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Questions tagged [structures]

Questions relating to or the engineering application of a device that must withstand a loading via deflection, stresses, resistance to buckling, or natural frequencies.

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2 votes
1 answer
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FEM 3D truss analyzer produces forces that do not sum to zero at joints

I am writing some code for the analysis of 3D truss structures. The program is a typical implementation of the direct stiffness method for truss elements. While testing it and comparing results to ...
John Kimble's user avatar
6 votes
1 answer
613 views

Dynamics of structures: combined plane stress and plane strain conditions

Problem statement For an engineering project in school, we are checking the stability in the longitudinal direction of an apartment building, taking into account the dynamic effect of earthquakes. ...
CJT's user avatar
  • 61
4 votes
2 answers
24k views

What angle - for a strut - provides the greatest vertical strength/support for a cantilever?

I want to affix a cantilever to wall. I will support the other end of the cantilever with a strut made of wood, that attaches to some point on the wall below the cantilever, as shown in this sketch (...
Kreeverp's user avatar
  • 143
5 votes
3 answers
4k views

Does the length of a beam change upon deflection?

I have made a Python program in which I have computed the deflection of a beam. I am plotting the deflected beam and am now asked to show the length of the beam. If the beam is not deflected, it is ...
Jamgreen's user avatar
  • 221
1 vote
2 answers
6k views

Beam with constant load distribution on three supports - force distribution to supports

I have following example (the question is at the bottom): The load distribution $q$ is constant. I add condition of zero bend in center of the beam, $w_B = 0$, and the assumption $F_{RA} = F_{RC}$. ...
Lluser's user avatar
  • 171
10 votes
3 answers
1k views

Is a permanent platform that is hanging and moving a dead load or a live load?

If a permanent room or platform is suspended from a larger structure (say, on a cable that is attached to a hook on a track in a ceiling) and designed to be in constant but not necessarily repetitive ...
Matt's user avatar
  • 203
6 votes
3 answers
957 views

Is a distributed load in two parts equal to a full distributed load?

I have a structure like such: Due to my lack of knowledge of ANSYS, I have made the singular distributed loading (GI) represented as two distributed loadings (GH and HI). Would this be an accurate ...
General Stubbs's user avatar
14 votes
1 answer
1k views

Why does prestressing in trees make them stronger?

In "Structures: or Why Things Don't Fall Down" James Gordon talks about trees being prestressed with the outside in tension and the inside in compression. Why does it make a tree stronger to have it ...
Voltron's user avatar
  • 141
5 votes
1 answer
3k views

Logic behind location of shear centre

When we apply a vertical shear force Sy and the structure is symmetric about x axis, then why is it logical to have the position of shear center at the location of intersection of line of action of ...
Manish's user avatar
  • 247
5 votes
0 answers
313 views

How to account for pistons inside a free body diagram? [closed]

If you have taken basic statics classes you'll remember the free body diagrams used to calculate the forces inside a mechanical system; such as a beam structure consisting of pivots, rollers, fulcrums ...
Sam Weston's user avatar
3 votes
1 answer
2k views

How high can you stack mobile homes?

In Ernest Cline's novel Ready Player One, the main character lives in the "stacks" - a dystopian vision of what a trailer park may look like in the future. The "stacks" are primarily composed of ...
Bobson's user avatar
  • 141
3 votes
1 answer
563 views

Is a building story actually 10ft (3m)?

In common US usage, the heights of tall things are sometimes converted to a "number of stories". The thinking is that people can better compare heights to similar tall buildings that they might have ...
hazzey's user avatar
  • 10.7k
5 votes
2 answers
690 views

Is there a theoretical bound to how tall a structure can be built?

Assuming that there are no constraints on cost, land to develop, or supply of materials, is there a theoretical limit on how tall a structure can be built? What are the main physical constraints that ...
Paul's user avatar
  • 2,569
7 votes
3 answers
978 views

What concerns would I need to consider for building a swimming pool of gold coins?

If I wanted to build a gold coins swimming pool [as in DuckTales], what engineering (not security) concerns would I need to address to make such a pool feasible? For example, since gold is much ...
durron597's user avatar
  • 179
8 votes
1 answer
2k views

Why build a cell lattice tower with square cross-section instead of triangular cross-section?

First, a neat image from Wikipedia Here the cell tower has three vertical (or maybe slightly inclined to the inside) thicker pipes which are located at angles of a triangle and those three thicker ...
sharptooth's user avatar
  • 2,099
2 votes
2 answers
2k views

What is the best insulation wall for a house? ACC wall, Cavity wall, etc

Normally, people use Autoclaved Aerated Concrete (AAC) to build a concrete house because ACC is a good thermal insulation brick that easy to buy and not expensive ...
fronthem's user avatar
  • 475
9 votes
2 answers
4k views

What is the practical limit on the number of storeys in residential buildings built with monolithic reinforced concrete?

I have recently bought a flat in a 25-storey building. I wonder what is the practical limit for the number of storeys in a mass-produced residential buildings built from monolithic reinforced concrete?...
Anixx's user avatar
  • 220
15 votes
1 answer
2k views

Why are hyperboloid towers not popular anymore?

Hyperboloid towers were very popular in the end of 19th and the first half of 20th centuries - water towers, powerline anchor towers, sometimes tall radio towers were built using this design. The ...
sharptooth's user avatar
  • 2,099
13 votes
1 answer
420 views

Additional jacking force to overcome stiction/dry friction

It is common to lift bridges to replace bearings, etc. In an ideal world the lifting capacity required of the jacks would be the self-weight of the bridge divided by the number of jacks (+ allowances ...
thomasmichaelwallace's user avatar
7 votes
5 answers
721 views

How can we prevent/detect hydrogen embrittlement?

There has recently been a series of high profile bolt failures on 'The Cheesegrater' in London, which have been attributed to hydrogen embrittlement. What can engineers do to ensure that hydrogen ...
thomasmichaelwallace's user avatar
11 votes
2 answers
1k views

Why are three way bridges rare?

It's true that most bridges are "two directional." But three way bridges are pretty rare, globally. I can understand why there wouldn't be many for rivers, but if bridges are designed based on the ...
Tom Au's user avatar
  • 665
11 votes
3 answers
3k views

What kind of protection should I give structural steel in a natatorium (swiming pool) environment?

What would be the best type of steel to specify? Would a heavy galvanization suffice? Are there specialty paints/coatings available for this particular application? If so, how long do they last?
cKrug's user avatar
  • 523

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