Determinate vs Indeterminate Structures - Intro to Structural Analysis

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Күн бұрын

This video defines determinate and indeterminate structural systems, and how to tell the difference.
The unknown reaction forces and internal forces of determinate systems can be solved using only the equations of equilibrium (i.e., statics). Indeterminate systems have more unknowns than can be solved using statics alone, and therefore new structural analysis techniques are required.
The number of unknowns can be counted and compared to the number of equilibrium equations. Examples are shown for how to do this with trusses and frames (or beams, which work the same as frames).

Пікірлер: 44

@The_Civil_Lab Жыл бұрын

I can't believe I finally found a youtube gem about civil... I've been struggling to find resources, the domain seems void of sharing intellectual knowledge! Thank you sir.

@StructuresProfH Жыл бұрын

Glad I could help, and welcome aboard!

@offthegridengineer2198 2 жыл бұрын

I greatly thank you for these videos. They are extremely helpful!

@StructuresProfH 2 жыл бұрын

You are welcome!

@jiteshyar1218 4 ай бұрын

How hard work have done during explanation can be easily noticed Really great 👍

@Harry-qc6ny Жыл бұрын

Your teaching style is amazing, very clear, straightforward which confuses me less. Cheers :)

@StructuresProfH Жыл бұрын

Thank you! I'm glad this was helpful!

@romarssieverything9667 2 жыл бұрын

thank you! You made this so easy.

@anarmyoftigers Жыл бұрын

Great video. You explained it well and I’m happy to have learned something.

@StructuresProfH Жыл бұрын

Glad it was helpful!

@harisshakoor7952 2 жыл бұрын

extremely helpful sir. very well explained. Thanks you sir

@islamqa5165 Жыл бұрын

You have a really good natural talent to teach.. it is surely making you feel better that you are helping and serving to students... May Allah bless you.

@StructuresProfH Жыл бұрын

Thank you!

@salemsimeon7471 7 ай бұрын

Thank you. It was really helpful.

@zxzhan5287 Жыл бұрын

Great and straightforward revision before my structural analysis final exam

@StructuresProfH Жыл бұрын

Yep, that is the goal here. Glad you liked it!

@MohamedAli-fo3xb Жыл бұрын

THANK YOU FOR HELPING ME WITH THESE VIDEOS

@StructuresProfH Жыл бұрын

Glad this was helpful!

@felixcsgocs2 Жыл бұрын

Beautifully explained

@StructuresProfH Жыл бұрын

Thank you!

@ronyshamcghee6927 3 ай бұрын

How do you know at what points equilibrium can be considered for the trusses example?

@stevenpro7321 2 жыл бұрын

Thanks for sharing, it really helps. May I ask a question for the last frame, if there is only one hinge in the middle on the top how could I make the cut?

@StructuresProfH Жыл бұрын

Great question, because this can get a little weird. Two cases to clarify here. (1) If the middle column only has a hinge on one side (instead of hinges on both sides, as shown in the video), then you would only need to make a single cut on the side with the hinge. The degree of indeterminacy would then be: 7 reactions + 6 internal forces - 3*(4 FBDs) = 1... meaning the frame is now indeterminate. (2) However, if both beams and the middle column all come together at a single hinged point, that's a bit different. This moment release is now applied to all three members, unlike in Case 1 described above where the hinge-to-the-side only affects a single beam and the column. To "cut" this, you'll separate all three members that connect into this hinge from each other. Once you've done that, you will have identical free body diagrams as in the video, so the DOI is still 0.

@stevenpro7321 Жыл бұрын

@@StructuresProfH It makes perfect sense and thank you for the explaination.

@shivasalehi2199 8 ай бұрын

Thank you🙏🏼🌺

@StructuresProfH 8 ай бұрын

You are welcome!

@Tankaxattri403 9 ай бұрын

Nice🎉

@MecTudor 7 ай бұрын

Hello, what about those systems where DoI=0, but you can't solve the reactions? (the critical ones)

@luziya7486 3 ай бұрын

This is my question as well

@MecTudor 3 ай бұрын

@@luziya7486 These systems are very dangerous (they allow some displacements nearby the position of equilibrium and the magnitudes of some reactions are tending to infinite) so you have to avoid them. The problem of recognizing the critical forms is a serious problem.

@ferozpatthan Жыл бұрын

Very Nice explanation ...

@StructuresProfH Жыл бұрын

Thank you! I'm glad I could be of service.

@burhanuddinmotiwala1428 2 ай бұрын

for the last example if there were no hinges in the frame then would it be indeterminate to the fourth degree?

@StructuresProfH 2 ай бұрын

That is correct!

@Dr.DineshaK Жыл бұрын

Thank you

@StructuresProfH 11 ай бұрын

You're welcome!

@bekehbenjamin775 Ай бұрын

Does it mean that when ever your calculations gives you zero as an answer, it shows that the trusses is determinate?

@StructuresProfH Ай бұрын

Yep, zero means determinate (unless there is some other issue that causes instability).

@clanwarme6152 Жыл бұрын

I don't understand the frames.. Is there any other simple way..?

@StructuresProfH Жыл бұрын

There is an equation too. For two-dimensional frames, the Degree of indeterminacy (DOI) can be computed as: DOI = Reactions + 3*Members - 3*Connections - Releases ... where ... Reactions is the total number of reaction forces or moments Members is the total number of members (beams, columns, whatever) in the structure Connections is the total number of connections between members (including connections to the ground) Releases in the total number of hinges, expansion joints, etc. in the structure

@StructuresProfH Жыл бұрын

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@joealex2463 2 ай бұрын

how do you find r?

@StructuresProfH 2 ай бұрын

"r" is the number of releases, where a release counts as a single known internal force. So for example, a hinge in a beam forces the bending moment to be zero at that location - that counts as one release, because we know that M = 0 at that point. You can also have releases for shear and axial forces as well. These can even be combined. For example, a roller-like expansion joint in a bridge might count as two releases if both the axial force N = 0 and the bending moment M = 0 at that location.

@joealex2463 2 ай бұрын

@@StructuresProfH thank you!