# 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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100 views

### How did this building's windows get like this?

I don't recall seeing the walls like this before, so I don't think it's just accumulated soilage. If it's wetness, what design flaw causes the windows to do that? Today was very hot and muggy so it's ...
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### Square box welding with T joint, welded with stick welding

When joining two square box beams in Tee, is it enough to weld them in only three sides or I have to weld the full perimeter of the square? If those 3 sided weld are suppose to bear weight, how much ...
31 views

### Mechanism and static determinacy

I was doing exam question and am confused as to how to determine if the structure is a mechanism or not. Say that j = number of joints, r = total number of reactions, b = number of bars. For both (a) ...
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1 vote
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### Symmetry to determine the support reactions of a statically indeterminate frame

The following is an indeterminate frame consisting of two beams that are rigidly connected to each other at the corner support. I want to find the support reactions. As far as I can see, this is a ...
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### What is the cause of this cracking pattern in a simply supported beam?

Background On May 5th 2022, a bridge was struck in Brantford, Ontario, Canada by a commercial vehicle. This vehicle struck a reinforced concrete protection beam placed on the on-coming side for the ...
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### Is it valid to solve for the young's modulus required for a given critical load with Euler Columns?

I am working on a problem for research that is about material choices. I was wondering if the following rearrangement of Euler columns would be a valid way to check to see if a material exists for a ...
18 views

I'm wanting to see if it is possible to create a functional prop that includes two blades that spring out creating a circular quad blade. 2 blades would be fixed at opposite ends of the circular ...
34 views

### Analysing a multispan determinate beam by separating it into spans

Say we have the following indeterminate beam: We can make it determinate by adding a pin at B, and then adding back the bending moment at B which was destroyed by the pin: My lecture handouts then ...
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### Steel retaining wall

Hi im doing a DIY project which need to build 30cm height retaining wall to hold up some gravels for an above ground pool 5000liter size 2.3x4m And the foundation pad area is 3x4m Im thinking to use ...
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1 vote
54 views

### Steel bracket fixing spacers on a wall

What could I do to address the uneven vertical wall (not plumb) behind the bottom of the steel bracket? Would you fill in the gap with sand/cement and once dried tighten the bolt or use steel plates ...
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### How do you calculate the maximum bending stress in a beam with different thickness along different parts on the beam?

Here is a practise question that I am working on. The beam has different thickness due to the supports in the middle. I would expect the maximum bending stress be away from the middle due to the ...
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### If you have unlimited space, how many toilets can you put into a public restroom? [closed]

Are there structural limits or legal limits of any kind?
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### How many more degrees of tilt can the Millennium Tower in San Francisco withstand before it becomes structurally unsound? [closed]

How many more degrees of tilt can the Millennium Tower in San Francisco withstand before it becomes structurally compromised/unsound? "...An examination in 2016 showed the building had sunk 16 ...
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### Why does a jumping rope have no bending stiffness and compression stiffness?

Can anyone just tell me that why doesn't a jumping rope, or any other kind of rope, have any bending stiffness? If I hold one end of the rope in my hand, the rest of the rope will just fall. It won't ...
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### A close coiled helical spring with torque acting about longitudinal axis

Consider a close coiled helical spring which is acted upon by a torque about its longitudinal axis as shown. I'm interested in knowing the effect of this torque on the spring wire. Here's my take: I ...
68 views

### Aluminum rivet used to join stainless steel and aluminum sheet

I am using Aluminum pop rivets to join stainless steel and aluminum sheet together. I am aware of the galvanic corrosion risk in this situation. Are there any other risks the joint may face over time ...
1 vote
346 views

### Tension cable underneath rafter tie?

I just bought a new property with a large garage and I'm curious about the roof structure. The roof structure is supported entirely on the front/rear walls using rafter and collar ties. The rear wall ...
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### Should we use Hooke's Law (that linearly relates stresses to strains) if the stiffness of body is changing during deformation?

Assume I have a slender cantilever beam, fixed at one end and force applied on the other. Now, during the deformation, we know that the beam's stiffness is going to change and the force-displacement ...
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### Is a ship a statically indeterminate structure?

We can consider that a ship is a complex implementation of forces on a beam, that a ship is essentially a beam. The support is the buoyancy force which is continuous but it takes different values ...
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### Double Integration Method

How can I solve this beam. I was able to find the moments of each section, from there I need help. Please if someone could help me. The method to use is Double Integration.
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### What happens when we remove the load, in different regions of the stress strain diagram of mild steel?

A: Proportional limit| B: Elastic limit| C: Upper YP | D: Lower YP Let us say, the gage length was 100mm (random, just for the sake of understanding). I know that if I unload the body anywhere between ...
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### Does the Superposition principle actually make sense in reality for a rod subjected to bending and axial force togehter?

