Questions tagged [structural-engineering]

Questions related to the integrity, design requirements, or analysis of structures.

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18 views

Inertial Torque Exerted By Engine on Crankshaft

In Shigley(5th Edition), in Chapter 14. Dynamics of Reciprocating Engine ,Section 14.7 Inertia Forces, the inertia torque exerted by the engine on the crankshaft is given as $$ \mathbf{T}_{21}^{\...
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57 views

Why are shapes with sharp corners structually weak?

Please explain my question like I'm 5 too? ELI5: Why do ships have circular windows instead of square ones? : explainlikeimfive The real answer is that shapes with sharp corners are structurally weak....
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26 views

Shear Stress in Shear Pin (Single shear)

Case is of a Shear Pin with Single Notch to cause single shear. Pin is All DOF constrained for half the length and the remaining half has constant shear force. The shear force immediately starts from ...
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1answer
41 views

Pullout Force of Screw from Epoxy

I would like to estimate the pullout force required to pull a screw out of epoxy. Mine is an unusual situation where I want the joint to fail to protect other parts of the assembly; that is, it is a ...
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1answer
66 views

Could Tesla have REALLY shaken a building with a little oscillator?

I came across this story while reading about Nikola Tesla ground-power scheme. Supposedly, he created a little oscillator that could be plugged into the ground, tuned to the right (resonant) frequency,...
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What is the purpose of end plates when connecting beams together?

Quite often this kind of arrangement can be seen when beams are connected together. A rectangular plate is welded into a beam, and the plate is bolted to the other beam. I suppose one purpose would be ...
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3answers
83 views

Why do cold formed sections buckle differently from hot finished?

Above is a chart from a Eurocode handbook. It gives a correct buckling curve depending on cross section and its dimensions. I noticed that for hollow sections, the choice depends on whether the ...
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1answer
43 views

Single shear bolt shear force and moment diagrams

I’m trying to determine what the shear and moment diagrams of a bolt in single shear look like. Before anyone says it, I know that it’s rare that a bolt will ever fail first in bending, and this is ...
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23 views

How do we derive the equation of motion of Cantilever Beam (Euler-Bernoulli Beam)?

I know that the equation of motion of a Cantilever Beam is: $m\frac{{{\partial }^{2}}v}{d{{t}^{2}}}+EI\frac{{{\partial }^{4}}v}{d{{x}^{4}}}+P\frac{{{\partial }^{2}}v}{d{{x}^{2}}}=0$ but how do we ...
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38 views

Where does Second moment of area come from?

Where does the second moment of area come from and how to derive it from scratch, or what is the basic intuition behind it? In other words, what are the origins of $$I_{xx} = \int\int yy \text{ }dxdy$$...
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50 views

What is the frequncy range of seismic vibrations?

I'm working on a structure which needs to sustain common seismic vibrations due to earthquakes. So I want to do some modal analysis to find natural frequencies of the structure and make sure they are ...
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1answer
56 views

Analysis Of Braced Frame By Hand Calculation

Suppose we have a rigid jointed, statically indeterminate frame with bracing as shown below: Note: there would also be a distributed lateral load along at least one side of the structure and all ...
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25 views

What's the rationale for closely spaced standard LVL sizes?

Generally LVLs in the US seem to conform to heights that were historically used for solid lumber. e.g., 5 1/2" is the height of a nominal 2x6. This makes sense because presumably LVLs had easier ...
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1answer
33 views

What is the structural factor in context of wind loads?

Coefficient called "structural factor" appears in building codes when calculation of wind loads in discussed. The wind load is proportional to this factor. I have a lot of trouble ...
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2answers
58 views

What is the purpose of those “dual parasols”?

Watching a live video stream from South Korea just now, I noticed these parasols in the background. They look like normal parasols but have two "layers". Like a hole in the top with another &...
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47 views

What is the significance of hinge in the internal structure of the beam?

I had come across a question on shear force and bending moment diagram where a cantilever beam with a roller support at point C is given and the portion beyond point C in overhang. Does this hinge act ...
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1answer
25 views

Clothoid Curve / Euler Spiral Energy Transfer

I've seen in an advertisement that Clothoid curves–also known as Euler Spirals–"transfer maximum energy" to a ball bearing that is rolled down it. Firstly, I was wondering if that might be ...
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30 views

What is the fastest possible slot car

What is the fastest possible slot car one can build? What are the limiting factors? Obviously, we have to require that the motor is aboard the car and that it's propelled by the wheels (we don't want ...
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1answer
85 views

Why are combination load factors necessary? [closed]

According to Eurocodes, we multiply designed loads by safety factors to account for non idealities and uncertainties. When multiple load types affect a structure, the corrected loads are summed and ...
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2answers
41 views

How do fiber optic sensors detect strains in a structure?

I am working on a project on detecting damage in structures using fiber optic sensors. I read the paper Structural Health Monitoring in Composite Structures by Fiber-Optic Sensors and found out that ...
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1answer
22 views

Centroid of unsymetric bending in T-section

Can anyone please explain how this 24 is coming while calculating the x-cordinate of the centroid.
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1answer
20 views

Should pressure vessel head be thicker than wall [closed]

I wondering should the head of a rectangular pressure vessel cylinder be thicker than the wall ?
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1answer
34 views

How would you go about calculating the force required for an actuator to lift a bridge?

