (Note 1)
AASHTO M223
ASTM A572, Grade 50
"ASTM A572 -