Falsework Adjacent to Traffic Additional Wind Load 1

[ChooChooBridgeEngineer]

In AASHTO's Guide Specification to Bridge Temporary Works, there is a requirement for the basic wind pressure to be increased by 5 psf for falsework members over or adjacent to traffic openings. (Section 2.3.5.2 in the 2nd edition if anyone is interested)

Does anyone know where this provision came from? Was is based on research?

Thanks in advance.

 

[bridgebuster]

I would imagine they’re concerned with suction produced by passing trucks.

 

[ChooChooBridgeEngineer]

That was my thought too. I was mostly curious about the history of it. I've never seen any commentary on it, and was curious of when and why it was included in the provisions.

 

[SlideRuleEra]

ChooChoo - I don't know the answer to your question about the history. But, during my time as a Bridge Contractor in the 1970's I don't recall any standards or guidance addressing bridge falsework, other than vague paragraphs in DOT Standard Specifications.

Based on that experience, I'll make an educated guess that a string of falsework failures, spread over many years resulted in the documents that exist today.
To that end, I did some informed Googling and have a couple of leads you could explore:

"Survey of Failures of Bridge Falsework Failures Since 1970"

"1993 Bridge Temporary Works - Technical Advisory"

http://www.SlideRuleEra.net

 

[ChooChooBridgeEngineer]

Yeah, I have seen one research paper vaguely state that the additional 5psf was because of importance, but it didn't expand on it in the slightest.