Hturkak, thanks for the suggestion. The consultants wouldn't budge on changing deck direction which throws a wrench into your proposed solution. I think KootK's suggestion offers the best chance of success. The framing on this end of the pedestrian bridge becomes a little messier, but when the...
KootK, now there's an interesting idea. I hadn't considered introducing web openings into Beam A but that would solve the outrigger dilemma while keeping the elevation changes to a minimum. Based on the distance between the concrete curb and Beam C, I suspect I would only need the one outrigger...
dhengr, I'll try to respond to your talking points in the order you listed them:
- deck slab cantilever beyond the movement joint (i.e. the deck portion that bears on Beam B) isn't an issue as you mentioned. That portion of the bridge (deck, beams, outriggers) is all properly connected to Beam...
Anticipated movement is ±40mm and the bearing design (PTFE+stainless) was the recommendation of the supplier. The bearing will be protected from the elements so it's a departure from the highway bridges you mentioned which are subject to pretty harsh conditions over its service life. Ideally...
BridgeSmith, your understanding of the original framing condition is correct. For your suggestion to work, you would require a sliding bearing whose length matches the width of the pedestrian bridge. Is this type of product even available? Most of the sliding bearings I've come across employ a...
KootK, I'm not sure I fully grasp the framing you're suggesting. I attached a quick mockup of the plan view of the framing. Red elements shown positively connected to each other, as do the blue elements. Red and blue elements connect to each other via the new sliding bearings (green elements)...
Thanks for the suggestions thus far. The infill beam for added stability of Beam C is a good idea. I also pondered whether lowering Beam A to create a physical separation with the deck would be viable. At this time I don't see a major problem with that. It unfortunately doesn't address the...
I've come across an unusual situation (at least for me) where the framing is requiring a sliding bearing to exist between the deck and the beam that supports the deck. The back story, it's a pedestrian bridge between two buildings. The attached sketch shows the framing situation. Beam A rests on...
@Hanstrulo
Is this analysis your doing based in the US code or in Canadian code (i.e. which code are you trying to stick to in conducting this analysis)? Crippling is approached rather differently by each code (why that is the case baffles me to this day). I suspect you are using the AISC spec...
So this is what you're analyzing, just with a pipe instead of a spreader plate? Are we safe to assume the 121mm hole diameter is common to the anchor plate, the angle, the channel and the pipe?
KootK's FBDs look to be right on the money, but there is one item that I would add. It is possible to eliminate that moment at the pipe wall by simply ensuring the weld center of gravity coincides with the line of action of the strand cable. With how the FBD is set up, you can see that there is...
For checking of the leg bending, you would likely want to employ a yield line analysis. As a work-around, you could use Fig 9-5(a) of the AISC Manual paired with Eq. 9-30 and a Qf=1.0. In Fig. 9-5, the 'L' term could be assigned as either zero or the diameter of the hole in the angle leg (that...
The plot thickens.... With this new information, the eccentric weld tables may not be the best approach to this design. So long as all the elements leading up to the welds to the pipe have sufficient flexural/shear capacity to transfer the force to the next element, AND so long as the pipe weld...
Any chance you could expand your sketch to show how the angles frame into the channel? If a 203x203x25 angle is being applied, that raises concerns beyond the weld design which should also be addressed. I'm thinking primarily pipe wall stability (i.e. plastification) and depending how the angle...
Welding the toes of the flange to the pipe?... definitely not what I imagined was the framing scenario. To respond to the Table 3-34 comment, it is quite restrictive in its application and I hardly ever refer to it in practice. In your scenario, you would be better served to apply the AISC...
It's not clear to me why you would want to apply that additional step in an attempt to make it dimensionless. The top of each table (in both manuals) clarifies the C coefficient by providing the formula for arriving at the weld group capacity, which defines the (required) coefficient C as the...
CISC is more restrictive and limits the C coefficients to loads acting parallel to the weld group. For inclined loads, the AISC is the way to go. Table 3-27 was primarily intended for in-plane loading. For out-of-plane loading, Table 3-34 was provided, but again is restricted for loads acting...
Thanks Joel. I have come across that article in the past and it definitely offers good insight into the Whitmore Section. To KootK's point #2, I too agree that the load dispersion continues beyond the 'overlap' region of connecting elements; the truncation as shown in most design articles is a...
I'm curious to get the community's opinion regarding this. Many connection details (let's focus on brace connections) I've made in the past constitute a single bolt row (transverse to the line of action of the force). Whitmore sections utilise the overlap length between the first and last bolt...
