Solid Mechanics. Reactions and internal force diagrams. Step by step example. part 1

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Solid Mechanics – Academic Year 2014/2015 Prof: Maribel Castilla Heredia @maribelcastilla v.1.0 October 2014

Bloque A. Sistemas isostáticos reticulados planos.

Solid Mechanics – Academic Year 2014/2015 Prof: Maribel Castilla Heredia @maribelcastilla v.1.0 October 2014

Solid Mechanics

Block A. Internal forces. Diagrams.

Degree in Architecture.

San Pablo CEU University – Institute of Technology.

Solid Mechanics – Academic Year 2014/2015 Prof: Maribel Castilla Heredia @maribelcastilla v.1.0 October 2014

1 – General layout.

Solid Mechanics – Academic Year 2014/2015 Prof: Maribel Castilla Heredia @maribelcastilla v.1.0 October 2014

1 – General layout.

Solid Mechanics – Academic Year 2014/2015 Prof: Maribel Castilla Heredia @maribelcastilla v.1.0 October 2014

1 – General layout.

Note that the 50 kN load that

rests on the hinge can be

located on any of the three

systems that converge at the

hinge.

Solid Mechanics – Academic Year 2014/2015 Prof: Maribel Castilla Heredia @maribelcastilla v.1.0 October 2014

1 – General layout.

As the hinge bonds both horizontal and vertical

movement of the three solids that meet on it, two

unknowns appear at point “C” on each of the three

subsystems.

Solid Mechanics – Academic Year 2014/2015 Prof: Maribel Castilla Heredia @maribelcastilla v.1.0 October 2014

1 – General layout.

As the hinge bonds both horizontal and vertical

movement of the three solids that meet on it, two

unknowns appear at point “C” on each of the three

subsystems.

Vertical movement is the only one linked by the roller at

E, so just one reaction will appear on each of the solids

that meet at that point.

Solid Mechanics – Academic Year 2014/2015 Prof: Maribel Castilla Heredia @maribelcastilla v.1.0 October 2014

1 – General layout.

As the hinge bonds both horizontal and vertical

movement of the three solids that meet on it, two

unknowns appear at point “C” on each of the three

subsystems.

Hint:

If unknowns are

positive you’ll always

obtain the correct sign

in the result.

Vertical movement is the only one linked by the roller at

E, so just one reaction will appear on each of the solids

that meet at that point.

Solid Mechanics – Academic Year 2014/2015 Prof: Maribel Castilla Heredia @maribelcastilla v.1.0 October 2014

1 – General layout.

If any of the subsystems is a 3-unknown one, this

will mean that it’s a statically determiate one and

it’s reactions don’t depend on the behaviour of the

rest of the solids.

Solid Mechanics – Academic Year 2014/2015 Prof: Maribel Castilla Heredia @maribelcastilla v.1.0 October 2014

1 – General layout.

If any of the subsystems is a 3-unknown one, this

will mean that it’s a statically determiate one and

it’s reactions don’t depend on the behaviour of the

rest of the solids.

System CDE meets this condition, so we’ll solve it

in first place.

Solid Mechanics – Academic Year 2014/2015 Prof: Maribel Castilla Heredia @maribelcastilla v.1.0 October 2014

1 – General layout.

Solid Mechanics – Academic Year 2014/2015 Prof: Maribel Castilla Heredia @maribelcastilla v.1.0 October 2014

Exercise 1 - Reactions on each subsystem

3 3

3

3 3

3 1000

3

0

100 3100

3

Solid Mechanics – Academic Year 2014/2015 Prof: Maribel Castilla Heredia @maribelcastilla v.1.0 October 2014

Exercise 1 - Reactions on each subsystem

3 3

3

3 3

3 1000

3

0

100 3100

3

Solid Mechanics – Academic Year 2014/2015 Prof: Maribel Castilla Heredia @maribelcastilla v.1.0 October 2014

Exercise 1 - Reactions on each subsystem

3 3

3

3 3

3 1000

3

0

100 3100

3

Solid Mechanics – Academic Year 2014/2015 Prof: Maribel Castilla Heredia @maribelcastilla v.1.0 October 2014

Exercise 1 - Reactions on each subsystem

3 3

3

3 3

3 1000

3

0

100 3100

3

3 4 3 40

Solid Mechanics – Academic Year 2014/2015 Prof: Maribel Castilla Heredia @maribelcastilla v.1.0 October 2014

Exercise 1 - Reactions on each subsystem

50 0 50

100100 3 50 2 0 100

3

100 1000

3 3

3 3

3

3 3

3 1000

3

0

100 3100

3

Solid Mechanics – Academic Year 2014/2015 Prof: Maribel Castilla Heredia @maribelcastilla v.1.0 October 2014

