# 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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### 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 ...
109 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 ...
464 views

### Seeing through walls and noninvasive structural integrity metrics

Walking into a building, how does one find out where the pipes are, how strong the walls are (currently) and other key structural integrity measures? without breaking walls or utilising harmful-to-...
137 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.
970 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 ...
2k views

### Logic behind location of shear centre

When we apply a vertical shear force Sy and the structure is symmetric about x axis, then why is it logical to have the position of shear center at the location of intersection of line of action of ...
477 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 ...
37 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 ...
54 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 ...
79 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 ...
74 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) ...
168 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 ...
1k views

### What kind of simplified structural system would a Leonardo bridge use?

What kind of simplified structural system would a Leonardo bridge use? I've tried approximating the system to a simple statically determined beam (see below) but our calculations did not give any ...
31 views

### 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 ...
64 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 ...
70 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 ...
181 views

### Stiffness as a function of thickness

Letā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: Letās say a force of 15 N is to be applied from ...
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 ...
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 ...
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 '...
74 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 ...
649 views

### How to calculate indeterminacy of pin-jointed frame?

I understand that to calculate the indeterminacy of a pin-jointed frame, the unknowns have to be considered i.e. the number of elements corresponding to the number of internal forces, plus the number ...
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?
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 ...
325 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 ...
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 ...
463 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 ...
148 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 ...
189 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 ...
161 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" ...
446 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 ...
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?
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 ...
78 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). ...
319 views

### Determining Ļxx 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 ...
177 views

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 ...
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 ...
437 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 ...
528 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 ...
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 ...
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 ...
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. ...
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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### How much ballast is required in 110 mph winds to stabilize: a 60 lb., 20ā pole; 3' below ground/17ā above ground, with a 24lb. wind turbine atop it?

I canāt seem to find an answer that doesnā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 ...
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 ...
146 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 ...
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 ...
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 ...