# Tag Info

38

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 leaves his/her car in neutral without the emergency brake set. Many municipalities require them and have codes and specifications defining their dimensions and ...

28

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 (benefit of wheelchairs). As such, there is literally nothing to prevent a car from drifting forward and hitting the building; it's not even clear where you ...

9

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 including government and multi-national corporation buildings. You probably just never noticed them. It is my opinion that you see more of the type above due ...

6

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 and distressed structures. Following is a steel beam with a post-tensioned tendon. If $X$ is the amount of force in the tendon, and $c$ is the distance to the ...

6

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 object that will impact the sheet. If the object is much more rigid than the sheet and pointed it will go through like a bullet. Imagine an impact force has ...

4

They are to prevent "smash and rob". A situation where someone steals a vehicle and drives through a store front to rob the store. Usually an accomplice drives a second vehicle to escape.

4

Pretty standard old technology; A moot point whether prestressed cable or rebar is used. However ; cold drawn cable can be stronger. The problem is civil engineers don't understand the possible problem of hydrogen stress cracking of high strength steels. There have been several TV mockumentaries ( eg. Engineering Disasters) of serious cable failures. ...

3

Simply said, no. These are tie refers and they carry the tension load of the attic framing. By looking at the ceiling insulation one can tell that the ceiling rafters are perpendicular to these tie rafters, so they couldn't help either. If you desperately need the space and only for lightweight storage (because eventually, you are planning of using a 10lbs/...

3

Bollards in Switzerland have been placed to prevent and hinder drivers from parking vehicles with 2 wheels on the pavement or to stop them from parking their cars in front of shops.

3

For safety. They are to protect whatever is behind them from cars. They're very strong and will stop or slow down a car that would otherwise cause a lot of damage or risk to life.

3

An option you may consider is called a rotegrity sphere. The numbers show the spacing for a unit radius sphere. For a one-half meter radius, divide the numbers by two and convert to millimeters. My first exposure was from TaffGoch web site which allowed me to build two different models of two sizes, one with 3D printed members, the other with laser cut ...

3

Assuming that you mean a "Hyperbolic Paraboloid", the answer is that it's easy to make from common construction materials due to the fact that the surface can be made up of straight lines. There are other reasons to choose a shape like this over e.g. a flat or pitched roof (aesthetics, drainage, etc.), but I take your question to mean "why choose this ...

3

There are a whole lot of terms in your photos. Photo 1: That vertical structure is referred to as a PIER. Another style of pier which as far as I know is a series of piles and a pier cap is referred more specifically as a BENT. Piers perform the job of supporting the bridge between abutments by carrying the vertical (and horizontal loads) to ground. The ...

2

Other answers have covered a lot of the original use cases but nowadays terrorism is one of the big reasons why you see them being put up just about everywhere. According to this article, the more study ones are designed to stop a loaded truck up to 80 mph: https://www.sdmmag.com/articles/97143-anti-terrorism-bollard-manufacturer-helps-secure-2-iconic-us-...

2

Supports on bridges or over-heads are called trusses in general. Made up of diagonal, vertical, and horizontal members (those adjectives get nouned a lot, diagonals for example). Some of those are just support columns. In California they tend to fill and/or surround them with concrete. I-beams when they are shaped like an I or an H. Some of those are ...

2

Could a string of large offshore wind towers support a Hyperloop tube? It's a well defined [tm] engineering problem well within the physical capabilities of available materials and methods, so, yes, they could. However, the practicality of integrating the two very different systems is vanishingly small. Offshore wind turbine towers are spaced at very ...

2

A linear analysis is ... linear. If you increase the loads by a factor of two, the results increase by a factor of two. If you increase the loads by a factor of 1 million, the results increase by a factor of 1 million, even though the results are likely to be wrong. The analysis does not understand that other effects occur when the results are so large. (...

2

I think that neither of your solutions is correct. a) you are assuming that the volumetric strain is zero. However, if there is a change of volume then the volumetric strain can never be zero. Also, in that scenario, I am a bit uncertain what is $\varepsilon_d$. Is it deviatoric strain or is it strain perpendicular to the longitudical direction and due to ...

2

External Reactions Solving for the support reactions of an externally determinate structure like this one does not require the method of joints. The three equilibrium equations suffice. There are 3 unknowns: horizontal reaction at A, vertical reaction at A, vertical reaction at B. There are 3 equations: $\sum F_x = 0$, $\sum F_y = 0$, $\sum M = 0$ One ...

2

The one with the higher mass on level three is worse. Assuming the building as an SDF vibration for simplicity: The period of the building will moderately increase due to the reduction of K, $$K=P/\delta$$ By moving mas from 2nd floor to 3rd floor we increase deflection by roughly 1.2 hence decreasing the K by 1/5. Natural frquency $\ \omega_n=\sqrt\frac{K}... 1 I am 68 kilograms and you could never convince me to sit on this! let's say the table is 90cm high and the legs can extend out, by just eyeballing and correct me please, 50cm. and your lege ar 2cm pipe and the screws are on a 3cm diameter circle. One can not carefully place the load at the center of the table every time, also because of the fact the legs are ... 1 The beam ac is a simply supported beam with uniformly distributed load of 40N so the reactions are $$V_B=V_C=40/2\rightarrow V_B=20N$$ $$\Sigma V=40,\ V_A=20N$$ 1 Kamran is much more experienced, so I would go for his opinion (I also upvoted his answer). Especially given the circumstances (i.e. level 1 hurricane). However if you are that desperate to use the space, one compromise which might be useful to you and maybe structurally sound at the same time (kamran might have something to say about that). You could try ... 1 From what I see in the picture I am getting the impression, that these two are for completely different uses. The one above seems to refer to connection of two wooden beams on top of a column, such as the following In that case the entire side for each beam will be moving away from the the center line, however the points near the bottom will be moving the ... 1 The floorboards functions are supporting and distributing loads on beams. Another function is to brace the beams. In the design of the beams we only consider the rectangle section beam, not I section. As you described in the question, the floorboards are nailed to the beam. Thus, if you cut the section of the beam, the connection between the boards and the ... 1 You have many options from friction brake, magnetic brake, oil damper or pneumatic damper shown below. Figure 1. The pneumatic solution. Toggling the manual valve will send air into the bottom of the air cylinder sending it up at a speed determined by the adjustment of the speed controller at the top of the cylinder. Switching it off again will allow the ... 1 To answer this question I need to assume that the material is linear the column is fixed at the bottom. the beam to the column joint is fixed. the load is applied at the tip of the beam It is noted that buckling of frames is complicated by nature, the code provisions do not provide a simple formula for buckling of frames. For more advanced information, ... 1 If your sketch is up to scale you need not worry about buckling under compression. This column will fail under the bending moment long before it reaches the critical buckling load. This is the critical load for an axially loaded column. $$P_{cr} = \pi^2\,E\,I\,/\,L^2$$ And this is the Secant formula for an eccentrically loaded column. Where e is the ... 1 The linear time history analysis of the response of the structure is calculated at small time intervals sequenced with appropriate seismic load, maybe even after the ground motion stops until the structure stops from vibrating. The FEA's programs either use Duhamel integral or numerical methods to calculate stress and deformations. During the loading and ... 1 At Sprint, the telecom company's headquarters in Overland Park, KS when they built their billion$ campus in 2001, the CEOs and Executive building had a separate entrance and these bollards. It was expressly there to prevent truck and car bombs. For those who only think of 9/11, remember the truck bombing by Iran in Beirut, Lebanon in the 1980s which ...

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