Bridge Crane build

[rabler]

H3ll yes, blockage resolved last night on steriods, antibiotics and a small bowell challenge/laxative. This non-surgical resolution is ideal. Yesterday was rough, maxed out on pain several times in the afternoon as the narcotics can only treat so much before suppressing respiration. But not even on tylenol at this point, finally slept last night.

I’ll be on longer-taper steriods for at least a month, which has it’s downsides, but this is a best-case outcome. Thanks to everyone here for the concern and best wishes. Hopefully they’ll send me home today.

 

[dkemppai]

Glad to hear you are on the mend!

Blockages like that are no joke, glad to hear it resolved without surgery.

 

[rabler]

"In 2016, ASTM A325 was officially withdrawn and replaced by ASTM F3125, in which A325 now becomes a grade under the F3125 specification. The F3125 specification is a consolidation and replacement of six ASTM standards, including; A325, A325M, A490, A490M, F1852, and F2280."

I’m quoting @aliva but am addressing this to the general discussion on bolts.

Selecting bolts is a very complex topic. I worked with civil engineering faculty and have some appreciation for this, with limited understanding. BUT: Strength and quality control is one set of issues. There are many, many others. One of critical interest that contrasts with simple strength is actual plastic region behavior. Bolts are design critical but not cost or weight limiting factors. Therefore bolts are often spec’d to be very redundant compared to the load at hand. For very simplified example, a design may call for 1.2 bolts to meet worst case loading. A design may therefore look at using 4 bolts in that case. But, it is often better to select lower strength bolts and use 6 bolts even if that doesn’t provide additional strength. This is because bolts fail deform better individually and equalizing the load across all the bolts is ideal, but challenging when dealing with multi-dimensional forces. Softer bolts are less likely to crack and more likely to slightly deform to accommodat tolerances, thermal variations, etc amongst other things.

Point being higher strength is not always better. ( This is where those engineers have to do it right. I will admit my crane design is not up to such modern rigor, but I feel comfortable my design meets my risk profile. I wouldn’t if it were a commercial building. ). This was my take-away from a lunch room conversation with a guy who owned a firm that previously designed several Atlanta skyscrapers, and was sought out for a faculty position as a “retirement” job.

 

[Dabbler]

100% yes. My usual rule of thumb is that if shear is the primary force, I use grade 8, but if tension is primary I often use grade 5. The bolt will show overstress by stretching. If I use grade 8 in tension, it just buckles the structure, and the whole rig is lost. Most structural steel is beween 60K and 80Kpsi, so it becomes vulnerable. Grade 8, BTW is 120,000 - 140,000 PSI (depending of manufacture and other factors).

 

[woodchucker]

Randal, I figured you'd be an "informed shopper" when I mentioned the programs. Many are not. I told the Humira story to many people at my former workplace. My babbling did benefit a couple as one had a parent and another a child with a chronic illness; both on long-term high-priced medication. Both ended getting ambassador cards for whatever they were on.

And you are sooo right about being educated and being your own advocate. Our son had a restriction in his sigmoid; normal plumbing diameter is 25 mm, he was down to 5 mm. He was on a daily colonoscopy prep just to get anything through. The docs were doing a dilation procedure to try to open him up some. They went a little too far, tore his sigmoid so he was leaking inside. High fever from infection as a result which lead to an ostomy bag for a year, etc. etc. etc. I'm cynical by nature, "There are doctors who get A's and doctor's who get C's; they both get to practice medicine. Send my kid to the hospital 75 miles away where I know they got A's, not the local one with many C's". Even with that, we had a few "duh" moments; docs looking at wrong tests, not looking at blood work, etc. Pays to be an informed shopper.

Bruce

Sometimes the A's aren't worth it. I went to a specialist at Columbia in NYC. He was supposedly one of the best in the nation. I felt like I was just another guy. Sometimes, attitude is important too. He didn't find the problem, but a few years later, a local guy did. You never know.. desire to resolve YOUR problem is more important than their grades. Although, usually the grades say something, some have a stick up their rears.

