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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3
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2answers
2k views

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?
3
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1answer
149 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
827 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, ...
3
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1answer
280 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 ...
3
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1answer
441 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 ...
3
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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 ...
3
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3answers
101 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 ...
3
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1answer
935 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 ...
3
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1answer
460 views

Does the use of the catenary in an inverted weight model imply a more solid structure?

I am studying Gaudí and how does he created some of his work. I found that he used inverted weight models (as the shown in the picture below) to recreate the catenary. In many articles it is pointed ...
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2answers
195 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
430 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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0answers
63 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
938 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 ...
2
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1answer
40 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 ...
2
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3answers
161 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? ...
2
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2answers
224 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 ...
2
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1answer
718 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 ...
2
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1answer
46 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
52 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
159 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 ...
2
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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
2k views

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 ...
2
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1answer
122 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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2answers
80 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
922 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 ...
2
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1answer
219 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 ...
2
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1answer
85 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 ...
2
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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?
2
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1answer
31 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 ...
2
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1answer
321 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
344 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 ...
2
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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 ...
2
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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 ...
2
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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 ...
2
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1answer
53 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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2answers
141 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
506 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
74 views

Design a part to straighten moment and reduce torsion

I have a configuration with two bolts and a point of force application (see figure). I understand that, if perfectly rigid, the two parts depicted in the figure will behave identically in how they ...
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1answer
171 views

Heuristics for Efficient Structure (Shed) Design

Are there any heuristics / thumb-rules to evaluate whether a shed-structure has been efficiently designed? To be specific, I have an industrial shed, 12 m tall, 270 m2 floor area (longest span 10 m) ...
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3answers
407 views

How much strength does adding a T piece add?

If I have a flat span of steel material, 3.0m x 150mm wide and 5mm thick, and apply an increasing downward force to the middle, at some point it will fail. But if the profile of that piece of steel ...
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2answers
39 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
3k views

Two storey brick building without using wood or steel

Is it possible to build a two storey building just using bricks (no wooden beams, steel beams or steel reinforcement) to suspend the floor of the second storey? I'm aware that using wooden beams is ...
1
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1answer
920 views

Critical Buckling Load for a Spring Supported Bar

The above is a past exam question from an introductory structural analysis course, one in which although we have studied the Euler buckling load equation, we have just been given parameters for the ...
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1answer
310 views

How to transfer reaction forces of beam to a weld?

I have modeled a beam as fixed-fixed. The reaction forces are -1494 lb.ft and 761 lb (vertical). There is no horizontal reaction. Now I know this beam is welded to another element. I am trying to ...
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2answers
167 views

How Do You Determine Truss Stability in a Modeling Program?

This question originates from this and that question. I have realized the concerns boil down to the following figure. Simply put, is the truss above, with the displayed boundary/internal fixity ...