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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11
votes
5answers
5k views

Why are some public benches made with arm rests that waste so much space?

While watching a YouTube video today, I noticed this public/park bench somewhere in the USA: It looks strange to me the way the arm rests on each side are so far into the bench, wasting a rather ...
2
votes
4answers
69 views

Bending moment calculation

Considering all the variables are the same, how to rank these connections from highest to lowest bending moment?
0
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1answer
88 views

Question on the determinacy of frame structures

I have been working on a program to solve frame problems, and I have used the following formula for determining whether a frame is statically determinate: $$RD=3m + r-3j-s,$$ where: $m$ is the number ...
0
votes
1answer
39 views

Why isn't there yet such a thing as a “Minimum Life Module” standard and concept deployed? [closed]

Why are large companies not producing, selling and maintaining the concept of "Minimum Life Modules"? What I mean is a standardized "module" hosting exactly one human being, with ...
0
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3answers
42 views

How to measure the stiffness of a rectangular beam, and compare it to a triangular beam?

I'm an amateur at engineering, working more on musical instruments, and I'm often in confusion regarding what exactly constitutes stiffness of a beam for a load applied on it so it could resist ...
3
votes
2answers
1k views

Is it safe to slightly cut the edge of RCC beam for passage of AC Vent and wiring?

My electrician made a cut in the wall and the beam as in the image in my absence. The cutting is done with hammer and chisel and it is around 1.5inch deep..I'm really worried that it might impact the ...
4
votes
1answer
18k 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 (...
-1
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2answers
74 views

Beam/column sizing

If a load P is applied as shown to a fixed column-beam, pinned at the bottom, should the beam or column (or both) sizes be increased to resist the load?
0
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0answers
15 views

Wind behavior and pattern

From the 5 options, which one shows the worse wind effect? Is it (b) because wind speeds accelerate through a gap? But how about in comparison to (c)? Or (d) due to the height and sharp corners? If it'...
2
votes
1answer
15 views

Seismic question

For a 3 stories building, in terms of seismic vertical instability which one is worse: a higher mass on Level 2 or, higher mass on the roof? Both are compared to L1 mass.
0
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0answers
41 views

Do any roller coasters actually use the brachistochrone curve?

Not sure if this is the right place to ask this. But I'm assuming roller coasters are related to engineering. I know that in theory, the brachistochrone curve is the fastest way from point A to point ...
1
vote
1answer
24 views

How to determine the fixed end moment?

I was trying to compute the fixed end moment for the beam (given below) using equilibrium equation for x, y displacement and moment but there are 4 unknown variables reaction and moment at both ends ...
1
vote
1answer
38 views

Reinforce foldable table legs

I'm trying to build a table with 4 swivel legs that can be locked into arbitrary angles so that it can stand over one to three rows of storage crates in my garage: As you can see, the legs aren't ...
0
votes
2answers
72 views

Loadcell / strain gauge sizing for a joist

I am looking to use some load cells (foil based type) to detect presence for home automation within in a room. I was looking to mount some loadcells to the joists for the floor (UK Based house so ...
0
votes
1answer
71 views

A Steel post and base question

I make solid curved wood furniture and frequently need something like a metal plate (1/8") with a (3/4" about) supporting pipe attached at 90 degrees. Welding is a little too cumbersome but I was ...
1
vote
1answer
41 views

column yielding under earthquake

In the buildings designed with strong column weak beam concept, the columns will remain elastic, their plastic deformation will be limited. but this is not true at the base of the building. i mean i ...
0
votes
1answer
76 views

Optimal method of attaching commercially-available heavy bag mount to finished ceiling with least risk of structural damage

Admittedly, this question is related to an earlier one on the same subject. I would like to mount a heavy bag using a system detailed in the attached picture (FirstLaw Fitness Shock Mount). The ...
0
votes
1answer
23 views

reaction of structure

all is this sturcture stable ? or structural determinate ? Let the top support as A , bottom support as B , By taking moment about A, i managed to get 10(4*4)/2 -HA(2) = 0 , HA = 40kN, HA = HB = ...
2
votes
1answer
60 views

