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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176 views

Stiffness as a function of thickness

Let’s say we have a thin band (made out of PLA, 3D printing material) with a rectangular cross section. In drawing, it would look something like this: Let’s say a force of 15 N is to be applied from ...
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34 views

What does 'Analysis Model Value' in NASTRAN optimization mean?

I am new to MSC NASTRAN and PATRAN. I am running a simulation on composite laminate optimization. While creating the design variables for the study, I noticed that there is a parameter called '...
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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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72 views

Disguising tall exhaust stacks

While architectural features are oftentimes more aesthetic than they are technically complex, this still seemed like a suitable question for here. I am working on a project for an industrial type ...
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2answers
66 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 ...
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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?
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104 views

strength of eggshell

It is a known fact that beams and spheres have the ability to carry relatively high loads. Beams are seen in bridges and other structures even since the days of ancient roman architecture. Spheres ...
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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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34 views

Independent constraints - Procedure to verify it

I am wondering if there is a procedure to verify that the constraints of a system of rigid bodies are independent. Here there is an example of a system with dependent constraints: L beam - Strange ...
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2answers
834 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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2answers
446 views

How to provide lateral support for adjacent masonry during installation of steel UC in an old cavity wall?

I've got a structural engineer ready to provide calcs on this job, but there is a specific aspect where I'd like a heads-up what the normal approach would be, before I raise it with him, in case he ...
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1answer
436 views

Using strain energy to calculate deflection

I have a solids 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, (perhaps there was an issue setting up my deflection ...
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1answer
120 views

Torsion on thin walled members

Is the formula $T=2qA$ valid for both open thin-walled and closed thin-walled members, where $T$ is torque, $q$ is shear flow, and $A$ is the area?
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143 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
138 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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2answers
74 views

Stress yield of a specimen, result confusion

I am trying to calculate the static yield stress of a specimen using the 0.2% offset line on a stress strain curve. I found the static yield stress of the specimen to be the number in bold (104.1239). ...
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65 views

Calculating the Structural Forces Required to Support a Robot on an Overhanging Beam

this is my first time posting on here and I have a question regarding the structural properties a beam will need in order to fulfill some requirements we have for our robotics team. The scenario is as ...
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1answer
306 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 ...
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1answer
365 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
494 views

Determine the strain energy of a bar

I have a Structures question about determining strain energy that I am unable to solve. I have attempted it and I have the answer, I would appreciate if if someone can just tell me where I am going ...
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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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2answers
3k 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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0answers
1k views

Structural integrity of a freestanding climbing wall [closed]

I´m planning on building a freestanding climbing wall with adjustable inclination (45-65 degrees). A very rough sketch is pictured below with some extra information in case it´s helpful. I´ve got one ...
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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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0answers
322 views

Beam element stiffness matrix for variable area cross section with mass and shear center not coinciding

I would like to find the full (12 by 12) Timoshenko beam element stiffness matrix for a variable cross section with mass center axis and elastic center does not coincide. I have the full stiffness ...
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0answers
67 views

How to design a shelving unit out of McMaster Carr Struts? [closed]

I apologize for the complete beginner question. I'm an Undergraduate Research Assistant trying to design a shelving 8'tall by 10' Long, 4' wide shelving unit to support about 200 lbs. I'm designing ...
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2answers
26 views

How much ballast is required in 110 mph winds to stabilize: a 60 lb., 20’ pole; 3' below ground/17’ above ground, with a 24lb. wind turbine atop it?

I can’t seem to find an answer that doesn’t involve more than a ton and a half of concrete. The manual for the wind turbine reports that the load on the turbine in a 110 mph wind is only 155 ...
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2answers
159 views

Why we don't use fillets while making buildings?

Why don't we use fillets when making buildings and houses (i.e why do we leave the edges sharp?)? Does stress concentration factor not matter in making structures? I am talking about the building ...
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0answers
30 views

How to support height extender on a rail?

I've got an 1/8" thick steel rail with 1.5" diameter and 15' in length sitting on two 5/32" thick steel rails with 2.5" diameter and 100" in length 14' apart: I want to add a diagonal support for a ...
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1answer
160 views

How to structurally bind bamboo stems for loads?

I would like to begin a case study in structural design using bamboo, which has currently become available to me. The design instance I would like to structurally copy is the Rogue RM-6 "Monster Rack" ...
4
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1answer
145 views

3D construction [closed]

Can someone please tell you what to start with to construct a Kids Bike Trailer as 3D. It should select material and geometry. I think I should start sketching with forces (children's weight) and ...
4
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1answer
2k views

What is the advantage of statically indeterminate structures?

Most of the real life structures are statically indeterminate. What is the benefit of designing a statically indeterminate structure instead of a statically determinate one? I don't mean only beams ...
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46 views
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37 views

Check of a nominaly pinned steel joint

I am interested how to check a nominally pined joint. Especially how to check its rotational capacity and whether i can define it as nominally pinned in structural fem model. I understand that there ...
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1answer
336 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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26 views

How to calculate a global strain from a field disitribution

For an arbitrary articulated structure subject to non-affine (non homogeneous) deformations, the components of the strain tensor are defined locally. Is there a way to calculate a numerical strain ...
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2answers
175 views

Conveyor Truss Analysis Problem with loading

I've been working on a schematic and its been going beyond my comprehension; so i thought i should consult better structural engineers here. (I'm a fresh Civil Engr Graduate though) i have this ...
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2answers
210 views

Iron Prince Rupert's drop [closed]

I'm wondering if molten iron was hurled into outer space if it might create a shape similar to a Prince Rupert's drop. Like, say, if a star had finally exhausted it's fuel and exploded.
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1answer
50 views

HELP Please! Depth of member

What is meant by "depth of member" and what is the formula of it? Can I use it in moment of inertia formula? How to use the given information to answer the question? and Thank you.
3
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1answer
178 views

How can I absorb shock on an existing steel structure?

I'm currently trying to extend the shock-absorbing capabilities of a welded steel structure that is shown in the following image. It is a structure that supports a slat conveyor. A load is to fall ...
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2answers
7k views

how to solve internal hinge problem with loading given on hinge [closed]

how to solve internal hinge problem with loading given on hinge
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2answers
891 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
184 views

What lining design holds better for a tunnel? Spiral lining or cylindrical lining?

Hy everyone :) I don't know much about structural engineering, maybe spiral lining and cylindrical lining are not the proper ...
2
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1answer
213 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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2answers
72 views

How to find strain in an inclined member of a struss

I'm working through an FEA problem and I'm stuck. Question: How can I determine the strain in member 3 from displacements known at node 3? It's at 45 degrees, I know I should be using some $cos\...
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0answers
33 views

Pressure-volume relation of thin-walled shell [closed]

Attempt to edit into a more specific question as suggested by moderator: I would like define the shape and material properties of a 3D thin-walled shell/membrane-like structure (for instance a baloon)...
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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 ...
3
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1answer
95 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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1answer
3k views

How to find the reaction forces, moments and the displacement of the fixed beam with a link?

The beam is fixed on both ends and there is a link in the middle. There is a force F on the link. My approach to solve this problem: A free body diagram is cut at the link and made into 2 systems. ...
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3answers
97 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.