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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50 views

Pin joint system displacement question

A pinned system comprising bars of the same material and cross-sectional area is subjected to a vertical load P. I am required to form a relationship between FAB and P. The first part of the ...
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+100

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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1answer
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Drop Panel Design Above Columns?

How to design a drop panel at a column in case the column above is rotated or not aligned to the below column (see image below), the code that i am using is the ACI Code if any reference for the ...
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2answers
68 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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3answers
73 views

How to get corrugated plastic roofing strips to span 3m for rainwater exclusion experiment without building additional ground supports?

I'm trying to build structures to exclude some percentage of rainwater on experimental plots. I have three 20ft beam supports across the plot, spaced 3m apart and held in place by 4x4 posts that were ...
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1answer
86 views

Looking to design a cantilever support to hold up an 80kg projector

I need to make a support (preferably metal) for a projector to be fixed on the wall. The projector size is: Width: 0.7m Length: 1.1m Weight: 80kg If anyone knows how i can solve this please let me ...
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2answers
74 views

Why do some guyed towers come to a point at the bottom?

Why do some guyed broadcast towers come to a point at the base. It seems that it would be more stable if each vertical bar was anchored separately rather than being balanced at one point.
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3answers
121 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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1answer
90 views

Can pinned support / pin joint transfer moments in 3D?

What's an authoritative definition of whether the idealized pinned support and pin joint can transfer moments in 3D? Most sources say both of them cannot transfer moments but are apparently only ...
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1answer
35 views

Shock/Isolation mounting under tension

I want to secure a box (roughly 20kg in total) that contains electronic equipment to the underside of a flat steel structure. We can weld onto the underside. The steel structure has a high chance of ...
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41 views

Need help with FEA bar analysis problem

I'm trying to solve this which is to find the total deformation of the bar. I'm trying to implement the finite element approach, but I am getting way too large of numbers. Here is what I did in ...
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2answers
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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
53 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 ...
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45 views

Calculating diameter of steel rod required to not bend over a given length

I want to use steel (or other material) rods to support weight over a 900mm cavity. The weight that needs to be supported is technically unknown, but I'd specify some rough guidelines as: 100KG (max) ...
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2answers
51 views

Vibration table for tests (7-200Hz) from extruded aluminium profiles bolted together - good idea (?)

I need to design a vibration table (approx. 1000mx1000mm) to test products between 7-200Hz. I was wondering if it is recommended to make the table structure from standardised, extruded aluminum ...
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Why do auxetic materials have higher energy dissipation rates

Below is an extract from a thesis called "Auxetic Structures: Towards Bending-active architectural applications" on page no. 80. In a NPR (Negative Poisson's ratio) material the energy ...
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2answers
102 views

How does one build a waterproof basement?

I have been doing a bunch of research online into how to build a basement that is below the water table. The common wisdom is to "not waste the money doing that" but as someone who doesn't like to be ...
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Research based bridge project? [closed]

I am a fourth year civil engineering student at IOE pulchowk, Nepal. In our syllabus one practical based curriculum called Project Engineering has been added. I, along with 5 friends, are interested ...
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1answer
53 views

compression buckling under lateral load

I'm trying to figure out what size of round tube to use for a tensegrity structure that'll probably have people climbing on it. The rigid elements are 21' steel tubes, and in normal cases they ...
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1answer
34 views

Is a bridge more stable on concrete or soil?

I understand that foundations are used in structures to support and spread the weight of the bridge over a large area. However I am struggling to understand why certain materials such as concrete are ...
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1answer
51 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 ...
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1answer
100 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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32 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
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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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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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54 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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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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88 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
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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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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
257 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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266 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
293 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
102 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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1answer
104 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
123 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
69 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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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
185 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
203 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
183 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
4k 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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1answer
2k 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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314 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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54 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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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
57 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
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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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140 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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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 ...