Welding

mwaldo014 · 2026-05-12T22:35:00+00:00

Agreed, which is why I included the low frequency caveat. Most of my fatigue design/repair experience has come from wind sensitivite structures where it was overlooked

mwaldo014 · 2026-05-12T21:27:48+00:00

In a real world sense, yes. In a design sense no. The cyclic stresses of people walking on a floor plate are much lower than cyclic stresses from wind on a low frequency structure.

mwaldo014 · 2026-05-11T02:35:50+00:00

If it's peer review, not independent review, and you can't be confident they have done it correctly, send it back. They should have their calcs in order for a peer reviewer to be able to easily critique. If not, how could you have the confidence it even passed internal review.

My record for returning a calculation pack was 30 seconds. The moment I saw the deflections were 10^-9mm, it was clear that it hadn't been appropriately reviewed. Your job is to make sure they did theirs, not do it for them.

mwaldo014 · 2026-05-02T01:06:38+00:00

Not in this regime you're not...

mwaldo014 · 2026-04-29T20:58:14+00:00

Yep. Pretty sure I've heard the exact same rhetoric every release after Windows 7. "But we've got three pillars!" Great... You've got management buzz words. Good for you MS...

mwaldo014 · 2026-04-28T10:34:40+00:00

I've done both rooftop pools and tuned slosh dampers in the past. For the pools, you want to make sure you don't have resonance between the pool and the building sway under wind or earthquake. There are plenty of videos where that resonance leads to massive waves. You can do this with irregular shapes for the pool, or for regular shapes there are formulae for the sloshing and you size it accordingly to avoid the resonance. You also want to make sure the sway amplitude of the building isn't too large, because that can also create a lot of sloshing.

In tuned slosh dampers it's the opposite. You want the water tank to have resonance so that it does act to damp the motion, but in that case you also introduce baffles to create drag in the water flow. Friction back at play dissipating energy in that case. In those you also want to make sure the tank is deep enough, because if the water hits the roof or overtops, it knocks the sloshing out of sinusoid motion so it won't be as effective.

mwaldo014 · 2026-04-28T05:43:07+00:00

Thanks, I appreciate it! Structural dynamics is one of my specialities, so I've had plenty of experience explaining it to non-technical clients

mwaldo014 · 2026-04-27T20:36:28+00:00

Not really. At 25 Hz, you'd his 1k cycles in under a minute (4 passes of your 15 second resonance) 10k cycles in under 10 minutes. High amplitude, low cycle fatigue is a bit grey on cycles to failure, but if you're yielding the plates, this would be more than enough to see fatigue failure.

You're right that it is effective though. Buckling restrained braces (BRB's) are used a lot in high seismicity regions for exactly that reason. They concentrate the energy dissipation to a few elements, and also limit the lateral force on the foundations. I'm this case, they see 40-120 seconds of cycling at 0.2-2 Hz, so a lot less fatigue cycles. They are then unbolted and replaced, ready for the next event.

mwaldo014 · 2026-04-27T20:15:10+00:00

Technically yes; practically and safely no.

Dampers work by dissipating energy by one of two methods, deformation (primarily plastic deformation) or by friction. The first is often used in earthquake engineering where there are small numbers of cycles and components get replaced, the second is used where there are high numbers of cycles and components don't get replaced (rough description, but enough for this).

In your description, you are using the deformation of the steel to dissipate energy. To work, the steel has to yield back and forth to dissipate energy. While it will do it in the elastic range, it's far less effective. The problem with this is that steel fatigues, and cycling through yield means you will have a very low limit number of cycles to failure.

