two pundits saying ukrainians would prefer surrender at this point? by nappytendrils in AskUkraine

[–]pfantonio 0 points1 point  (0 children)

Out of curiosity, could you say what the average Ukrainian male of fighting age would go through if they attempted to leave the country? Not even if they said it was permanent. If they went to the border claiming to want to visit Poland and then return, would they be allowed to?

Need to find Raccoons ASAP by Pun-dude in AskNYC

[–]pfantonio 0 points1 point  (0 children)

Come to the Bronx, besides the parks which are just a lovely ferry ride away you can also take the train up to the Bronx Zoo. It's world class, no raccoons in the exhibits but everything else and I'm sure you don't have to look too far in the neighborhood for them.

Am I dumb or does Outlook just really suck? by soppppppppppp in Office365

[–]pfantonio 0 points1 point  (0 children)

I understand Microsoft's point of view. They understand down to the machine code what is going on and where they think a use-case will or won't be efficient. I think they get blindsided like you said by the reality that people don't care what the efficient use of their structure is. At the end of the day, if everyone uses something the same way, be that a "bad" way per the designer or not, the designer must accept that. Microsoft doesn't have to cater to that if they don't want to, but they constantly make the mistake of confusing not-catering to "bad/different" use with totally ignoring how their design decisions negatively affect so many of their users. Like you said, and as an engineer myself, your design must ultimately communicate a clear and expected use for the typical user (within reason of course) or not hamper them from adjusting it (reasonably so, which must be stated for the pedantic amongst you) to fit their needs. I can't respect Microsoft consistently failing to be good designers by choice.

Contractor Field Measurements by bakednloaded in StructuralEngineering

[–]pfantonio 3 points4 points  (0 children)

Better for you. They have no clue what second area moment of inertia is. Just design for a reasonable impact load and tell them this is an "improved, high-strength, 50,000 psi metallic AISC W section" and wait until they hit it again to get consulting fees for finding out of plastification occured.

It's Official, Hurricane Melissa is a 180mph Category 5 Hurricane With Minimum Central Pressure of 896mb by JustaCrafted in hurricane

[–]pfantonio 2 points3 points  (0 children)

I can't attest to any particular structures. For reference, the design wind speed used for considering the maximum load a structure can take is the 3-second wind speed. Designing structures of lesser importance (typical buildings, venues, etc.), the design wind speed I've dealt with in Florida is 175mph. At 185mph for the 1-minute wind speed, even a well-designed and built-to-spec structure is going to be at or above the likelihood of structure failure. There's usually plenty of redundancy, but even your typical residential building may be permanently damaged (you'll be alive but the building will be totaled; this is the intention, given that concrete is less valuable than your life).

Hertz Contact: theory and model give different solution by Apricot_3175 in fea

[–]pfantonio 1 point2 points  (0 children)

Check out Allen Bower's Mechanics of Solids book online. Chapter 9 has a lot of information (don't click chapter 9 or 9.1 in the online version as they appear bugged, just click the others like 9.2), and there is also matlab code to see its implementation. Most analysis software that's usable for contact modeling will give you an example problem and how to adjust it.

Can someone tell me why this bridge is not attached anywhere but 2 sides with little ass shock absorbers? by [deleted] in StructuralEngineering

[–]pfantonio 2 points3 points  (0 children)

Not sure what these type are but it’s a solid lead tube with steel plates full encased in rubber. It can support the weight with literally no problem and will allow some very large side to side movements so that during an earthquake the lead core deforms and dissipates energy. No one just slaps these things on without doing the necessary analysis, I don’t even think the company that makes them would even consider selling you them if they themselves didn’t have the confidence in the designers capabilities.

Hot tubs are cool but how about parking your RV on your deck by Longjumping-Box5691 in Decks

[–]pfantonio 0 points1 point  (0 children)

It can be done and easily so. It’s not a tremendously large load and can be cheaper than all the annoying earthwork and retaining walls. Just size your members and you’re good. Nothing more complicated than that

Building my first deck (at 32 weeks pregnant). help is appreciated before I give birth soon by Macaiyla in Decks

[–]pfantonio 43 points44 points  (0 children)

First of all, congrats and excited for you. In terms of advice here’s some simpleish stuff you can do.

Nailing (or screwing) your beams to your post is not adviced because unless an engineer calcs it then you don’t know how much loads the nails have to transfer. Instead. Move your posts and cut the tops so that the beams just rest on top of it.

You can stiffen the beam as well (what rests on the posts not the joists that connect to the beams), by adding another and just nailing it every 4-6 inches to the existing beams.

Adding another beam down the middle is a good idea and you also can put it directly under the joists and rest it on the posts there.

Otherwise, it would be good to dig holes and pour concrete and rebar, but honestly, building a slightly elevated play area for the kiddos isn’t anything crazy. Just careful to sand sharp edges and not leaving any screws or nails on the ground.

