Questions tagged [structural-engineering]

Questions related to the integrity, design requirements, or analysis of structures.

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6 views

What CAD program is easiest for designing Ninja Warrior courses?

It would be nice if there was an easy to use CAD program with prebuilt parts such as trusses and ropes and mats, vertical wall... things that go in a ninja warrior course. Just so I can drag and drop, ...
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1answer
39 views

Wood support calculation [closed]

Does anyone know how to calculate the width of the support (x) required for 6x10 lumber spanning 5’ supporting 2700 lb of uniform load and a load perpendicular to grain of 2000lb/ft2?
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Distance of raft foundation outwards

Can you tell me (for USA) which code (or standard or guide) and in it where exactly I can see the distance required for the raft foundation, as far as how much it should extend horizontally beyond the ...
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10 views

FEM matehmatical methods

Are all advanced methods used in FEM, other than the Direct Stiffness Method, also ultimately based on Direct Stiffness Method? If not is there still a common starting point? Why did other methods ...
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4answers
50 views

Fiberglass camper plus steel trailer

Hello to all of you with more expertise about engineering than me...and anyone else that is curious. I like to fantasize about projects, so this may be more of a thought experiment, but I'll throw it ...
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1answer
30 views

Mesh generation in FEM [duplicate]

When a frame structure is analyzed using a FEM computer software, does the program still generate mesh, even as a line mesh, on frame members, or we must do it ourselves?
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46 views

Does Finite Element Method use direct stiffness method?

Does Finite Element Method use direct stiffness method? Or it is another mathematical method? We definitely use direct stiffness method to solve frames. FEM is based on entirely this or depending on ...
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1answer
35 views

Modeling the structure vs FEM

When you model the structure to be analyzed with a structural analysis program, indicating the beam elements, shell elements, nodes, rigid links etc... The analysis is still called Finite Element ...
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3answers
66 views

Buckling of Parallel rods

I am trying to calculate critical force $P$, if two rods (same diameter and length - rigid fiberglass sandwiched on two steel plates) are parallel to each other. $$ P = \frac{\pi^2 EI}{(KL)^2} $$ I ...
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1answer
41 views

Bending of an L-shaped beam

First post so bear with me: I am designing a frame for a press, which needs to be able to withstand 250 N. I am planning to make the frame an L-shaped beam, turned around. With a side view, it will ...
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28 views

Lifespan of steel frame houses

We are considering to build our family house. Where I live, people build either: Concrete beams for the structure and then thermal bricks for the external walls; or, Heavy duty steel structure and ...
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2answers
45 views

Failure in Hollow, Thin Beam due to Collapse of Cross Section

I'm having trouble figuring out how to predict the failure of a hollow channel due to bending. If I'm correct, for a beam with a static second moment of area, $I$, the following equation could be used ...
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2answers
42 views

How do I connect multiple water-filled syringes?

I'm trying to connect 4 separate syringes containing water and we need water-tight tubing to prevent water from leaking out of the system. The water would theoretically need to be pushed out of one ...
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42 views

What is the use of secant modulus?

Secant modulus is defined as the slope of a line connecting the origin and a specified point (like yield point) in stress-strain diagrams. Instead of elastic modulus, which is the slope of the tangent ...
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3answers
43 views

Why is there a difference in the deflection between the top and bottom of this truss?

In this truss scenario, why is the deflection of point 3 less than that of point 8? I'm assuming it has something to do with the shape of the truss. If we extend the shape we will get a circle and the ...
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4answers
76 views

Swing safety: maximum load of beam (supported at one end, free with load on the other)

My husband and his dad built a fort for our two boys. Coming off of one side of the fort is a 4x6 wooden beam with a tire swing attached at the end. It is supported on one side by the fort, but not ...
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1answer
39 views

How to plot bending moment diagram from shear force diagram

With conventions that I adopted shown below I drew roughly the shear force and bending moment diagram of a simply supported beam with concentrated load at the middle. Now while drawing I drew both ...
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1answer
38 views

Optimal placement of two support points along a wooden beam

Assuming a beam that is supported at 2 points as per attached image, what would be Lc (length center) and Lo (length overhang) for maximum strength. (or load bearing capability) For actual material ...
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2answers
50 views

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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2answers
39 views

Low pile capacity during pile driving

When driving piles, the resistance from the soil is constantly measured. What happens when the expected resistance values from the soil are not obtained? For a single pile or for multiple piles? What ...
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3answers
61 views

Aluminum square tubing capacity question

I have an awning that I am attaching to the corner of the house. I needed to extend it so I got a piece of 6063 square aluminum tubing. It's 1 inch wide with .125 wall thickness. It has about 2 feet ...
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21 views

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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1answer
50 views

What is the difference between to Eurocode design equations (6.10a and 6.10b)?

In Eurocode, two equations for loads are given for STR limit state: $$1.15K_{FI}G_{kj,sup}+0.9G_{kj,inf}+1.5K_{FI}Q_{k,1}+1.5K_{FI}\sum_{i>1}\psi_{0,i}Q_{k,i}$$ $$1.35K_{FI}G_{kj,sup}+0.9G_{kj,inf}$...
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Is it structurally sound to cut an I beam to a T on one end?

I'd like to confirm whether the replaced beam in the attached picture is structurally sound given the end was cut to a T instead of an I. I had a qualified structural engineer approve the work but I'm ...
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1answer
34 views

Why isn't von Mises criterion valid when compressive and tensile yield stresses differ?

For example here, it is mentioned: The von Mises criterion is NOT a valid yield (failure) criterion for materials with different yield stress values in tension and compression. I can't really ...
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1answer
30 views

Does having a basement level increase overall earthquake resistance of a high rise building?

