Why support for diving board case is assume as pin/roll?

1. Dec 5, 2015

enotyphoon

Sorry for silly question, but have been wondering.
Diving board it is bolted to the ground(base platform) (vertically), why not assume it as fix. the way bolt is secured is same direction as the load, hence it is not easy/resist to rotate up and down like pin or hinge. so there is moment. Isn't?

2. Dec 5, 2015

jackwhirl

Are you comparing a hypothetical diving board with a real one? I can't really follow your question. Try explaining what is confusing you more fully.

3. Dec 5, 2015

enotyphoon

http://[url=http://postimg.org/image/fqof29xxj/][PLAIN]http://s15.postimg.org/fqof29xxj/Capture.jpg [Broken]I'm pretty sure the end of beam(bolted) will be considered as pin(from many example I have seen).
however 2 bolts is bolted vertically (not sideway like huge pin), that mean it the beam to go up and down as pin. So shouldn't it be fix?

Last edited by a moderator: May 7, 2017
4. Dec 5, 2015

jackwhirl

From your second picture, it is certainly bolted to something. Is that part rigidly attached to the base?

5. Dec 5, 2015

enotyphoon

I would say it is just bolted by two fastener to base, and assuming the body is rigid when try to find the reaction force.

6. Dec 5, 2015

jackwhirl

One of the pictures you have didn't come through properly. Did it also have springs?

7. Dec 5, 2015

enotyphoon

Nevermind, ignore the picture that didn't come through properly. Only 1 pics.

8. Dec 5, 2015

jackwhirl

So. If I wanted to make a homework problem for highschool students, or anyone who hasn't learned about beam deflection, I would model it with a pin. They could calculate reaction forces and maybe spring compression, all while assuming the beam was a rigid body.
After learning about beam deflection, I would model it rigidly attached.
Who is the intended audience for the model that confused you?

9. Dec 5, 2015

enotyphoon

yes to find reaction force, we would assume the beam is rigid at first.
However my work colleague ask me why we would use pin support and not fixed support at the end of beam? Because from the pics, the bolt prevent the beam from rotate(unlike pin which easy to rotate) which would match with the characteristic of fix support. so that is the thing that I need to justify.

10. Dec 5, 2015

jackwhirl

What is the context? Who are you modeling this for?

11. Dec 5, 2015