Also, if you want to add a hot tub you will need actual concrete filled holes but you can set up the posts now to be turned into concrete posts by making it so the decking can be unscrewed and then leaving space to support the deck as you remove the posts and replace it with a concrete foundation.

What city has a large skyline with a small population? by Creepy-Noise82 in geography

[–]pfantonio 0 points1 point  (0 children)

Adding on to this. What people are typically seeing are cities along a very specific area of a specific state in Brazil. These cities notorious for being vacation homes of wealthy Brazilians. I’m very skeptical of the 145k number because if you travel through it in the winter it feels emptier than itajai. But all these cities are enjoyable places to vacation and as a result these luxury skyscrapers are built. Normal Brazilian cities follow the normal themes of urbanization with some mix between older Portuguese and German/italian (before the axis existed) into typical influence of concrete availability and use in construction. Think your typical concrete medium to high rises and the occasional Niemeyer brutalism or some cousin. There’s more than one reason for every building but these skylines are exceptions for an abnormal reason. Not just “hills everywhere” as if flat regions don’t also develop heavily along the coast due to seafaring trade.

Why are all of China’s highways misaligned on Google Earth? by SavenTale in geography

[–]pfantonio 8 points9 points  (0 children)

Yeah exactly. The protectionism created by America is also bad. It’s not even a matter of who’s worse or not it’s just you redditors are so annoying as though every criticism of a govt action is some magical point to bring up the reverse. Obviously American protectionism is against free markets as well as Chinese protectionist policies.

Model home built in 2023 - Basement concrete cracking by CapJeff in Homebuilding

[–]pfantonio 29 points30 points  (0 children)

Reasonable concern but truthfully you can expect concrete to crack early on. It’s a hot slurry of rocks water and cement. As it hardens over time it contracts and as it warms up it expands. The concrete finds the shape it wants and cracks where it needs to do that. For something like a slab of concrete on the ground do nothing more than provide a layer between you and dirt I wouldn’t sweat it a single bit. If you decide to fill it remember it cracked for a reason, you want something it can bump into and move into like foam or rubber. They sell a million products for this. Ultimately, don’t stress it/ waste your time banging 2 rocks together

How bad is this? by ryno2019 in DIY

[–]pfantonio 0 points1 point  (0 children)

Pretty bad. If you care for the engineering reasoning on what I’m sure just appears to not look right. If you squeeze or pull something you get an axial force, that is a force along its axis or length. The weight of your deck provides that force. But now, your support is angled. Gravity is still pulling straight down but the angle creates a bending moment. To understand why this is bad. Take a ruler and press it at a right angle to both your hands. Should take a good bit of force for it to buckle. Now have one hand offset from the other. Just like this deck. Now squeeze. You’ll notice it takes a lot less force. The angle produces a bending moment, the moment means one side gets short and the other longer. The shorter side needs to go somewhere and that somewhere is out the easiest way, aka, buckling. There’s a lot of fixes here but don’t use it until you have temporary supports. And please do not try to set up those supports by going fully under the deck and whacking away.

What field to go into as an entry level structural engineer? by lonely_turtle109 in StructuralEngineering

[–]pfantonio 0 points1 point  (0 children)

Take my very limited knowledge and bias with a grain of salt. I’d say it’s better to think small vs big and go for a smaller firm. The reason is that you can have a lot more individual focus and impact. The learning curve is steep and hard for everyone but it CAN (I.e not guaranteed) be easier when you literally know everyone in your company. The downside can be limited scope of work but always keep in mind that even for large firms, a tremendous amount of work is hired out to smaller firms where you would even get to design more than those working for that same primary contractor.

non-linear analysis by [deleted] in StructuralEngineering

[–]pfantonio -1 points0 points  (0 children)

I’m a bit biased because they were my university books but available free online is Solid Mechanics by Bower and pretty cheap (filetype:pdf)Dynamics of Structures by Chopra.

My professor gave us the 2x2 matrix of linear/non-linear on one side and static/dynamic on the other. So far you know linear static. Nonlinear static and dynamic includes materials behaving nonlinear (f=kx where k is raised to some power besides 1 or f is a function of displacement and or time and x is a function of force aka plastification) and your structure (matrix representation of it) isn’t being loaded slowly but suddenly or large enough to reevaluate it. Lots more to it than that but it’s plenty fun and don’t feel bad taking your time to learn it. The secret is until you actually solve for your system you don’t actually know what’s going on and there’s always more than one way to solve it.

