# Tag Info

## Hot answers tagged civil-engineering

35

They're V-Mesh panels. V-Mesh panel from Irish Wire. The offset of the vee gives rigidity in the horizontal direction. The vertical rigidity is addressed by the fence posts. It's available in 2, 3 or 4 vee depending on the panel height.

33

I will expand on DKNguyen answer, because to my knowledge also the two reasons are: reduce contact/bearing stresses (having a significant effect on thin finishes live galvanisation) change the joint tightening characteristics (see joint diagram). reduce contact stresses on surfaces. The basic idea is that since contact stress is defined as: \sigma = \...

32

The picture, below, of the exaggerated long section of the Channel Tunnel was taken from Wikipedia. Full-sized image here. Some of the limiting factors for the Channel Tunnel are: Railways don't like steep gradients The tunnels comprising the Channel Tunnel were excavated using tunnel boring machines (TBMs). Like railways, they cannot tolerate steep ...

31

I assume you are asking the deepest structure of any sort that exists. Here is an infographic : Source : https://alansfactoryoutlet.com/the-deepest-underground-structures-in-the-world/ One mystery undersea structure: Cuban Underwater City The Cuban Underwater City is another underwater structure that raises more questions than it answers. What appears to be ...

29

As others stated before, induction loops are the primary - most reliable method: the coils (usually just several loops of wire) embedded in the road; fed given frequency from a generator, in presence of metal the frequency of the LC circuit changes and the sensor circuitry detects the change of frequency, producing a presence signal. In some cases these may ...

27

It is for spreading out the stress. But it is also for giving the bolt a bearing surface to turn on. The washer always goes on the side (nut or bolt) that is being turned. It prevents it from marring up the work surface and also changes the tightening characteristics. I don't know the specifics of that though but that's what I was told by a toolmaker. Always ...

26

That looks like a Pratt truss. These trusses have diagonals which go from the outer-top nodes to the inner-bottom nodes (i.e. they connect to the top chord on the node furthest from the center of the span, and to the bottom chord on the node closest to the center). This design means that the diagonals are under tension and the verticals are under ...

26

It is a trench shield. It gets placed in a trench after the trench is dug to prevent workers from being hurt or killed in the event of a trench collapse. This picture from GMC trench shield shows a partially collapsed trench with a shield installed that would protect the workers installing the blue brute pipe.

26

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 subtle discomfort. Also, they have to be easy to scan by security cameras and not have hard-to-see corners easy to hide contraband material or even explosives! ...

24

This is called Slope Paving. (In the US at least.) It is done for two reasons at bridge abutments. These reasons are related: Steeper slopes are possible. Protection from undermining abutments and piles. Steep Slopes The soil that is used to create the earthen fills will only stand up naturally to a certain steepness. By placing a layer (~4in) of ...

23

Most bridges (and overpasses) are built to cross over something. With a few notable exceptions, most of these "somethings" are relatively long perpendicular to the desired crossing direction and fairly narrow parallel to it. Therefore a simple "two directional" bridge best meets the needs of the engineering problem. Engineers always try to solve a problem ...

22

There are a few main reasons why suspension bridges aren't used for railroads. The main reason is that suspension bridges are typically used where very long spans are needed. Trains are very heavy, especially when compared to lanes of highway traffic. This means that long spans require very strong support structures, which in the case of suspension bridges ...

22

The 'steps' are called weirs, and they are used for a number of flow control reasons in rivers. In the case of the images you posted, they are probably being used to stabilize the grade (slope) of the river. When used for this application they are sometimes called drop structures which "pass water to a lower elevation while controlling the energy and ...

20

The main reason for the stepped arrangement of the slope is slope stability and safety. Such walls/cuttings are divided into two components: sub vertical walls between two flat horizons flat sections between sub vertical walls By having a stepped arrangement, material and hence weight, is removed from above the toe of slope (where the bottom part of the ...

20

The two photos in the post show the same structure: Pulteney Weir, downstream of Pulteney Bridge on the River Avon in Bath. The shot of the "Seine" in Les Miserables was filmed on location in Bath. Pulteney Weir was designed by architect Neville Conder, and built between 1968 and 1972. It's one component of the Bath Flood Prevention Scheme, which was ...

