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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1answer
96 views

Translating the name of a type of beam from Russian to English

I am trying to translate the name of a special kind of beam from a set of Russian-language drawings. The dictionary translates the name as simply supported beam, but it's not that simple. There is a ...
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3answers
118 views

Is there a specific name for diagonally braced truss members like those on the Queensboro Bridge?

I am wondering about this specific type of truss in particular, any links to further source information and images regarding this particular geometry would be much appreciated.
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What exactly is the thin wall assumption in regards to beam cross sections?

What does it mean with respect to calculating stresses on a beam undergoing loading and when should it be applied?
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1answer
158 views

Distance of Pivot from the Rear axle

I am designing an NSAM crane. I have encountered the following issue when designing the vehicle: Generally the pivot(or the point about which the NSAM crane rotates) is in the center. But from two ...
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2answers
898 views

3D problem to 2D plane problem

I have general problem of understanding how forces are transfered from 3d members problem to plane problem. For example what would be 2D representation of forces F1 and F2 acting on horizontal A beam,...
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1answer
1k views

How to estimate the required thickness of a transfer floor

I am examining a high rise building project of 30 floors with a podium underneath and 2 basements. The structure in the tower and the podium varies between flat slabs, steel structure for wide spans, ...
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1answer
320 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 ...
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1answer
472 views

Caulculating maximum shear stress at certain points

I have a structures problem I cannot solve, I have the answer and I have attempted the question. I just need to know where I am going off track. Any assistance would be highly appreciated. My work is ...
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1answer
6k views

What is the effective depth of a beam with two layers of tension reinforcement?

In EC2 for calculating crack width and deflection, does the effective depth d refers to the depth from compression face to centroid of the tension reinforcement or is that calculated to the centroid ...
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103 views

choice of steel plate for simple application

I am an occasional hobbyist "DIYer" (not an engineer) who needs help choosing a steel plate for a small home improvement project: I will use it to create a 20" circle, suspended from a bolt at the ...
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1answer
1k views

Torsional Constant of Thin-Walled Multi-Cell Structures

I'm asked to analytically calculate the composite torsional constant of the following structure. No other information is given, such as the applied torque. I know how to calculate the torsional ...
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2answers
213 views

How to calculate rotations from displacements?

I'm trying to develop a finite conical shell element with six dof at each node. I want to express the rotations $\phi$, $\theta$ and $\psi$ in terms of the displacements $u$, $v$ and $w$. The ...
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2answers
445 views

First glance: structural integrity of this roof

There's a rooftop we recently discovered with a great view, and it's easily accessible for us. Obviously we'd like to go up there a bit more, particularly in summer with a couple of fold up chairs or ...
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68 views

Normal stress - shear stress pairs not lying on Mohrs' Circles

The three Mohr's circles depict all the possible normal stress / shear stress combinations when material is taken and rotated along one of it's axes of principal stress. Nevertheless, it is clear that ...
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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 ...
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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 ...
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3answers
194 views

Base or foundation?

Please help, what is the correct term for: The bottom/foot part of building or structure which carries loads from the building/structure and transfers the loads to the soil/earth/ground beneath it? ...
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2answers
231 views

How do I build a miniature concrete house?

Our teacher gave us a project before Christmas break, it was to build a miniature house, she didn't state what specific materials should be used, so I built a cardboard house. She didn't accept it ...
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1answer
750 views

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 ...
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1answer
48 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 ...
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1answer
54 views

Boring through joist

I just started my BEng, so I actually don't feel ready to assess real cases. Upper floor of my quite standard British terraced house. We would like to hide an existing drainage pipe which is ...
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2answers
160 views

Can a speedbump safeguard a pipeline located below?

Recently I noticed a concrete speed bumper created near my parking. On enquiring the purpose, the committee who took the decision told me that the purpose of the bumper is to safeguard an existing ...
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2answers
43 views

What is the 'application standard' referred to in EN 1993-1-7

I'm using the Eurocodes for some structural analysis and am looking for the limiting value of deflection of a plate. EN 1993-1-7, Section 8.2 states: For limiting values of out of plane deflection w ...
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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 (...
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1answer
78 views

is a cylindrical pylon just as sturdy as a cubical one of the same volume?

I'm wondering if the structural integrity of a solid cylindrical pylon is just as sturdy as a cubical one of the same volume given that they're both the same height.
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4answers
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What loads does the safety factor apply for?