Does having a basement level increase overall earthquake resistance of a high rise building? Does it also lessen the burden on pile foundations?
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1answer
52 views

Maximum hole size in brickwork before a lintel is required

Holes are made in brickwork walls for all kinds of reasons including gas flues, to route cabling and to fit windows. At some point that hole gets large enough that a lintel is required to support the ...
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2answers
53 views

Probability of structural failure

In structural engineering we have to accept the fact that you can never be exactly sure how much load a structural member can resist, that the load carrying capability of an element is not one exact ...
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1answer
21 views

Stress Concentration: Hole in infinite thin plate loaded in biaxial tension vs biaxial compression

Is there a difference in the stress concentration of a hole in an infinite thin plate loaded in biaxial tension vs biaxial compression? I ask because in numerous books (one of them in the screenshot ...
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15 views

Should I use ST or LT values for extruded rod?

In MMPDS for AA7075-73511 (extruded rod) the Table 3.7.10.0(g3) show both ST and LT values for transverse directions. For a rod with circular cross section there is really no Short and Long transverse ...
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1answer
28 views

Are tetrahedron spaceframes strong versus flex?

I am considering how a spaceframe would work as a rigid batten in a sail. Tubes are most often used, so I can't imagine this would be cost effective; it's mostly a thought experiment. I'm not a ...
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1answer
45 views

Initial shallow gradient in measured stress strain curve

What's causing the initial shallow gradient of the stress strain curve of ceramic in this graph? The rest of the curve is a straight line alright until the yield point. Edit: the material being tested ...
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18 views

Limit state design/ LRFD of short steel columns

Why do we use the yield strength as the limiting strength in short column design when using limit state design. Why is the full capacity of the material not utilized (as is the case with beams when we ...
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2answers
41 views

Other than yielding, what type of stress you check for ASD?

ASIC 360-16, in page pdf 330, it says "For any single element, there may be a number of different allowable stresses that must be checked." I can think of yielding. What else? Rupture for ...
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2answers
63 views

Does a change in specimen dimension affect the measured yield strength and tensile strength?

I am having a hard time trying to understand the effect of geometry on a specimen's yield and tensile strength or if there even is one. If there is an effect or not, why is it so? Thanks in advanced!
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1answer
69 views

Shock loading stresses due to falling: what strength to use for acceptance criteria?

We are evaluating a design in which a fall-arresting safeguard would be subject to a shock load in the event of a catastrophic failure of a different component, which is required to meet compliance ...
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1answer
125 views

Mechanical/electronic chalkboard cleaning device to replace the conventional duster to clean the chalkboard

The chalk board duster which is used by teachers to wipe the chalkboard seems very agonizing for them. What new mechanical/electronic devices can be devised to replace conventional chalkboard duster ...
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2answers
66 views

Beam/column sizing

If a load P is applied as shown to a fixed column-beam, pinned at the bottom, should the beam or column (or both) sizes be increased to resist the load?
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1answer
32 views

Is it just surface area alone that causes bridges to freeze?

Scenario: Object 1, a bridge freezes over do to the surface area exposed to the below freezing air. Object 2 has the same surface area exposed to the same air, but its base sits on the ground that is ...
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1answer
49 views

Question on the determinacy of frame structures

I have been working on a program to solve frame problems, and I have used the following formula for determining whether a frame is statically determinate: $$RD=3m + r-3j-s,$$ where: $m$ is the number ...
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4answers
84 views

Speed breaker design

Speed breakers are safety devices that keep check on the fast-moving traffic. But what does the speed breaker do when the vehicle is already slow approaching. Is there any better breaking system ...
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20 views

Is it possible to get the hardening exponent and coefficient (n, k) if I just know the yield point, the ultimate stress, and the failure strain?

For a certain steel I have the following data: Yield stress and strain (engineering) Ultimate tensile strength (engineering), I don't have the strain at this point Strain at failure (engineering), I ...
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1answer
80 views

Engineering in the great pyramid

From an engineering perspective, how are the 'relieving chambers' above the kings chamber supposed to work? The 5 layers of horizontal lintels separated by air-gaps are normally described by ...
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1answer
26 views

How to choose bracing type and location

I was given a question (see image: elevation) and was asked which type of bracing (the bottom 3 types: v, inverted v or k) should be used and on which bay. Can someone please chime in? I know it's not ...
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1answer
20 views

How does the imperfection factor in buckling include the effect of residual stresses?

Let's say we have a beam with pinned connections at both ends. The beam is subjected to axial load $P$. The beam has a cross sectional area $A$, radius of gyration $r$, distance from the neutral axis ...
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1answer
25 views

Deflection of a cantilever beam composed of separate (not bonded) planks Uniform load

This is related to this question It is the case of a simple cantilever beam having a uniform rectangular cross-section. cantilever beam composed of separate planks - taken from The question in the ...
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1answer
79 views

Why are shapes with sharp corners structually weak?

Please explain my question like I'm 5 too? ELI5: Why do ships have circular windows instead of square ones? : explainlikeimfive The real answer is that shapes with sharp corners are structurally weak....
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1answer
43 views

Pullout Force of Screw from Epoxy

I would like to estimate the pullout force required to pull a screw out of epoxy. Mine is an unusual situation where I want the joint to fail to protect other parts of the assembly; that is, it is a ...
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1answer
68 views

Could Tesla have REALLY shaken a building with a little oscillator?

I came across this story while reading about Nikola Tesla ground-power scheme. Supposedly, he created a little oscillator that could be plugged into the ground, tuned to the right (resonant) frequency,...
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75 views

What is the purpose of end plates when connecting beams together?

Quite often this kind of arrangement can be seen when beams are connected together. A rectangular plate is welded into a beam, and the plate is bolted to the other beam. I suppose one purpose would be ...

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