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 ...
- 22.1k
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 ...
26
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 ...
- 22.1k
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 ...
- 24.3k
18
votes
Accepted
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 ...
- 24.3k
11
votes
Accepted
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 ...
- 13.1k
11
votes
Accepted
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 ...
- 1,166
11
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 ...
- 3,597
9
votes
How different is using styrofoam rather than empty cans when pouring concrete?
I suspect that the reason to use it is that the cans and the associated empty space is cheaper than actually having solid concrete (and may be partly necessary to reduce the weight of the concrete and ...
- 3,587
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 ...
- 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 ...
- 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 ...
- 14.3k
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 / ...
- 15.5k
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 ...
- 15.5k
7
votes
How to calculate deflection of a simple beam with a load in the center?
I am specifically thinking of a wooden beam...
Wikipedia suggests I also need to know "Area moment of inertia of cross section" but I have no idea how to obtain this.
If you're using standard wood ...
- 3,587
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.
...
- 7,125
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:
$$W_{max} = \frac{\pi d^3 \sigma}{8L}$$
$\sigma$ ...
- 5,343
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.
...
- 22.1k
6
votes
Is hydrostatic pressure a dead load or a live load?
Eurocode looks into this with very much detail, see the "Loading Standards" list, attached. You can see that there is a document dedicated to actions in silos and tanks. This deals with hydrostatic ...
- 1,226
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 ...
- 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 ...
- 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 ...
- 3,135
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 ...
- 12.5k
6
votes
Accepted
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 ...
- 22.1k
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 ...
- 22.1k
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.
5
votes
Accepted
Loaded Truss problem
It may be worth reconsidering your deduced zero force members. But for this question it is not really necessary to determine which are zero force members in advance as this will come out in the ...
- 2,631
5
votes
Accepted
How is biaxial bending considered for reinforced masonry design?
Unity Equation
The Unity Equation is a very standard method of analyzing a section under combined loads. Even though the masonry code doesn't specifically call it out in the reinforced pages, it would ...
- 10.7k
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 ...
- 347
Only top scored, non community-wiki answers of a minimum length are eligible