Steel Bridge Truss
Steel Bridge Truss
(OP)
I have a plan showing a pedestrian steel truss bridge showing a bottom chord of 8"x 8" steel tube.Specifications read "The steel truss shall be designed to include a redundant bottom chord comprised of double channels"
Can anyone tell me whats that means since the drawing doesn't depict what the specifications are asking for?Or am i missing something here?
Can anyone tell me whats that means since the drawing doesn't depict what the specifications are asking for?Or am i missing something here?






RE: Steel Bridge Truss
Usual defence of contractors about these issues is to firmly state that they only are compromised to build what they offered, in a list of works made by themselves. On no agreement, you know the path. And not always the changes to the project made in such lists are innocent, or based on project error.
So seek who has to decide, who can support your point, and state it firmly before all the involved.
RE: Steel Bridge Truss
RE: Steel Bridge Truss
RE: Steel Bridge Truss
According to one interpretation of the internal redundancy concept you would have to have three or more separate elements in each bottom chord member to avoid having a fracture critical bridge. According to another even more strict interpretation (promoted by the FHWA) you should not consider internal redundancy regardless of how many separate elements the member has when deciding whether a bridge is fracture critical. The FHWA also denies the validity of structural redundancy (span continuity) and only wants State DOTs to consider load path redundancy when classifying highway bridges as fracture critical.
The requirement for double channels on the bottom chords seems a bit arbitrary and unusual as well as unnecessary for a pedestrian bridge since by their nature pedestrian bridge do not receive the kind of significant fatigue loading that would lead to fatigue fractures. Moreover, most of the ususal steel truss pedestrian bridges are made with HSS sections for the chords and or web members as you described. For some unexplained reason almost all of these bridges are manufactured by one of several companies in Minnesota that specialize in steel truss pedestrian bridges. This type of pedestrian bridge is considered attractive and is used all over the country. I inspect bridges and have seen hundreds of these mostly in city parks, hike and bike trails, and golf courses.
RE: Steel Bridge Truss
RE: Steel Bridge Truss
RE: Steel Bridge Truss
RE: Steel Bridge Truss