What Defines 'n' in the Equation r = n+3?

[chetzread]

Homework Statement

from the equation r = n+3 , some notes stated n = number of hinges , while some book stated n as number of joints ...Which is true ?

Homework Equations

The Attempt at a Solution

taking the example 3.1 , if it's number of joints , then there are 1 hinge (pin) , right ? I don't really understand the notes on the internet ... What does joints in beam mean ?

 

[phinds]

your tiny attachment is unreadable.

 

[chetzread]

your tiny attachment is unreadable.

your tiny attachment is unreadable.

 

[chetzread]

your tiny attachment is unreadable.

i checked it an open the uploaded image ...There's no problem . Perhaps you can refresh your browser and try ?
http://imgur.com/a/IDi0d

 

[PhanthomJay]

in this equation for beam determinancy, r is the number of possible force and moment reactions at the external supports, and n is the number of internal hinges (pins, or joints) that sometimes join 2 members together.

In the example, the left support can support forces in 2 directions, and the other support just a vertical force, so r is 3 , and since there are no internal hinges in between supports, n is 0.

These equations tend to cause confusion so don't dwell on them too much.

 

[chetzread]

in this equation for beam determinancy, r is the number of possible force and moment reactions at the external supports, and n is the number of internal hinges (pins, or joints) that sometimes join 2 members together.

In the example, the left support can support forces in 2 directions, and the other support just a vertical force, so r is 3 , and since there are no internal hinges in between supports, n is 0.

These equations tend to cause confusion so don't dwell on them too much.

although there's pin and roller , but there's only 1 member ( not joining 2 members together) , so n = 0 ?

 

[PhanthomJay]

although there's pin and roller , but there's only 1 member ( not joining 2 members together) , so n = 0 ?

Yes