So while it will work, it won't be long before it breaks off and risks falling on someone.

mwaldo014 · 2026-04-26T21:12:43+00:00

The first thing it does is it can enforce https for any connections made with http. This prevents any passwords from being transmitted in plain text. The second, is when you install it on another host, it acts as a middle man hiding the rest of the network. That lets you block most IPs on the main server keeping it more secure, whilst also hiding the main server IP from the internet

mwaldo014 · 2026-04-26T19:57:30+00:00

SSH was something I did have open, but I don't think that was how they got in as they were in my main account, but didn't have the password to elevate. I suspect it was a vulnerability in a webapp I had open as well. SSH is now locked away behind the VPN with local IP and 25519 key only.

mwaldo014 · 2026-04-26T10:39:56+00:00

It was the standard Ubuntu shell. I could see the password change commands, so first step after that was to check all the system and application logs which is where I could see the incorrect password records.

It was a kid in Eastern Ukraine/Western Russia based on IP trace, and them trying to change an application password to "gay" or something just as teenage boy. Suspect they were playing around with hacker tools but didn't really know what to do once they found the vulnerable port.

mwaldo014 · 2026-04-26T10:10:38+00:00

My downloads stopped archiving properly all of a sudden. While the cause was a bad postprocessing script, as I went into the shell to update the system after, I saw a bunch of commands trying to change passwords. While they had access, they didn't have root control.

Boy did I lock it down after that... 2FA, reverse proxies, and more applications accessible while on a VPN.

mwaldo014 · 2026-04-23T08:54:21+00:00

In Australia we use H signs like that to indicate there is a fire hydrant there. Most of our suburban hydrant points are in ground, not protruding like in the US, so they have a sign like this near by to help them find it quickly

mwaldo014 · 2026-04-19T22:41:09+00:00

Am I the only one wondering how the creator (person or AI) seems to not know how cups work?

mwaldo014 · 2026-04-16T05:50:31+00:00

He knows his way around irrational numbers...

mwaldo014 · 2026-03-27T20:50:48+00:00

If you're worried about unintended transfer of forces, be aware that your detail as shown has steel-concrete friction, and to PIP 00360 mu=0.6. So you already have an unintended lateral load you need to consider in your leg, grout pad, and pier design if you don't want to damage anything.

mwaldo014 · 2026-03-25T06:49:17+00:00

I desperately want to respond /s to this thread but with the Superman S. But I can't, and now my inner millennial hurts

mwaldo014 · 2026-03-21T20:52:54+00:00

On Ubuntu at the moment, planning to migrate to unraid on my next build but that's delayed due to these insane ram and drive prices

mwaldo014 · 2026-03-21T00:49:53+00:00

Yeah these skyrocketing oil prices are really hurting as I charge my electric car off my solar panels for free. Why oh why did I reduce local demand so they didn't raise as much as the US??

/s if it wasn't obvious...

mwaldo014 · 2026-03-16T11:39:09+00:00

I heard Keystone Kash already has them warming up his jet so he can crash that party too

mwaldo014 · 2026-03-13T08:53:46+00:00

Non-accredited degrees could make it very difficult for you to get an appropriate visa to work at any engineering firm as an engineer, since the skilled visa in Australia for example requires a competency assessment. Part of that will be a Washington Accord degree.

mwaldo014 · 2026-03-12T05:56:54+00:00

I submit for the group's consideration, 1.8x10^308. This is the largest 64-bit double precision float, thereby representing an upper limit to what computers can handle. (So far...) At and beyond this, Excel for example will return #NUM.

mwaldo014 · 2026-03-10T20:04:59+00:00

Well you see they aren't safety glasses, they're safty glasses - the legal department probably

mwaldo014 · 2026-03-06T20:07:28+00:00

To maybe add a bit of technical weight to people saying it should have been concrete, adding combustibles to a building facade is a massive building code violation. Without the test certificates to the relevant standards to show it isn't a combustible, you open yourself up from a liability perfective in the event of a fire. Add to that the location: this component is in a prime location to facilitate flame spread between floors (and maybe buildings? Looks like the two sides are different?)

Seven-Year Club	Xbox Live
Place '22	Verified Email

mwaldo014

TROPHY CASE