Wood beam connection

Can someone please explain why the top left image is correct and the bottom left image is not? Both of these images have the bolts on the lower half of the wood beam (tension) side.
1
vote
1answer
62 views

Mounting outdoors camera using aluminum 5052

I designed a simple U shape 2mm sheet metal bent mount for a 4kg outdoors CCTV camera. The mount was accidentally produced from 5052-H32 Aluminum instead of 6061-T6. Is it common to use 5052 ...
0
votes
2answers
91 views

Why does stress act a point instead of on an entire area normal to the stress?

I've often heard stress acts at a point and not on an entire cross-sectional area to which the load is applied normally. Im a little confused here, Let us consider an area of cross-section ...
1
vote
0answers
23 views

Help sizing of lug attachment flange/plate?

Apologies for the crude drawing attached, but here goes. Given Fx, Fy, and Fz loads applied at the lug hole, I've distributed the loading into each of the 6 fasteners to size them. I've also sized the ...
1
vote
2answers
155 views

Are these horizontal timbers removable in an attic/loft?

There are 3 horizontal lengths of timber stretching across the centre-level of my attic/loft space and are attached at either end to the rafters with a single nail. I can wobble them by hand and they ...
2
votes
2answers
75 views

Do the floorboards in timber beam floors have a structural function?

Timber beam floors with perpendicular timber floorboards as indicated in the drawing below are common throughout northern Europe. The floorboards are nailed onto the beams and are quite substantial ...
2
votes
2answers
52 views

Is it practical to use tensile cables in a composite beam?

Many composite beams combine material that has a good tensile strength with material that has a good compression strength (like concrete and rebar). I was wondering if there has ever been a beam that ...
2
votes
2answers
4k views

Transfer of moments in beams with internal hinges

We have a beam with 1 internal hinge just like the picture. We know the internal hinge can not transfer moments between AB and BD. We know the 30 kN force makes some moments on BD & AB. If B (...
1
vote
0answers
25 views

When settlement criteria of a foundation is satisfied, bearing criteria is also automatically satisfied?

We design the foundations to settlement criteria than bearing correct? Because settlement criteria is stricter? I mean, can there be an example where the settlement criteria is satisfied but bearing ...
0
votes
1answer
31 views

What is the linear strain for given lateral strain?

So, I am trying to calculate the linear strain of a shaft which is under plastic deformation in yielding region. The diameter is changing from 2d to 1.5d I'm assuming that the volumetric strain is ...
-1
votes
1answer
30 views

Wood Dimensional Stability

Between Glue Laminated and steel plate sandwiched between two wood beams, which one is more dimension-ally stable?
-1
votes
1answer
26 views

Shear connections

Question: which of the three shear connections (beam/column) below will require diagonal bracing?
-1
votes
2answers
107 views

Unable to obtain closed system of equations using method of joints

I am currently working on some code to solve 2-dimensional truss and frame problems, and I have come into an issue with one of the problems. I need to come up with a system of linear equations that I ...
1
vote
2answers
83 views

Fixed-Free End Column Design

I am currently working on a problem where I have to design a column. The structure I am currently designing currently takes the following form, When designing the column, I know that I have to ...
1
vote
0answers
18 views

Secure loads to gearbox shafts

I have a sculpture that is designed to rotate over 3 axes at max. 30RPM and is mounted on an aluminium disc. My plan is to use 3 of these geared steppers and secure the sculpture to the Z-axis shaft, ...
2
votes
1answer
49 views

Cheap but durable design for a quick-to-assemble, portable globe?

This question has a bit of an arts & crafts / DIY flavour, but looking at those Stack Exchanges made me feel it fits better here. I have no background in any of these things, so apologies for my ...
-1
votes
2answers
60 views

What is the easiest way to regulate the speed of a falling object?

