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38 votes

What are those large poles for that are always in front of US stand-alone store buildings?

They are called bollards. Their function is to provide safety for pedestrians from traffic, distracted drivers who may encroach into the sidewalk, or runaway cars e.g a driver who inadvertently ...
kamran's user avatar
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29 votes

What are those large poles for that are always in front of US stand-alone store buildings?

They are called Bollards. But these aren't defensive as suggested. Look closer. There's no curb. This is a new style of store (from the architecture) and curbs have been eliminated for ADA reasons ...
Harper - Reinstate Monica's user avatar
25 votes

Why are some public benches made with arm rests that waste so much space?

I am not sure about this particular design. But in public places, the benches are designed to provide temporary comfort but discourage using them as a vagrant or homeless hang out, hence designed ...
kamran's user avatar
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23 votes
Accepted

Why does a gear have extra holes?

Different gears have different drivers for having holes. One way you can categorize gears is by whether they are used primarily for transferring: motion: transferring angular position and angular ...
NMech's user avatar
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18 votes
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Why does a jumping rope have no bending stiffness and compression stiffness?

TL;DR: The bending and compression (buckling) stiffness is so small because the second moment of area of the fibres is small. Bending stiffness It does have a bending stiffness however it is really ...
NMech's user avatar
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11 votes
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How do the columns in the 'magic mountains' sculpture stay up?

This marketing video shows moments of their construction. At 0:40 you can see them all upright. They aren't painted, but you can tell it's the same installation. At 1:37 and 1:46 you can see guys ...
Wasabi's user avatar
  • 13.1k
11 votes
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What is the advantage of statically indeterminate structures?

For example, take a look at the following static systems. Assume they have the same length and the same (constant) cross-section. Thus an equal allowed bending moment $M_u$. The first system is ...
Andrew's user avatar
  • 1,166
10 votes

Why are some public benches made with arm rests that waste so much space?

Benches are not usually engineered as such. They are being made by furniture designers, (landscape/interior) architects etc. Now generally these professions put a lot of work into making their items ...
joojaa's user avatar
  • 3,577
9 votes
Accepted

Where did I go wrong conceptually when attempting to calculate the maximum force on a truss at a given joint?

The reason is that you assumed that the elements around node $\text{D}$ will be the first to fail. That is not the case. Indeed, it is the elements under compression ($\text{AB}$ and $\text{BC}$) that ...
Wasabi's user avatar
  • 13.1k
9 votes

What are those large poles for that are always in front of US stand-alone store buildings?

Bollards and other defensive oriented structures significantly predate the 2016 Nice attacks. They have been in place at the construction of many buildings in the US and across the world for decades ...
Will's user avatar
  • 191
9 votes

How did this building's windows get like this?

OP states that the staining is not always present. here is a possible reason for it: If the building is air-conditioned and has single-glazed windows, then the outside of the window glass might be ...
niels nielsen's user avatar
8 votes

Why does a gear have extra holes?

In addition to the other answers such as weight reduction and inertia, there are other possibilities: Often there can be a precision machined hole for timing purposes. A common solution for some / ...
Solar Mike's user avatar
  • 15.8k
8 votes

How did this building's windows get like this?

To add to the other answer: When ledges protrude out from the wall then the water, and dirt, falls away from the wall surface. Also, the underside of the ledge usually has a drip channel or groove to ...
Solar Mike's user avatar
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7 votes

Seeing through walls and noninvasive structural integrity metrics

Depending on the region and structure of building the techniques might vary. Below are few suggestions Termite inspection is another popular method to determine the structure integrity of building. ...
Mahendra Gunawardena's user avatar
7 votes
Accepted

Given the tensile strength of a rod, how do you calculate the max weight that can be hung from it?

You're hanging it from a rod supported by both ends - and need to use the bending equations. For this case (case 7 in the link), the max weight is: $$W_{max} = \frac{\pi d^3 \sigma}{8L}$$ $\sigma$ ...
Mark's user avatar
  • 5,333
7 votes

Why does a gear have extra holes?

It could be for combination of reasons. lubrication: the holes will both pump and let the lubricant pass through. Reduced angular momentum reduces backlash and adds to gearbox responsiveness. ...
kamran's user avatar
  • 22.4k
6 votes

How do you check a weld for applied moment?

What chapter/section of AISC codifies this kind of problem? If you're looking for a specific code provision for this exact type of weld, you're out of luck. However, it is possible to solve this ...
grfrazee's user avatar
  • 3,587
6 votes

Why would a column expand before accepting load through a narrow thunk?

The column top holds some narrow thunk and that thunk holds the driveway floor. I think we have some nomenclature that needs to be cleared up here. What I believe you're calling a "thunk" is ...
grfrazee's user avatar
  • 3,587
6 votes

Rectangular hollow section vs square hollow section

Use an RHS over an SHS when you want significantly more bending/shear capacity about/in one axis than the other. The additional depth that an RHS has in one axis gives it greater shear capacity in ...
AndyT's user avatar
  • 3,143
6 votes
Accepted

Why do some guyed towers come to a point at the bottom?

If the base of the tower is "rigidly" fixed to the ground, the foundations have to withstand the bending moments from the side loads (e.g. wind) on the tower. Otherwise, the foundations will work ...
alephzero's user avatar
  • 12.5k
6 votes
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Calculate whether a polycarbonate plate can withstand a certain force

For impact force calculations you need some more information such as the shear modules and the material properties like toughness and tensile yield and shear yield. Also you need to define a physical ...
kamran's user avatar
  • 22.4k
6 votes
Accepted

Is it practical to use tensile cables in a composite beam?

Steel beams and columns can and have been prestressed by steel tendons in major buildings. Because steel tendons can be applied post-construction many times they are employed in refurbishing bridges ...
kamran's user avatar
  • 22.4k
6 votes

Why does a gear have extra holes?

Also someone may have to pick the machine up and carry it. Reducing weight is not just related to the intrinsic function of the machine, its shafts and so on.
Adrian Midgley's user avatar
5 votes
Accepted

Steel Structure connection pin or fixed

Pinned connection in structural context doesn't mean free rotation/zero moment. Pinned connection means much bigger rotations and much lower strength compared to the connected members. According to ...
minas lemonis's user avatar
5 votes
Accepted

Rectangular hollow section vs square hollow section

Obviously this depends on the relative size of the sections. Assuming that the rectangular section's smallest dimension is equal to (or greater than) the square section's side and their thicknesses ...
Wasabi's user avatar
  • 13.1k
5 votes
Accepted

How do I build a miniature concrete house?

Concrete isn't a good material for such a small model. I would suggest foamboard. You can get it at craft stores. If you can't find half inch thick material, laminate two layers of quarter inch board. ...
Eric S's user avatar
  • 915
5 votes
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Trying to shed some weight on my design, any thoughts?

Your equation for bending is wrong. Force x distance is appropriate for a cantilever. For a point load applied to a "table" you are either talking simply supported (in which case Mmax = Force x span / ...
AndyT's user avatar
  • 3,143
5 votes
Accepted

Pin support, why is there no horizontal reaction force?

Assuming I'm understanding the problem statement correctly and we have a vertical load transferred to a beam via a sort of angled frame, then here's how I'd think about the beam reactions. The Quick ...
CableStay's user avatar
  • 2,760
5 votes

Why does a gear have extra holes?

Depends on the application, but generally there are two reasons why: reduced weight lowers inertia loads (opposite of a flywheel), but more often less material = lower costs if these are high volume ...
jko's user avatar
  • 2,347

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