ppt for enignerrng mechanics second semester

1. TRUSSES AND ITS
APPLICATION

2. WHAT IS TRUSS ?
A truss is a structure comprising one or more triangular units constructed
with straight members whose ends are connected at joints or nodes.
If all the bars lie in a plane, the structure is a planar truss.
The main parts of a planar truss.
TRUSS ANALYSIS
 In other words, Trusses are designed to form a stable
structure.

3. DIFFERENT TYPES OF TRUSSES
There are tree types of Trusses:-
 Perfect Trusses (m=2j-3)
 Deficient Trusses(m<2j-3)
 Redundant Trusses(m>2j-3)
Here m=members
j=joints

4. 1.PERFECT TRUSSES
 A Structure that is made of members just sufficient to
keep it in equilibrium, When loaded without change of
shape.
 m=2j-3
 It is efficient and optimized structure.

5. 2.DEFICIENT TRUSSES
 A structure that is made of members less than
sufficient that leads to change of shape when
load is added, leading to collapsing of structure.
 m<2j-3
 Not very efficient and optimized.

6. 3.REDUNDANT TRUSSES
 A structure that is made of members more than
sufficient that doesn’t let the shape of the
structure to change.
 m>2j-3
 Very efficient and optimized.

7. IMAGES OF TRUSSES

8. ASSUMPTION IN TRUSSES
 All members are straight and have uniform cross section.
 All members have negligible weight.
 All members are connected at joints through pin
connection which are frictionless.
 The external force must be applied at the joints.
 All members have axial force.
 Couple movements which produce bending do not act on
the member of the truss.

9. TRUSS ANALYSIS
Following characteristics of Truss
* The members of the truss should be in a plane.
* Members are connected at their intersections by means of
frictionless pins or hinge.
* Loads and reactions are applied only at joint.
* The centroid of the members must coincide with centroid of
the joints.

10. TRUSSANALYSIS
Application of trusses-
 Roof of factory shade.
 Ware house
 Railway platform
 Garage shed
 transmission towers
 Crane truss
 Bridge Truss
 Sport Stadium Truss

11. HOW TO SOLVE A TRUSS PROBLEM
For method of Section
 Draw a free body diagram.
 Take an imaginary section to cut the truss into two pieces
in condition that the number of unknown forces doesn’t
exceed three.
 Apply equilibrium equations on one piece of the truss.
∑V=0, ∑H=0, ∑M=0.
 After determining all the forces, positive forces are
tension and the negative forces are compression.

12. HOW TO SOLVE A TRUSS PROBLEM
For method of Joints
 Draw a free body diagram.
 Find the equilibrium of the truss that is
∑V=0, ∑H=0, ∑M=0.
 Select the joint whose number of forces doesn’t exceed
two and then study its equilibrium by using static
equations.
∑V=0, ∑H=0.
 Go to next joint and follow the same procedure.
 The Horizontal equation will be Tension and the Vertical
equation will be Compression.

13. EXAMPLE OF A QUESTION

14. CONTINUE

15. CONTINUE

17. Done by :
Milan Joshi BE/50024/15
Bhairvi Singh BE/50036/15
Asman BE/50054/15