When to kingpost
When to kingpost
(OP)
After spending some time looking at a project and possible design methods (or remediation measures in terms of an existing structure), I can tell whether or not kingposting is the best option. I was wondering if anyone knew of some rough guidelines as to when to look at this first. I can generalise and say that kingposting is only attractive when live loads are much greater than dead loads, but I haven't been able to develop anything more concrete than that.





RE: When to kingpost
RE: When to kingpost
------- or a prestressed steel girder?
\ l /
\ l /
\l/
You can go to books.google.com and find numerous 19th/early 20th Century books with info on a kingpost truss.
RE: When to kingpost
Clearance is definately an issue. I have seen a fair number of bridges with enough clearance to make this option possible lately. Temperature changes can be a problem, as can fatigue detailing.
Bridgebuster
It would be as you have pictured, though typically the steel girder is also pre-stressed due to tensioning of the ties.