I want to design a system that allows a 1kg metal brick to fall under gravity at variable speeds. The brick initial position is 20cm above a flat table. I want to have control on the duration (to ...
-1
votes
1answer
34 views

Method of joints not working on simple truss, supposed to be stable and determinant

In the process of editing the question to put better pictures of my dimensions in, I realized that how I calculated my angles was incorrect, and that is why my answers were yielding inconsistent ...
0
votes
2answers
30 views

Earthquake time history analysis

Time history analysis of earthquakes for structures, is a NON-LINEAR dynamic method correct? Then why is there also something called "LINEAR response history analysis"? What is the difference of this ...
-1
votes
1answer
84 views

What is the strongest structure?

I am not an engineer, but I thought maybe this could be a very old and classic problem in structural/mechanical engineering. I need to build a support structure to hold a uniformly-distributed load of ...
-1
votes
3answers
34 views

How to solve a system of second order ODE from time t = T to t = 0

I have a system of second-order ODEs $$ \mathbf{M\ddot{x} + C\dot{x} + Kx = f} $$ I want to know some good numerical methods to solve this system of the equation given the initial conditions at time $...
2
votes
1answer
48 views

Calculate whether a polycarbonate plate can withstand a certain force

I need to calculate whether a polycarbonate sheet can withstand a certain maximum force. The force is an impact force on any one point of the sheet at any given time. All I have are the Young's ...
14
votes
8answers
8k views

What are those large poles for that are always in front of US stand-alone store buildings?

Screenshot of a video where they are featured in the background: They appear to have no electronics built in, such as an electric charge station, or a parking ticket dispenser or something like that....
4
votes
1answer
46 views

Why is a paraboloid hyperboloid shape preferred on some structures?

Why is preferred on the construction of big stadium roofs and of cooling towers, per example? What is the advantage of this geometric figure that makes it more economical?
1
vote
1answer
115 views

Is it safe to slightly cut the edge of RCC column for passage of pipe in bathroom?

The RCC column was cut in my absence due to passage of pipe for bathroom fittings. The thickness is about 1.5 in. Will it hamper the stability of structure?
1
vote
2answers
511 views

Vocabulary: NYC Elevated Highway & Trains, Industrial Park

I'm writing a story set in NYC and trying to describe certain industrial objects. I'm having trouble with specific technical terms for the items that I've marked w/ arrows. E.g. I don't want to use ...
-1
votes
1answer
30 views

Flexure Deflection - Both ends fixed (one translation free)

I have a flexure problem. One of its ends is fixed to a frame (say F1) which is stationary (no rotation & no translation) and the other end is also fixed to another frame (say F2) which can move ...
-1
votes
1answer
28 views

Could a string of large offshore wind towers support a Hyperloop tube? [closed]

I live on the east coast of Australia, where a Hyperloop faces the challenges that we have a mountain range pretty much right up against the coast, where most people live. There's very little flat ...
-1
votes
1answer
30 views

Elastic waves in very thin plate

Elastic waves in structural elements are described by \begin{align} \rho \frac{\partial^2 u}{\partial t^2} &= (2 \mu + \lambda) \frac{\partial^2 u}{\partial x^2} + \mu \left( \frac{\partial^2 ...
1
vote
2answers
541 views

Buildings sinking into the ground

My friend has proposed that the buildings in the images below have been sinking into the ground over time and that they're not planned with basements. He thinks that the bottom of the building was ...
0
votes
1answer
82 views

Maximum I-beam girder S12x31.8 span

Does 200lb/in of load on a S12x31.8 over 15 feet seem reasonable? I'm having a tough time trusting the numbers. Two story house with an attic as below. Dotted lines show load bearing walls W1 and W2. ...
1
vote
2answers
3k 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 $F_{RA} = F_{RC}$. ...

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