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Guardrail Over Culvert Weld Detail

State IL
Description Text

a question about the weld detail for the guardrail attached to the top of a culvert slab. I'm wondering if we have misinterpreted the intent of the weld detail. The intent is to attach the post to a ½ inch plate such that the plate is deformed during a crash. A strong weld was needed for this, and we understand that this is a three pass 5/16 inch weld. Is the three pass 5/16 inch weld intended to express the total final dimension? We had interpreted it as three passes, each 5/16. We are getting industry feedback suggesting that this is a problem. (See weld detail.)

  • Guardrail
Other Keywords none
Date August 11, 2009
Attachment weld detail.jpg


From my recollection on this issue, a single pass weld was used in some of the early dynamic component tests. For some of these tests, the posts tore off of the base plate due an inadequate weld. Later, a three pass weld was utilized in the dynamic component testing program, thus resulting in the post remaining attached to the plate as well as the ability for plate deformation and energy dissipation.


I have reviewed the CAD details and photographs from the successful dynamic component test, test no. KCB-7. I have attached selected photographs from this bogie test as well. From the photographs and CAD details, it is my opinion that the intent was to utilize a 3-pass weld to achieve a weld size that would meet the 5/16" size in total for the front and back edges of the front (traffic-side) flange. This same weld detail was used for the steel posts that were attached to the actual concrete box culvert for the crash testing program. However, I am unable to determine the size of the three individual weld passes that were used to complete the weld process. Due to the results obtained from the original seven bogie tests, MwRSF cannot recommend the use of the single pass weld at this time. If a single pass weld is desired in the future, MwRSF would need to perform similar bogie testing on the post-plate assembly fabricated according to your alternative design to ensure that similar behavior is provided.

Date August 12, 2009

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