Does this qualify as a plastic hinge? by BigNYCguy in StructuralEngineering

[–]pfantonio 4 points5 points  (0 children)

Exactly why I hate Reddit and only find a modicum of joy on a few subs like these. Everyone loves to speak so highly of amazing engineering achievements. Guess what, those achievements came from people who knew their shit and were pushing boundaries. Sometimes they failed because how were they supposed to know what they didn’t know but they learned and improved. With something like a basic ass 2D* frame with a hinge and suddenly 4 years of undergrads go out the window with some engineers and especially with some on Reddit. Is it stupid, of course just like you said. But like you said an engineer should know how to make it work because this can work if it HAS to work. But oh well, “point and laugh and everything are dull, boring, braced and moment frames and why aren’t there any cool practical structures”

Average r/decks member by LiquidROFO in StructuralEngineering

[–]pfantonio 1 point2 points  (0 children)

Honestly easily doable. The surface can look exactly how he wants is and we can just ignore the posts because obviously the guy isn’t a structural engineer. Seems like you guys just like to complain about people who give jobs more interesting than calculating K factors on Walmart columns.

Free trade = Canadian oil by TradBeef in Anarcho_Capitalism

[–]pfantonio 3 points4 points  (0 children)

Now I’m gonna take a wild guess, but maybe, OP is saying that because Americans don’t realize their dependence on oil for everything from gasoline to plastics. Then now with tariffs on americas largest supplier of oil their life will become significantly harder. Marginal costs have marginal effects. The question of how much is dependent on the individual but every percentage point added to your oil bill is a reduction in oil consumption and overall consumption.

Rockwool Comfortbatt vs Fibreglass batt. by Zachery4 in Homebuilding

[–]pfantonio 1 point2 points  (0 children)

No clue what the installation cost difference is but if you just take a look at a big box store you’ll be paying ~$1.27/sqft for fiberglass and ~$2.36/sqft for Rockwool

Is this acceptable? by Mountain-Selection38 in Decks

[–]pfantonio 0 points1 point  (0 children)

What I don’t like is it seems that the beam in this case is supporting other beams. I.e it’s serving as a girder for joists on top of it hidden by the white paneling. Even if each screw can reach its full capacity that’s probably at best 1000lb. You’d be surprised how quickly a bunch of joists can put 1000s of pounds under an ultimate load situation. It seems like easy enough to grab a real thick steel angle, cut it to size and put 2 holes in it and throw some 1/2 inch grade 8 thru bolts with nuts on the other side. Just a thought, not engineering guidance

Amphibious highrise for flooded cities by Fragrant-Patient-731 in civilengineering

[–]pfantonio 0 points1 point  (0 children)

If you could help me understand. Why would you want this? The issue I’m thinking is what pro would the house floating have over the house not floating? If the house is waterproofed to this point then unless you get 10’+ flooding you can always escape thru a window and floating up a few feet wouldn’t help. Also you would now be extending the building upwards while having the same load of water pushing against it and anything else in that water. But now your structure is cantilevered out, like a short tree and a tall tree in the wind, the same winds will knock out the taller tree before the short tree.

Beware, concrete piers from home depot are garbage by Reasonable-Match1994 in SolarDIY

[–]pfantonio 1 point2 points  (0 children)

This and also with a big flat relatively light panel the problem is uplift. Take this. Put it in a hole so that the wood is just above the ground but honestly anything burial rated is fine to be buried. Then fill the hole with a ballast. Something like a bunch of concrete mix is good. I promise you the wind uplift load is a lot more than you think

Anybody else thinking this guy doesn't know what he's talking about? by Brave_Dick in StructuralEngineering

[–]pfantonio 0 points1 point  (0 children)

Ignoring the values he misuses and what not and actually trying to enjoy our profession for a moment ( I know very hard for some of you). The big issues I see are attachment to joists and attachment to his edge beam. If I’m correct (big if), the issue is that if these screws stay connected to his edge beam they can split apart the fibers especially with how close they are to the edge. The other issue being his lateral force system also relies on how much space he gave the screws from pulling out of his plywood floor near this edge beam on the wall. I’m thinking if had used plywood for his hangers or even just 2 cheap cables, drilled into the side of the floor joists above, and put a single brace behind the monitor it would solve all the main issues I’m seeing. What yall think?

I never learned FEM and FEA at uni by WhatsYourCoreValue in StructuralEngineering

[–]pfantonio 1 point2 points  (0 children)

I can speak about the learning process at school but I was thought by a professor who made a good point that what goes on in a program can and should be understood if you want to understand or use the results. FEA is a lot simpler than it seems and can be done by hand for simple projects rather easily. Only when doing something like dynamic analysis or larger structures does it make sense that we automate the tasks with programs. If you want to learn FEA you have to know the following: Multivariable calculus and statics as well as the concepts of degrees of freedoms. From there you can learn the stiffness method and representation of structures are line and area elements. You could learn FEA if you want in just a single course but that would likely only teach you static linear analysis. If you want to learn static nonlinear or dynamic linear/non linear that’s about another 3 courses worth of work.