 

[rabler]

Sometimes the A's aren't worth it. I went to a specialist at Columbia in NYC. He was supposedly one of the best in the nation. I felt like I was just another guy. Sometimes, attitude is important too. He didn't find the problem, but a few years later, a local guy did. You never know.. desire to resolve YOUR problem is more important than their grades. Although, usually the grades say something, some have a stick up their rear

Definitely. And frankly, I'm not the easiest person to get along with, (although retirement has made me quite a bit more introspective on that). Anyway, that means I do much better with a particular personality of Doc. You need to find all three, brains, motivation to work with you, and suitable personality.

To go one step further I think it behooves someone with anything other than very routine medical issues to learn something about the medical system. I grew up in a very medical oriented family, so I can ask questions of my brother (a GP) for example, on how to negotiate issues. By having a general understanding what issues they face, I'm better able to communicate with them. That helps me get better service because I am better able to interpret what they are saying, not necessarily from a purely scientific standpoint but also from a procedural, legal and also from when I have room to negotiate, or press, based on what authority/responsibility I have (actual and perceived). It's not easy, and I work at it even when feeling like ****. But from my perspective with a fair amount of experience, it makes a difference. This applies to working with ALL of the medical profession, not just the Docs. I make an effort to respect the nurses, and other hospital staff. It doesn't come naturally for me. But it pays off on the instances where I do something stupid. And the reality is, you are certainly are going to do some fairly stupid things in case you're hospitalized.

 

[extropic]

A few decades ago, before I became old, an attorney friend told of his experience getting good service for his elderly parents at the Emergency Room. His advice was double barreled. First, have the patient arrive in an ambulance. Next, let the staff know you're an attorney.

 

[rabler]

A few decades ago, before I became old, an attorney friend told of his experience getting good service for his elderly parents at the Emergency Room. His advice was double barreled. First, have the patient arrive in an ambulance. Next, let the staff know you're an attorney.

Argh! That is one approach. But it has significant downsides. Medical staff fear lawsuits alright. This leads to them wanting to follow procedures that are most defensible in court, rather than what they professionally think has the best outcomes for you. And every one else suffers for the fallout of this mentality.

 

[woodchucker]

A few decades ago, before I became old, an attorney friend told of his experience getting good service for his elderly parents at the Emergency Room. His advice was double barreled. First, have the patient arrive in an ambulance. Next, let the staff know you're an attorney.

Not a great idea. tying up an ambulance so you can be considered more important. Also, I was rear ended by a drunk driver while on my motorcycle, I was cut up and had fuel in my wounds. We were brought in by ambulance. We waited while sun burn patients were treated before us. After a few hours, we called a friend and had them drive us to another hospital. It's not always what it should be.

 

[rabler]

100% yes. My usual rule of thumb is that if shear is the primary force, I use grade 8, but if tension is primary I often use grade 5. The bolt will show overstress by stretching. If I use grade 8 in tension, it just buckles the structure, and the whole rig is lost. Most structural steel is beween 60K and 80Kpsi, so it becomes vulnerable. Grade 8, BTW is 120,000 - 140,000 PSI (depending of manufacture and other factors).

Good points. The reality is that the static load on my bolts will be zero. Design is such that all static load is supported by the structure, not the bolts. House framing is suppose to also be done this way, nails don't normally carry load, studs under headers/plates carry the load.

Doing a rigorous dynamic analysis just about requires CAD/simulation (although the Eiffel tower was designed pre-CAD, so it's not impossible). FreeCad has some FEA capability but trying to do that right across the whole crane is beyond what I feel is necessary. The extreme dynamic challenge would be having a full load suspended high (minimal pendulum length) and running that load into the crane stops, giving a substantial hammer effect and subsequent swinging of the load). At some point that falls under operator error, like sticking your hand in a moving chuck.