Search results for query: *

I'm looking at a protentional redesign of rail bridge. The design calls for and EMD SD70 Locomotive, 33,700 Gallon DOT 112 Tank Car, and a Cooper E60. AREMA only discusses design using the E80, the E60 is easy enough but I can't seem to find anything on the other two loads. Sample calcs...

I have a bridge replacement project where we need to remove and replace a fire stand pipe attached to the bridge structure that is being replaced. The standpipe will extend from the top of deck down into a tidal waterway. The bridge size or geometry itself does not fire a standpipe, it's mainly...

In water work can be expensive plus the impacts of scour and H&H on the design, not to mention any permitting and approvals. If you can keep piers out of the water, that's where I would start.

I need to design some CFAs. Basically a steel micropile tube pushed into grout. From what I gather they are designed either as micropiles or drilled shafts. These are small diameter CFA and will be seeing some moment. AASHTO doesn't really provide any guidance for design other than axial...

Is the bearing pad offset or the girder? Isn't there an end diaphragm there? wouldn't that inhibit the placement of a diaphragm or the cross frames near girder end? I would have them jack and reset it or THEY should demonstrate it's ok to leave as is. You shouldn't have to justify a contractor...

. Thanks. Im not sure the owner knows either which is what is leading to our confusion on the subject, and admittedly I am not a PS beam expert. I can design one easy enough but I don't have experience with long-term performance. Their design manual, used to say, "negative final camber of...

Thanks, let me restate, the owner says no downward deflection to ensure there will be no tension in the bottom of the beam (for cracking). I agree, downward camber does not equal tension. But simply designing for service loads I don't think is enough as the issue is that long term effects...

The bridge owner doesn't want any downward camber in the long term (i.e. no tension in the PS beam bottom flange over time). PCI has a procedure for estimating long term camber from creep and shrinkage using multipliers, but states that these multipliers are not applicable to bridges with...

That's a tall abutment. How do you manage the earth loads and provide retaining walls? typically, what I have seen is to use a shorter integral or semi-integral stub abutment behind a MSE or other retaining wall. This way the wall holds back the earth and the abutment carries the vertical and a...

I agree, I use it for preliminary analysis to quickly size up some member for alternatives. STLRFD gives a better design result and provides, construability checks, and gives nice outputs for use in additional design (bearings, splice plates, etc)

wow, you are in for some fun. You are going to have really large heels to resist that all that earth pressure. The last time I needed to design an abutment that tall we had huge footings. Are deep foundation an option, I suspect with that potential much scour they should be. You could also do a...

concrete or steel? if you want steel AISC SIMON is free and will do line girder analysis and design. PennDOT PSLRFD and STLRFD are really simple, yet powerful, concrete and steel offerings. If you are looking for influence lines you could use any of the market options, STAAD, RISA, etc but you...

Thanks. This is all great information!

The agency spec doesn't limit this. Honestly, I don't have a problem with it either. VDOT discussed this in their manual and allows it, including how to finish properly however they don't say how you are allow to attached to a steel beam. This is a stage line very close to an existing...

I have a contractor that want to set the screen rail on top of a girder. They want to use a pipe receiver set on the beam and tack welded to the shear studs since they aren't allowed to weld to the flange. The receiver would have a smaller pipe and adjustable threaded rod that would be pulled...

We check every member, horizontal and vertical, AAHSTO will allow simplification (eg. ignore axial loads) if the axial loads are below 10% or 20%. For your last point, if the structure isn't showing distress, we have made the assumption that a plastic hinge can form and you end up with a simple...

Interesting question and one I never admittedly asked. Without analyzing this bridge in particular. My bridge is a 3 span continuous. 60' ends spans, 75' main span. If we look at 3 equal span and idealize the live load to a distributed load, a simple span max positive moment is 0.125wl^2. For...

Working in Washington DC, they have a lot of longer span older rigid frame structures that I have load rated. Easy to analyze but there isn't any software that can perform a load rating so it's all done with spreadsheets to calc out the capacity of the variable depth span.

Thanks for the replies. Some background. This is indeed referencing the bridge response shown in AASHTO 5.12.3.3.9 above. This issue I was having is the moment generated at the supports due to differential creep and shrinkage between the beam and closure pour. Turns out buried in the state's...

I have a PS beam design where I am now designing the positive moment connection. The design calls for a significant amount of reinforcement at the pier diaphragm. The ends are going to be pretty congested. I could mix some hairpins with extending some of the prestressing steel but it's still a...