I have been trying to come up with the optimal way to calculate the force required for an actuator to be able to lift a bridge 90 degrees. (A drawbridge) The actuator is placed as follows: (The bridge ...
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1answer
61 views

Why does the ceiling have to be so high up in large supermarkets?

I just noticed this while watching a stream in Thailand, but this also seems to apply to the West (where I live) and the USA and everywhere because everything is globalized and standardized these days....
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2answers
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What is the technical name for temporary construction fences?

My structural engineering friend and I passed a construction site years ago, and he called those temporary fences a technical name. Now I ask him the technical name he said those years and he doesn't ...
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2answers
38 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 ...
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1answer
43 views

Missing items in geotechnical reports [closed]

In your experience, what items that should be in geotechnical reports are sometimes missing, and what do you do in that case, can you provide example? Do we look at codes or make best guess and based ...
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How to determine impact load factor on small beams

For small beams, the following equation explodes to high values, which seems unreasonable: $n = 1 + \sqrt{1+\frac{2h}{\delta}}$, where $n = \dfrac{F}{W}$, with $F$ the maximum force on the beam and $...
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40 views

Structural design approaches ASD or LRFD

I have several questions regarding terminology as I get confused reading different sources. What I learned so far: ASD is also called WSD (working stress design) LRFD is also called Limit State ...
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1answer
27 views

Control joint and contraction joint in concrete

What is the difference between a control joint and a contraction joint in concrete? I mean, a control joint is to control the cracks in concrete due to temperature or shrinkage etc... I understand it. ...
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2answers
31 views

Representing slabs in FEM

When making structural analysis with FEM, do we normally use plate or shell elements to represent slabs? I checked and did some reading for the difference between shell and plate elements in FEM in ...
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29 views

Determinating Reactions for the following frame

According to the frame below, the goal is to determine the reactions of this frame in order to draw after the diagrams N, T and M. The frame is asymmetric by reference at point C. All reactions ...
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1answer
31 views

Wind load vs Earthquake load and R factor

I read somewhere that if for instance for a building earthquake forces are expected to be much higher than wind loads, we can increase the R (response modification factor) value, so that we bring down ...
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19 views

What is the difference between base shear and pseudo lateral load in seismic analysis of buildings?

What is the difference between base shear and pseudo lateral load in seismic analysis of buildings or are they the same?
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1answer
20 views

How to make the earthquake response spectrum graph

As far as I understand, there are two ways to make the earthquake response spectrum graph. One by experiment with a set of oscillators with different periods, to which we apply the earthquake's time ...
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1answer
44 views

Plastic hinge locations in pushover analysis

In pushover analysis, why do we force the plastic hinge locations, such as indicating in our model instead of waiting for them to occur naturally? Also, do we usually need to show the spread of ...
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2answers
42 views

Soapbox - GoKart material - Bamboo or steel?

I am building a soapbox (go kart) and I am planing on what materials I could use for the frame and the chassis. I have thought about using bamboo or steel. Steel is normally the go to material when ...
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1answer
31 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 ...
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3answers
54 views

In the Principle of Virtual Work, what's the meaning of virtual?

I'll talk here of the principal of virtual work in the context of virtual forces. The idea of virtual work may seem strange at first. But it's one of the most fascinating I've encountered. The ...
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1answer
480 views

How should the welded corner of this bracket be detailed?

Consider the design of the bracket shown in the figure below (it is assumed that the anchors are sufficient and are not considered below). My question concerns the detailing of the welded connection ...
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1answer
34 views

In structural mechanics is virtual work an approximation?

In the principle of virtual work a unit virtual force imparts virtual forces on the structure internally. When real loading is then applied the additional work done by these forces is their ...
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43 views

How to strengthen the floor to support a 120gallon fish tank

My house was built around 1920, and has field stone foundation. The joists seem to be all 2"x8". I want to put a 120 gallon(as measured in the United States) fish tank in my home office, which will be ...
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26 views

names of some earthquake analysis methods

For structure earthquake analysis methods, do these all below mean the same thing, just ways of calling it differently? Linear Response History Analysis Linear Elastic Time History Analysis Linear ...
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1answer
28 views

Modal Response Spectrum analysis

Is "Modal Response Spectrum Analysis" the same as response spectrum analysis? How about modal superposition analysis? This is the same or different? Or all are same?
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27 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 ...
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1answer
65 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 ...
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1answer
50 views

How do you ensure that a beam is loaded through the shear center?

Reading about shearing stresses in beams, it is commonly stated that it is necessary to load a section through its shear center, so no twisting is applied to the beam. This is specially important in ...
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2answers
40 views

Have tunnel boring machines been mass produced? What are the difficulties in mass producing a tunnel boring machine?

Tunnel boring machines are a common tool in deep tunnel construction. I am curious if they have ever been mass produced in specific types. What are the possible problems in (a possible) mass ...
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32 views

Provide stability for a 3D object with a support structure

This is a follow-up to this question. I wonder if structural engineering tools like Finite Element etc. might help create such support structures. If so, how?
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24 views

How is response spectrum result used for earthquake analysis

For simpler buildings we can use response spectrum analysis. How is this used? The maximum acceleration we get from this , is simply multiplied by the mass of the building to get F=ma , total ...

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