There is no requirement for spacing a cooktop from a wall.

Practically speaking, you usually end up between 1.5″-3″ from the wall in most 24″ deep counters.

Most installers will either center the depth or place the front edge within 3″.

This would be difficult to say in most cases due to the way bridges are designed.

AASHTO has basic guidelines based on the traffic level of service and site conditions. Depending on who has jurisdiction over that bridge can further increase the amount of loads on the bridge.

The engineer(s) then determine the weight of the bridge itself along with environmental factors (soil conditions, wind loads, earthquakes,…), and the design the bridge to withstand all of these plus an additional factor of safety.

The result of all of this is that any given bridge should be able to take an 80,000lb trailer (about 8′x45′) and load the bridge with these; you should have a bridge that can take several times that under “bad” conditions.

Just as a parting thought. It is rarely the weight bearing capacity of a bridge that causes it to fail, and thusly tends to be one of the strongest capacities of a bridge.

This isn’t quite the comparison you make it out to be.

Bone has great compressive strength, but two thirds the tensile strength and one third the shear strength.

Bending strength is one of the most common forces exerted on objects. This involves both compressive and tensile strengths. Because they differ you tend towards the lower value as it is unlikely you’ll find yourself in a strictly compressive situation. You just cut the strength down by a third, and bending forces (torque or moment) are exponential in magnitude so that strength goes away quickly as you make the bones longer.

Shear strength comes in on forces not along the axis. So, if you aren’t bending the bone but pressing against it your strength is one third.

As you can see you get away from that great compressive strength quickly.

Also, concrete. Modern concrete has great compressive strength but poor tensile and shear strength rather like bone. But, we add steel reinforcement to handle the tensile and shear forces. So, if we were to reinforce bone rather like concrete you would be correct in that animals would be able to grow a great deal larger.

9″-12″ on center. 11″ on center being the most common.

You would be able to start today.

Keep in mind that if you are unfamiliar with construction you’d likely start as unskilled labor.

In the meantime take classes and/or learn as much as possible.

You do realize that you only need rebar when you encounter tension forces, right?

Basically, any part that would flex under its own weight.

If this means nothing to you get 6″x6″ wire mesh (or something similar) and place it 1″-3″ below the surface of the sculpture. It is far more important in thinner areas than thicker ones. Any portion thicker than 12″ in cross-section, for sculpture as you’ve described, probably doesn’t need reinforcement.

This general assumes you’re working with cement, concrete or plaster.

Much like the others have stated: it can be.

There are at least two major areas of concern (assuming that environmental issues have already been resolved).

First, river bed implies river water. What amount of water and how often? Flowing water can easily sweep a normal building away so the measures to counter this can be significant.

Second, river beds tend to have a lot of loose sediment and clays. Both of these tend towards poor foundation soil. The usual solutions are either wide mat foundations that float the build on the soil or deep foundations that bypass poor soil until acceptable base is encountered. This can be more than 100 feet deep in case of river beds.

At the end of the day it isn’t a case of can it be safe, but what would it take to be safe.

Ian Marr·May 22, 2020Architect

As far as the actual withdrawal force, we look that up in the NDS.

Let’s go with a 16d nail in douglas fir framing. Let’s also assume that it has annular rings as many framing nails do.

We get 32 lb/in. At 3.5″ we get 112lb required for withdrawal.

Now let’s not forget that this assumes perfect, straight out withdrawal not levering out like with a claw hammer.

There are very much magnets capable of supplying 112lb of force, or hold per se. But if all you got to work with was the head of the nail:

16d nail have a head of roughly 11/32″ across. Let’s assume that this is a regular nail and not a pinhead, moon head, or other type of pneumatic nail. That gets us 0.0928…, call it 0.09 in2. That’s 1,244.44 lb/in2.

So, if you have a magnet with a field capable of grabbing the whole nail you get 112lb. If your magnet can only grab the nail head you need a magnate capable of providing 1,244lb/in2 to pull it out.

As to which of those two numbers better reflects the realities of magnetic flux, that’s for somebody else to figure out, but here, at least, are some numbers to go off of.

Chris Snyder·August 10

I like your numbers. Practically speaking, it seems unlikely that one could easily provide 1245 lb force to the magnet to separate it and the nail from the wood. If the nail was in a loose peice of lumber, the magnet has just become a handle for lifting the piece of wood. And if the wood was part of a wall of the building the magnet has become a handle on the side of the building that nearly half a dozen people could hang off of. The cartoons are definitely fiction, as far as I’m concerned.

Copper.

But, keep in mind that in most cases all three would be greatly similar after a few moments.

Following suit with some of the other answers: economics.

Regardless of how you feel about the local land costs, it hasn’t gotten high enough to support the cost of such structures. Skyscrapers tend to cost 3–5 times the cost of low and mid rises per sqft. Super-tall buildings tend towards 5–10 times that of skyscrapers.

If it costs a fraction of that to build nearby it becomes hard to justify that cost.

Plus, once built you need tenants willing to pay that kind of rates.