Consider a rectangular rod, for example. I fix it from one end and apply a transverse force on the other (to cause bending) and also a axial force (lets just assume its compressive). Now, according to ...
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1 vote
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### Mechanics: example of less mass/volume gives more strength

Lets assume we have a mechanical element from uniform material that is supposed to work in a static load conditions. Moreover lets assume there is no gravity or gravity is negligible. Are there any ...
1 vote
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### car steering to enter the parking lot [duplicate]

I would like to understand if a "typical" car could be able to turn in this space at the entrance to the underground garage. How can I set up my calculation? I have a 2.5 meter mouth at the ...
1 vote
51 views

### How to find the reaction at the pinned support A as shown in the picture? [closed]

Please help me solve the problem. I need to know the reactions at A for both the cases as shown. Please note that E is a roller, D is a pin support , B is an internal hinge and A for case 2 is a fixed ...
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### Do windows add to strength or rigidity?

A friend who repairs washing machines told me that the window adds rigidity to the front cover and compresses the gasket. Also the windows of cars act against shear forces, he said. Do you know ...
54 views

### Hencky nets/slip-line fields on the the interior of a closed domain

This is a crossed post. The equations for Hencky nets are usually solved in the exterior of some domain; typical examples are the upper half plane or the exterior of a circle. I would like to know ...
1 vote
45 views

### Where to place air, water and electric cables in a composite beam [closed]

If water, gas and electrical cables have to pass through three (3) openings provided in the cross section shown in Figure 2, with tangible and scientific arguments specify the adequate opening for ...
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1 vote
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### What Causes Asymmetrical Buckling in this structure?

I've been playing around with structural modelling on the SkyCiv platform and have created this structure, related to a project I am working on to educate myself. It is 2m wide, 3m long and 1.5m high ...
1 vote
109 views

### How is any kind of structural reliability achieved if the probability of annual wind speed exceedance is 0.02?

Above is the definition of fundamental basic wind velocity from Eurocode 1. According to its instructions, wind loads on building are supposed to be calculated based on this velocity. It says that ...
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1 vote
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### How many support beams/rods needed for a firewood storage cabinet

I am building a firewood storage cabinet which should support around 100-150 kg of firewood. The cabinet is made out of wooden boards (...
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### Is it possible to use Plain Cement Concrete post for fencing?

I am in need of around 700-800 posts to fence my farm in a semi-arid area in TN state, India. In my place granite posts mined from quarries are normally used. It costs around Rs 300-400 per post(6-7ft)...
568 views

### How to derive fixed end moment of a beam fixed at both ends with a point force not in the center

So this is as far as I have gotten. The formulas written in green are the formulas that I have to find/ derive but I am hitting a wall. I know I am supposed to integrate but I am not sure where to go ...
1 vote
244 views

### Hollow (rectangular) sections versus solid sections

I have an engineering competition coming up and one of the things I need to build is structure with both compression and tension members. The structure is scored based on the load held/weight ratio, ...
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### Why are some public benches made with arm rests that waste so much space?

While watching a YouTube video today, I noticed this public/park bench somewhere in the USA: It looks strange to me the way the arm rests on each side are so far into the bench, wasting a rather ...
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1 vote
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### Why isn't there yet such a thing as a "Minimum Life Module" standard and concept deployed? [closed]

Why are large companies not producing, selling and maintaining the concept of "Minimum Life Modules"? What I mean is a standardized "module" hosting exactly one human being, with ...
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1 vote
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### How to measure the stiffness of a rectangular beam, and compare it to a triangular beam?

I'm an amateur at engineering, working more on musical instruments, and I'm often in confusion regarding what exactly constitutes stiffness of a beam for a load applied on it so it could resist ...
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### Wind behavior and pattern

From the 5 options, which one shows the worse wind effect? Is it (b) because wind speeds accelerate through a gap? But how about in comparison to (c)? Or (d) due to the height and sharp corners? If it'...
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### 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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### How to determine the fixed end moment?

I was trying to compute the fixed end moment for the beam (given below) using equilibrium equation for x, y displacement and moment but there are 4 unknown variables reaction and moment at both ends ...
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1 vote
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### Reinforce foldable table legs

I'm trying to build a table with 4 swivel legs that can be locked into arbitrary angles so that it can stand over one to three rows of storage crates in my garage: As you can see, the legs aren't ...
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### 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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### Why does a gear have extra holes?

In a gear you normally have a center hole for the shaft to be put into. Why do some gears have holes surrounding that center hole? Is it for weight reasons? Does it add stability? Is it so you can add ...
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### reaction of structure

all is this sturcture stable ? or structural determinate ? Let the top support as A , bottom support as B , By taking moment about A, i managed to get 10(4*4)/2 -HA(2) = 0 , HA = 40kN, HA = HB = ...
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### Help sizing of lug attachment flange/plate?

Apologies for the crude drawing attached, but here goes. Given Fx, Fy, and Fz loads applied at the lug hole, I've distributed the loading into each of the 6 fasteners to size them. I've also sized the ...
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1 vote
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### 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 ...
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346 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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### 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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### When settlement criteria of a foundation is satisfied, bearing criteria is also automatically satisfied?

We design the foundations to settlement criteria than bearing correct? Because settlement criteria is stricter? I mean, can there be an example where the settlement criteria is satisfied but bearing ...
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