Because of the rigidness of a truss form. it is non hard to happen the familiar trigons in many constructions. Interior designers must accurately find how much force occurs at locations of a truss design. The interior decorator may alter the stuff. the sum of stuff. or the figure of members in a truss in order to do a design safer or more efficient. The computations for finding truss forces are besides a good footing for ciphering forces for many other systems.

Equipment

Straight border

Calculator

Procedure

In this activity you will do alterations to given trusses to do them statically determinate. You will so work out for the outside forces and forces at each pinned connexion of trusses.

Inactive Determinacy

It is of import to cognize that a truss is statically determinate before trying to work out for the internal forces. If the truss is statically undetermined. so you will non be able to work out for all of the forces.

The trusses 1. 2. and 3 are statically undetermined based on the expression 2J = M + R. Use the expression to show that each truss is statically undetermined. so chalk out a solution that would ensue in the truss being statically determinate. Remember when you sketch solutions that each should retain triangular forms in order to stay stiff.

J = Number of articulations

M = Number of members

R = Number of reactions within a support 0r

2J=M+R ( 2*40= ( 5+4 ) 8?9|

2J+ M + R ( 2*4 ) = ( 3+4 ) 8?7|

2J=M+R ( 2*4 ) = ( 5+4 ) 8?9|

Solving Statically Determinate Trusss

Use the method below to cipher the forces happening at each pinned connexion.

Pull a free organic structure diagram of the full truss. Label applied forces. known dimensions. and replace supports with labelled reaction forces. Summarize the minutes happening about one or more pinned support ( s ) to work out for reaction forces at supports. There may be occasions when this will non work out any unknown reaction forces. If that happens. move to the following measure. Use method of articulations to make free organic structure diagrams for each joint to work out for all of the forces moving at that joint. Precision ( 0. 0 ) . * BY 50. 0

BY 50. 0

Bx 50. 0

Bx 50. 0

70. 71 ( T )

70. 71 ( T )

0. 0

0. 0

Ax 50. 0

Ax 50. 0

50. 0 ( C )

50. 0 ( C )

50. 0

50. 0

EY 1. 000. 0

EY 1. 000. 0

500. 0

500. 0

500. 0

500. 0

Ex 1. 500. 0

Ex 1. 500. 0

Dx 1. 500. 0

Dx 1. 500. 0

Decision

1. What is the significance of including roller connexions instead than pinned connexions? *

* Roller connexions merely have one force moving on them. while pinned connexions have two. *