As is well known, a safety factor is often applied for engineering structures as a measure of precaution. I would like to ask for which loads (if not all) does the safety factor apply for. For ...
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1answer
125 views

Siding for Industrial Shed: Rain protection vs Ventilation

When building a 12 m tall industrial shed with a peaked roof it is desirable that the sides of the shed should stay open as much as possible for ventilation / safety / access concerns. On the other ...
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1answer
14 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.
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2answers
87 views

Need Help to Remove Sway from Steel Post + Glass Panels

I have spanned ~15' with 2x 10mm tempered glass panels. They're connected in the middle with a 1.5" x 1.5" 16-gauge, 316 stainless steel post filled with concrete. This post has a 316 base welded on ...
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1answer
43 views

What is symmetric?

What is symmetric?Please explain geometrically and in terms of displacements. I have encountered this while looking up for engineering strain and true strain values have totally different compression ...
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2answers
1k views

Projected area in hoop's stress structural mechanics

While calculating hoop's stress we consider projected area. Infact in bearing stress from pins in a truss something similar is applicable.Can you explain why we are taking something like this instead ...
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1answer
243 views

How to calculate bending of shell

I'm an electrical engineer, so please bear with me :). I came across this situation and I tried to find some equations to solve it, but all I could find was some Finite Element Theory, and I was ...
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1answer
87 views

Expressing Derivative of Cable Tension Component

I am looking at Hibbeler's section on a `Cable Subjected to a Distributed Load' in Engineering Mechanics - Statics, Ed13, as shown in the attached images. I am getting stuck deriving equation (7-7). ...
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2answers
2k views

Resolving forces in a simple truss

I'm trying to re-remember how to resolve forces in pin joint frames. I seem to have gotten stuck rather quickly and the examples I've been through don't replicate the same issue. Here is my truss I'm ...
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1answer
4k views

Finding Neutral Axis of a simple shape undergoing axial load

I know that the neutral axis occurs where the sum of stresses (bending + axial) is equal to 0. I have found the stresses and drawn a diagram to represent forces. How do I determine the neutral axis?
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1answer
57 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.
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2answers
70 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 ...
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1answer
33 views

What calculation to find how much force before tipping over?

I was thinking of building a free standing structure out of plumbing pipe that would go flush against the wall to hang jackets and other items. Attached is a sketch of the general thought of what the ...
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1answer
372 views

Determining σxx on a 3d system with resolved forces (stress, strain, shear strain energy)

I am having trouble conceptualizing this problem. I have attempted it but am confused about a few things, I would highly appreciate any insight or advice for this. I know you need to resolve P into ...
2
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1answer
408 views

Percentage error in calculated Forces during simple structural analysis for a truss pin-jointed strucures

I am currently trying to design a simple truss (pin-jointed) structure able to withstand a 1.2 kN load. I carried all the analysis and found the forces, stresses and strains in the members. My ...
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1answer
50 views

Acoustic transmission through houseboat hulls

The short version is: should I be worried about bass transmission through water into my neighbors' hulls? I am renovating a small houseboat (12x30 ft) to live on. It is one large room, and I plan on ...
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2answers
4k views

Best angle and length for a diagonal wood support for a pull-up bar

I want to construct a freestanding pull-up bar like the one described here. But I was wondering what would be the best angle for a diagonal support considering that the things I care are: That it ...
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2answers
1k 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 ...
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2answers
42 views

Bending moment calculation

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

How should I position two shelf supports for the minimum deflection? [duplicate]

The above is the shelf that I'm intending to put up. It will have two symmetrically placed supports. This is probably a simple question that really should be answered in all DIY shops but... ...
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2answers
149 views

Trying to shed some weight on my design, any thoughts?

I am trying to design a lifting mechanism and I would love some insight/opinions as to how I can shed some weight off it. The current weight I have for my mechanism is 187.5kg, however, this is ...
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3answers
1k views

Pin support, why is there no horizontal reaction force?

I am trying to understand this problem: If we break down the 10T, they behave like this: The right end of the beam can move as much as it wants, but the left end is pinned. Why is there no ...
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2answers
509 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 ...
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1answer
1k views

Loaded Truss problem

Hi, I'm having some problems with this truss question that I have in my homework. So far this is my solutions. I worked out my solutions to the reaction forces but don't know if they're correct. The ...
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2answers
115 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 ...