Exercise 1 - Reactions on each subsystem

Subsistema 4

50 0 50

100100 3 50 2 0 100

3

100 1000

3 3

3 3

3

3 3

3 1000

3

0

100 3100

3

Solid Mechanics – Academic Year 2014/2015 Prof: Maribel Castilla Heredia @maribelcastilla v.1.0 October 2014

Exercise 1 - Reactions on each subsystem

Solid Mechanics – Academic Year 2014/2015 Prof: Maribel Castilla Heredia @maribelcastilla v.1.0 October 2014

Exercise 1 - Reactions on each subsystem

Solid Mechanics – Academic Year 2014/2015 Prof: Maribel Castilla Heredia @maribelcastilla v.1.0 October 2014

Exercise 1 - Reactions on each subsystem

1 1

2 2

4 3 60 3

53 4 100 0

2

3 2500

2 3

1 2 1 2

Solid Mechanics – Academic Year 2014/2015 Prof: Maribel Castilla Heredia @maribelcastilla v.1.0 October 2014

Exercise 1 - Reactions on each subsystem

2 2

2 2

2

2

4 3 340

4 3 0

59073 750 8

9015

250 6

1 1

2 2

4 3 60 3

53 4 100 0

2

3 2500

2 3

1 2 1 2

Solid Mechanics – Academic Year 2014/2015 Prof: Maribel Castilla Heredia @maribelcastilla v.1.0 October 2014

Exercise 1 - Reactions on each subsystem

2 2

2 2

2

2

4 3 340

4 3 0

59073 750 8

9015

250 6

1 1

2 2

4 3 60 3

53 4 100 0

2

3 2500

2 3

1 2 1 2

Solid Mechanics – Academic Year 2014/2015 Prof: Maribel Castilla Heredia @maribelcastilla v.1.0 October 2014

Exercise 1 - Reactions on each subsystem

Solid Mechanics – Academic Year 2014/2015 Prof: Maribel Castilla Heredia @maribelcastilla v.1.0 October 2014

Exercise 1 - Reactions on each subsystem

Solid Mechanics – Academic Year 2014/2015 Prof: Maribel Castilla Heredia @maribelcastilla v.1.0 October 2014

Exercise 1 - Reactions on each subsystem

Solid Mechanics – Academic Year 2014/2015 Prof: Maribel Castilla Heredia @maribelcastilla v.1.0 October 2014

Exercise 1 - Reactions on each subsystem

Solid Mechanics – Academic Year 2014/2015 Prof: Maribel Castilla Heredia @maribelcastilla v.1.0 October 2014

Exercise 1 - Reactions on each subsystem

8 60 6 80 60 3

58 100 0

2

3 3 2500

2 2 3

3 25060 3

2 3

Solid Mechanics – Academic Year 2014/2015 Prof: Maribel Castilla Heredia @maribelcastilla v.1.0 October 2014

Exercise 1 - Reactions on each subsystem

8 60 6 80 60 3

58 100 0

2

3 3 250 500 6 25

2 2 3 8

3 250 59060 3 73 75

2 3 8

Solid Mechanics – Academic Year 2014/2015 Prof: Maribel Castilla Heredia @maribelcastilla v.1.0 October 2014

Exercise 1 - Reactions on each subsystem

Solid Mechanics – Academic Year 2014/2015 Prof: Maribel Castilla Heredia @maribelcastilla v.1.0 October 2014

Exercise 1 - Reactions on each subsystem

Solid Mechanics – Academic Year 2014/2015 Prof: Maribel Castilla Heredia @maribelcastilla v.1.0 October 2014

Exercise 1 - Reactions on each subsystem

Solid Mechanics – Academic Year 2014/2015 Prof: Maribel Castilla Heredia @maribelcastilla v.1.0 October 2014

Exercise 1 - Reactions on each subsystem

Solid Mechanics – Academic Year 2014/2015 Prof: Maribel Castilla Heredia @maribelcastilla v.1.0 October 2014

Exercise 1 - Reactions on each subsystem

Solid Mechanics – Academic Year 2014/2015 Prof: Maribel Castilla Heredia @maribelcastilla v.1.0 October 2014

Bloque A. Sistemas isostáticos reticulados planos.

If you want to learn how to draw internal force diagrams for this example go for it on Part 2.

Solid Mechanics – Academic Year 2014/2015 Prof: Maribel Castilla Heredia @maribelcastilla v.1.0 October 2014

Solid Mechanics

Block A. Internal forces. Diagrams.

Degree in Architecture.

San Pablo CEU University – Institute of Technology.

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