22
votes
Accepted
Why would a bearing plate that further concentrates load onto small surface be used?
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 ...
- 6,874
20
votes
Aluminum weight saving
I believe it has less to do with strength and more to do with stiffness. A rod of aluminum of the same length and weight as a a steel rod will be just as strong (force required to break) but have ...
- 5,312
19
votes
How thick is it reasonable for the walls of a steel gas pipeline to be?
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 ...
- 2,631
19
votes
Is it structurally sound to cut an I beam to a T on one end?
While not an ideal situation, it is common enough that this type of cut/reduction of the beam as it comes to its support actually has a name. This is more often referred to as a coped or dapped steel ...
- 1,201
17
votes
Why do we use multiple reinforcing bars instead of one bar with a big diameter in reinforced concrete?
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....
- 13.1k
16
votes
Is it structurally sound to cut an I beam to a T on one end?
This is a textbook example of what not to do.
We don't get into stress concentration at the cut off of the corner of the beam, or the fact that the two very different stiffnesses of the beams are a ...
- 22.1k
13
votes
How thick is it reasonable for the walls of a steel gas pipeline to be?
Is such wall thickness realistic for an industrial gas pipeline?
Looking through ASME B36.10M-2004, Welded and Seamless Wrought Pipe, there are plenty of pipes that have thicknesses in that range. ...
- 3,587
13
votes
Accepted
Why do manufacturers still make aluminum kitchen utensils?
Yes, steel (even some stainless) may be cheaper than aluminum, but the material cost of an item is seldom the majority of the total cost, especially a small item such as a potato peeler.
Making ...
- 246
11
votes
Accepted
What happens from B to C in this stress strain diagram of mild steel?
One point of note is that the yield region is not as cleanly defined as BCD is in the image (although most books have it that way).
In reality the yield region looks like
The following image is one ...
- 24.3k
10
votes
Why do we use multiple reinforcing bars instead of one bar with a big diameter in reinforced concrete?
The main purpose of rebar is to improve the tensile strength of concrete and in practice most of these loads come from bending rather than pure tension.
When a beam in subject to bending forces the ...
- 15.2k
10
votes
Why would a bearing plate that further concentrates load onto small surface be used?
The reason is pretty simple. Steel is significantly stronger than concrete.
Nowadays we have high-performance concretes with $f_c > 100~\text{MPa}$ (and ultra-high-performance, which is ...
- 13.1k
10
votes
Accepted
How does the strength of a square tube depend on the side size?
Flexural capacity is based on the stress at the extreme fiber (the point farthest vertically from the neutral axis).
$$\sigma = \frac{My}{I}$$
Or, rearranging
$$M = \sigma \frac{I}{y} = \sigma S$$
...
- 2,760
9
votes
Steel selection for building a trailer
Here's the formula(s) we use
Beam Bending (available on Wikipedia)
$$EI\frac{d^4\,\delta y}{d\,x^4}=q(x)$$
$$I=\int (y-\bar y)^2 dA$$
$$\bar y= \frac1{A}\int y \;dA$$
$$\sigma_{max} = y_{max}E\frac{...
- 1,335
9
votes
What do you call the steel property that reduces the likelihood of shattering?
There are three (or four) possible terms for what you are asking: resilience, ductility or toughness (a steel that is resilient, ductile and/or tough)
A material's resilience describes its ability to ...
- 13.1k
9
votes
Steel vs Bamboo strength types/ weight and in various directions & orientations? Specific, Tensile, Compressive, Shear, Lateral etc?
Stating categorically that bamboo is stronger than steel is a bit like stating that automobiles are faster than planes. On its face, it is a bit shocking, and seems wrong. But a rocket-powered ...
- 4,041
9
votes
Aluminum weight saving
TL;DR: Materials perform differently under different loading conditions. Some applications are more suited for steel others for aluminium
I will try to give another more general perspective/approach, ...
- 24.3k
8
votes
Accepted
How to strengthen an I beam
If your beam design is governed by yielding in bending (not lateral-torsional buckling/plate buckling, etc) then you need to increase the second moment of area (I) to increase the bending capacity.
...
- 2,631
7
votes
Accepted
Does weathering steel corrode the same as carbon steel when it doesn't develop a protective patina?
In a situation where the environment does not allow the patina to form, does weathering steel perform any differently than carbon steel?
Weathering steel is specifically designed to form a protective ...
- 3,587
7
votes
Accepted
Do "non-iron steels" exist?
Iron and carbon have an interaction which make them different from most engineering alloys. This is to do with both the relative size of C and Fe atoms and their chemistry.
Carbon atoms are just the ...
- 15.2k
7
votes
Can I weaken a coil spring consisting of spring steel?
You could try a bath of concentrated acid. As long as you could maintain circulation so the concentration was fairly constant, a spring presents a very uniform cross-section and should be dissolved at ...
- 81
7
votes
Is it structurally sound to cut an I beam to a T on one end?
If the white beam on the left is adequate, the one on the right is much bigger than it needs to be, so hacking a piece out of it might not matter.
In general this idea is a horrible example of ...
- 12.5k
7
votes
Is there a maximum life for things made out of stainless steel or cast iron?
Strictly speaking, very few metals are "stable" in terms of the laws of thermodynamics. True chemical stability is when the atoms are in their lowest energy state. For most metallic elements,...
- 191
6
votes
Accepted
Schaeffler, De Long, and WRC welding diagrams - which steels can be used?
You are not exactly right. The purpose of Cr and Ni in stainless steel, besides the stainless part, is to tailor the microstructure. Cr promotes ferrite, Ni promotes austenite. Other elements have ...
- 4,041
6
votes
Why do manufacturers still make aluminum kitchen utensils?
I looked up 6000 grade aluminum to be about \$2/kg, while 304 stainless steel is about \$3.40/kg.
This means stainless steel is about 70% more expensive than aluminum, which is consistent with my ...
- 3,575
6
votes
What thickness of aluminium sheet do I need to achieve the same strength of a 1/8" steel sheet?
Using your plate as boat hull implies a complex load profile probably involving compression, shear and bending, possibly even torsion.
In such cases, it is effectively impossible to give a simple ...
- 13.1k
6
votes
Is it structurally sound to cut an I beam to a T on one end?
TL;DR: Since we can't see how the beam is supported on the other end, its not clear whether its structurally safe. Still, I don't believe this configuration can transfer safely any substantial ...
- 24.3k
6
votes
Aluminum weight saving
Sometimes the strength isn't required, so size for size, aluminium is lighter.
e.g. bicycles often use aluminium screws to hold the bottle cage to the frame. The size of the screw is set to be ...
- 7,726
5
votes
Use of 410 Stainless Steel for replacement of 420 Stainless Steel
In general, I would be hesitant to switch the grade of stainless steel used. You are asking to switch from a more unique grade to a common grade. There was probably a good reason why the grade 420 was ...
- 10.7k
5
votes
Accepted
How to calculate tensile strength of braided steel wire?
First off, the tensile strength is a property of the material, not the spring itself. Strength, often denoted as $\sigma = F/A$, can be considered how much force a material can withstand for a given ...
- 1,220
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