20

Because bridges and other structures are not static objects. They must be allowed to flex under varying loads and also accommodate changes in length from thermal expansion. The hinge pin allows changes in angle. and the sliding joint between the upper hinge plate and the flat plate on the bottom of the beam allows changes in length. If the connections were ...

19

It seems realistic to me. This is an undersea pipeline at depths of over 2 km. The pressure would be considerable at those depths (on the order of 20 MPa or 200 atmospheres). The pipe would need to be thick enough to withstand these (very high) pressures. The Nord Stream pipeline under the Baltic sea is at depths of up to 210m and uses 1220 mm diameter ...

18

A yahkchal is an example of a type of passively cooled building in Iran They utilise a combination of passive evaporative cooling and thick thermally insulating walls in order to keep the interior temperatures low enough. First, wind is directed into underground aquifers known as qanat. They are then cooled due to the low humidity desert air causing water ...

18

This is very common misunderstanding. When we look a a road, we see few centimeters thick layer of bituminous surface, and we think about "the road" as "the asphalt/tarmac." It's not. When you look how a road is build (or rebuilt), you can see that "the road" is actually over half a meter (or more) deep, consists of layers of sand and gravel and has ...

18

If I'm understanding your question correctly, you're asking why a flyover has excess clearance beneath it for traffic below. For example, if the tallest vehicle expected beneath the flyover is 12ft tall, the flyover may have 14ft clearance. There are many reasons for this, some of them more obvious than others. You don't want to try to squeeze a 12ft tall ...

17

There are a few reasons. I'm firstly going to assume you're talking about replacing a bunch of small rebars by a single reasonably-sized one: i.e. instead of $15\phi8$ (7.54 cm2), using $1\phi32$ (8.04 cm2). One reason is to improve ease of constructibility. Reinforced concrete beams also have transversal reinforcement, and it's very common to place rebars ...

16

Theoretically pontoon bridges with rope anchors keeping them to the bottom would work against wind and flow, overcoming the problem jhabbot mentioned in his answer (same as train length limit - stretching force). In practice these come with more problems of their own. They drift on water surface and as result, rise and fall with water waves. The larger the ...

16

Not everything scales linearly. In particular, the cross-sectional area of supports required scales faster than height of a structure, all else held constant. This explains why ants have tiny thin legs compared to elephants. An ant linearly scaled up to elephant size would not be able to stand, or would snap its legs trying. The same thing happens to ...

16

Except for special applications, most washers are made of dead soft steel, which deforms under the compressive load imposed by a tightened bolt head. As the washer smooshes, it minimizes stress concentrations caused by bumps under the bolt head and surface flaws in the part the bolt is running through.

15

Your question sort of has two parts: How to supply heat, and how to keep it in. Large open rooms with a high ceilings are most efficiently warmed with radiant ceiling heat. Warm air rises, which renders forced-air systems inefficient because the pumped heat ends up at the ceiling and the coldest part of the room is near the floor where you actually want ...

15

The strength of a horizontal beam is defined based on a property called the section modulus. Shapes that have more material distributed near the top and the bottom have a higher section modulus. This is why I-shaped beams or tall rectangles are common choices. Round shapes, on the other hand, have most of their material concentrated around the center of the ...

15

Euler buckling occurs because the world isn't perfect. So that theory assumes that there is an initial infinitesimal deviation along the column (assuming the column is in fact not perfectly vertical*). This deviation causes a bending moment along the beam, which increases the deviation, which increases the bending moment, which increases the deviation... ...

15

To visualize part of Nmech's answer: in the image, the washer actually greatly increases the contact area of the bolt head. The bolt head looks pretty big: But most of that is the shaft, which obviously does not spread out load on the material. So the actual contact area looks like this: Comparatively, the bolt head on the washer looks like this: That's a ...

15

If your volunteer is a very small person, maximum shoulder width of 23 cm/9 inches, then the answer is 12,262 metres (40,230 feet) deep in the Kola superdeep borehole in Russia. I can't find the "height above sealevel of the start" to subtract from total depth of borehole, sorry. Best I can find is 230 metres above sea level. They probably won'...

15

The Kidd Mine in Ontario, Canada: per the Wikipedia article, it is "the deepest accessible non-marine point on Earth" at "2,733 metres (8,967 ft) below sea level". I found this from the Wikipedia article on Extremes on Earth, which differentiates between depth from the surface and depth below sea level, and also between an actual mine vs. ...

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